The PlotClock must surely rate as one of the coolest things EVER dreamt up - even my wife thinks it is the cutest thing.
Check it out!
Tuesday 25 February 2014
Morgan prints something useful
After hours of printing calibration squares and stars, Morgan spent hours printing something useful. A filament spool holder that bolts to one of the frame support pipes. Idea shamelessly stolen from Quentin. This also marks the first print of something that I drew up in OpenSCAD myself.
I learnt something today. Create holes in your design, don't just drill them afterwards. Especially not with only 15 percent infill. The plastic doesn't like it...
I learnt something today. Create holes in your design, don't just drill them afterwards. Especially not with only 15 percent infill. The plastic doesn't like it...
Monday 24 February 2014
Calibration phantom
I might have taken my extruder multiplier too far, currently I am printing the calibration phantom supplied with the Morgan datapack, at a multiplier of 0.775.
While that figure still gives good thin wall adhesion and a beautiful print, it looks a little skinny when printing a part that needs a solid base.
The "skinny" phantom (bottom layer), surrounded by calibration squares:
I also note that the edges of the phantom, printed in ABS, lifts. I have cleaned the Kapton tape properly with acetone before the print, so that is something to keep in mind.
The initial calibration (according to the calibration flowchart) can only ever approximate accurate calibration, as the steps per degree value for the two drive wheels are kept the same. After measuring up the phantom, I realised that the two factors are different (only slightly, but different), probably meaning that the two wheels are ever so slightly differing in size.
This was fixed quickly, but remember, the offsets (M360 and M364 movements) need to be re-set and I also re-did the bed levelling calibration.
Tip: Bed levelling can be specified, number of X increments and number of Y increments. Default is X5 Y5. I use M370 X3 Y3 (I use a plate glass bed, therefore expect no bending).
While that figure still gives good thin wall adhesion and a beautiful print, it looks a little skinny when printing a part that needs a solid base.
The "skinny" phantom (bottom layer), surrounded by calibration squares:
I also note that the edges of the phantom, printed in ABS, lifts. I have cleaned the Kapton tape properly with acetone before the print, so that is something to keep in mind.
The initial calibration (according to the calibration flowchart) can only ever approximate accurate calibration, as the steps per degree value for the two drive wheels are kept the same. After measuring up the phantom, I realised that the two factors are different (only slightly, but different), probably meaning that the two wheels are ever so slightly differing in size.
This was fixed quickly, but remember, the offsets (M360 and M364 movements) need to be re-set and I also re-did the bed levelling calibration.
Tip: Bed levelling can be specified, number of X increments and number of Y increments. Default is X5 Y5. I use M370 X3 Y3 (I use a plate glass bed, therefore expect no bending).
Calibration prints
On my treefrog print it was fairly obvious that I am extruding too much filament, as it was oozing a bit at the ends, like on top of the feet and eyes. Trying some larger prints this afternoon showed this to likely be accurate, as the extruder would jam ( carve a hollow in the filament and then get stuck).
I started printing the thin wall square from the "Essential Calibration Set" on Thingiverse, and progressively lowered the extruder multiplier (in the Slic3r filament config file). Coming down in steps of .05 (5%), it seems that 0.80 is a good multiplier for a diameter of 1.75 (on my Filament Factory ABS filament).
The side wall is thin,the print is much lighter (weighed on my digital reloading scale), and it just looks and feels better, whilst still retaining good strength. I will continue calibration with the other shapes in the set to get my frog as good as Quentins!
I started printing the thin wall square from the "Essential Calibration Set" on Thingiverse, and progressively lowered the extruder multiplier (in the Slic3r filament config file). Coming down in steps of .05 (5%), it seems that 0.80 is a good multiplier for a diameter of 1.75 (on my Filament Factory ABS filament).
The side wall is thin,the print is much lighter (weighed on my digital reloading scale), and it just looks and feels better, whilst still retaining good strength. I will continue calibration with the other shapes in the set to get my frog as good as Quentins!
RepRapping under Linux
I knew there was a reason I started all this under Windows! I have not been into the Linux (Ubuntu 10.04) partition for about 3 years, and decided to give it a go. It almost gave me a go.
Mentioned previously, my weapons of choice are OpenSCAD, Slic3r and Pronterface, and under Win7 I just installed them and was up and running. I must say, OpenSCAD was the same under Ubuntu, no pain.
Pronterface complained about my libstdc++.so.6 being a newer version (?), and I had to revert to an older version. Google is my friend, as I'd forgotten about these things. And Slic3r also needed its nappy changed, but they all play nicely now.
Mentioned previously, my weapons of choice are OpenSCAD, Slic3r and Pronterface, and under Win7 I just installed them and was up and running. I must say, OpenSCAD was the same under Ubuntu, no pain.
Pronterface complained about my libstdc++.so.6 being a newer version (?), and I had to revert to an older version. Google is my friend, as I'd forgotten about these things. And Slic3r also needed its nappy changed, but they all play nicely now.
Sunday 23 February 2014
Third time lucky
I attempted the treefrog model a third time, and even though the small ABS gear broke two teeth in the process, I have a treefrog.
Quentin mentioned that it is best to have both gears of the same material (either both PLA or both ABS). Because the PLA is more hard an brittle than the ABS, it tends to wear the ABS more. I will therefore attempt to print the larger gear in ABS as well.
First I want to print the calibration phantom properly and complete the calibration accurately.
One thing I have also learnt is that fingerprints (any oil) on the print bed is not a good thing. Have your bottle of acetone ready and wipe the bed occasionally. The ABS (only filament I have) sticks to the bed well if it is clean (it is Kapton taped) and I run at 90 degrees (Quentins standard slic3r profile for ABS).
I have a list of parts I want to print - another small gear or two after calibration (to get it exactly round), a large gear, a filament spool holder, a fan mount for the Arduino.
Speaking of fan mount, I changed the extruder drive to one of Quentins drivers (available on his site), it has a slightly higher current capacity than mine, and it runs hot. I need aiflow over the electronics...
I also want to get going under Linux (I have been using Linux for years, dual boot system on the laptop, but I got everything going under Windows). The printer occasionally loses contact and then I have to reboot Windows to see COM14 again.
Quentin mentioned that it is best to have both gears of the same material (either both PLA or both ABS). Because the PLA is more hard an brittle than the ABS, it tends to wear the ABS more. I will therefore attempt to print the larger gear in ABS as well.
First I want to print the calibration phantom properly and complete the calibration accurately.
One thing I have also learnt is that fingerprints (any oil) on the print bed is not a good thing. Have your bottle of acetone ready and wipe the bed occasionally. The ABS (only filament I have) sticks to the bed well if it is clean (it is Kapton taped) and I run at 90 degrees (Quentins standard slic3r profile for ABS).
I have a list of parts I want to print - another small gear or two after calibration (to get it exactly round), a large gear, a filament spool holder, a fan mount for the Arduino.
Speaking of fan mount, I changed the extruder drive to one of Quentins drivers (available on his site), it has a slightly higher current capacity than mine, and it runs hot. I need aiflow over the electronics...
I also want to get going under Linux (I have been using Linux for years, dual boot system on the laptop, but I got everything going under Windows). The printer occasionally loses contact and then I have to reboot Windows to see COM14 again.
New extruder
I spent a good afternoon/evening with Quentin at House4Hack yesterday. I also met Schalk, which, I'm told, means I am now a member of H4H!
We fitted a new extruder, and started printing the calibration phantom. About halfway through the small extruder gear stripped, and I spent the rest of the evening learning about calibration of the Morgan. I will dedicate at least one post to that.
Quentin's small extruder gears printed badly (probably due to calibration) and I took another gear home. This morning I confirmed calibration again (after driving with the printer) and printed a small gear:
After that, I started printing the tree frog (in low resolution), unfortunately the small gear started slipping around the stepper shaft halfway through the print. I then fitted the blue extruder gear and printed another THREE gears, and then tried the frog again.
The frog does not want to be printed. The filament jammed horribly underneath the extruder (I do not have a filament spool holder yet), and the frog ended up without a head. But the extruder works like a bomb!
I
We fitted a new extruder, and started printing the calibration phantom. About halfway through the small extruder gear stripped, and I spent the rest of the evening learning about calibration of the Morgan. I will dedicate at least one post to that.
Quentin's small extruder gears printed badly (probably due to calibration) and I took another gear home. This morning I confirmed calibration again (after driving with the printer) and printed a small gear:
After that, I started printing the tree frog (in low resolution), unfortunately the small gear started slipping around the stepper shaft halfway through the print. I then fitted the blue extruder gear and printed another THREE gears, and then tried the frog again.
The frog does not want to be printed. The filament jammed horribly underneath the extruder (I do not have a filament spool holder yet), and the frog ended up without a head. But the extruder works like a bomb!
I
Saturday 22 February 2014
New extruder drive gear
I have a friend with a lathe, and called him up and asked for a favour. Thinking that I will re-purpose the 10.5mm diameter copper earthing rod (purchased to earth the ham radio station), I cut a 6 inch section of the rod, only to find out that the rod is mild steel which is copper plated.
At friend Ronnies, I explained what I needed, and he proceeded to pull an offcut section of half inch brass rod from his junk bin. A few minutes on the lathe and another few minutes with the Dremel tool later, we have version two of the drive gear, which will be tested shortly.
At friend Ronnies, I explained what I needed, and he proceeded to pull an offcut section of half inch brass rod from his junk bin. A few minutes on the lathe and another few minutes with the Dremel tool later, we have version two of the drive gear, which will be tested shortly.
Friday 21 February 2014
Calibration Part 4 (Epilogue?)
It all ends well. After changing the wiring back to the original (and reversing that of the extruder), and running through the calibration procedure once again, the printer seems to be calibrated. The only cause I can think of is a bad connection on one of the stepper wires before (although they ran smoothly). If one stepper was missing some steps (one of its coils being open circuit) the calibration would not work.
Manually moving to random X and Y locations work as expected. I was also able to run through the bed-levelling calibration procedure. I then sliced the calibration "phantom" supplied with the Morgan data pack, and decided to print it.
The printer works wonderfully, except for the extruder. It is a hit-and-miss affair, sometimes just slipping, sometimes (and with a bit of manual feeding) it drives the filament. But it is not yet right (at least I can work on another drive gear).
So close, and yet so far...
Manually moving to random X and Y locations work as expected. I was also able to run through the bed-levelling calibration procedure. I then sliced the calibration "phantom" supplied with the Morgan data pack, and decided to print it.
The printer works wonderfully, except for the extruder. It is a hit-and-miss affair, sometimes just slipping, sometimes (and with a bit of manual feeding) it drives the filament. But it is not yet right (at least I can work on another drive gear).
So close, and yet so far...
Calibration Part 3
This is very frustrating. I know I can print if I can get the calibration sorted out. I don't see my way through this without outside intervention (I'll speak to Quentin tomorrow, it's Friday evening so I won't bother him...)
I have discovered the following: I'm not the first to experience these type of problems. On the builders forum (on Quentins website) there are more people describing similar issues. One common cause seems to be reversed wiring on the steppers, and one case of reversed X and Y motor connections.
My X and Y motors are connected right way round. The four wires per motor might be the wrong way round, the document I followed (referenced in an early RAMPS post) has got the wiring the other way round than the RepRapWiki RAMPS wiring page. Mine is connected with the black wires towards the USB connector.
The Z-axis works properly (going DOWN when homing). The homing works perfectly (rotating counterclockwise from a position over the bed, to the home position). The extruder is however the wrong way round (I have to push the REVERSE button on Pronterface to feed the filament towards the print head). This might just be a case of the new extruder large drive gear having its teeth towards the inside of the wheel reversing the rotation direction than the original extruder the software was written for.
Just to make sure, I reversed the wiring order on the X and Y motors, and then the printer tries to home CLOCKWISE (as I expected), which physically it cannot do. So I'm still stumped.
I have discovered the following: I'm not the first to experience these type of problems. On the builders forum (on Quentins website) there are more people describing similar issues. One common cause seems to be reversed wiring on the steppers, and one case of reversed X and Y motor connections.
My X and Y motors are connected right way round. The four wires per motor might be the wrong way round, the document I followed (referenced in an early RAMPS post) has got the wiring the other way round than the RepRapWiki RAMPS wiring page. Mine is connected with the black wires towards the USB connector.
The Z-axis works properly (going DOWN when homing). The homing works perfectly (rotating counterclockwise from a position over the bed, to the home position). The extruder is however the wrong way round (I have to push the REVERSE button on Pronterface to feed the filament towards the print head). This might just be a case of the new extruder large drive gear having its teeth towards the inside of the wheel reversing the rotation direction than the original extruder the software was written for.
Just to make sure, I reversed the wiring order on the X and Y motors, and then the printer tries to home CLOCKWISE (as I expected), which physically it cannot do. So I'm still stumped.
Calibration Part 2
I retract my statement of yesterday. Calibration is NOT straightforward. I only thought so.
Last night, over a movie on TV, I sleeved the two PTFE tubes, my wife commented that this is the single most difficult part of the printer so far. I disagree. I have probably spent 6 to 8 hours trying to calibrate the printer and am pretty much where I started.
I can follow the flowchart, get the Theta arm to be parallel and perpendicular to the front of the machine with the M360 and M361 commands, and the angle between the arm joints to be 90 degrees with the M364 command. In the process I have adjusted the steps per degree (M92 command) and the home offset position (M206 command). Now the printer thinks that X0 Y0 is sharing space with the drive shaft and tries to jam the head into the copper pipe.
I cannot convince the printer to reset the 0,0 position with the G92 command (no effect), and manually adjusting the M206 values to what the book describes it to be, causes the printer to try and break it apart.
Moving the head by clicking on the +X or +Y buttons in Pronterface causes the head to move in approximately the right direction, but slightly diagonally and also not in a straight line. So, even though the calibration procedure completed as described, the printer is clearly not calibrated. This was the reason I claimed calibration posed few problems (I only completed the procedure last night, did not experiment further).
Even the M360 command from the home position tries to move the print head through the drive shaft, I have to issue M361 BEFORE M360 to force the head to take a more circuitous route to the Theta arm 0 degree position.
Good news is that the Bowden tube and extruder seems to work, and I convinced a thin strand of blue ABS to come out of the head last night! The bed was lifted by approximately 15mm this afternoon, so now the platform can lift the bed to against the print head with a few millimeters of lead screw left.
Last night, over a movie on TV, I sleeved the two PTFE tubes, my wife commented that this is the single most difficult part of the printer so far. I disagree. I have probably spent 6 to 8 hours trying to calibrate the printer and am pretty much where I started.
I can follow the flowchart, get the Theta arm to be parallel and perpendicular to the front of the machine with the M360 and M361 commands, and the angle between the arm joints to be 90 degrees with the M364 command. In the process I have adjusted the steps per degree (M92 command) and the home offset position (M206 command). Now the printer thinks that X0 Y0 is sharing space with the drive shaft and tries to jam the head into the copper pipe.
I cannot convince the printer to reset the 0,0 position with the G92 command (no effect), and manually adjusting the M206 values to what the book describes it to be, causes the printer to try and break it apart.
Moving the head by clicking on the +X or +Y buttons in Pronterface causes the head to move in approximately the right direction, but slightly diagonally and also not in a straight line. So, even though the calibration procedure completed as described, the printer is clearly not calibrated. This was the reason I claimed calibration posed few problems (I only completed the procedure last night, did not experiment further).
Even the M360 command from the home position tries to move the print head through the drive shaft, I have to issue M361 BEFORE M360 to force the head to take a more circuitous route to the Theta arm 0 degree position.
Good news is that the Bowden tube and extruder seems to work, and I convinced a thin strand of blue ABS to come out of the head last night! The bed was lifted by approximately 15mm this afternoon, so now the platform can lift the bed to against the print head with a few millimeters of lead screw left.
Thursday 20 February 2014
Calibration
Calibration can be straightforward if you don't mess up too much before starting. On the RepRap Morgan site, Quentin has a calibration procedure, nicely set out in the form of a flowchart. Before you start calibrating, you need to add two measurements to the software - the X and Y offset of the SCARA tower to the zero position of the bed.
I got that part wrong, I entered the offset to the HOME position. What you need to enter is the position of the DRIVE SHAFT. Otherwise Pronterface will just not allow you to do the adjustments necessary to complete calibration.
Once that was sorted, few problems to calibrate.
The extruder is working more or less, it feeds filament down the Bowden tube. But my tube-with-sleeves-on-either-end idea was not a success. The inner tube just pulled out of the tool head (the outer tube remains clamped by the compression collar). If the outer tube is full length, there is nowhere for the inner sleeve to go, but with the outer sleeve only at the edges, it allows for the inner sleeve to pull out. I had feared for this, so I will have to fit the whole length. But that is a mission for the weekend.
Good news is that the plate glass seems to withstand 110 degrees (ABS default) without cracking (so far). I ran it hot for a while.
I got that part wrong, I entered the offset to the HOME position. What you need to enter is the position of the DRIVE SHAFT. Otherwise Pronterface will just not allow you to do the adjustments necessary to complete calibration.
Once that was sorted, few problems to calibrate.
The extruder is working more or less, it feeds filament down the Bowden tube. But my tube-with-sleeves-on-either-end idea was not a success. The inner tube just pulled out of the tool head (the outer tube remains clamped by the compression collar). If the outer tube is full length, there is nowhere for the inner sleeve to go, but with the outer sleeve only at the edges, it allows for the inner sleeve to pull out. I had feared for this, so I will have to fit the whole length. But that is a mission for the weekend.
Good news is that the plate glass seems to withstand 110 degrees (ABS default) without cracking (so far). I ran it hot for a while.
Z axis problems
I addressed the problem of the Z axis not wanting to lift - simply adjusting the current setting did not solve the problem.
I noticed that I inadvertently fitted a 0.9 degree per step motor on the Z axis, I intended for that to be a 1.8 degree motor, so I replaced that. The 1.8 degree motor also has a higher current specification. Of course, with all the wiring so neatly done, replacing the motor was a bit of an exercise.
After putting everything back together, it was better, but still stalling on lifting. I contemplated fitting a counterweight (string pulling upwards on the bed platform, looping over a hook under the top platform with a weight suspended off the string), but before all that I decided to adjust the spring tension between the lead screw "nuts". This solved the problem (it was too tight). I also used petroleum jelly (Vaseline) on the lead screw and smooth rods for lubrication.
Homing seems to work well, the Z-axis calibration is almost spot-on, but the Theta and Psi adjustments are still confusing the hell out of me. I think I have the right initial steps per degree settings for my build configuration, but the M360 command does not take the Theta arm close to parallel with the upper platform front edge, and I cannot get it parallel by manipulating Y from Pronterface (as the online calibration guide seems to suggest).
Doing it twice (as the flowchart indicates) causes the Morgan to attempt to wring its own neck again (M360 command then causes the arms to try and go around the BACK). I have to reset everything back to default.
I noticed that I inadvertently fitted a 0.9 degree per step motor on the Z axis, I intended for that to be a 1.8 degree motor, so I replaced that. The 1.8 degree motor also has a higher current specification. Of course, with all the wiring so neatly done, replacing the motor was a bit of an exercise.
After putting everything back together, it was better, but still stalling on lifting. I contemplated fitting a counterweight (string pulling upwards on the bed platform, looping over a hook under the top platform with a weight suspended off the string), but before all that I decided to adjust the spring tension between the lead screw "nuts". This solved the problem (it was too tight). I also used petroleum jelly (Vaseline) on the lead screw and smooth rods for lubrication.
Homing seems to work well, the Z-axis calibration is almost spot-on, but the Theta and Psi adjustments are still confusing the hell out of me. I think I have the right initial steps per degree settings for my build configuration, but the M360 command does not take the Theta arm close to parallel with the upper platform front edge, and I cannot get it parallel by manipulating Y from Pronterface (as the online calibration guide seems to suggest).
Doing it twice (as the flowchart indicates) causes the Morgan to attempt to wring its own neck again (M360 command then causes the arms to try and go around the BACK). I have to reset everything back to default.
End stops
Trying the "Home" command (G28 in Pronterface text input box) caused havoc (this was not unexpected). I had to rescue the printer from itself by cutting the power (it tried to do a 360 degree turn with the arms).
To make a long story short - I made two mistakes. It seems that the Hall effect devices are sensitive to the polarity of the magnet. Mount the magnet (or Hall effect endstop) the wrong way round and it does not work. I figured this out by measuring the signal on the RAMPS board with my multimeter while manipulating the arms and bed manually. This can be done in Pronterface as well (M119 I think, it echoes the endstop status).
Secondly, the RAMPS 1.4 board has six endstops, and I wired into Xmin, Ymin and Zmin respectively. The software reads Xmax, Ymax and Zmax. This can be set in software, I just relocated my wires to the pins next door.
Homing then worked as planned. On my printer, the offset from the zero position was approximately 18mm in the X direction and 82mm in the Y direction. This of course is dependent on the mounting of the big drive wheels, and where the end stops detect the magnets. It should be different for each printer (these values are entered into the Configuration.h file in the Arduino IDE).
To make a long story short - I made two mistakes. It seems that the Hall effect devices are sensitive to the polarity of the magnet. Mount the magnet (or Hall effect endstop) the wrong way round and it does not work. I figured this out by measuring the signal on the RAMPS board with my multimeter while manipulating the arms and bed manually. This can be done in Pronterface as well (M119 I think, it echoes the endstop status).
Secondly, the RAMPS 1.4 board has six endstops, and I wired into Xmin, Ymin and Zmin respectively. The software reads Xmax, Ymax and Zmax. This can be set in software, I just relocated my wires to the pins next door.
Homing then worked as planned. On my printer, the offset from the zero position was approximately 18mm in the X direction and 82mm in the Y direction. This of course is dependent on the mounting of the big drive wheels, and where the end stops detect the magnets. It should be different for each printer (these values are entered into the Configuration.h file in the Arduino IDE).
Wednesday 19 February 2014
Initial tests look promising!
So I fired up the RAMPS 1.4 test software quickly, before work, this morning, and almost everything seems OK. The arms wiggled smoothly, as well as the extruder gear, but the z-axis was only moving one way. I could hear the stepper straining to lift the bed, and with a slight amount of manual support from below, it lifts. Not a big deal, I am working on the assumption that the current to the motor is limited at a too-low level. The StepSticks have an adjustment pot, I will tweak that tonight.
I then uploaded the Morgan Marlin code to the Mega, and fired up Pronterface. I set the hot end to heat to 185 degrees and the bed to 60 degrees (default PLA settings). The hot end controls beautifully, the heated bed not. No LED, no power on the wires. The hot end draws about 4 A.
Almost alarmed, I then remembered that the default setting for heated bed thermistor in Configuration.h is "0", meaning no thermistor present. I changed that to "1" in the Arduino IDE, recompiled and uploaded, and started Pronterface again. Success!
The heated bed draws about 8 A from my power supply, and temperature is reached fairly quickly. I'm using a Nissei 25A switch-mode power supply (from my amateur radio), which has a voltage adjustment (approximately 9 to 16 Volts) and both voltage and current meters on the faceplate (see photo in previous post).
The thermistor (little glass bead one from ebay) is mounted by spread-eagling the (very thin) legs and Kapton-taping it to the bed PCB from below (glass bead protruding through the hole in the centre of the board). The tracks are oriented UP in my build, with the glass sheet right on top of that. The thermistor stands slightly proud, so the glass pushes it down against the Kapton tape, so it touches the (underside of the) glass well.
This means the motors, heating elements, and thermistors are all connected properly. The end-stops will be tested next (tonight).
Unfortunately, I also have a proper day-job, which means I can only play again tonight.
I then uploaded the Morgan Marlin code to the Mega, and fired up Pronterface. I set the hot end to heat to 185 degrees and the bed to 60 degrees (default PLA settings). The hot end controls beautifully, the heated bed not. No LED, no power on the wires. The hot end draws about 4 A.
Almost alarmed, I then remembered that the default setting for heated bed thermistor in Configuration.h is "0", meaning no thermistor present. I changed that to "1" in the Arduino IDE, recompiled and uploaded, and started Pronterface again. Success!
The heated bed draws about 8 A from my power supply, and temperature is reached fairly quickly. I'm using a Nissei 25A switch-mode power supply (from my amateur radio), which has a voltage adjustment (approximately 9 to 16 Volts) and both voltage and current meters on the faceplate (see photo in previous post).
The thermistor (little glass bead one from ebay) is mounted by spread-eagling the (very thin) legs and Kapton-taping it to the bed PCB from below (glass bead protruding through the hole in the centre of the board). The tracks are oriented UP in my build, with the glass sheet right on top of that. The thermistor stands slightly proud, so the glass pushes it down against the Kapton tape, so it touches the (underside of the) glass well.
This means the motors, heating elements, and thermistors are all connected properly. The end-stops will be tested next (tonight).
Unfortunately, I also have a proper day-job, which means I can only play again tonight.
It's done
Another marathon session last night saw me first fixing the extruder (after a fashion) and then completing the wiring. Now for testing...
I picked up a handful of 624 bearings yesterday, as well as an M10 brass bolt. I drilled a hole down the bolt (by hand) and tapped it with an M4 tap, and cut it to length, before cutting slots into the thread lengthwise using the Dremel tool. It is not perfect (the hole is ever so slightly eccentric) and the surface is rougher than I would like it to be, but for the moment it will drive filament and this is what I need. I will have access to a lathe late next week, then I will re-do the drive gear.
I was not able to fit the 4mm OD PTFE tube through the newly acquired 6mm OD (4mm ID) tube, even after shaving the thinner tube to size by pulling it through a 4mm hole drilled into a piece of steel, so I only sheathed the two ends (approximately 6 inches each side) in the thicker tube. The centre part of the Bowden tube is single tube only. I hope this is enough to allow the conical compression sleeve and the M6 nut on either end of the Bowden tube to grip the tube.
The wiring of the RAMPS board must be one of the most daunting aspects of a RepRap printer, for non-electronically minded builders, in my opinion. The multitude of options make a single instruction manual practically impossible, and the online resources I have found only covers mechanical and opto-isolated (separate board) endstops, so the specified Hall-effect device endstops needed some reading of the data sheets.
Luckily, the Hall effect sensors can be wired to the RAMPS board by a single wire, and the sensors need 12V and ground as well (common on all three endstops). The input on the RAMPS board is already referenced to ground, so a single signal wire should do.
Testing will proceed with caution, as it is possible that I may have done something silly like swapping endstop signals, and I don't want the X-axis, for example, to start moving moving towards the endstop but looking at, say, the Z-axis signal (which will never trigger if only the X-axis motor is running).
I picked up a handful of 624 bearings yesterday, as well as an M10 brass bolt. I drilled a hole down the bolt (by hand) and tapped it with an M4 tap, and cut it to length, before cutting slots into the thread lengthwise using the Dremel tool. It is not perfect (the hole is ever so slightly eccentric) and the surface is rougher than I would like it to be, but for the moment it will drive filament and this is what I need. I will have access to a lathe late next week, then I will re-do the drive gear.
I was not able to fit the 4mm OD PTFE tube through the newly acquired 6mm OD (4mm ID) tube, even after shaving the thinner tube to size by pulling it through a 4mm hole drilled into a piece of steel, so I only sheathed the two ends (approximately 6 inches each side) in the thicker tube. The centre part of the Bowden tube is single tube only. I hope this is enough to allow the conical compression sleeve and the M6 nut on either end of the Bowden tube to grip the tube.
The wiring of the RAMPS board must be one of the most daunting aspects of a RepRap printer, for non-electronically minded builders, in my opinion. The multitude of options make a single instruction manual practically impossible, and the online resources I have found only covers mechanical and opto-isolated (separate board) endstops, so the specified Hall-effect device endstops needed some reading of the data sheets.
Luckily, the Hall effect sensors can be wired to the RAMPS board by a single wire, and the sensors need 12V and ground as well (common on all three endstops). The input on the RAMPS board is already referenced to ground, so a single signal wire should do.
Testing will proceed with caution, as it is possible that I may have done something silly like swapping endstop signals, and I don't want the X-axis, for example, to start moving moving towards the endstop but looking at, say, the Z-axis signal (which will never trigger if only the X-axis motor is running).
Tuesday 18 February 2014
Wiring
Most of last night was spent wiring up the electronics. I have decided to mount the Arduino Mega/RAMPS on stand-offs (I had some), and terminate all wiring into terminal blocks below the electronics. Short wires from the terminal blocks directly soldered to the RAMPS pins will complete the wiring (I cannot source nice 4way plugs locally).
There are, by my count, at least 35 wires from the RAMPS board to the printer. Four wires each for four stepper motors (16 wires), two heating elements (four wires), two thermistors (four wires), two for the bed fan, and three each for three Hall effect end-stops.
I still have to mount and wire the end-stops (the magnets are mounted already but I had to drill out the holes to 6mm, as that is the size of the magnets I had around).
Wiring and positioning of RAMPS board:
Morgan progress at this point:
The extruder is still completely absent, as I do not have all the vitamins to complete that yet. I need small bearings (624), the brass drive gear, and more PTFE tubing. The wiring to the mount point for the stepper motor is in place, though.
There are, by my count, at least 35 wires from the RAMPS board to the printer. Four wires each for four stepper motors (16 wires), two heating elements (four wires), two thermistors (four wires), two for the bed fan, and three each for three Hall effect end-stops.
I still have to mount and wire the end-stops (the magnets are mounted already but I had to drill out the holes to 6mm, as that is the size of the magnets I had around).
Wiring and positioning of RAMPS board:
Morgan progress at this point:
The extruder is still completely absent, as I do not have all the vitamins to complete that yet. I need small bearings (624), the brass drive gear, and more PTFE tubing. The wiring to the mount point for the stepper motor is in place, though.
Bed material
I did some research yesterday regarding bed material. The only safety glass available locally is 6.35mm laminated, which is no good for a heated bed. The plate glass I had cut at ZAR10 a piece, can be tempered / armourplated at a cost of around R200 each. Tempered glass can NOT be cut, it is cut to size before tempering. Pyrex glass is not available locally in the size I'm interested in.
So, plate glass it will be. Plate glass can crack if heated non-uniformly. My plate glass sheets are 200 x 200, smaller than the heated area on the PCB. Let's hope for the best (I'll probably only run at around 80 degrees initially), and if plate glass does not work out, I'll move to an aluminium plate.
I did, however, heat the plate glass in the oven to 150 degrees C without problems (slowly).
The plate glass was Kapton-taped using soapy water, similar to window tinting films. It is not perfect, but will do for the first round of tests.
I also found that my hot-end is slightly high, the bed does not elevate quite high enough. Currently the HBP is about 1 inch above the aluminium platform plate (40mm long bolts and nuts with springs to adjust for level). I had to lift the entire platform by inserting M8 washers between the aluminium plate and plastic brackets, now it can touch (with the build plate as far up as it can go). If not enough, I can add more washers or even an extra washer on the arm joints (to lower the hot-end another mm or two).
So, plate glass it will be. Plate glass can crack if heated non-uniformly. My plate glass sheets are 200 x 200, smaller than the heated area on the PCB. Let's hope for the best (I'll probably only run at around 80 degrees initially), and if plate glass does not work out, I'll move to an aluminium plate.
I did, however, heat the plate glass in the oven to 150 degrees C without problems (slowly).
The plate glass was Kapton-taped using soapy water, similar to window tinting films. It is not perfect, but will do for the first round of tests.
I also found that my hot-end is slightly high, the bed does not elevate quite high enough. Currently the HBP is about 1 inch above the aluminium platform plate (40mm long bolts and nuts with springs to adjust for level). I had to lift the entire platform by inserting M8 washers between the aluminium plate and plastic brackets, now it can touch (with the build plate as far up as it can go). If not enough, I can add more washers or even an extra washer on the arm joints (to lower the hot-end another mm or two).
Bed assembly
If this build blog sounds negative, with me reporting on all the difficulties, please forgive me. I mention the things I battled with, wishing I had known what to look out for, and maybe it helps someone else down the line.
It isn't all bad, much of the assembly went plain sailing, such as the arms. I believe there is a detailed illustrated build instruction coming out soon, and that should help. In the mean time I do many of the things twice or even three times to get it right.
I sourced a backlash spring locally and could get on with the bed support. I found the PLA arms very hard and brittle, and the LM8UU bearings would not click into the ridges provided. Eventually I forced a spare bearing down the tubes, removing some of the ridge completely, and glued the linear bearings in place (my bearings are already fitted on the rods so the arms are assembled in place and I am scared of straining the rods, having broken the support already).
With the support in place it became clear that the brackets underneath the universal aluminium plate are in the wrong place, as the bed does not clear the top platform. Time to disassemble the bed and fix that.
I will be replacing the plate glass top with safety glass, apparently single layer safety glass is good for 200 degrees C, as opposed to around 80 for plate glass.
I am also slowly doing the wiring properly. From what I've seen, RepRap printers tend to be a rats nest of wiring, probably left as is after testing. I would like the Morgan to look neat, and am modelling the wiring after some looms I've seen in military boxes. This is slow going, though.
It should not be too long before I can start movement testing...
It isn't all bad, much of the assembly went plain sailing, such as the arms. I believe there is a detailed illustrated build instruction coming out soon, and that should help. In the mean time I do many of the things twice or even three times to get it right.
I sourced a backlash spring locally and could get on with the bed support. I found the PLA arms very hard and brittle, and the LM8UU bearings would not click into the ridges provided. Eventually I forced a spare bearing down the tubes, removing some of the ridge completely, and glued the linear bearings in place (my bearings are already fitted on the rods so the arms are assembled in place and I am scared of straining the rods, having broken the support already).
With the support in place it became clear that the brackets underneath the universal aluminium plate are in the wrong place, as the bed does not clear the top platform. Time to disassemble the bed and fix that.
I will be replacing the plate glass top with safety glass, apparently single layer safety glass is good for 200 degrees C, as opposed to around 80 for plate glass.
I am also slowly doing the wiring properly. From what I've seen, RepRap printers tend to be a rats nest of wiring, probably left as is after testing. I would like the Morgan to look neat, and am modelling the wiring after some looms I've seen in military boxes. This is slow going, though.
It should not be too long before I can start movement testing...
Monday 17 February 2014
Arm assembly
Progress was halted over the weekend due to me running out of bolts and nuts, mostly 3mm, but also I did not have 40mm and 100mm M8 bolts for the arm joints (I thought I had). I did add the stepper motor in their mounts yesterday (complete with the drive belts), as well as the "A" sections of both Theta and Psi arms.
This afternoon/evening I added the "B" sections of the arms, including the tool head with J-head mounted. I pulled the hot-end and z-axis stepper motor wires through the hollow centres of the Psi arms, and down to the lower frame through one of the support pipes.
As Francois mentioned in a comment, it is not simple to pull the wiring through the pipes afterwards - remember to fit a piece of string/wire during assembly! I actually found it easier to work from the bottom upwards (I pushed a piece of white twin flex through and taped my wires to the flex with insulation tape before pulling it down through the pipe.
Difficulties in assembly:
I had a few hassles during assembly: the biggest of which was the fact that the top platform was not parallel to the bottom one. It was sloping down towards the back (enough to have a drill bit roll down). I must check the pipe lengths - maybe I misread and cut the longer pipes too short.
I fixed SOME of the slope by fitting 28mm washers (1.5 to 2mm thick?) on either side of the ported pipes to tilt it upwards. It is not level yet, but close. I also tilted the z-axis motor slightly to level it by fitting two 4mm washers underneath the rear corners when I screwed it to the platform from below.
The second difficulty is that I broke two of the smooth rod "receptacles", one on the top and one of the bottom brackets which accepts the rods and drive shaft bearings. These shear fairly easily from the flat bit, be careful.
What remains to be done is the bed platform. I cannot currently fit that as I do not have a spring to take care of the backlash, and then it is on to the RAMPS wiring. The heated bed was fitted to the aluminium platform with three spring-loaded screws today, that still needs wiring as well. I will probably be working on that over the next few evenings.
I also still have to sort out the extruder - I got the 1.75mm extruder, and need the small bearings, the hobbed drive gear, and a second (4mm) length of PTFE tubing to fit it all.
Oh, and the Kapton tape and thermistors were in the post box today.
This afternoon/evening I added the "B" sections of the arms, including the tool head with J-head mounted. I pulled the hot-end and z-axis stepper motor wires through the hollow centres of the Psi arms, and down to the lower frame through one of the support pipes.
As Francois mentioned in a comment, it is not simple to pull the wiring through the pipes afterwards - remember to fit a piece of string/wire during assembly! I actually found it easier to work from the bottom upwards (I pushed a piece of white twin flex through and taped my wires to the flex with insulation tape before pulling it down through the pipe.
Difficulties in assembly:
I had a few hassles during assembly: the biggest of which was the fact that the top platform was not parallel to the bottom one. It was sloping down towards the back (enough to have a drill bit roll down). I must check the pipe lengths - maybe I misread and cut the longer pipes too short.
I fixed SOME of the slope by fitting 28mm washers (1.5 to 2mm thick?) on either side of the ported pipes to tilt it upwards. It is not level yet, but close. I also tilted the z-axis motor slightly to level it by fitting two 4mm washers underneath the rear corners when I screwed it to the platform from below.
The second difficulty is that I broke two of the smooth rod "receptacles", one on the top and one of the bottom brackets which accepts the rods and drive shaft bearings. These shear fairly easily from the flat bit, be careful.
What remains to be done is the bed platform. I cannot currently fit that as I do not have a spring to take care of the backlash, and then it is on to the RAMPS wiring. The heated bed was fitted to the aluminium platform with three spring-loaded screws today, that still needs wiring as well. I will probably be working on that over the next few evenings.
I also still have to sort out the extruder - I got the 1.75mm extruder, and need the small bearings, the hobbed drive gear, and a second (4mm) length of PTFE tubing to fit it all.
Oh, and the Kapton tape and thermistors were in the post box today.
Sunday 16 February 2014
Frame assembly
The top part of the frame was measured out previously. To start assembling, the holes need to be drilled, and the bottom part of the frame measured and drilled. The frame is made of wood (chipboard).
The first hiccup I experienced was when one of the captive nuts dislodged inside a pipe while assembling the frame. Luckily it was one of the ported caps, so I could access the nut and managed to fasten the bolt as designed. With the frame holes drilled as per the dxf file in github, the PVC pipes are slightly bent around each other, but the frame is nice and stable.
Other snags: the hole in the top platform, through which the drive shaft passes, can be at least 1 inch diameter. I originally made it only slightly larger than 22mm, but the outer pipe touched the wood once assembled, making the one arm difficult to turn. Disassembling, fixing and reassembling took a good portion of the afternoon.
Another thing: the printed parts break easily. I'm sure the second assembly will go much easier, but I have broken some parts. Nothing that I could not fix with a bit of glue, though.
The progress so far:
The first hiccup I experienced was when one of the captive nuts dislodged inside a pipe while assembling the frame. Luckily it was one of the ported caps, so I could access the nut and managed to fasten the bolt as designed. With the frame holes drilled as per the dxf file in github, the PVC pipes are slightly bent around each other, but the frame is nice and stable.
Other snags: the hole in the top platform, through which the drive shaft passes, can be at least 1 inch diameter. I originally made it only slightly larger than 22mm, but the outer pipe touched the wood once assembled, making the one arm difficult to turn. Disassembling, fixing and reassembling took a good portion of the afternoon.
Another thing: the printed parts break easily. I'm sure the second assembly will go much easier, but I have broken some parts. Nothing that I could not fix with a bit of glue, though.
The progress so far:
Frame pipes
Next up, the pipes for the frame. These have been cut to length already, so I only needed to fit the printed end caps.
The ported end caps go on the long pipes, and they are mounted at the front (on the bottom of the frame). I started by drilling the holes out to 4mm, and pulling the M4 nuts into the captive holes from outside (leaving the bolt in for the moment).
The end cap surfaces need to be parallel, so the ports point in opposite directions. I aligned these by eye and fastened the caps with a liberal helping of PVC Weld. To get the end caps in more easily, I beveled the inside of the PVC pipe with a Stanley knife. This worked well.
The only thing I forgot was a piece of string through the long pipes to pull the wiring through. This should not be too difficult to get through, though.
The ported end caps go on the long pipes, and they are mounted at the front (on the bottom of the frame). I started by drilling the holes out to 4mm, and pulling the M4 nuts into the captive holes from outside (leaving the bolt in for the moment).
The end cap surfaces need to be parallel, so the ports point in opposite directions. I aligned these by eye and fastened the caps with a liberal helping of PVC Weld. To get the end caps in more easily, I beveled the inside of the PVC pipe with a Stanley knife. This worked well.
The only thing I forgot was a piece of string through the long pipes to pull the wiring through. This should not be too difficult to get through, though.
Drive shaft assembly
Assembly of the printer has started with the drive shaft. Having done a mock assembly of the drive shaft earlier, I decided this would be where I started. The first step would be to prepare the drive wheels. I quickly realised that all openings/holes on the printed parts are slightly smaller than they need to be, so I drilled out the rod-mounted wheel's centre hole to 8.5mm, in order to get an M8 bolt through to pull the nut into its captive hole. It is a tight fit but using a bolt as puller (28mm washer on the bolt head on the other side of the wheel) makes it easy.
It is only possible to do one side like this, and the other side was more difficult. I ended up pulling out the nut already placed, pulling in the other side nut, and then replacing the first nut (which now fitted much easier once having been in there).
I reamed the pipe mounted wheel hole with a 22 mm drill bit, and mounted the pipe using two 3mm self tapper screws. Enough space was left at the bottom for the flanged bearing. It is important that the self-tapping screws need to be very short (or grind/file off the tips) as the 15mm copper pipe fits inside the 22mm pipe.
Quite predictably, I mounted the rod-mounted (bottom) wheel upside down, i.e. with the flat side towards the bottom. A lot of unnecessary screwing and unscrewing was the result!
It is only possible to do one side like this, and the other side was more difficult. I ended up pulling out the nut already placed, pulling in the other side nut, and then replacing the first nut (which now fitted much easier once having been in there).
I reamed the pipe mounted wheel hole with a 22 mm drill bit, and mounted the pipe using two 3mm self tapper screws. Enough space was left at the bottom for the flanged bearing. It is important that the self-tapping screws need to be very short (or grind/file off the tips) as the 15mm copper pipe fits inside the 22mm pipe.
Quite predictably, I mounted the rod-mounted (bottom) wheel upside down, i.e. with the flat side towards the bottom. A lot of unnecessary screwing and unscrewing was the result!
Saturday 15 February 2014
Printed parts are here
On my way back from a work function in Johannesburg this morning, I stopped in Centurion at the house4hack open day / Robobeast launch, met Quentin Harley (designer of the RepRap Morgan 3D printer), and collected the printed parts for my build.
The next week or two is going to be busy, with lots of progress!
The next week or two is going to be busy, with lots of progress!
Friday 14 February 2014
Stepper drivers are here!
Yes, after a week the mail is starting to trickle in. The postal worker strike was called off on Monday, agreement signed on Wednesday, and first mail in the post box today. There are still three international parcels in the pipeline (amongst others Kapton tape and small thermistors) but at least something is happening.
The drivers are Stepsticks supplied complete with small heat sinks and adhesive tape to attach the heat sink to the surface mount driver chip.
Testing will start this weekend - I will post the test procedure and results. I will be using the RAMPS 1.4 testing software.
The drivers are Stepsticks supplied complete with small heat sinks and adhesive tape to attach the heat sink to the surface mount driver chip.
Testing will start this weekend - I will post the test procedure and results. I will be using the RAMPS 1.4 testing software.
Sunday 9 February 2014
Autodesk 123D Design fail
Still suffering of postal non-delivery (and resultant non-progress on the Morgan), I have been looking at 3D design software to introduce mainly the kids to 3D making. I have downloaded and installed OpenSCAD, but for the rest of the family that is not going to work that well. I have previously used Google Sketchup, and from what I could see the Autodesk 123D Design software might be easy enough to use to introduce the rest of the family to making.
At 282 MB download, I waited till after midnight to save some bandwidth (we have a lot of "Night Owl" data available), and in the small hours of the morning I battled to get 123D Design to work.
The software starts up, with splash screen, and simply closes down directly after the splash screen. No error messages, no event log entries, just a fail. I scrutinised the system requirements, and although the laptop is a few years old, should easily fulfill the requirements. Searching the web and forums on the Autodesk site was no help, and I was in no mood to go to extreme lengths to search or contact tech support, so I just deleted it from the PC.
I did try an install on the newer Windows 8 laptop, but that is a 64bit machine, so I need to do ANOTHER 300MB download, no thanks...
At 282 MB download, I waited till after midnight to save some bandwidth (we have a lot of "Night Owl" data available), and in the small hours of the morning I battled to get 123D Design to work.
The software starts up, with splash screen, and simply closes down directly after the splash screen. No error messages, no event log entries, just a fail. I scrutinised the system requirements, and although the laptop is a few years old, should easily fulfill the requirements. Searching the web and forums on the Autodesk site was no help, and I was in no mood to go to extreme lengths to search or contact tech support, so I just deleted it from the PC.
I did try an install on the newer Windows 8 laptop, but that is a 64bit machine, so I need to do ANOTHER 300MB download, no thanks...
Wednesday 5 February 2014
Update on Noteworthy thing #2
Just a few days after I posted the bit about the 3D models for Space:1999, the Eagle Transporter has landed on Thingiverse. Still not printable, created in Sketchup, and not as detailed as the models in the original post, but better (a little more detailed) than the previous one!
On another note, it seems as if I have fallen victim to the postal worker strike here in South Africa. I have some four parcels inbound, and I visit the post box every second day. Nothing (not even a bill) for well over a week now.
On another note, it seems as if I have fallen victim to the postal worker strike here in South Africa. I have some four parcels inbound, and I visit the post box every second day. Nothing (not even a bill) for well over a week now.
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