3 Points Leveling for Makerbot Replicator
by aubenc, published
A test with plenty of room for improvement and still a couple of (important) details to be addressed.
This thing comes with NO waranty, do it at your own risk.
Handle with care! it's not a heavy duty thing, however, I can see quite a few easy ways to reinforce it and...
I'm very pleased with the result !!
Unfortunatelly I was not taking 1000 pictures of the assembly process :( Also to be taken in account, I was not using the spacers that can be downloaded here but calipers, I'm confident (but not 100% sure) about those spacers. I'm afraid that the instructions are way too long. My apologies.
Update, Dec. 2nd, 2013. This thing has been printing a ton of different things and it's holding up without issues. You can see a timelapse video from a 10h+ print here: https://www.youtube.com/watch?v=O1QXk9H4yW8
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Read everything before printing the STL for the caps, you may need to use the OpenSCAD to change them if your hardware differs from what I used (aluminum profiles and LM8UU bushings).
- 3.2mm, 6mm and 9mm Drill Bits
- Metal hand saw
- Small carpenter's square (should not be required using the spacers)
- Drill (I used a powertool)
Extruded Aluminum profiles:
- 40x40x3mm "L" shaped: one length of 235mm and another of 119mm (better if you find something bigger, say 60x60mm, you'll need to use the OpenSCAD to generate again the front caps but don't do it yet)
- 15x15x2mm "U" shaped: 2 lengths of 70mm and one length of 210mm.
- 10x10x2mm "U" shaped: 3 lengths of 15mm (not really required, you could use something else for those...)
- 16x M3x30mm bolts.
- 11x M3x10mm bolts.
- 2x (or 3x) M3x30 flat countersunk screws.
- Washers and lock nuts (I used nyloc like ones) for each and every bolt/screw.
- Thin double side tape.
- 2x front_spacers.stl
- 1x back_spacers.stl (or two)
- 1x lead_screw_mask.stl
Other printed parts and miscellaneous:
- 2x front_cap.stl
- 2x rear_cap.stl
- Tons of care
- A pich of patience.
Still to be addressed:
- Z endstop trigger. I'm just using some old prototypes I had laying around kept in place with double side tape.
- Cabling management. For the moment I use a couple of zip tyes kept in place in one of the build platform... far from ideal...
I used the stock bushings from the printer, you may like to use other, check that they are 17mm long or use the OpenSCAD and recompile the caps (front and rear) with the changes for the bushings and the "L" shaped aluminum profile if required. I printed the caps in ABS with one extra shell (total: 2), three solid layers (bottom and top) and 30% infill, it was just a fitting prototype, I was thinking in double the infill for the "real" parts but finally I'm fine with the prototype.
That's how I did it, you're are welcome to do it your way, also, I may have forgotten something... use aways common sense.
DO NOT drill the holes for the 3p leveling until the very end of everything.
Let's do it!!!
Arrange the 3 arms (2x 70mm & 1x 210mm) and the front spacers and hold everything in place with the double side tape. Drill at least 2 holes (3.2mm) for each arm (a little bit disaligned is better). Remove the double sided tape and fasten everything with M3x10mm bolts.
The front_caps.stl should hold in place, never mind, use also tape to avoid that they move whyle drilling. Install them properly spaced (you can use the back_spacers.stl and the 119mm length of aluminum for the aligment) and drill the holes. Without removing anything, fasten the front caps but not too tight (you may or not add the rear caps yet).
Shorten one of the 40mm sides of the 119mm 40x40x3mm to some 30mm. See that the left over piece is at least 8mm wide and keep it carefuly aside.
Put together the 2 aluminum parts (take a look at the pictures for positioning) again I used tape and a flat corner to align them properly. Drill at least 5 holes. Remove the double side tape and fasten tight the 2 aluminum parts with the required number of M3x10mm bolts.
With the front caps still in place use the lead srew mask to drill the 5 lead screw nut holes with the 3.2mm drill bit, remove the mask and then use the 9mm drill bit for the center hole. The mask goes in what will become the bottom of the stage and touching the wall formed by the 2 aluminum profiles. Pay attention to have it well centered, if it is too long you may file a little both sides, if it is to short you may shim it with some paper or thin cardboard, same amount in both sides! In all cases we are talking about less than 1mm of error!
Remove the front caps and the tape that was holding them in place. Install the LM8UU bushings in the front caps (see bellow if you plan to use the stock ones that came with the printer), add the rear caps and install everything in the aluminum assembly. The caps are designed with a gap of 0.75mm. That should allow to fasten everything tight enough without breaking the parts...
Remove the coils of filament from the back of the printer, see that the printer is powered off, move the extruder(s) carriage to the center leftmost position, unplug the power supply, place the printer on its left side, remove the wodden plate that protects the electronics in the bottom, unplug the cable for the Z stepper (at the stepper end!), unscrew the Z steeper, remove it and let it aside.
See that the Z stage is at the bottom and replace the printer in its normal position, disconnect and remove the build plate, remove the top rod retainers by unscrewing the bolts in the edges, remove the rods, take out the Z stage (mind the cabling, still fastened to the bottom of the stage!!).
Do your best to remove the bushings and lead screw nut without any damage! Install the lead scew nut in your new Z stage. Place the stage inside the printer, slide the rods in place* and secure but quite loose the top rod retainers, they just need to hold in place. I was lucky (or did it right) and everything was fitting into place. If there's no way to install one rod in the bottom retainers you may need to loosen those bottom retainers (good luck with the one in the electronics side!).
Replace the 2 screws from from the corners in the back of the build plate with the 2 M3x30 flat countersunk head. Keep them safe aside! Remove the 2 long bolts from the front of the build plate, take that little left over of aluminum and drill 3 holes (3.2mm drill bit) two of them to match the holes in the build plate and a 3rd one well centered with the 2 previous ones. Use the 6mm drill bit in the center hole to allow you to install a screw that is flush with the aluminum.
Install one of the long screws that you where removing from the front in that center hole (or the 3rd M3x30 flat countersunk) ensure that it is tight and use the 2 small screws from the back corners to secure this set in the front of the build plate.
Carefully place the build plate in your new Z stage. With the bottom of the build plate parallel to the aluminum wall of the stage, the three leveling bolt should res gracefully well centered (or with aproximatelly the same amount of side offset) into the "U" shaped arms. You are in trouble otherwise, sorry.
In case of problems you may consider to enlarge one of the holes in the arms in trouble (only in the arm! Not in the 40mm profile). A small file is recommended for this task.
Take a break, enjoy a nice coffee (or tea) breath a little of fresh air and relax.
Now, with the build platfor resting in the arms, set the extruder(s) carriage to the back right-most position until you hear the click of the mechanical end stops. Use a couple of small pieces of flat wood (or something else) between the build platform and the middle arm. Mind the thermistor! Choose a thickness that keeps the screws as close as possible to the arms and quite level with the stage.
Carefully raise the stage and align the back right corner with the nozzle (the left one for a Repicator Dual). You need to hold everything well aligned here and measure how deep are the screws from the front edge of the arms. It should be something close to 7.5mm.
Well, time to lower down the stage, remove the build platform, top rod retainers, rods, stage and drill the holes! Don't forget to keep in mind the thickness of the screw!! Before putting everything back into the printer, check how things fit, the platform must be able to swing for leveling, if required, enlarge the holes as less of a bit as possible.
Let the build platform out of the stage and install this one into the printer. Secure the rods with the top retainers, re-install the Z motor, do not tighten the bolts too much, just until the motor is flat with the wood, move the stage to the top, tighten the top retainers, and the Z motor, move down the stage, keep an eye to the top of the lead screw, when moving the stage. If it swings too much you'll need to re-adjust rod retainers (top and bottom) and motor position.
The stock springs are too short, even with the stock spacers, I used the 10x10mm "U" shaped aluminum as spacers, you can use anything else that fits in the arm and has a hole for the screw.
Install the build platform into place, tighten it down taking in account the connector at the back! Let one of the points in the back clearly (but not too much) higher than the other two poins, raise the Z stage (turn the lead screw by hand) place the nozzle in top of that higher point, use whatever the trick you like the most to determine the spacing between nozzle and platform, move the extruder to the other two points and adjust to that spacing.
You still need to find something to trigger the Z end stop. I cannot help that much with this, it's gonna take some time before I come with a solution I like...
Don't forget to find a way to secure the cable to the build platform!!
Double/tripple check everything!! (did you pluged back the Z stepper?)
Measure what travel your Z stage is able to do, this thing is not optimized and your printer may have lost a few mm of travel! Take a conservative number, take 145 if your measure shows 147, edit your machines.xml file accordingly, connect the ReplicatorG to the printer and let it do the update.
You may need to fine tune the spacing/leveling, once everything is fine you may use another nut to ensure that the knobs dont get loose.
Thanks for reading and sorry for the loooooooooong tale.