Build log and project page for AMT Mendel Prusa
=== History ===
DaveR had an incomplete Prusa project that he’s willing to donate to AMT. I’ve (Anup) volunteered to finish the build and donate any missing components.
=== Status ===
Incomplete. Current at stage of Y axis & heated print bed assembly (see 9Mar notes below)
=== Reference Information ===
Build instructions – [http://www.reprap.org/wiki/Prusa_Mendel_Assembly_(iteration_2)] BOM – [http://www.reprap.org/wiki/Prusa_Mendel]
=== 2013-03-09 Assessment & BOM ===
Spent time measuring the frame and trying to assess how far along the build is. Looks like a Prusa iteration 1 kit but with some assembly changes to follow iteration 2 recommendations (Z-axis cross bar is set below the Y-axis framing rods).
*Frame needs tightening and alignment
Since it’s been on the shelf for several months, it needs to be re-aligned and several joints need to be re-tightened
*Y rods are not parallel
Only a couple millimiters off
*Y motor mount seems warped
This might need measurement but the printed Y motor mount seems warped. The motor is held up by wire wrapped around the back end. Might be best to make a mount plate for the rear of the motor in addition to the front.
*Y axis bearing guides need to be aligned
Front and back belt guides need to be aligned. They’re currently off by 4-5mm. Bearings + fender washers are currently installed. Iteration 2 suggests PLA printed parts but I’m fine keeping the fender washers.
*Y motor gear is not installed properly
Needs to be aligned to put set screw on motor shaft flat surface. Set screw is tightened down on the round part of the shaft rather than the flat.
*Y base plate bushings (PLA?) are very rough on surface
One of these seems to bind a bit on the rod. Re-print these to the iteration 2 design which uses screws to fasten to the build stage rather than glue. Idea is to align & square the new bushings to the stage bottom, screw it all together and then slide the bushings onto the rods. This might make alignment hard to adjust but I’m hoping I can get it right the first time and not have to fiddle with it much once it’s back in the frame. The placement of the bushings should help align/parallel the rods.
*Print/Mill baseplate alignment gauges to simplify making Y smooth rods parallel
There is a reference in the build instructions about alignment jigs but I’ve not yet found the source post/STL. Basically I want a rigid frame 140mm wide to fit the rods up against it. A set of 3 with precise dimensions would be sufficient to keep the Y smooth rods aligned properly while the ends are clamped down.
==== BOM elements for Y assembly ====
4 PLA bushings ”[iteration 2 uses screws for connection to the build plate – avoids use of epoxy and the rough surface on the tops won’t matter]”
2 RP belt clamps
1 225x140mm print bottom plate ”[wood]”
1 225x225mm print top plate
1 840mm x 5mm T5 pitch timing belt ”[there is a recommendation in the build instructions NOT to use T5 pitch]”
1 NEMA 17 stepper motor ”[have this – needs to confirm specs of Y motor currently installed]”
3 M3x10 bolts ”[seem to be in the motor, need to confirm]”
4 M3x25 bolts ”[used for belt clamps]”
8 M3 washers ”[used for belt clamps]”
4 M3 nuts ”[used for belt clamps]”
1 M3 grub screw ”[have this installed already]”
As the electronics have long lead times for shipping, ordered Sanguinololu 1.3a kit ($40). Should arrive in early April.
=== 2013-03-10 Build platform ===
Doing some more research on stage construction: Decided on Heated Bed Prusa Mk1 design, mainly because I could get it cheap from a reliable vendor ($25 inc shipping). Ordered with early April arrival expected ($25). Expecting to use wood substrate/stage, heated bed, 2 sheets of interchangeable glass (one each for ABS and PLA). It would be nice to etch the glass to label them. Binder clips will be okay I’m sure but I’d like to design/build a better mechanism. Maybe something like the binder clip but built into the stage? Leveling may be an issue so consider 3 point mounting instead of the traditional 4.
eventually move to Category: Equipment
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