Prism

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Prism

Release status: Working

Prism.png
Description
Mendel Frame
License
unknown
Author
Contributors
Based-on
Categories
CAD Models
External Link


This extruded aluminum frame is a quick upgrade to your standard Sells Mendel. It makes it cleaner, more open and, more importantly, more rigid.

You can start printing parts today, but wait to order parts 'till next week while I finalize a screw/nut count. If you just can't wait. know that I've used less than 100 screws/t-nuts for my build, but over 100 M4 washers.

The only part I don't have designed yet is a mount for the endstops. You can use the endstop holder designed for Prusa, or run without endstops while I design one for 20x20 mounting, or design one yourself and put it up here or on thingiverse.


Prism Specifications

Manufaturer Reprap
Model Prism Mendel
Technology FFF/FDM
Cost to build $600 US
Size 440mm (W) x 440mm (L) x 410mm (H)
Weight ~7 kg
Max Potential Build Envelope 250mm (W) x 250mm (L) x 200mm (H)

Prism vs. threaded-rod Mendel

Prism has the following key improvements over threaded-rod Mendel:

  • Bigger print area in the X- and Z-axis directions
  • Increased rigidity for better prints
  • Simpler assembly
  • Simple parts with few overhangs. (easier printing)
  • Lighter and more portable
  • Potential for light milling more likely

New non-printed parts

(Misumi parts numbers are listed, where applicable, for easy ordering; Not an endorsement. See also this list of alternative extrusion suppliers. )

Extruded Aluminum Profile
20x20x400 - 9 (HFS5-2020-400)
M3
M3x10mm SHCS - ~10-20
M3x15mm SHCS - 2
M3 Nut - ~10
M3 Washers - 2
M4
M4x12mm SHCS - ~70
M4x20mm SHCS - 16
M4 T-Nuts (which are compatible with your extrusion) - ~70 (HNKK5-4)
M4 Washer - ~140
NOT REQUIRED M4 Post-Assembly T-Nut - 20 will run about $10 - makes it easy to attach parts without having to disassemble the whole frame. (HNTA5-4)
M8
M8 Studding - 320-350mm x 2 - for the lead screws
M8 Nuts - 6
M8 Washers - ~20
Smooth Rod
8mmx390-400mm - 2 - for Y axis
8mmx330mm - 2 - for Z axis
Bearings
608 - 2 at least - for the lead screws
624 - 2 at least - for the belt runs

Printed Parts

Files

Up-to-date files will be on github: https://github.com/Buback/Prism-Reprap

Part Images

Optional pieces:

Build Instructions Notes

The Thick 90 degree part is mainly just to raise the printer up high enough so the z rods and motor shaft don't hit the table/workbench your printer is upon. You can use the thin part for all the vertexes but you're going to need to print out the spacer in order to get the proper height. The spacer/thin parts use much less plastic and print faster, but might not be as rigid --Buback 18:24, 27 December 2011 (UTC)

There isn't a dedicated X or Y axis for the Prism yet, but the frame as-is will work with anything that's compatible with a Mendel variant.

Visual Assembly Guide

Build the Prism fast.
For the quicker it is done,
the sooner you print.
--Buback 04:49, 29 December 2011 (UTC)

Further Development

-There isn't room at the top of the z rods to get a tool in and tighten the screws, which is why you need to put in the z rod first. I'm not pleased with this, and so the first order of business is to figure out a way to fix this. Adding longer 'arms' to the Ztop piece is the obvious solution, but then it's a longer unsupported angled print, which i feel leads to week parts. the other option is to split the part down the middle and make it two parts. the problem here is alignment becomes a bit of an issue, potentially. Anyway, if you'd like to design a part that holds a 8mm (or larger) rod in between two 20x20mm extrusions at a 60deg angle, feel free to post it here.

-Perhaps a dedicated Y and x carriage would be nice. I prefer a vertical X and ball bushings. The X build area could also be made bigger, but is now limited by the x length of the x carriage, and not by the space between the angled bars.

-Fully Parametric parts, a la OpenSCAD.

-A Circuit board mount that attaches to the bottom frame rails, under the bed.

-A travel case