Huxley
Release status: experimental
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Contents
Introduction
RepRap Version III "Huxley" is being developed on this and associated pages. It is based on Ed's Mini-Mendel design, together with a lot of work already put in by others (especially Erik). Huxley is named, like all RepRaps, after a biologist: Thomas Henry Huxley.
The machine uses M6 threaded rods and M3 nuts and bolts (as opposed to the M8/M4 used on Mendel) and NEMA 14 steppers. The reprapped parts are about 30% of the volume of those for Mendel, which is to say it could reproduce three times faster.
Mendel can print itself, and so will Huxley. In addition, Mendel will be able to print Huxley, and Huxley will be able to print Mendel. We will continue Mendel development to turn it into a multi-material machine. Huxely will be a one-material machine, though we will probably also add a pen plotter so we can write etch-resist on PCBs and use an oil pen to facilitate separation of support material for overhangs.
Things to do
Add to this list...
- CAD Files
- Put them in which !*$!! format?...
- OpenSCAD versions would allow the entire machine to be parametric.
- Upload .stl and OpenSCAD files to wiki.
- Put files in Git repository
- Get rid of filament storage underneath
- This is a neat idea in principle, but should not be integral. How about a filament cartridge with the geared extruder drive built in, and a PTFE Bowden tube with the filament coming out to a snap connector onto the extruder? Huxley could clip onto the top of the cartridge, or it could be placed elsewhere.
- Get rid of under-dents on X motor bracket
- Redesign X motor bracket so belt does not go back on itself (A basic version of this has been posted on thingiverse here and here).
- Nema 14 geared extruder
- Roman gears?
- Mount by Y idler?
- Polymer transport path?
- Add Mendel/huxley buttons to host software and make them do something sensible
- pinch-block y-bar clamps
- 4 vertices - add feet
- Slider bearings (or bushings) rather than ball bearings?
- Printable frog
- Bed with only 3 sprung support points - no redundancy.
- This will also prevent the bed from wobbling because the screws are not all at the same height.
- This could be done by attaching the screws to the froglet rather than to the bearing parts. This would make the bed sit lower (increasing build height) and would prevent the screws from transferring heat from a heated bed to the bearing parts.
- Heated bed
- XLR bracket on frame
- Electronics location?
- Opto stops
- Add PCB-pen/oil-separator-pen holder
- Redesign motor brackets to allow for Nema 17's
- Redesign Z-base pieces to work like Vik's simplified Z-axis (or like Nicholas C Lewis' http://www.thingiverse.com/thing:3216)
Done
- Z gears incorporate 1 flange [done - in SVN]
- Nop's pulleys [done - in SVN]
Supplies
I've (Erik) found suppliers for all of the parts, and the estimated cost of the Mini-mendel would be under 350 euros (in Europe). Note that because the design is not yet stable, you may need to order more to get everything working satisfactory.
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<iframe width='900' height='400' frameborder='0' src='http://spreadsheets.google.com/pub?key=tw60t_E6G8tVNhBgMqAjcbw&single=true&gid=1&output=html&widget=true'></iframe>
You can ask ErikDeBruijn for edit permissions to this Google Docs sheet.
Parts
Apart from the sources listed here, also check out the forSale-subforum in the RepRap-forum.
Printed parts
- Check Mini-Mendel Variation for updates and improvements.
- You can easily print these production files in 10 makerbot-sized plates.
- You may print an (experimental!!!) shelled MiniMendel using less material and time
- single parts can of course be printed too
Electronics
The primary electronics design will probably be the Pololu Electronics, as we are very close to being able to make the PCBs for these in Mendel. Huxley will also be able to make them.
Identical to Mendel or you can use the BitsFromBytes -electronics that allow standalone operation from SD-card. When using the BitsFromBytes electronics, be advised that this requires a proprietary tool chain to build new firmware that works with the mini-mendel. Also, the latest versions of the source code for their electronics are frequently not publicly available.
Sources:
EU:
- German RepRap Foundation
- Watterott
- BitsFromBytes (alternative Elektronik)
US:
- Ultimachine (Arduino Mega/Pololu electronics)
- Makerbot (Gen 3 electronics)
- Techzone (Gen 3 electronics on smaller boards)
Bowden cable
EU:
Steppers
Standard 3xNEMA14 and 1xNEMA17(extruder) steppers. Smaller and less expensive than on the full sized Mendel.
Sources (steppers):
- EU
- US
- makerbot store NEMA17
- pololu NEMA14 (1400 g-cm holding torque!)
- Canada
Sources (Allegro A4983 based stepper-drivers):
(or use the BitsFromBytes-electronic that include stepper-drivers)
Extruder
The MiniMendel uses a bowden-extruder that has less moving mass and thus higher speed due to the stepper not being on the print-head.
Sources for parts:
- EU
- reprapsource/shapercube
- watterott (use the hot-end -part of the MK4-kit)
- German RepRap Foundation
- US
- makerbot-store (use the hot-end -part of the MK4-kit)
- MakerGear
Timing belt
The MiniMendel uses the same 5mm pitch Synchroflex timing belt as is used on the Mendel.
"Synchroflex(R) timing belt,800Lx10Wmm" and
"Synchroflex(R) timing belt,550Lx10Wmm"
sources:
- EU
- German RepRap Foundation
- Watterott (2010-05-05: avaliable within this week)
- rs-online
- farnell (slightly different lengthes, need adjustment in other parts)
- US
Bearings
- EU
- US
- VXB
- ebay 623 10-pack, 626
Nuts and bolts
All metric and obtainable from mcmaster in the US, and in every home-improvement-store in the rest of the world.
Thick sheets
These 2 sheets can be cut from plexiglass or wood with simple tools.
Success stories
- Erik
- I've printed all RP parts in ABS, they weigh about 300 g. This means you can print 2 sets with your first kg of ABS if you use rafts.
- Update: Mini-Mendel built and working!
- Whosawhatsis?
- I've built an oversized Huxley by cutting the rods and belts longer to make it almost as big as Mendel. The build platform is 8"x8" (about 195x195mm usable), but the outside is only 15"x14"x13".
- I've had a lot of trouble getting reliable extrusion, and I've taken the bowden cable out of the equation (at least temporarily) and have been working with carriage-mounted extruders. This seems to work fine with the NEMA 14 motors I bought, which meet the 13.7 N-cm torque requirement for Mendel. The picture is an old one, before the pulley extenders and the other modifications I made to get it working. I'll post a new one when I get the extruder put back together with the new motor I ordered.
Ongoing development
- Main development seems to be going on in the RepRap-forum and on Thingiverse.
- Marcus Wolschon is currently trying to create a hollowed Mini-Mendel that can be found HERE and uses even less material. Prints and tests for mechanical stability will have to be conducted.
- Marcus created a Shelled MiniMendel that only required 110g of ABS and less then 10h to print. (It may be filled with epoxy after printing but that is not required in all cases.)
- The Mini-Mendel is the first step in optimizing replication time; further steps in that direction are discussed at RepRap Breeder.
- Whosawhatsis? has redesigned the y-bar clamps for Huxley (and Mendel) to print in one piece and require no screws. Instead, the nuts on the threaded rod are tightened-down on piece to clamp the smooth rod.
- Whosawhatsis? has designed pulley extenders to fix the x-belt alignment so that it no longer rubs against the carriage. There are also replacements for x-blunt-plate_1off.stl and x-motor-end-clamp_1off.stl that have these extenders integrated. Note that these are not symmetric, and the L-shaped portion is designed to align with the belt clamps on the carriage. The carriage is backwards in Erik's picture above.
- Erik has designed a belt extension clip so that the pulley extenders can be used without a longer belt.
- Whosawhatsis? has designed an idler pulley for Huxley (and Mendel), suggested by Erik, to replace the mudguard washers on the belt idler bearings.