Monday, October 04, 2010

 

Story of simpler Mendel: PLA bushings and X-axis



Hello, I'm new here so I guess I should introduce myself first. My name is Josef Prusa, I'm 20 years old student from Prague, Czech republic and I'm in RepRap world for about a year now. You can follow me on http://twitter.com/prusajr.

2 months ago I started process of simplifying Mendel design, so far I was able to reduce parts count, assembly time, use of vitamins and also price. I introduce my simplifications in few articles here on blog. Here is wiki page http://www.reprap.org/wiki/Prusa_Mendel, its not updated yet to final state, but I'll do it soon. You can always find most recent files on my GitHub http://github.com/prusajr/PrusaMendel.


RepRappable PLA bushings
Great alternative of bearings, if you dont have huge load. VikOlliver inspired me with his set of parts, using PLA "sleds". This is radically improved, tho.

Also, it makes whole x-carriage snap on to axis rods :-) Its great if you are experimenting with extruders a lot!!







They sits really nicely on rods. With regular Igus bushings I had a problem, because I dont have bearing rods, it was all little wobbly.
I printed about half of regular Mendel with these on all three axes and they are still good as new. Quality of prints with them are also comparable with linear bearings which I have on RapMan.

They will not last forever, thats obvious, but price for us RepRappers is near $0 which makes them nice alternative. I also designed all parts to be able to change the bushings when they worn-out.

You can find files and instructions how to use them on http://www.thingiverse.com/thing:4177 and I'll soon make a Wiki page for them too.

X-axis
X-axis is where I actually started my redesign, there is originally like gazillion parts and its real mess to assemble it. My version only has three big parts, two belt clamps and few printed bushings. Parts also includes Z axis functionality. Its really easy and simple design.

Parallelnes of two main rods is ensured by the teardrop type of holes for rods plus securing bolts from bottom (there is nut bracket inside the part). By pushing the rods upside, they will self center.

You can see the principle here on cut part. (Note: its older version of x-end-motor, principle is still same tho)



X-carriage

X-end-motor
X-end-idler

I hope you like it! Next time I'll introduce Y and Z axes.
(Note: This is still development!! Not officially released.)


Comments:
thanks for sharing. I just bought one of your production heated beds as well. I look forward to trying out your mendel design. One thing I'd love to see is a side by side comparison of many of the alternatives, cost + print quality
 
This is an excellent piece of work. I especially like those snap-in PLA bushings. I look forward to hearing more! :-D
 
Moc pekna prace.
 
This is excellent stuff, less vitamins is good as is simplifications.

Maybe you should take a look at this from the MakerBot blog Printable ball bearings
These could be even better than bushings if you incorporate them

regards
Al
 
Nice work. The current 'vanilla' bearing arrangement of Huxley's X-carriage is not without it's problems. I had to file away some from my part to make the bearings tight. Normally I never have problems with tolerances, so I think it's a problem in the model.
This seems to be a very nice lowered cost and ease of logistics, sacrificing little performance.
 
@Erik, I dont know about any lowering of performance, Im printing at 50mm/s with 0.35nozzle and objects are beautyful!!
 
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