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Substitute for using printed pulleys?

Posted by nigel_mck 
Substitute for using printed pulleys?
November 03, 2011 06:08PM
Hello all,
I am currently working on a Prusa Mendel and am curious about the specifications of the pulley. Firstly I am using these belts for my build: http://mixshop.com/index
I have heard that to increase print accuracy it is recommend that one use plastic or metal pulleys rather than printed ones. What are the specifications I should be looking for? And if anyone has a source for them in Canada/USA it would be greatly appreciated.

Re: Substitute for using printed pulleys?
November 03, 2011 11:58PM
I used XL timing belt pulleys and belts from McMaster. You need to modify the steps/mm settings in your firmware. Details of my experiences are here



Check out my blog: AdventuresIn3-DPrinting
Re: Substitute for using printed pulleys?
November 05, 2011 10:35AM
Danger! No disrespect to James here, but I had many months of problems from a similar suggestion about a year and a half ago.

I was using the original 3G electronics that didn't do microstepping (well, it did half stepping, but not 16).

So once I made my calculations for the 10-toothed pulley, I thought I was fine.

What I didn't know was this led to me missing steps. The symptom appeared similar to backlash.
My axes would accumulate error until the next home operation.

My guess was that since a 10-toothed pulley uses less steps per mm, you end up with effectively less resolution, and some rounding error or something in the firmware causes an accumulated error over time during the print. For me the problem was harder to see because I used RepRap host which homes after every layer, so I only saw it on large prints (like an entire bed of Mendel parts).

My experience was that I had far LESS precision with a 10-toothed pulley, even with the math done right for steps/mm.

Use the 8-toothed pulley. Lots of people have RepRaps now - you should be able to get replacements if you damaged them.





--Jeff Keegan (Just Another RepRap blog)
Re: Substitute for using printed pulleys?
November 05, 2011 05:26PM
i use machined 10 tooth t5 pulleys and get better results than printed 8 tooth pullies
Re: Substitute for using printed pulleys?
November 08, 2011 05:19PM
I have always been using printed pulleys (nophead model) and I never had any trouble.
Moreover, I do not see any difference in quality compared with more professional machines with proper bought pulleys - are you sure that there is a problem with printed ones?

Said that, my axis are very light to move as it is a small machine with bowden cabled extruder.
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