Printing mendel pulleys and other difficult parts

I'm printing off my hackerspace's mendel, this weekend has been frame weekend among other things. So far the main parts that have been giving me problems have been the pulleys etc(though getting m3 holes to print correctly is also a bit of a problem). I've found that my machine simply doesn't have the resolution to print these correctly and instead of being a circle with teeth it comes out as a circle with a bunch of bumps on it. I'm using a .5mm filament, with a .57mm setting as my build height. My machine is a 2.0.1 BfB machine(the one they used to sell without electronics etc and running on gearmotors, it's essentually Vik's design of the ponoko reprap)

Has it been found that vik's solution of using ball chain isn't viable for the mendel, or was it just decided that we weren't going to go down that road. If it hasn't been tried because of a major flaw then what is it? Looking at the chains, they tend to not go through pieces, so changing the type of belt to chain shouldn't be very hard given it just goes over a bunch of bearings.

Vik's Mendelssohn uses ball chain, and the Y axis was the only place I saw a problem, which is easily fixed, Y idler bracker, one of the holes needs moving to enable the chain to pass over one of the threaded bars under the bed, not doing that would mean that the chain on that axis would break eventually from rubbing against this.
This is just my observations, and looking forward to seeing the complete machine next week.

letsburn00 - do you have any photos of your parts? I usually print at 0.5 mm diameter filament, but I use a build height of 0.4 mm - I seem to get better results when printing that way. Going slower can help with the accuracy too, depending on your machine.

That said, I picked up some cheap MXL pulleys to use on Mendels, as they're pretty crucial to the smooth operation of the machine.

Wade

Wade: any reccomendations on the spec of the pulleys, because I agree that the pulleys are probably the most important part when it comes to resolution of the piece.

I went for 20 tooth MXL, and just matched the bore diameter to the steppers I had. You can get them for about $10 each at SDP-SI. McMaster Carr probably has them as well, but they don't ship to Canada, so I try not to torture myself by looking at their website.

I did manage to print some gears that look half decent at a 4 mm tooth pitch, but that's still twice the size of MXL teeth. 5 mm teeth, like Adrian's plan, could be pretty doable then.

Here's a photo:

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