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Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

My Graber I3 improvements

by wgrube Dec 22, 2014
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Hi, Could you supply the chain links for the Prusa i3 as well as they are pictured in the drawing.
Many thanks

The best I've found so far is this one: http://www.thingiverse.com/thing:666118

Cable chain, perfect fit and rounded edges

Phew! Hard times working on the x-ends... There's not space enough by the original design, I'll have to move the z-axis stepper motors outwards to gain some. Still waiting for bearings to arrive to test the threadless ball screws and then define which system to use for the z axis. Threaded rods are simple and work, but aren't reliable and durable. On the other hand, threadless ball screws may not support the weight of the x axis mechanism, I hope they will...

I've decided to use threadless ball screws for the z-axis. After seeing designs and results from others, this is the solution. My prints are coming out with bad layer sticking and banding, ruining everything after certain height. Common threaded rods aren't enough for the precision I'm aiming. Also, threadless ball screws can be customized, the pitch can be adjusted to achieve higher resolution on the z axis if needed. I'll maintain the pitch at 0.8mm, to keep the compatibility with the original design of the printer, requiring less adjustments on the firmware parameters.
This kind of mechanism demands some workarounds, like the stepper motors connectors that I'll have to redesign to fit 8mm smooth rods. Not a big problem, but there will be a lot of details to correct after printing the pieces for testing. Soon I'll be printing the left x-end, by my experience this will be a 12hour print... Time to stock up coffee and find some good movies on Netflix... ;)

There are many modifications coming! I corrected some mistakes and at the moment I'm working on the x-ends. it will take a while to get everything ready to print and test. The printhead is working like a charm! Even with flaws I've only detected later, at 0.2mm layer height I'm getting perfect prints, with beautiful finishing.
I'm also designing a servo mount for a z-probe, just in case. The aluminum heatbed and its baseplate (also aluminum) is working perfectly, steady and after a software calibration, the temperature is incredibly stable. I used 0.16mm nichrome wire simply sticked on the aluminum plate with Kapton tape.
I'll have to substitute the z-axis threaded rods, the prints work nicely up to 60mm height, but then the layers won't stick together and everything becomes a mess. Both rods are bent, maybe I'll buy NEMA 17 stepper motors with threaded shafts, This will require a new design for the x-ends... For now I'll stick with common 5mm threaded rods.

I forgot to say that the frontal fan duct (autocooling fan duct) includes supports for printing. The design of this duct is based on one I found on Thingiverse, but I can't find it again. I'll link it later...

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