Y motor mount torsion box for Prusa simplified Mendel
Description
This is part of a small audit I am doing of the current Mendel structure for the utter lack of stiffness of some key parts. The general aim is to have a superior Mendel while still keeping plastic (here: only 27 + 16 grams) & vitamins needs at moderate levels . Any help, comments, contributions and evolutions of the design most welcome!
The aims of this torsion box mount are:
* to put a mercy end to the y axis motor sorry flexion on its mount (and the consequent lack of parallelism that has the pulley and belt doing very unwanted things)
* to provide support to the Y axis pulley on both ends, thus reducing the forces exerted on the stepper motor bearings
* to improve the general ability to correctly tension belts and improve stiffness, precision and fight backlash.
The design uses one 28x12x8 bearing.. Clearances are OK with or without a printed idler / bearing cover. Lately I have switched to two bare 608 bearings side by side.
There is a 16 mm wide space inside the box for the idler and all the washers that will fit.
The starting point is the dxf from Adrian's mods.
Note: a similar "treatment" will be applied to the X axis in the near future.
Instructions
I am using a vitamin aluminium machined pulley from eBay (that determined the bearing's diameter), but it should be very easy to adapt an existing printed pulley design, and also to adopt a different type of bearing.
Check the clearances with your particular setup first.
I printed this with 4 solid layers, 3 extra shells and 60% infill in hexagonal pattern.
slip in place, add washers as needed, bolt on, also secure with nuts on the M8 threaded rods, re-tension the belt. Enjoy!
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Lanthan, you're making me want to build a Prusa.
It is always good to know that, for the sake of fast printing and kit sales and low price, the shaving off of plastic has gone too far in a few key elements.
Not all of it is bad. First it is like "Wow! how fast I all the parts printed!". Then, after some time getting into the workings
&
amp; details, the agonizing "Whish I had spent my time and plastic printing a Selis Mendel" (or the variant: "I should have cut an Ultimaker just for the fun"). Finally: "well, this _can_ be improved!"
But the beauty of Open Source is that, given enough time and patience, you can tailor your machine to your exact needs. I want my mendel to print parts (with "sufficient precision") for homegrown mech projects, this is well within reach. 8-)
License
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What bearing do you use in the box itself? I measure 16x27x9mm, but I cannot find any bearings of that dimension.