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Idler end for Rostock

by Johann, published

Idler end for Rostock by Johann Mar 24, 2012

Description

Rostock is a delta robot 3D printer.

This part is the top bracket that holds a pair of 8mm smooth rods, two ball bearings, a micro switch (endstop) and a plywood board.

Newer versions of the OpenSCAD source files will be published here: https://github.com/jcrocholl/rostock

Recent Comments

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Now you know I got to ask, for the motor_end and joint, did anything actually change? In other words, does one really have to reprint them, haha.
Thanks for uploading pics of your printed parts. You're right, there's a problem in idler_end.stl in the rostock-2012-05-10.zip file. I have uploaded a new rostock-2012-06-29.zip file which fixes idler_end.stl, motor_end.stl, and joint.stl. All the other STL files are unchanged.

I think the problem was caused by nondeterministic OpenSCAD output for rotate with less than 3 values. So I replaced rotate([x]) with rotate([x, 0, 0]) in all OpenSCAD files, and I think this fixes it.
Here are some pics of printed parts and a bolt in place to show the angle.

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License

GNU - GPL
Idler end for Rostock by Johann is licensed under the GNU - GPL license.

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Instructions

Print three of these and install them at 120 degree angles on a plywood board (see RostockBaseDims.pdf by Modpod http://www.thingiverse.com/thing:24973 or print the drill jig http://www.thingiverse.com/thing:25000). The plywood mounting holes are sized to work with #11 wood screws or M4 screws, no nuts needed.

Clamp the smooth rod with 16mm M3 screws, washer on the outside, hex nut on the inside. Stainless steel fasteners are recommended.

30mm M8 socket screw holds two 608 bearings (skateboard bearings) followed by two M8 washers, then the printed part, another M8 washer, and a M8 hex nut.

The printed part forces a 2 degree upward tilt for the M8 screw, which will prevent the timing belt from falling off. I like to add a printed plastic flange ring on the outside of the rear bearing.

UPDATE: It's better if you can use a flanged 608 bearing, http://www.vxb.com/page/bearings/PROD/F608ZZ works really well, see pictures.

The micro switch is the common ZM series with 9.5mm center distance between the mounting screws. If you use M2.5x12 or similar, they will screw directly into the plastic, no nuts needed.

Are the files you have in the main Rostock STL zip angled for a reason?
Just read the scad code, so it's there to compensate for the belt pulling. But shouldn't it be angled upwards and not to the side?
The idler_end.scad file says:

tilt = 2; // Tilt bearings upward

rotate([90 - tilt]) bearing_mount();

I think this should correctly rotate around the X axis.

It is also angled upwards correctly if you look at the thingiview live 3D preview (click on the little blue box in the preview image with the green STL object, near the photos at the top of this page).
Right, the part you have here is different than the one found in your git repo. The one in the repo is angled to the side as wells as slightly up.
Here are some pics of printed parts and a bolt in place to show the angle.
Thanks for uploading pics of your printed parts. You're right, there's a problem in idler_end.stl in the rostock-2012-05-10.zip file. I have uploaded a new rostock-2012-06-29.zip file which fixes idler_end.stl, motor_end.stl, and joint.stl. All the other STL files are unchanged.

I think the problem was caused by nondeterministic OpenSCAD output for rotate with less than 3 values. So I replaced rotate([x]) with rotate([x, 0, 0]) in all OpenSCAD files, and I think this fixes it.
Now you know I got to ask, for the motor_end and joint, did anything actually change? In other words, does one really have to reprint them, haha.
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