Igus bearing with zip ties
September 10, 2016 09:21AM
Hello! I am designing my X carriage and I'd like to know your opinion about using zip ties to hold an igus bearing in place without the classic aluminium shell. I don't know if the compression of the ties and the weight of the carriage could deform the igus (something the alu shell avoid), what do you think? Any direct experience of this solution?


Voronix Core XY (custom model): Radds 1.6 (DRV8825) - Nextion 7" - E3d Titan + Hotend E3d V6 Direct - MK4DUO 4.3.3
Re: Igus bearing with zip ties
September 10, 2016 12:19PM
Bearings/bushings on guide rails require precise fit to work properly. You can't adjust zip ties to provide precise fit. Zip ties are the duct tape of the 3D printing world. Use zip ties for their intended purpose- bundling wires. Use screws and bolts for precise mechanical attachments/adjustments.


Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Igus bearing with zip ties
September 10, 2016 01:24PM
Most Igus bushings need to be fitted in matching tight mounts. They put pressure on the bushing that shrinks it to it's correct inner diameter.
You either have to usei the LM8UU replacement bushings, or better yet sinter bronce bushings with at least 2mm wall thickness.


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Re: Igus bearing with zip ties
September 10, 2016 02:50PM
Quote
the_digital_dentist
Bearings/bushings on guide rails require precise fit to work properly. You can't adjust zip ties to provide precise fit. Zip ties are the duct tape of the 3D printing world. Use zip ties for their intended purpose- bundling wires. Use screws and bolts for precise mechanical attachments/adjustments.

I do see your point, but an important aspect is locating the bearing as well as fixing it. Someone could, in theory, machine a carriage that locates the bearing precisely, and a zip tie secures it. It isn't outside the realm of possibility. Though, even better would be a flexural compression/clamping mechanism.
Re: Igus bearing with zip ties
September 10, 2016 03:35PM
Before I knew better I designed this:

[www.thingiverse.com]

and this:

[www.thingiverse.com]

This is where I finished, before switching to linear guides:

[www.thingiverse.com]

The last one was far better than the other designs.


Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Igus bearing with zip ties
September 10, 2016 06:52PM
Zip ties work great as long as you are aware of how you are using them. When installed with the proper tension, they provide two force vectors along the lines of the tie that push your bearing (or whatever) up against something rigid. As long as the load working against the zip tie doesn't exceed these forces, they work fine. Last year I designed an omni-directional wheel that used 150# test zip ties to hold 12 axles in place. This made the wheel hubs really easy to machine, and overall, the zip ties worked great.
Re: Igus bearing with zip ties
September 13, 2016 11:25PM
Quote
the_digital_dentist
Before I knew better I designed this:

[www.thingiverse.com]

and this:

[www.thingiverse.com]

This is where I finished, before switching to linear guides:

[www.thingiverse.com]

The last one was far better than the other designs.

Only that last one does any attempt at locating the bearing, so of course it's the best one.
Re: Igus bearing with zip ties
September 13, 2016 11:36PM
It isn't the bearing location that it does so well, it's the closing of the body around the bearing that really does the job, and that is finely adjusted by the screw. The bearing races in the super8s can tilt independently which makes them tolerant of out of parallel guide rails. When the screw is tightened, the room for the bearing race tilt is reduced, increasing the precision, preload, and friction all at the same time. The first link design does the same but doesn't have the fine adjustment capability because it relies on the step spacing of the zip-ties. The second design (which was the actually the first design chronologically) doesn't adjust the preload at all because the zip-ties don't touch the races.


Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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