Trouble sourcing US manufacturers for a precision ceiling mounted linear rail

[aer0s]

I am having trouble sourcing a linear rail to be mounted overhead on a ceiling for a precision application with +/-0.1mm repeatability, manually operated at low speed <0.5m/s, 200kg load, track length of 20m. If I use two inverted Hiwin rails in parallel, would that be considered bad practice due to bearing failure? The ceiling is ~2.8m high. Any suggestions on manufactures that I should look at? I plan on designing adjustable mounts 1m apart and base structure of 8020 aluminum.

 

[handleman]

Sorry, I'm having difficulty understanding your problem.

Are you looking for made-in-the-USA parts? I think THK manufactures in Chicago.

What do you mean by "bad practice due to bearing failure"? There are multiple different shapes of rails and blocks, all designed for loading in different orientations. If you're worried about the blocks coming free of the rail if all the balls fell out, I believe (although not 100% sure) the 4-way equal load type blocks can't fit over the rail even if all the balls are gone.

 

[MintJulep]

This set of requirements don't make much sense together.

+/-0.1mm repeatability
manually operated
mounts 1m apart

 

[aer0s]

Thanks for the replies,

Handleman - yes this exactly what I mean, I've never seen linear rails installed inverted and overhead and thought there was a reason for it. And I guess it doesn't matter where it comes from, but the 20m track length (cut into sections) would be easier to ship if sourced locally.

MintJulep - the repeatability I mean the position accuracy on the y and z axis, not the x-axis that the equipment is sliding along. If I have two pieces of equipment they should be able to join together (+/-0.1mm) 2m down from the rail. The substructure will attach to the ceiling every few feet so I can remove potential bending of the rail.

 

[handleman]

You may want to reconsider your ±0.1mm. That is a tiny number. You state 2m from the ceiling... There is no possible way that you can construct any type of frame that moves on 1m centers that will weigh only 200kg and yet be rigid enough that it doesn't move 0.1mm when you breathe on it. You need to design some sort of guides or lead-ins or something to help it line up.

Pretty sure two linear rails in parallel along 20m length is going to be difficult to install and keep aligned. You may want to look at something like Bishop Wisecarver DualVee system.

Also, are you actually in the US?

 

[IRstuff]

Hiwin rails seem a bit flimsy, by themselves, since they look like they were intended to be mounted on a steel mechanical bench. So, I would think that rails associated with lifting gantries would be what you would mount your Hiwin rails to. Certainly, no normal ceiling is ever flat or rigid enough to support ±0.1-mm height accuracies. I think that steel is almost always the way to go for anything that needs to resist deflections; your nominal requirement will require excessively thick aluminum.

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