Need supplier for *precision* crossed roller slide rails or other suggestion...

[peter.blais]

Hi guys,

We are building a wire EDM for a professor, that is doing some quite small and intricate work. We require 1 micron tolerances (total!) over a ~25-30mm travel in two axis.

We are looking to use an off the shelf rail or way which will be bolted onto either ground granite or steel to build our linear stages.

I'm having trouble finding much that has this sort of accuracy. Our budget doesn't allow us to simply go and buy off the shelf stages with this sort of precision and resolution, so we are looking to just buy the rails.

There is a ton of stuff available from optical sources off the shelf but much of it would not survive our environment. Right now we are thinking our Y stage will be completely submerged in cutting fluid and that means possible particulate matter getting in to / around the components.

Let me know if you guys have any suggestions or any possible sources for this stuff. FWIW we have to build the whole machine for 4-5k tops, including both axis, pump and tank system, wire feeder / tensioner / routing / encoders / etc, but we are provided the EDM power supply and there IS some axis control hardware we may be able to use.

[DareBee]

There is a reason why a machines capable holding of holding 1 micron are hundreds of thousands of dollars.

FWIW I like IKO CRW linears but they are not sealed and depending on the size you want they could be 25 - 50% of your budget.

[RICHARD ZASTROW]

Ditto DareBee's first sentence!!!

Dick Z

[peter.blais]

LOL. Well, this isn't a hobby / some stuff like that, this is a project which has been assigned to us, we were given the budget and the specs, so it's really out of our control. All we can do is do our best to make it work. I really don't need a lecture telling me it can't be done though because there is nothing I can do about it anyways. If you want, call our professor and tell HIM that.

That said, holding it over an inch will be a LOT easier then holding it over long travels.

I will check out the slides you have listed, other then that we are considering buying some slides and grinding them again for higher straightness locally, at the same time as our frame components are being ground.

[sergizmo]

DareBee is right. Think about it, 1 micron! That's .00004". To hold it all components must be significantly more precisie then that and you would have to align them all perfectly. Flatness, parallelism, perpendicularity to a third of a micron or better as tolerances stack. You would need a AAA grade granite plate at minimum to start. Forget about ground steel. Any kind of rails good to that will be many thousands even in short lengths. Oh, and temperature would have to remain consistant to within probably a degree F or better when assembling and using the EDM.

He is probably giving you the 1 micron spec to get you guys to make it as precise as you possibly can in budget. Just to push you as hard as possible.

I don't mean to come accross as a jerk here, but this is just crazy.

Good luck.

[peter.blais]

Looks like their "super precision" CRW slides would get us in the ballpark for our short travel. It's still pretty borderline though, looking at their chart on page 5 of their catalog it appears to get close down around 100mm of travel. Perhaps with some software calibration.... I need to call them as our 25mm travel is basically not on their chart it is so far at the short end.

Thanks for your input, we understand the challenges regarding stacking tolerances and thermal expansion. We also have to worry about vibration both in the machine and in the wire across the cutting span- there are all sorts of things to worry about trust me. We are considering them.

More suppliers / parts suggestions please!