[lasterixsuedois]

Hi guys, do you think that a twin rail SSR 15 system from THK is suitable for the Z axis for a medium size router aimed for wood and composites?

The reason I'm asking is that the mounting screws for the blocks seems to be M4 and the rated load handling is very different for different axis.

Would it be rigid, precise enough?

[jalessi]

http://tinyurl.com/yak6st4

[ger21]

15mm THK's are more than strong enough. Just be sure that they are securely mounted to a rigid surface.

[jsheerin]

I forget what the SSR's are for, but several of the THK's are meant for use in a certain plane. So I'd recommend checking into that. I think I decided to go with the HSR's over the SSR's for my z axis due to something about the SSR's, but I might be remembering the model wrong - I might have the RSR's or something else. The info is available on their website I believe.

[isvflorin]

The SR and SSR (stainless) are meant to be used on HORIZONTAL surfaces with loads coming up from above. They are NOT 4 way equal load guides, instead moment loads are very different depending rotation axis of the carriage.

However you have to consider 2 things : these type of rails are usually much more strong than what hobby machines need and you can build a succesfull Z axis with them by using them in a BACK to BACK configuration instead of normal mounting on a flat surfaces and offset centers.

Back to back means designing the Z in a way that you can mount the rails facing each other, for example mounted laterally on a profile support instead of mounted on the same side of the support surface.

Ca va ?

Florin

[lasterixsuedois]

Thank's for the advice.
I bought the SSR15 from ebay today, I will try them out and see what can be done.

I looked at the THK home page and yes they do not have equal load characteristics.

But each block can handle an excesss of 4KN in any direction!

So now I just need to get my building finished!

I will consider making a back to back arrangement, maybe it's possible!