Silly questions probably, but there is nothing in the literature and I have no equipment using these rails to reference......

Should I be using washers and/or lock washers on the bolts to mount linear rail? The specs never really say much about the hardware to mount the rails. They don't even specify a recommended bolt size specifically (although they do mention it in the section for the hole caps). They do give the dimensions of the hole of course. There is enough room to fit a washer it seems.

I think I just use a socket head cap screw and no washers, but I am not positive and that is why I am asking.

Specifically I am mounting THK SHS15 and SHS25 rails. They will be fastened to tapped holes.

Also, the SHS25 rail has 7mm holes. Should I use 6mm bolts or would 1/4" be better, or are they sized at 7mm so either is acceptable?

Same question on the SHS15.....4.5mm holes, so M4 Bolt or #8, or designed for either to work?

I realize these are metric designs, but they leave room to fit an English size that slightly fills the holes better. I am wondering if this is so you could use the English bolts, or they want the wiggle room for alignment and only intend for you to use Metric bolts?

Thanks