THK SR20 linear guide question

[vpl]

Hi All,
I'm on the fence here with using a set of THK SR20 linear guides (for x axis) that I can buy on ebay or go with the .250x4 1018 flat bar and skate bearings with the appropriate sleds. So I want a 4 x 8 usable cutting area and have it be about as heavy duty as a mechmate. So my question is are THK SR20 linear guides a good option and are they stout enough for this application. A used set is a few hundred dollars more than setting up the skate bearing affair. I would assume more accurate and less hassle in the long run......?? 20mm wide doesn't seem too sturdy but I don't have any practical experience in this area...what do you think. For the length I want 2 rails will have to be mated.....

Yes I looked up the load ratings and all I can say is way too much info for a noob. If someone who knows would just say, "they are too small and you need a "XXXXX" width that would be great." Or maybe, "that's what Ive been using and they are fine...."

Please help I want to start my build and this is my biggest stumbling block.

I wanna buy some steel and start building....

Thanks People,
Vince

[ger21]

If price isn't an issue, I'd go with the THK's in a minute. They can carry far more loads than anything you'll throw at them. Not even anywhere close to the same leage as skate bearings.

[vpl]

Originally Posted by ger21 If price isn't an issue, I'd go with the THK's in a minute. They can carry far more loads than anything you'll throw at them. Not even anywhere close to the same leage as skate bearings.

Thanks Gerry-
I figured this was the case, so specifically are the THK SR20 linear guides good for the build I'm after? I know they come in different widths and different load capacities. I hate to keep asking but your answer was fairly general. As far as $ goes there is a set that may be affordable. After pricing out a bunch of skate stuff the linear rails are more but not entirely too much. I really like "carveone's" finished unit. Its a very enticing design, and not too spendy. His handy work makes a nice finish and looks very pro. I would like to do something similar but use the THKs and tuck them under the table to keep them away from chips and what not. So what do you think-are 20mm THKs specifically more stout that skate bearings on .250" cold rolled...even for a 8' + travel.....

Thanks again Gerry I'm sure these questions get monotonous. However your answers are very appreciated and anticipated.
Vince

[ger21]

20mm THK's can typically carry several thousand pounds. However, the surface they are mounted to is critical to achieve that. You need a steel or aluminum surface to mount them too, and the rails will only be as flat and straight as that surface. If the mounting surface can flex or bend when force is applied to the rails, then the rails will bend as well.

Odds are that you won't use 25% of their capability, but again, they must be used correctly.

[mactec54]

vpl

What is the price on Ebay, & only buy them if they are new,PM me with what you want & I can most likely get you a better deal, for new rails & bearings