Linear rails question...

[SatanKlawz]

Ok, so I have purchased my complete z axis, some acme thread, and a g540 driver I got a recommendation on right here on the zone. I am now looking at linear rails. For the style of table that I am going to build I want to mount the rails in the same orientation as the rails in the picture that I have attached. I also want to use this type of rails. In reading different information about these rails it seems that some of them take loads in different direction better than others. If I am going to use this type and mount my rails like these what type of rails and blocks will work best for me?

[rrdiaz30]

This is from the 5 Bears CNC mill site:

http://www.5bears.com/cnc02.htm

THK LM Prefix summary of the common block types
SHS (Best, 4-way loading, caged balls)
HSR (Good, 4-way loading, uncaged balls)
SSR (OK, need to be used horizontally, caged balls)
SR (OK, need to be used horizontally, uncaged balls)
RSR (Avoid; balls fall out)

So Look for THK HSR or SHS rails on EBay. Or if you won the lottery, you can purchase them online at
http://www.technico.com/lm_guides.html
or
http://www.tos-world.com/webapp/wcs/...atalogId=10051

I am sure HIWIN has similar models as that's what is in the image you had posted.
http://www.automation4less.com/linearh.htm

These will work as well:

http://www.homeshopcnc.com/LinearGuide2.html

Rick

[analogman]

Often called "THK style" linear rails. A ndyes, they are definitely directional dependent.

If you are going to purchase them new or surplus ( like from http://www.automation-overstock.com/ ). Review the documentation on the company's web site. They will often have an "application guide" which will give an overview of their products and indicate what direction of force they are designed for. This information will also be in the individual products data sheets as well.

If you are going to purchase used off ebay or somewhere, get the make and model number from the seller and go to the manufacturer's web site and look for the info.

Don't get overstressed about the amount of force etc. just make sure they are design for force in that direction. And get the same size as in the picture of your CNC.

[JimPAC]

Except for the speed / weight and inertia loads you have none for torch / plasma cutting!

I would look at he most inexpensive sets you can find and keep all the same size and type!

Jim

[ger21]

For a small homebuilt machine, chances are the loads they'll see will be so small in relation to what they can truly handle that the orientation really won't matter.