thk rails and loads from different directions

[endgrainguy]

I"m planning to use THK SR rails for X and Z axis on a fixed gantry, a set up where my y axis is on a horizontal traveling table. This guy,
http://www.5bears.com/cnc02.htm ,who seems to know his stuff,says SR series "need" to be used horizontally. THK web-site says "best" used horizontally. Does "horizontal" mean that only the traveling table on my set up is best use for these? I have a completed gantry set up with x and z axis already in place. Is it worth hunting up the prefered rails "(SHS (Best, 4-way loading, caged balls)
HSR (Good, 4-way loading, uncaged balls)," or is the distinction mostly applicable for high loads, industrial use?
Router is to be used for woodworking, -- joinery (dovetailing and mortise and tenon) with spindle horizontal to table, and inlay work with router in usual vertical orientation, professional use in a one man shop, whrere machine will probably only run a few hours a week. Thanks!

[greenb_60097]

I used the sr 15 rails on my router, search my name for details and we had a brief discussion of the load ratings of these rails. I have them mounted both ways and they run fine cutting aluminum(withing limits) and so far any woodworking. I haven't had time to update pics but I was thinking of adding them in. From the fog in my memory the horizontle loading is 2x what the vertical load (something like 1500 vs 750/truck). The main difference in Swede's design is that his mill is set up for precision metalworking. The cutting forces in metal vs wood is an order of magnitude greater.

Brian

[ger21]

A quick look at THK's website shows 15mm SR's are able to handle over 2000 lbs of vertical force and about 60% or 1200 lbs of side force. I doubt you'll be anywhere near those numbers, so you should be fine. You'll probably only be using 10% of their capacity. On a side note, I was looking at ShopBots website earlier, and noticed that their standard machines only have 60-80 lbs of cutting force.