I've put together a design for a plasma and I'm trying to decide on if I should go with Hiwin 15mm rails or cold rolled flat bar and a bearing set up built by cncrouterparts.com. My cost between the two is comparable, only about a $40 difference for the X and y. I have seen lots of lower end machines use the bearing methoud and lots of higher end machines use linear rails. My design requires my rails to be on the top of each axis due to rack and pinions on the side.
Question 1: Will I encounter lots of problems with plasma gunk messing up my rails? I have heard of the flat bar systems having trouble with stuff getting on the rails and causing the steppers to skip. I also have noticed that torchmate uses linear rail on the front of their gantrys, which seems like it would be in a spot to get alot of junk on it. I was thinking that since my rails will be mounted on the top of my gantry and sides they may be a bit more protected.
Question 2: Am I a fool if I try to use one bearing block on either side of my gantry? My gantry is 60" long and has dual drive rack and pinion. The rails I planned on using where hiwin 15mm. Should I be looking to rely solely on the steppers to maintain squareness or should I do two blocks on either side to add more ridgity.
Thanks alot for any advice you can give.