Retrofit PRTalpha X rails?

[scottgus]

I have a 96x60 PRTalpha. Despite carefully trying to cut all over the table so as not to wear down the rails improperly, as the instructions say, I find that the long X rails are much more worn in the middle than at the ends. My machine cuts in a U-shape along the X axis. A shallow, 1/32" deep U, but not flat.

I understand that the PRS machines have hardened steel v-roller stock mounted to the X rails. Has anyone done a retrofit to mount these hardened steel V-roller wheels to their existing PRT-style X rails?

How much did it cost, and how is the machine working now?

Anyone with a PRS notice how the rail stock is holding up now, in comparison with how the PRT rails held up to use?

[coach]

I have a PRS and I have cut a lot of large 3D files. All have started from the same 0,0 on the table. I never thought about changing locations. I think I might now. Makes sense. But I have no wear that I can see. I clean the rails at least twice a week and do look at them closely.
I have been running my bot for 2+ years now on an almost daily basis.

[ken_rychlik]

Scott, I don't know how old your machine is, but have you considered just re-shimming the rails? It shouldn't be to hard to get that dip out of there.

Kenneth

[scottgus]

Good Idea, Kenneth. Hadn't thought of that! Will definitely be looking for all those shims Shopbot sent me three years ago.

Has anyone mounted the new v-roller stock to the PRT X rails?

[bleeth]

Scott: I'm in the process of doing something like that now. I mounted the new rails to a pillow block of aluminum and then mounting that to a 1 1/2 x 1 1/2 aluminum extrusion shimmed level on the c channel. The original angle is going away altogether. This means I maintain my original height (actually it raises it a little)but can keep the designed width. If you put the rails directly on the angle then they need to sit down tight to the angle and then you are shimming it to level. If you have a "swoop" in your angle you would have to shim it out anyway as kenneth suggested. I figured if I was doing all that drilling anyway I would rather do it in aluminum and have a stiffer result with the block and the extrusion bolted tight to each other.

[scottgus]

Dave, that sounds interesting.
If you don't mind my asking, how much did the new v-roller stock cost you, and how long are they?

[bleeth]

I got them from superior bearing. 10 feet each With new wheels (I got the larger number 3 size and appropriate track predrilled) I think it was around a grand. I can check after Monday. The 1/2 x 2 aluminum I got from a friend with a metal shop and it was 300 drilled and tapped as necessary. The extrusions were 100 plus shipping.
Plus the misc nuts and bolts.
I'm reusing existing rack.