[davida1234]

The bearings are a little too small to do any sanding

My mistake, I meant steel surfaces where the bearings are running on.

[imbaine13]

My mistake, I meant steel surfaces where the bearings are running on.

Oh Yeah. I bet that would make a difference. I'll try filing the edges down until I think I've got a uniform track. Then with the bearing assembly, I'll squeeze the bearings down on the filed edge to provide a smooth finish. If that ends in vain, my next best option would be to get some 3/4" (1mm thick) aluminum angle to brace along the edges of the steel hollow section where the skate bearings would ride. The aluminium's really smooth and it might resolve the occasional binding.

If that still fails with the square steel tubing, I'll switch to some 1.25" diameter curtain pipes I found that had an almost perfect mirror finish. The only problem is they are only 1mm thick, and that, combined with the small diameter means there'll be significant deflection if they're used unsupported. Now, to resolve this, I came up with a crazy idea of filling them up with concrete!!! I know, really crazy, but I'm working with what I have around. The inside of the pipe is rough enough for the concrete to stick. I am aware that concrete shrinks slightly when cured, which might not help with tiny deflections, and the set up will weight much more, but as I mentioned earlier, if it gets the job done, no worries (not sure if vibrations would break the concrete up into powder, only time will tell). Before heading down that road, in order to get a baseline of how much deflection is acceptable, I need to find the JGRO CNC plans and calculate how much his X-axis rails deflect, after finding out how heavy his gantry is. This would all be in an effort to get those thin walled tubes more rigidity. Still open to better ideas regarding this.

I'll start with your idea first though.
Thanks.

Isaac.

[davida1234]

Don't file anything. It's too much, you will get low points. Just sand slightly with FINE sandpaper. The rest should be smoothed out by the bearings.

[imbaine13]

Don't file anything. It's too much, you will get low points. Just sand slightly with FINE sandpaper. The rest should be smoothed out by the bearings.

Tell you what, just seen this post, after I had already done the filing! Your advice worked great! I've been busy with work, but I managed to put a few hours into the machine. The quality of almost everything in the market in this country is appalling! Fact! Sanding alone wouldn't have done much! Here's a shot of what one of the edges looked like before, and after filing. I run a really fine sand paper over where i'd filed and ended up with a smooth straight surface for the bearings to ride on.