Lowrider2 wandering to one side of y axis.

If i square the one of the x rails on the gantry to the edge of my table and start jogging it down the y axis it wanders rather quickly to the right side. I’ve read that the unistrut rails can cause an issue due to the fact that they may not be relatively flat with the rest of the cutting surface, more importantly the opposite unistrut rail.

Is it actually turning, or is the edge of the table not square to the end? Plywood isn’t always square I’ve found out.


My unistruit table tracks straight.

Its definitely turning. No matter how I position it.

I did have to order and return two pieces of stainless tubing because I felt they wouldn’t be straight enough and finally settled on the last shipment from amazon after I realized they wouldn’t get any better. This could be the main issue the last one I checked on the surface plate was out like .125"… If I skew the gantry alot I can get it to go the full length of the table.

Manually drive it back and forth a few times and see if it finds it’s own center. The only thing that could cause it to not drive straight would be one of the sides not square with the long tubes, or maybe one of the wheels is dragging, but the steppers should be pulling it straight.

I’ve been manually jogging it back and forth. I can only make it about half way down the table till the zrails rub the unistrut. I’m going to disassemble the one zrail that has a slight bend in it at put it on the other side and see if the issue changes.

The Z rails are extremely short, if it is bent enough for you to notice you probably should replace it, Maybe you can bend it back but…

The side pieces relative to the X rails are what makes it track. Like Barry said, check the table for square (measure diagonals), then do the same for your build. If it turns within 4 feet there is a pretty major issue. At the same time if you build it with the rails close and almost touching the side it should never be able to move more than 1/16"-1-8" and be forced to track correctly.

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Also take the belts off to make sure both sides are indeed powered, and one side is not just dragging along.

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Thank you guys for your input. The thing I thought would be the easiest has turn out to be a little difficult, lol. I removed the belts just to check that both y axis motors are working and they were. My y plates are flat as well and all wheels roll nicely. I’ve snug up the bearings on the zrails as well to stiffen everything up a tad too. I took apart everything and checked all my tubing as well. The slight bit of curve in my one xrail was so tiny there is no way it could be an issue but still maybe. And all the other zrails looked fine. I also reassembled everything in a different position and my problem is still persisting… it leads me to believe that the unistrut surface is not flat to both sides or that thier is just enough of a bend in one or two rails that is creating the issue. It’s just weird because I would not think that that would create such a drastic drift.

Did you ever solve this problem? I also use Unistrut. It’s been fine for months, but developed a drift issue in the last week that sounds just like yours.