Hey there,
finally my LowRider did the first movement.
But it´s not running straight.
Tried things like adjusting the Tubes, checking wheel nuts, tightening belts.
I measure the weel distances (like told in FAQ) and set the machine straight.
As soon as i drive more than 10cm the distance varies and Z tubes hit the table.
(Table is straight, checked 1000 times)
Motors are wired in paralell.
Any ideas on this?
Thank you guys!
Try wiring them in series, more power, and they have to stay in sync.
I have my z rails touching the table, as a guide, to keep them rolling straight. I always set my zero and drive it longer past the entire planned cut and then start it. To ensure the whole thing will run smooth, I lost a long job because I started it a bit cockeyed and it stalled out at the far end. I was even doing some measuring last Friday to see how it was doing (testing a cool mod) and it stays really straight, better than I could measure with a tape.
YMMV, but I added some pieces of plywood next to the wheels to force it straight. Mine also has a little travel side to side without these. I called them “hack tracks”, but they have been installed permanently and they work well for me. I didn’t end up installing any on the bottom of the table, but I could do that too. They have an added advantage of keeping most of the sawdust away from the wheels as well.
https://www.v1engineering.com/forum/topic/jeffeb33-low-rider-build/page/4/#post-32394
Jeffebs’ way might be the better way, I am always looking to find a straight edge when positioning smaller material.
Thank you!
Working flawlessly now 
Added some guides on the wheels and wired the motors in series.
I ran in to the same problem, and had some trouble squaring. I modified the yz rollers to make it easier to square.
that looks neat!
if i ever run intro problems again, i´ll check this out
But for now my machine works flawlessly