Long arm quilt machine/frame question
 

I have a 18 inch throat mid/long arm on a 10 foot frame.
Recently I've noticed that my quilts end up skewed a bit, with the right hand side ending up slightly higher than the left to middle area by the time I roll it up several rolls.
I use the horizontal lock to set a line to mount the quilt top to.
I've checked that the quilt and backing are mounted squarely.
The bars are parallel and not bent.
Machine is mounted square to trolley.
I'm puzzled by what might be happening, as this out of square thing only happens on the right side of the frame.
And it happens with every quilt, so something has changed, but I can't figure out what!

Any and all suggestions to problem solve welcome!

I have the same set up. I had been quilting for several years before I was watching a longarmer with a 36" machine. I noticed that he did the first row left to right and the second row right to left. I asked why and he said it was just like when you sew strips together, if you don't alternate the direction of sewing, the whole thing comes out skewed with one side shorter than the other. I had been quilting always from the left side.

Could it be that your cloth leaders are stretched from lots of use? I recently ran across a video on how to determine if your leaders were not straight and how to correct it. Sorry, but I don't remember who was demonstrating or where I found it. Try googling it.

I usually do alternate rows as well, so that's not a factor, but thanks for thinking of it.

I don't think it's the leaders, but I will change them out if nothing else seems to help. I'll try googling for the video too. Thanks for the suggestion.

I mount my quilts farther to the right. When using robotics, the machine goes from left to right. I measure to the rail, and after the first pass I always have to stretch out the right side to get it to be where it needs to be.

If I use the channel locks to work my way down, each pass will end up a smidge farther in than the one before. I assume it's just from the quilt being drawn up because of the batting. I will use the channel locks to check the center and along the front edge, and I can use it for the left edge after I've gotten the right edge and center looking good. But I still prefer to measure from the frame end instead.

Example, I'll load a quilt and measure and the top will be 14" to the side frame rail. I'll quilt and roll, and then when I measure the back edge, it will be 13 3/4" and I have to tug it a bit and get it out to 14". Then I'll put the clamps on the back, and measure and pin the quilt top to the back and the middle and front edge. I never baste the top or sides - gave me too much trouble when putting on the binding so I quit doing it. I pin instead, and remove the pins as I go.