Accuracy issue, loosing .04 on a .5 inch circle

Extremely frustrated, with getting the x-carve to the accuracy specified in the spec of the machine.

I have followed all of the online guidance on getting the machine accurate and several third party one, and now im wondering If i just have bad parts in my machine…

So, Im consistently cutting smaller dimension than I specify, here is whats tricky, the machine has been calibrated, I can move it 700mm and is spot on and and will move 700mm back exactly to the original spot. after all cuts I will come back to my zero perfectly inline. It took me a while to realize this much. So my cuts are consistently smaller, but here is another thing that makes it tricky, its inaccurate in a scaleable way, but only to a point… The error will scale upwards but once I get to beyond say an inch in size the error will stay the same.

So far my trouble shooting has included…
calibrating the xyz steppers, setting belt tensions, setting vwheel tension, tightening pulleys. Replaing the router. adjusting the potentiometers. and surprisngly none of these made ANY difference to the slop im getting.

The one thing i discovered today is that if I go crazy slow, with a cut that takes a .003" pass going 2"/m… the cut gets more accurate. but is still loosing a .05" on a half inch circle. So now I feel like maybe the problem is the carriage on which the router sits. If i wiggle it it feels like the v-wheels have slop on their track… so have I a bad carraige/gantry? or is this just what t x-carve is?

Here is a video of me wiggling the router holder, thsi is after reasembly and retightening everything… I think this is where the error comes from but I dont see hwo to fix

Mine has the same issue. The rollers are just guide rollers, the play is coming from the bearing on top. I think mine might be worse then yours. Sometimes running the same carve again without removing your project will help clean it up some. Especially if you are running a deep carve

I am seeing something remarkably similar, I wish I had a solution, but no luck so far. If I find anythng effective in resolving this I will definately post it! I can’t see the play in my Z axis V wheels, but my inaccuracy of cuts (but NOT calibration distace traveled) is very similar to yours.