Newbie Question. Not coming back right?

[cpcapace]

I have picked up a used diy CNC router, and it seems to work ok, but when I make a cut. Let's say a circle it' start off ok, but once it completes the circle, it's off just abit.

So my drawing shows a perfect circle, but then it cuts like this.



Any ideas!

Help!

P.S. The main table does not movie.

[epineh]

Looks like the old missed steps problem, but we will need more info, a pic of the machine will help, generally if you push steppers too fast they can miss steps and lose position, this is a classic example of the result.

Look for things like an axis binding, maybe due to friction, dust anything.

Another cause is a feedrate that is just too high for the machine to handle, slowing this down may fix the problem.

What drivers, power supply, leadscrew, steppers (I assume it is using steppers) are on the machine ? More info will help us find the problem.

Cheers.

Russell.