Small circle cut quality

[frankles_42]

I am using a torchmate 4800 with a flexcut 80 and have been having some trouble with the cut quality of circles that are less than an inch or two. The smaller circles that I cut out are not super round and circular and they often look out of shape a little. I have done some research online and have seen some solutions such as slowing down cut speed some. I also am still having trouble with dimples/divots at the end of the cut when the plasma completes the circle so I was wondering what types of lead ins/ lead outs work the best. Here is a picture of a recent small circle.

 

[LECS-Chad]

Inside perimeters: Arc lead in that has a sharp angle and a little overlap.
Outside perimeters: Arc lead in with a little overlap and a lead out.

Obviously, slowing the machine down for the smaller holes/circles will help with the shape of the circle.

Looks like there is some mechanical stuff going on as the circles look a little out of shape.

 

[frankles_42]

Thanks for the input. What could I do to check/fix mechanical issues that I might be having?

 

[LECS-Chad]

With the machine on, try to move the gantry by hand. Obviously if you FORCE the gantry it will move, but what we are looking for is any little movement that can be generated by hand. This will exaggerate when the machine is moving and could cause the issues you are having outside of the lead in/outs being generated.

 

[frankles_42]

I tried that and I had to push pretty hard to get it to move.

 

[LECS-Chad]

I tried that and I had to push pretty hard to get it to move.

The point is to determine if there is any slop in the gantry. You shouldn't have to push hard to get it to move, just a wiggle to see if there is any looseness in the gantry itself. This would exaggerate when the machien moves around.

 

[frankles_42]

Yes, when I wiggle the gantry around, both the x and y axes seemed to move a little bit but the x axis moved a little bit more I think.