Plasma Circles?

[jlenelms]

how do u get good cuts when dealing w/ circles???having some luck w large circles say 1'' or bigger but anything less is giving me fits.Any ideas?Cutting 1/8'' mild steel

[Redline]

I agree with torchhead

[Torchhead]

First you need to slow the feedrate way down for small circles. Anything less than 1" is not a circle, It's a hole. The type of lead-in will help. If you need round, accurate holes you need to mark them with a single pierce and drill them using conventional methods.

Plasma is not a precision machining process. There are methods to optimize the detail but at it's best conventional plasma is ten times less accurate than milling.

If you have a machine that will take smaller tips (like Hypertherms Fine Cut) you can get better cuts at slower speeds but trying to spin a 60A tip around a 1/2" dia circle will just be a frustrating experience.

[mcarvey]

Can you clarify what you mean by "good cuts?" Are you having problems with too much dross, edge squareness, eccentricity of the hole/circle? As Torchhead says, plasma cutting is not a precision machining process, and when I spoke to one of the guys at Hypertherm, he said that if you're getting edge squareness that's less than 7 degrees you're in good shape.

-Matt