Re: [CAD_CAM_EDM_DRO] plasma accuracy

On 12/17/04 8:51 PM, Raymond Heckert wrote:

>I have an ESAB PCM-875 hand-held that's accurate to about
>..005. (I can pull it against a straightedge, and the only
>irregulaarities I can see is where my hand faltered).

Hi Raymond,

Funny you should mention the 875. That's what I've been using for about 5 years
with my mostly homebrew setup.

Yes, a CNC solution will give you a lot better edge than handheld. But it's not
going to be anywhere near as accurate as you suggest. I typically cut a kerf
around .060" with an .030" nozzle. And even more for anything over about 11
gauge. The kerf is always conical; bigger at the top than the bottom. And if the
nozzle gets dirty or the torch gets bumped, it's not uncommon to see an edge
that's angled at maybe 20 degrees. One little bit of blowback can change the
direction of the arc, which will throw everything out of whack.

It's certainly plently good enough for my uses, but you might be disappointed if
you plan on machine shop accuracy.

Hal Eckhart - Casa Forge - Minneapolis MN - <http://www.casaforge.com>