Re: plasma accuracy

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

> Jim Colt, an engineer at Hypertherm has the fine cut, high
> deffination in his shop. IIRC, a $35,000 machine, and he claims
> "you could probably fine tune the process and get tolerances of .005"
> with high definition"

Dave, the plasma unit itself is around $35 to $40K for the
hi-definition models. The next step in the chain is the degree of
precision necessary in the table itself to be able to make use of the
accuracy of HD plasma. The Komatsu Rasor is an excellent quality HD
machine, and it goes for roughly $100 grand complete. I believe they
use Hypertherm's hi-def unit on their machines, so you can figure the
table itself is about $60K. A lot of money for a plasma cutter to be
sure, but there's a lot of stuff that's being cut with a laser that
can actually be handled by a high definition plasma. A similar
capacity laser from one of the major manufacturers like Bystronic is
closer to half a million, so the hi-def plasma doesn't look so
expensive if the work falls within its range. Regarding the shim
stock cutting, a friend here has 2 6x12 Bystronic lasers in his shop,
and when I asked him about cutting shims, he said they had tried it
for a job they run regularly that requires a lot of shim stock
thickness material, and that they had found it really doesn't do a
good job at all. He says the reflectivity is a problem, as it is with
any reflective surface and a laser, and that the lack of flatness on
typical shim thickness material is also a problem. Back to the
original question, I believe Jim Colt also said the top drawer
commercial plasma cutters employing standard plasma and their fine cut
consumables can hold +/-.015", so that would seem to give the home
builder somewhat of a benchmark to shoot at for gaging the quality of
a homebuilt machine, and also somewhat of a "you ain't gonna get no
better than" number to use when the subject of how to best position
the head to 50 millionths for less than 10 bucks comes up :)