[CAD_CAM_EDM_DRO] Re: Router to plasma cutter

Hi Ron

Have a look at the PlasmaCAM videos on you-tube, to see excellent results
from a very simple machine. There's quite a few videos.

This is a bit long winded;
http://www.youtube.com/watch?v=4knPtYjc2s8

Regards
Roland

On 3 October 2012 17:45, Ron Thompson <ron@...> wrote:

> **
>
>
> On 10/3/2012 11:34 AM, Tom wrote:
> > Ron: It's hard to predict what issues you are going to face. Plasma
> > cutting is different animal than other types
> >
> > 1. You have to account for a different pierce height (prevents blow
> > back of molten metal) so the "pierce cycle" consists of a set of
> > coordinated and properly timer moves. If MACH is your control choice
> > you can do that through a POST in your CAM
> > 2. The thinner the material the faster you have to cut (see some cut
> > charts like for the Hypertherm 45)...they won't work for your ESAB BUT
> > they will give you an idea of what speeds you will need.
> > 3. While there are little cutting forces in plasma you do have to have
> > good acceleration rates at the higher feedrates....translated: You
> > need plenty of torque to the final drive mechanics to make sharp turns
> > and square corners at higher speeds
> > 4. Make sure your expectations for plasma cutting are realistic. It is
> > NOT a precision cutting process. It is like carving out a door with
> > RPG's comared to milling. You are vaporizing metal and blowing it out
> > the back with air. The flame is "floppy" and trails behind the motion.
> > The kerf width is dependent on the feedrate, the arc Gap (height above
> > the material) the age of the consumables and to an extent, air
> > pressure and the current setting. If you can hold + or = .015 on a cut
> > you are doing better than average, Typically plasma is a process used
> > for large sheets being used in fabrication (weldments) or for
> > decorative cutting neither of which requires tolerance fits
> > 5. While a 12 x 12 work area is interesting it will end up like a
> > hockey game in a closet. Even the little 24 X 24 tables are more a
> > novelty than really usable for what plasma is intended
> > 6. Torch Height is essential for any thinner material or for larger
> > cut areas. You have to skim along the cut hovering up at .063 to .120
> > while moving at 65 to 250 IPM and all it takes to ruin a set of
> > consumables is to let the gap get too low. to pierce too low or to let
> > the material bow up and have the nozzle contact it while cutting. That
> > being said a THC on a tiny table may not be practical. the process of
> > IHS (initial height sensing) is part of the THC process where the
> > top-of-material can move on you and Z zero has to be reset. The "touch
> > off" (probe) process can be done using several ways: ohmic ,
> > capacitance proximity, and mechanical[floating torch holder]. Each as
> > pros and cons. Even if you elect to not use THC than consider the
> > inclusion of a Floating Torch Holder to act as the IHS and as a safety
> > backup in case the Z tries to drive the torch through the metal.
> >
> > There is a misunderstanding that plasma cutting is just routing with a
> > hot tool....it is actually a lot more complex than that and converting
> > a table or building one to do both takes some engineering and an
> > understanding of the Physics involved.
> >
> > Sorry to be so verbose but these are questions I answer several times
> > a day and you need a minimum set of details.
> >
> > Tom Caudle
> > www.candcnc.com
> Tom,
> Thanks for your time! I was aware of most of this. My router is made
> from laser cut steel from a place I used to work. I also have a supply
> of scrap plate from the same source, mostly 12 ga., that will fit my
> machine.
> This will be a starting point for making a larger machine. A learner, if
> you will.
> The brackets I am needing will be fine at those tolerances, but I
> expected more like .005" with proper kerf control.
> I am looking forward to the adventure.
>
>
> --
>
> Ron Thompson
> On the Beautiful Florida Space Coast, right beside the Kennedy Space
> Center, USA
>
> Think, Draw, Print. 3D printers ROCK!
>
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>
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>
>


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