Re: [CAD_CAM_EDM_DRO] Building EMC software

Thanks for the info!
Bruce Roberts (the naval architect of the vessel I'm considering) told me that
approximately $30,000 USD of the cost of his metal kit is or cuting charges!
That's what's motivating me to think about building a cutting machine.

Regarding contouring: what is that? Can it be done with EMC?

Regarding OS: I am an electronics engineer by profession and a longtime Linux
user, so my OS of choice is actually Linux. The open source software model is
also my first choice :)

I was thinking about proximity control also. Can EMC run that too? How about a
simple mechanical follower?

Keith

>
> Concerning EMC.
>
> What is called "brain dead install" (BDI) CD which has the linux operating

system and EMC has been created by list members and will

> be available at the North American Model Engineer's Show I think the last

weekend in April. This is what I plan on starting my EMC

> adventures with.
>
> To answer your question about supporting the sheet I have seen it several

ways. There are little ceramic pyramids that you can buy

> for this purpose and this I have seen on really big flame cutters. An easier

way is to just use .125" Hot rolled flat bar (whatever

> thickness you need for strength I.E., 2" or 3") that is standing on end.

You make a grill out of these and make them easily

> replaceable. For long spans you may need to support them in the middle.

There are also several variations of this method.

> Underneath you lay down fire brick or a shallow tub of water. Water will help

with the dust control.

>
> I made a 12" by 24" plasma gantry that had a wooden frame and .125" by 2" flat

bars that fit into Dados cut in the wood frame. This

> worked very well. The resolution was .015" and feed rates of up to 200

inches/minute. I strongly suggest that you KNOW what your

> requred cutting speeds will be and design your system to run at these speeds.

I found the .015" resolution to be totally

> acceptable, but the first machine I built ran way too slow and just melted the

material I was trying to cut. If you are cutting

> thin (.060" or less) sheet then you need to move really fast.
>
> I'm sure you are aware that a 9 by 25 foot plasma cutter will probably occupy

a space of about 12 by 30 feet or more.

> I also think that if you are spending enough money to build that big of a

gantry that you go with CNCpro as the controller. It's

> only 150 bucks and has excellent performance on contouring (which is critical

for consistent cutting), it has virtually no learning

> curve and works on any old PC without having to learn a new operating system.
>
> You may also want to investigate gap control. On a machine that big it will

probably become an issue. If your sheet stock is wavy

> or has turned up edges then you get inconsistent flame gap which makes

inconsistent kerf, slag, burned up tips, etc. The one I have

> seen uses a proximity sensor and controls the height independant of the x,y

control.

>
>
>
> OUTWATER ~ KEITH J /5G3110 wrote:
>
> > Greetings all -
> > I am trying to evaluate EMC as a controller for a large plasma cutter (25' x

9'

> > capacity) that I want to build for cutting metal for a (large) boat.
> >
> > I have successfully installed rtlinux-3.0 with linux kernel 2.2.18 under
> > redhat 7.0.
> >
> > emc-1.17 dosen't want to build under this setup. I have a couple of

questions:

> >
> > 1. EMC seems to be heavily dependent on the specific versions of the kernel

and

> > rtlinux. Is there any future plan to use the 'standard' GNU
> > autoconf/automake/configure tools to make the build process a little easier?
> > for example, I see a lot of copying and linking going on to a platform

specific

> > directory and there appear to be separate spec/definition files for each
> > platorm, OS and rtlinx variant.
> >
> > 2. If not (or in the meantime), is there an EMC package that will copile

with

> > rtlinux-3.0 and kernel 2.2.18?
> >
> > 3. Finally, for anyone out there who knows a lot about plasma cutters (I

don't):

> > a. For a large (25 x 9 foot capacity) plasma cutter, how is the plate to

be

> > cut supported? What issues are involved with the plate support as far

as

> > not interfering with the plasma jet, not welding to the workpiece,

etc... ?

> >
> > b. What is the generally acceptable accuracy of cutters today?
> >
> > c. has anyone out there built a large (or small) plasma cutter with EMC?
> >
> > Thanks!
> > Keith
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>
> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the discussion

of shop built systems, for CAD, CAM, EDM, and DRO.

>
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>
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