[TheForge] Backhoe in highlift.

Sat Nov 8 07:23:00 2003

And Deb about freaked out when I moved the backhoe off the trench from the
well to the house.

http://www.safetycenter.navy.mil/photo/archive/photo73.htm

I LOVE this site!

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

----- Original Message -----
From: "Harland Johnson" <[email protected]>
To: <[email protected]>
Sent: Saturday, November 08, 2003 1:44 AM
Subject: [TheForge] Re: 3 axis plasma cutting

>
> My "rope wrench tools" were cut on an optical cnc using an ESAB plasma
> torch.   I had originally designed them on that wonderful CNC program
called
> MS Paint <g> but ran the resulting image print thru my Brother Fax Machine
> which used a roll of carbon type paper, which the CNC optical then
followed
> without a glitch.
>
> Another neat thing about an optical CNC is that an artist can make
sketches
> using a special ink, and these can translate directly into steel.
Following
> this thread, it should be possible to marry a sheet of thin "scrap" steel
to
> wood like from an old 55 gallon drum...  to wood, and get it to burn a
copy
> of the design on other media.
>
> Dann Johnson
>
> ***********
> Jay Hayes writes:
> *********
>
> > I have a CNC plasma that was originally programed via a tracer eye that
> > followed a line or edge of a line. The machine can cut a 72 x 128 plate
> > and was built by ESAB / Heath with a Compupath controller. There were
> > several short comings with this type of setup. First the speed needs to
be
> > slow for the tracer to stay on the line when it came to a sharp corner
or
> > it would get an off line error. The eye would sometimes get confused on
> > inside corners and just stop dead. Even worse a microscopic break in the
> > like would cause the eye to reverse direction. This would be very
> > frustrating on a complex shape when the eye would jump the line after it
> > spent a half hour creeping around the edge of the pattern. Fortunately
we
> > were able to record the trace before actually cutting the part. The
trace
> > could then be scaled up or down and played back at a faster or slower
> > speed for cutting.
> >
> > Optical tracers are somewhat complex. They have their own light source
and
> > use a small oscillating convex mirror to read the  black on white line
or
> > edge of a silhouette. Dirt is always a problem. A dirty lens or dirt on
> > the pattern can cause problems. I once had a fly land on a pattern and
the
> > eye followed it around for a while. Luckily it wasn't cutting an
expensive
> > plate at the time. The pattern must also lay flat and stay put. If part
of
> > the pattern curls up the line will be out of focus and can not be read.
If
> > the pattern moves during programing the part will be distorted.
> >
> > After the controller on the machine was fried in a lighting hit we
> > eliminated the eye and went strictly CNC. Now if I want to cut a part
from
> > a free hand drawing I scan it and use Corel Trace to create a dxf file.
> > Then I use a CAD-CAM program to generate the G-code that the CNC plasma
> > uses to cut the part. For the most part this works much better. I can
> > actually cut more intricate parts and simple parts are a snap. If the
> > drawing was done on a napkin it might take a while to clean it up to
> > generate good clean code. But a good clean drawing can go from scan to
> > code in about the same time as the old tracer.
> >
> > The down side is the new setup can not retrace in reverse. Reverse trace
> > is especially helpful when cutting a part and the torch stops cutting.
The
> > torch could be backed up along the cutting path by pressing the Back-up
> > button and the arc could be reestablished where it was lost. When the
> > button is released the cut proceeded as normal. With the new setup we
have
> > to return the torch to the home position or start of the cut. Then do a
> > dry cut until the torch approaches the point where the cut was lost. The
> > machine is than paused until the cut is reestablished. Corner slow down
> > also has to be programed in.
> >
> > Some systems can do both but they are not cheap. With most systems the
> > operator must tell program which part of a part needs to be cut first.
The
> > holes in a part should be cut before the outside of the part is cut or
the
> > part may drop before the holes are cut.
> >
> > Jay Hayes
> >
> > shannell Sugrue wrote:
> >
> >> Yup, CAD or however you use a puter to do a .dxf or whatever type of
file
> >> your cnc software uses can be a NIGHMARE!
> >> Is this a table you built or bought? The optical trace is intersting
and
> >> I
> >> havent really seen one up close. Its got a computer in the loop
> >> somewhere??
> >> how does it scan and find cuts within the main outline and how does it
> >> determine, what to cut out first? or has that never been a problem, its
> >> really only matters with small pieces that will drop to the floor
through
> >> the grate. What is the eye? do you need to illiminate the drawing? Does
> >> it
> >> work on a scale up method, you draw at x and the machine cuts at 3x?
> >> ----- Original Message -----
> >> From: "Ries Niemi" <[email protected]>
> >> To: <[email protected]>
> >> Sent: Saturday, November 08, 2003 5:19 AM
> >> Subject: Re: [TheForge] Re:3 axis plasma cutting
> >>
> >>
> >>
> >>
> >>> My plasma table, which is not cnc, but optical trace, has 3 axis
> >>> motors, and I wouldnt think of having one without it. The third, z
> >>> axis, is controlled by  a voltage sensing circuit that samples the
> >>> voltage from the plasma power supply. It then adjusts the height
> >>> accordingly, so the arc gap is always consistent. This means the torch
> >>> is always cutting at its most efficient, but more importantly it will
> >>> follow the warped surface of a piece of plate. Even though I built my
> >>> water table flat, then levelled it in the shop, not every piece of
> >>> sheet metal is flat. And then, when you start cutting it, it warps
like
> >>> crazy. Especially thinner stuff like 16ga- It can warp an inch or more
> >>> in height as you cut parts out. If the plasma cutter doesnt have z
axis
> >>> adjustment, the torch either runs into the metal, and you lose
> >>> registration, or it gets so high you lose contact and the torch goes
> >>> out. Either way, bad news. So 3 axis is needed unless you want to
> >>> manually adjust the torch height every inch of the way.
> >>> Personally I prefer my optical trace table to a full on cnc one. I can
> >>> do a full size drawing of the part up to 4' x 8', and it goes on the
> >>> right side of the machine, then I lay a 4x8 sheet of metal on the
water
> >>> table on the left. It is a little slower than full cnc when you are
> >>> cutting more than 20 or 30 parts, but I dont do that kind of quantity
> >>> anyway very often. More often I will be cutting a full sheet in a very
> >>> complicated pattern, once. I just finished a job where we had to make
a
> >>> 4 foot by 16 foot artwork panel out of 3/16" plate, and to
troubleshoot
> >>> the design in software on the computer would have taken twice as long
> >>> as cutting it would have. Plus, I am an artist, and it is easy enough
> >>> for me to draw what I want.
> >>>
> >>> ries
> >>>
> >>> _______________________________________________
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> >>>
> >>
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> >>
> >>
> >>
> >
> >
> > _______________________________________________
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> >
> >
>
>
>
> Dann Johnson
> _______________________________________________
> http://mailman.qth.net/mailman/listinfo/theforge
> theforge mail list group photo site is
> http://www.photoaccess.com
> Login:  [email protected]
> password:  anvil
> ___________
>
>
>