Re: plasma cutting table

Hi Chris,

great information.

Another question as to how dirty this work is.

Does the effluent (is there and term ? on my lathe I make swarth)
get above the table ?

I had though of using uni-strut as the main rail and to hang it
upside down and use the uni-stru rollers (a style like glass shower
doors) the roller being above the table and inside the track.

It seems that using angle iron and some V rollers might be just as
good or better.

If the effluent does not rise, then I could hang the gantry and let
it roll in that manner.

about table size, I was not planning on a large unit, probably only 5
foot by 10 foot to allow me to cut a 4 ft x 8 ft sheet of stock. The
overhang would allow the cutting tip to move to the edge of the stock.

about cutting speed, 500 inches a minute ? wow ! now that is FAST !
I was timing my current table NEMA-23, 2:1 pulleys on a 1/2-13
leadscrew fed from a 12 v supply running on a serial controller and
only getting 4 inches a minute. (I am chewing my nails waiting for
my Gecko's to arrive.)

Do you cut aluminum sheets that fast ? 0.08" thick ? I can see that
a rack is the way to got for that type of speed. (where do you get
cheap rack ?

What type of accuracy do you typically get ?
+/- o.oo5" or +/- 1/64th"

and the last question is ventilation. I was planning on a separate
table pulling a snorkel around below the table. This unit I was
planning on using a cable pull to move. That would (hopefully) not
get destroyed from the effluent. do you think this would be helpful ?

Dave

--- In CAD_CAM_EDM_DRO@y..., CL <datac@l...> wrote:
>
>
> dave_ace_me wrote:
>
> > Hi all,
> >
> > My current desire is to make a plasma cutting table.
>
> Awesome!
>
> > I know that these are similar in design to router tables and I
assume
> > that there are a few in this group that have made these tables.
>
> True, Similar, but can be much lighter duty if you are using it as
a non commercial - hobby - fun type machine.
>
> > If you have any pointers, I would greatly appreciate your input.
> >
> > My intention is to cut 1/8 and 0.08 aluminum sheets
> >
> > Some of the concerns I have are:
> > how fast to I need to move the table,
>
> You might want to be able to move as fast as 500ipm, but that is
only necessary for really thin stuff.
>
> >
> > how messy the process is, does it create splatter like torch
cutting.
> > does it reak havoc on the slides ?
>
> Messy, Very Messy and Yes, hard on the slides IF you use the real
stuff. If you think you need the added accuracy of a REAL Linear
Rail, I would probably suggest the common Bishop-Wisenheimer "V"
> groove wheels and track. These will "scuff" off any garbage on the
rail while it is in motion. Other options might be Frelon Lined
bushings on round, supported linear rail with good wipers.
>
> Because of the level of accuracy generally needed, because of the
concept of the process itself, Some have been able to get by with
simple Cold rolled steel for rails and generic Cam followers. Some
> of this depends on how big of a machine you are building. I scoffed
at this first, until I built a machine using the technique. Now that
I see how messy this is, I am glad I do not have much mooola
> invested in true linear technology. Cold rolled is cheap, and
suprisingly straight enough for any Plasma Work I'd ever do. Laser ??
No, not accurate enough for that but Plasma ? Absolutely !
>
> > How large of steppers should I plan on using ?
> > and how you move the table, single center lead screw ? twin
screws on
> > the outside linked by a timing belt ?
>
> I have one running 400ipm with dinky little 80oz motors. Non
contact operation makes this possible. I would however shoot for
something no less than 150, and target 220ish.
>
> Leadscrews? No way, not unless you can spend a million protecting
them. Otherwise they won't last long.
> use cheapo rack and pinion, and because you are building from
scratch, make sure you drive the pinion via a toothed belt setup so
you can help yourself out later getting the most out of the particular
> combination of Drivers and motors you end up using. Rack is plenty
accurate for the process, just keep the "grooves" vertical so the
Swarf falls out.
>
> Also, Don't move the table for Plasma.... At least I wouldn't. Why
move around a full and sometimes heavy sheet of goods when you could
move a "known and calculated" gantry weight ? of course me and
> moving tables have never seen eye to eye on gantry type machines.
>
> If you are building it small enough, you might want to consider
nuilding your "Gantry" in the shape of a large "T" square, driving
the main axis from one side only, letting the other end ride free on
> a roller. It's a fast and cheap way to do it, and I have yet to
stumble across any higher accuracy needs for plasma use.
> If you were doin a laser or water jet, It'd be a whole nuther
story............. Or if it were a combo CNC Router.
>
> > Also, if you do have one, do you make parts for people ?
>
> Sorry, No. Too much goin on. (maybe too much time spent in NG's!)
> Hope this gives a little insight as to what works for me in regards
Plasma Cutting.
>
> Chris L