Re: plasma cutting table

Dave,
I to am building a plasma table. As I have not completed mine yet I
could hardly be considered an expert, but I have researched it almost
to death, so I may have some info that will be of use to you.
First,if you are doing this just for cutting aluminum, look in to
the Quality of cuts plasma gives on aluminum. In one of the foums i
will share further down a user likened the plasma cut quality on
aluminum to cutting foam rubber with a bic lighter. the manufacture
of the machine confirmed the difficulty of the process. Better
results may be obtainable, but I would check it out.
I would recomend visiting the sites of the hobby class machine
manufacturers. you will get many Ideas from the pictures and
information at these sites. They all do it a bit differently. see
www.plasmacam.com www.torchmate.com www.shopbot.com
www.supertech.com. if any of the addresses aren't correct, you will
be able to find them with a search of the root name. (the addresses
are from memory.)Shopbot and torchmate both have forums attatched to
their websights. users of their machines discuss modifications to
their machines for ventilation, material support etc. The water
submersion seems to be the best for ventilation and keeping the
process clean. A fellow on the torchmate forum gives pretty good
detail on how he constructed the water system.
The best way to support the material seems to be with a row of flat
Iron strips placed vertical in slots to allow easy changing when they
become to cut up. Also take note of the plasmacam table which has
multiple points sticking up to support the material. this crates less
spots to actualy get cut by the traveling torch. You just use your
plasma table to make spare "point strips" ahead of time, then replace
them when needed.
Also, here are some e-bay numbers of some tables that have sold. I
have printed the pictures to study how they went about building
theirs for Ideas on mine. Item #1712215826 Item #1672683317
Item # 1701922972
For rack & pinion try www.mcmaster.com part # 6295k143 for 6'
or6295k143 for 4 foot. They can be butted together to make a 10 foot.
I hope this isn't like when you were 5 and asked your parents where
babies came from, and then after the "talk" wished you hadn't asked.
I just get so much more from this list than I can give, and I get
carried away if I think I have something that might help.
Good luck, Dale


ps. If you need info on torch height control, do a searh on the list
and you will find a couple of threads on a system Mariss is helping
us to design, but you've probably seen these as I've seen your posts
here for a
while.

--- In CAD_CAM_EDM_DRO@y..., "dave_ace_me" <davemucha@j...> wrote:
> 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