Re: [CAD_CAM_EDM_DRO] Re: Build CNC Plasma cutting Table

----- Original Message -----
From: Deborah Cordero <cordero_deborah@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, May 07, 2003 12:00 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Build CNC Plasma cutting Table


> Chris,
>
> We have some small parts to make out of galvanized
> sheets. On a given day they can ask us to make 1000 -
> 1500 pieces.
> I calculated it would take me around 4 weeks to make
> 1000 of these things manually.
> Because I have to cut the sheet in 5cm strips, then
> cut the strips again in 11cm pieces, then drill 4x
> 1/2" holes, then 2x 3/16" holes, then bend it to make
> a U form.
>
> Lucky for us we have an Ironworker, but stil the
> manual labor is alot.
>
> Naturally I want to build a machine that I could use
> for other purpuses later on
>
> Deborah
>
> --- Chris L <datac@...> wrote:
> > indy123456 wrote:
> >
> > >I used heavy steel floor grating (24"x24" sections)
> > in the cutting
> > >area (bought one to check it out, found it was very
> > flat, so I got
> > >more) and got them all leveled to the carriage
> > axii, and was able to
> > >bolt risers in fixed locations where the cut path
> > wouldn't hit them,
> > >since I would always be cutting the same parts.
> > >
> > Same here. I picked mine up from a "Raising company"
> > who tears down old
> > buildings. Far cheaper than new stuff. The only
> > thing I did maybe
> > different is put that on a completely seperate
> > table, that rolls between
> > the frame of the plasma cutter. This way I can load
> > stuff away from the
> > machine and roll it into place. I too have adjusters
> > to level if necessary.
> >
> > If I had time to do it again though, I would use the
> > typical zigzag cut
> > points to set stuff on. This way things "fall thru"
> > after cutting and
> > you have a lesser chance of the torch tip getting
> > caught when you are
> > not looking.
> >
> > >The problem I ran into was gap control... no
> > problem making the torch
> > >travel in a flat plane of course, and no problem
> > establishing a flat
> > >table plane. The steel being cut is the problem.
> > Even assuming it
> > >is flat to start with (I got a lot that wasn't, and
> > was useless), it
> > >doesn't stay that way long when you start
> > cutting... edges of cut
> > >sections pop up, catching on the torch tip, moving
> > the part or
> > >stopping progress.
> > >
> > This is true.... But it does depend on the thickness
> > of material, and
> > how fast and even you can transverse the steel.
> >
> > > I know some costly systems use sensors that
> > >manipulate torch height with a servo... I tried to
> > come up with a
> > >mechanical version that rode the surface. I know
> > people have plasma
> > >tables that work, so I'm not discouraging you from
> > your project...
> > >just warning that, with HEAT involved, things don't
> > always go the way
> > >you envision.
> > >
> > I see Torch Height Control discussions in the MACH1
> > newsgroup now and
> > then. It could be that there are fellows who have
> > this working under
> > Mach1, but I am not sure. I do know it requires a
> > Plasma cutter that can
> > deliver a signal that indicates current amperage
> > draw as that changes
> > continuously as the tip gets closer or farther from
> > the material. Not
> > everyone needs torch height control though.......
> >
> > > To avoid headaches and heartbreak, investigate
> > the
> > >marketed systems thouroughly and ask lots of
> > questions first and talk
> > >to people who use them; see how they handle the
> > heat warp problems.
> > >The feed control that CNC allows vs. my manual path
> > tracing (hard to
> > >maintain a steady path following a pattern,
> > fighting carriage
> > >inertia, etc.) may go a ways toward reducing the
> > heat induced into
> > >the sheet.
> > >
> > The ability to control feeds under CNC control is
> > the key to keeping
> > heat minimzed. You must have a controller capable of
> > very smooth motion
> > thru mixed geometry to avoid excessive heat and also
> > to avoid any
> > jittery cuts. Good adjustable Acceleration is also
> > important because you
> > need as little ramp up and down time in the corners
> > as well.
> >
> > > (snip)I thought plasma cutting was a neat,
> > "little-guy-enabling"
> > >technology until my experience with it... now I'm
> > not a fan.
> > >
> > There is no doubt that it depends on your needs. If
> > you are really in
> > need of a "production" machine in the immediate
> > sense, you likely do not
> > have the time to fiddle with building a CNC Plasma
> > cutter. However, if
> > you cut things occasionally, or if you would like to
> > be able to cut any
> > "one off" item now and then without the hassles of
> > getting another
> > company to do a "onesey twosey" for you, you will
> > very much appreciate
> > the time and energy you spent getting your own
> > machine.
> >
> > The one I built could *never* run as a production
> > machine. It was built
> > so I could create "prototypes" rapidly to make sure
> > they work. In my
> > case, I made 50 or so prototype designs for one
> > application before
> > concluding how it really should be. I would have
> > went crazy and lost
> > lots of time waiting for someone else to "fit in"
> > those 50 samples on
> > the way to the final item. I do send all the final
> > work to someone else
> > and like mentioned, I don;t think I could do it for
> > what they charge.
> > But I'm not giving up the ability to make what I
> > want when I want
> > anytime soon. Even though it could never be a
> > production machine, It
> > takes little time to slam out a few hundred things
> > now and then.
> >
> > I do not have Torch Height control either. I do have
> > a "machine torch"
> > style head with holder, which allows me to simply
> > rotate a knob to raise
> > or lower the torch. On any challenging cut, I can
> > just stand there and
> > move it up and down if necessary, but with what I
> > cut, it is seldom a
> > problem.
> >
> > I could envision a half dozen cheap alternatives
> > for my Torch height
> > control needs..... A cable operated hand held device
> > to "Squeeze and
> > Release"- Raise Lower.... while standing at a
> > distance, A motor Driven Z
> > axis using my Kids servos and Radio from his Rc
> > Car...... Or even a
> > "full pull" electric selenoid lift just for
> > emergencies.
> >
> > I guess really, If all it takes is a motor driven Z
> > axis, an easy to
> > build circuit, and a control software with some THC
> > functions built in
> > like Mach1 (you'd have to research how that is
> > coming along), you may as
> > well "design for the future" and at least make sure
> > you could ADD the Z
> > axis if necessary. You can start with just a to
> > axis.
> >
> > So, My advise would be to consider your needs. Then
> > determine just how
> > "in depth" the machine to fit your needs must be. If
> > you plan on turning
> > out thousands of parts with no-one standing there,
> > you should consider a
> > proven OEM machine. However, if you need to computer
> > generate a hundred
> > parts now and then, it is amazing how little of
> > machine you really need
> > to accomplish that goal.
> >
> > Chris L
> >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES:
> > http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >
> > Subscribe:
> > CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > Unsubscribe:
> > CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> > wanliker@..., timg@...
> > Moderator: pentam@... indigo_red@...
> > [Moderators]
> > URL to this group:
> > http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> === message truncated ===
>
>
> __________________________________
> Do you Yahoo!?
> The New Yahoo! Search - Faster. Easier. Bingo.
> http://search.yahoo.com
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
timg@...
> Moderator: pentam@... indigo_red@... [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>