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

Hi Deborah;

Have you considered Laser or Hydro jets? When you say galvanized
sheets, I think thin; so I can't possibly imagine that you will be
successfull with any heat producing process.

Also a heat producing process run on galvanized steel will produce
emmissions you may not want to deal with.

Dave


Deborah Cordero wrote:

>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
>>
>>
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>=== message truncated ===
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