Group, I plan to mount my plasma cutter in a fixture in such a way
that I can feed 4130 tubing under it to cut saddles. The tubing
would rest on a receiver which would allow me to move it in and out
and also rotate it. I don't plan to follow templates, just silver
pencil marks the same as I do now when grinding the saddles. The
advantage would be that the cut would be perpendicular to the wall
(grinding and all rotating tools make feathered edges), it would be
very fast and much cleaner than grinding. Does anybody see any
reason why this would not work? Jerry
Sounds like a great idea Jerry. You could make paper templates
using 3D and
transfer the curves to the tubing with silver pencil.
--
Paul Lamar ...No rotor no motor.
Jerry,
That will work great. I have had tubes laser cut using a 4 axis
laser system
to do the same thing. The squared up edges make a far better
weld. Even in a
manual system, you could do hard templates on a larger piece of
tubing, and
clamp a guide pin to the part you are cutting. This would allow
you to
replicate a cut very easily and make your parts very `. If you want
a drawing on how to do this, let me know.
Larry
Jerry,
I have been trying to think of any easy way to do those elongated
notches,
but for the life of me I can't. As Larry said the laser would be
the best,
quickest but most expensive. Next would be the new CNC plasma
cutters, not
as expensive to have done as the Laser but nearly as expensive and
all too
expensive to buy for your needs. Also leaves some slag to clean up.
Then there would be the small CNC ( digital readout) Mill,
probably more
than you want to outlay anyway. So I guess you have looked at all
these
options.
The punch notches are the quickest and easiest, but I don't know
if you can
buy special punches - I guess you can but would they be cost
effective.Perhaps there is a manually held punch nibbler, that
nibbles away
at a predetermined sized and you could finish off with a belt
sander. I
believe that would be my preferred option.
George (down under)
Jerry,
I suggest you give Don VanRaay a call at VR3 Engineering. I met
him at
an air show a couple of years ago. He has built a custom CNC mill for
the purpose of tubing notching. The tubing is chucked and both
ends are
finished in one operation. Since the notches are milled, the edges
are
square to the tubing wall. He needs the tubing diameters and wall
thicknesses, and a CAD drawing or just the node coordinates. He
provides a complete set of tubes, cut to the nearest thousandth,
labeled, ready for welding. I was amazed at how snugly the tubes fit
when they are cut perfectly. In many cases they can be tied together
with bungies and tacked.....no jig needed. His pricing is very
reasonable, even for one-off designs. I would expect that he can plug
Paul's drawings directly into his system. The VR3 website with more
information is here: http://www.vr3.ca.
I'm betting that once you have experienced the assembly of CNC cut
tubes, you will not want to hand fit again.
Aubrey Thompson
Aubrey, I know what you mean. Some years ago, I built a One Design
from a kit and all the tubing was cut on a CNC mill. It "snapped"
together like a jig saw puzzle. Cutting tubes for the same airplane
over and over is a good job for CNC. That is not my situation. I
need to be able to free hand accurately and quickly. Tubing
nibblers have been developed for this and they do a wonderful job but
are extremely costly. I got to thinking I could do it with plasma
and the more I have thought about how to go about it the more
feasible it seems. Jerry
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