Robo welder is rotating. Not welding yet but soon.
It amazes me that tiny motor and gear box is all you need.

Here is a movie to prove it.

Just because something you are building is small does not
mean it does
not take a lot of time.

I tried the rubber tubing coupler but it did no rotate
smoothly.
It would wind up and then would release.
This is a special coupling nut with a 4-40 set screw.

Paul Lamar


I am getting a degree in robo welder design.

I have discovered several things. Don't use caster wheels
that
are the least bit soft. It is best to make your own rollers
out of metal.

The grounding of the tube resting on the stop doesn't work
very well.
I found some 4 gage wire in  an automobile hi fi audio
shop that is
very flexible. A zillion tiny copper wires.
I stripped the insulation off but not entirely necessary.
The insulation is soft and flexible as well.
About 2 bucks a foot.


I will attach that to the tube with
a hose clamp and wrap several turns around the tube to be
unwrapped
as the tube turns and is welded.

I found a 110 Volt synchronous motor at MaMaster Carr that
rotates
at exactly 1 RPM no matter what. It has enough torque to
twist your
wrist off.

It takes the speed of welding out of the equation. All you
need set
is the welding current and the distance of the tungsten to
the metal.
The gas flow can be near the bottom of the recommended scale
to
conserver that expensive consumable.

Paul Lamar

A bit of advice from someone who has thousands of hours
experience with
welding wire in a physically dynamic environment. First,
properly size the
wire for the current load. #2 for 100A give or take
depending on the
insulation(bumping 1 or 2 languages here won't kill you).
You always want to
size on the high side because.. it's expensive to replace.
Welding wire has
many fine conductors, composed of alloys that resist fatigue
and heat
crystallizing. Welding wire, is quite properly more
expensive because it
handles abuse and motion.
If your robo welder only needs 360/380 degrees of rotation,
get enough
length so you can perform the rotation without too much
twist per inch of wire, but
always turn it back to a start index.
C. Smith



tig does not use wire. Filler rod sometimes but not needed
here.
This is basically an over lapped joint.
Here is a picture of the part that is welded on to the end
of the
4130 .049" wall one inch OD tube. The turned down part goes
inside the
end of the tube.

Paul Lamar

I believe C.Smith is talking about the ground wire. Being an
electrical
engineer, he is right, #2 copper is the right size for 100
amps.

H.Lunt

Thanks.

BTW everybody please set your editors to send plain text to
me.

html does strange things to email programs.

We are getting email from different OS's XP, Wind 7, Wind 8
etc., etc.. Mac, cell phones etc., etc., etc. Apparently
they send
messages in different ways. Some in html.

Paul Lamar

I'll go buy another 3 feet of the 4 gage and double up on
it.

Paul Lamar

This was a wild ass guess on current (80 amps), gas flow
(12.5 CFH) and tungsten
distance (about 1/8 inch).

The 60 Cycle synchronous gear motor was rotating at 1 RPM.
You can set your watch on it.

I am going to have a party tonight :)

This is as close to a perfect weld as it gets.

The last picture was some welding done by the best welder I
know. He is a guy that works for
George Talbot Talins company in Torrance Ca.

Paul Lamar

That looks very good. Is that autogeneous welding or are you
using filler?
You might make the taper a tad longer on the electrode.
Typicly 2 to 1-1/2
electrode diameter. What is the make/model of your welder
power source?
C. Smith


Thanks for the tip (pun unintended) :)

I'll try that.

Do you know of a hand held device that one can put a length
of tungsten electrode in and have it rotate it while you
are grinding the tip? In theory the tip would come out
perfectly
symmetrical.

What is  autogeneous welding ?

No filler rod.
Lincoln square wave tig 175 pro.

Paul Lamar

Autogeneous means..... No filler.

There are many nice tip grinders out there.
http://www.usaweld.com/Tungsten-Grinders-s/34.htm
this is just one source, you may find them on sites like Amazon, or eBay
for less money.
Since you are planning on selling these kits, I would highly recommend
that you make a destructive test on at least one piece to ensure that the
weld has complete fusion and penetration. Saw one end in half, grind or
file the surface smooth and inspect with a loupe or microscope. You should
be able to see the change in the grain structure of the fused material.
Even when something looks good on the outside, doesn't necessarily mean
the same all the way through.
C. Smith

OK Graig

Paul Lamar