Removing weld seam inside rectangular tubing

[willjordan]

I'd like to use 1x2 1/8th wall rectangular steel tubing as center sills and coupler pockets. The only difficulty is the weld seam that is inside the tubing. I need to remove it so the couplers will fit. On short pieces, I've filed it. A shaper with a gooseneck tool would be perfect, but I don't have a shaper.

What suggestions do you have for removing the bead far eough into the tubing to mount a spring shank coupler. About the only thing I can think if is figuring out a workholding fixture that would allow me to remove it using an end mill chucked in the headstock of my lathe. I've got enough of it for a number of cars, so I suppose I could build a fixture just to hold it.

[Bryan]

Athough the finish wont be as neat, I have in the past used a long-reach die grinder (as used for porting cylinder heads) and a stone to remove the weld bead up to 4" from the end...

[gregvasale]

real skinny (1") "long nose" belt sander or a pencil die grinder (Dremel) or (Dumore) . Belt sander, most expensive. Hopefully weld will be on the wide side. Probably better than shaping, as welds can be very hard. Example, I tried to make spring keepers for clocks out of some steel pipe that was handy by turning it the lathe. Never got a clean cut over the weld. Your results may vary.

[willjordan]

Hopefully weld will be on the wide side.

No such luck, a belt sander would have to be less than 3/4" thick to work. On the stock I have now, the seam is about a half inch or so from the corner on one of the wide flats.

I've tried using my cordless die grinder and found it unsatisfactory, although I may have to try something with making a base for my toolpost grinder and an x-y drillpress vise I have. I'll need to make the base long enough to provide support away from the grinder, though, since I plan to make some 4' long center sills. I haven't looked at my toolpost grinder closely enough to determine whether it has inside grinding capabilities, but I imagine something can be done in that area. The toolpost grinder came with the lathe, but I don't forsee any projects that will use it on the lathe in the near future. It's just sort of nice to have.

[Scotty]

Will,
You can get rec tubing with the seem on the short side.
Also you might be better off getting rec tubing with .09
wall thickness. Some couplers are a little thicker on the
shank.
Scott

[Makinsmoke40]

Will,
I think Mountain Car Co. uses that type of tubing, and I did not notice ant grinding on the three cars I helped a bud assemble. Maybe they use thinner wall material?
One other thing. Why not just touch up the coupler shank instead?
Brian

[ehulshiz]

How about a Broach? You could make an adjustable tool holder and drive the broach through the tubing, cutting the weld out a few thou at a time. just like cutting a keyway.....

[gmacoffline]

if you are really desperate:

1 mount a small round ( cylindrical) stone near the middle of a piece of bar stock twice as long as the part you need to grind, these parts of the diameter that will fit inside the tube.

2. thread the square stock over the bar and hold the bar between centers or in the headstock and a live tailstock, in the lathe.

3 remove the toolpost and clamp the tube horizontally to the cross-slide, spacing and aligning it square and parallel to the bar with the weld on the vertical side closes to the operator. advance the tube into the grinder using the cross-slide. travel using the leadscrew or the handwheel/rack.

4. same setup works using a horizontal milling cutter but the welds may tear up the cutter.

[jpfalt]

HF has a belt sander attachment that fits on their 4" and 4 1/2" angle grinders. The end is about 1/2" wide. That may work well for you.

On the other hand, consider putting a relief cut in the mating part to clear the bead. This requires that the bead be oriented in tube parts so that the mating part will consistently mate up and clear the weld bead.

It's also possible to put a hardened mandrel that fits the tube and use a HEAVY soft hammer on the outside of the tube to push the bead to the outside where an angle grinder will knock it off quick.

[GeorgeGaskill]

so even for a long piece, you could epoxy a long handle to a file (probably have to make the connection in the middle of the file instead of the tang) and stroke the file through the tube. You could add a flat spring to provide pressure on the file when it's deep in the tube.

[raylrodr]

I guess I don't understand the problem at hand. Most of my large files are like 10" long....and most draft gear applications that I have dealt with (scale) are only around 4" deep....what am I missing?

[Chris_W]

I had a trailer hitch receiver built for a truck about 20 years ago and the guy got rid of the seam with a small tip on a gas welding rig. He just worked back and forth over the bead until it was smooth enough for the hitch to slide in. Granted, it was 1/4" wall but this trick might work on the small stuff.