cutting and rewelding tubing

[s27sam]

Hi, I wanted to see what you guys thought about cutting and then rewelding a main hoop in the roll cage part of the frame. I'm not to that point yet, but just wondering in case it comes up. I'd be using 1.5in .095 DOM if it makes any difference. Obviously I'd rather not, but I have read about people shorting their upper bars if they were too high, and it seems like it would be pretty difficult to have to take a whole bar out.
Thanks,
Sam

[yoshi]

Originally Posted by s27sam

Hi, I wanted to see what you guys thought about cutting and then rewelding a main hoop in the roll cage part of the frame. I'm not to that point yet, but just wondering in case it comes up. I'd be using 1.5in .095 DOM if it makes any difference. Obviously I'd rather not, but I have read about people shorting their upper bars if they were too high, and it seems like it would be pretty difficult to have to take a whole bar out.
Thanks,
Sam

long as you sleeve the tubing with another piece of tubing on the inside you will be fine, it will actually be the strongest part of the cage at that point....

[s27sam]

Do you drill holes in the outer tube to plug weld it, or ...? Also, how close can you get to the ID of 1.5in tubing to fit inside?
Thanks,
Sam

[s27sam]

Also how far should the inside tube slide into each side of the cut tube?
Thanks

[yoshi]

I use about a 3 to 4" long piece every time I sleeve tubing. 1.5" tubing will prob. need some 1.25" tubing to fit inside. Hopefully it's a little bigger so you can turn it down on a lathe to be a nice fit. I stick it half way into one of the tubes, weld it all the way around with a tig, then put the other tube on leaving about an 1/8" gap. I then tig it up and it welds all the way around both tubes and the sleeve. I then sand the weld down to hide the seam...

[s27sam]

Thanks a lot Yoshi
Sam

[boilermaker]

I agree with Yoshi except, you only need just a short piece 1/2"-3/4" and inserted and welded like Yoshi does. When i used to weld boiler tubes we sometimes used a "chill ring" which was a close fit between both pieces of tube and was to allow a hot, full penetration weld and that is all thats needed. In this case the tube inserted inside will help aline the splice and give a backup for the weld.

[evan]

1.25" will be a loose fit. 1.5" - .190" = 1.310". Carroll Smith (author of the bibles) suggests the cut be angled (45-60deg) and a sleeve length of 5d. Either way im sure you'll be fine as the material is more then sufficient.

[dillon_b12]

Originally Posted by boilermaker

I agree with Yoshi except, you only need just a short piece 1/2"-3/4" and inserted and welded like Yoshi does. When i used to weld boiler tubes we sometimes used a "chill ring" which was a close fit between both pieces of tube and was to allow a hot, full penetration weld and that is all thats needed. In this case the tube inserted inside will help aline the splice and give a backup for the weld.

I'm going to have to disagree with you on using that short of a sleeve length. I think you would be much better off with a couple inches of tubing that a tiny little .5 or .75 piece. On your boiler tubes was there any kind of exterior load being applied to them like the potential impacts/crashes a mini-buggy will see? If it was just internal pressure I can see how what you are suggesting would work great. I just think for a buggy a little longer sleeve length would be beneficial. At the very least, it's not like that 2" of tubing is going to make or break your buggy as far as weight goes.

[TutTech]

I agree with Dillon b12, when your dealing with an impact or a bar bending having extra inside is a great way to go.
I personally cut a 6 inch piece mark center and slide 3 inches in both ways.
I then leave an 1/8th inch gap or so (whatever you feel comfortable as a gap to weld closed.) I leave a gap so I can penetrate down to the sleeve inside and build up onto the two sides really conecting everything together. When done you should have a great looking weld actually.

I just did this on my car and I do it on my bumpers to double wall them and add more strength to them from impacts etc.

If you are using .120 wall tubing then the next size down is a perfect fit and you have to lightly tap it in. Very cool and what I do on my bumpers etc. Really nice.

.095 is going to be a little loose if you slide a piece of 1 1/4 inch inside it.
You can do it but it will be a little loose because tubing stays true to the outside and thickens to
the inside. .120 by 1 1/2 inch with a 1 1/4 is what I use on all my frames and they work great.

Anyways I am sure you can find something to work and yes it is very common and done all the time
safely so I am sure you can do it no worries.

Good luck.