Another Rebirth For The 3b

You could probably market a vertical drum sander with a 45° grinding wheel for this purpose.

 

A carbide chop saw with a decent jig would’ve taken a lot of work out of the job.

 

I have plenty of scrap…

 

Damn fine beveling.

 

This is where using a wooden bench shoots me in the foot. Normally, on a steel bench, I could weld scrap to the top to form a jig as I tack these pieces together to keep them from moving on me. With a wooden bench, I have to try to clamp it the best I can, then chase warps with opposing tacks to counteract the draw from each previous tack. It’s a time-consuming game of cat and mouse.

I got the front section tacked together and straight within 1/32”, then I stacked the other side’s pieces up against it to make sure they’re identical. (Sorry, no pics of that part. I was in a zone with Slayer cranked up to 11.)

Then I slid the whole assembly forward and down to the edge of the bench so I could use the straight edge of the top as a guide. I made a guide line 5” from the edge, used 3” spacers, and I used the speed square to locate the rear sections.





I’m happy with this so far. I’m sure it’ll move all over the place when I finish weld it; I’ll have to pull it back in place with fire.



I’m leaving the front and rear sections extra long until I figure out a plan for them. I might let the rear protrude past the body so that a tire carrier can be built from it, rather than adding to it after-the-fact like we normally have to with old jeeps. It would also allow more room for a bigger gas tank.

 

Oh that’s so horrible.

 

That might be my new favorite song.

 

What? No sections of angle iron and plate welded together?

 

I’m not as desperate as when I was 19.

 

I had a solid five hours to work on this this morning, rather than my usual two. I got the frame rails fully welded and mocked up in place with some temporary crossmembers.



And for those interested in the process…

Here’s a shot of the part I forgot yesterday because I was busy rockin out. The measurements and angles don’t have to be perfect as a whole, but they do have to match side to side. Stacking them like this to tack them ensures a mirror image.



Since buying another 33# spool of wire is a pipe dream at the moment, I’m stuck filling these craters with .030” wire. So rather than fry my brain on the concentration required to fill that gap and not blow through in a single pass, I went with a root pass first, then a fillet on the second pass.





I checked the penetration inside the tubing, and you can’t ask for much more than that.



The straightness was well in-check after the root pass, but the final burn-in blew it all to hell. It’s going to take some flame straightening with the torch to get everything back where it should be. But, that was expected. It’s just part of the process.

 

Nice job...

 

Here’s a cool time lapse I just shot of some flame straightening.

https://youtube.com/shorts/VkVO1dMHI0s?feature=share

 

Two days of hitting this with the torch (I had to quit early yesterday because I ran out of O2), and it’s finally perfect.



After welding, when clamped in the middle with 1/4” spacers to hold the weld fillets apart, the front rails were mashed together hard and slightly different heights (see video), and the rear was a mess. They should’ve been 6 1/4” apart and parallel, and they were, well…



I was most concerned with the levels of rise matching.

I don’t have a great way of measuring/adjusting that after it’s together down on the floor. Any lateral movement can be pulled or pushed in place as the crossmembers get welded in, and the act of welding them will just make it walk again anyway. But the height is another story; using the short sides to pull the long sides of the tubing is a lot harder than heating/cooling the 3” to bend the 2”.

Out of the 40’ of material I bought for this, this is all that’s left after accounting for four crossmembers.



The two lengths up top are for the cage outriggers…. which I tacked in while the rails were clamped together.



I had just enough time left this morning to get a few crossmembers tacked in place. It’s now ready to drop it down onto jack stands and stick the axles under it to start figuring out suspension linkages. Permanent crossmembers won’t be fit until everything else is in place.

This thing is heavy!

 

Impressive work.

I'd have thought that the frame rails would move back after cooling down.

 

Every time a weld is made, the weld and surrounding metal expands, then shrinks as it cools. In a perfect world, you can weld opposing sides with alternating welds with equal cooling times in between to counteract any warping. But that takes a lot of patience and planning.

The closer to complete that a joint is welded, the stiffer it is, and the more it resists expansion as it heats, until the hot area reaches a temp that is hot enough (soft) that the expansion can happen within itself. The stress is basically relieved within itself while it’s red hot, but then the contraction during cooling is still present.

So a weld joint will almost always shrink, but the first weld will appear to shrink less than the last joint, because the first joint could expand and contract, whereas the last weld can really only contract.

Throw long welds into the mix, and a warping action is added. The heating/cooling, expanding/shrinking process is dragged across a long distance; the back of the weld is shrinking while the front is expanding, and the effects are pulled across your work like caterpillar tracks.

 

And when you consider the length at 10 feet long, it only takes 1° of deflection to be 2" out.

 

When I made my frame, I had very little deformation. I also used long lengths of material and there were no angles. Real simple. I'm pretty sure if I made this, it would be all over the place.