Farm Boy Chassis Rotisserie

[baxsie]

I was reading Hondapop's 75 Super elecric vehicle (ev) build, and I instantly liked the Chassis Rotisserie he had borrowed from his local club.

I had always thought of a car rotisserie in terms of what you would need for a US automobile . . . kind of a fully framed structure where the front and back are connected. I had never thought of just letting the frame/chassis of the bug be the "axle" of the rotisserie.

Well we have a lot of chassis work coming up on the 1975 LaGrande Super Beetle project, and my son needed some welding time, so I bought some square tubing and we put this together:

95% of the welding here was done by my son, which probably tripled his experience with the welder. I did a bit of the fussy parts at the clamp.

The construction is fairly simple.

The mounting of the axle to the chassis must be solid. In the back I used some 3"x1/2" strap, and that is still a bit on the flexy side. The front uses 2" square tubing (capped for rigidity) and 2" x 1/2" strap.

I wanted the rotation to be smooth, and I wanted to be able to lock the rotation firmly. To this end, I used 2" 0.120" wall DOM tubing for the outer sleeve, which has a nominal inside diameter of 1.760". The inner tube is 1.75" OD, which leaves a tight 0.010 tolerance. Surprisingly, the de-burred tubing slides nicely one over the other. Well, that is BEFORE welding. After welding, we had to work quite a while with a cylinder hone to remove the imperfections created by the heat of welding.

It was a lot of work, and about did theat cheap HFT hone in, but having the nice close tolerance allowed us to make a clamp that works great.

OK, here is a dump of the construction photos.

Fitting the massive 1/2" x 3" rear strap:

Mitering the outer pivot sleeve to the apex of the frame:

Welding the inner pivot to the rear strap. That is my son's work with the MIG. The stop collar is already in place :

We used the cutoff saw and Dremel to slot the pipe for the clamp. We intentionally left the bridge until after welding/honing so stuff would stay lined up:

Clamp fitting before welding. 1/2" square nut fits great in the 1" square tubing:

Shot of the finished clamp:

Here is the assembled rear pivot and clamp:

This is the front brace, ready to have the inner pivot welded to it. Keep in mind that it does not sit perfectly flat . . .there is like a 4 degree slope that we compensated for with a slight angle cut on the inner pivot tube:

Test of the rotational holding ability of the clamps:

Another (now boring) check of the rotational holding ability of the clamps:

[mgamike]

Very nice. What size MIG welder did you use?
_________________
77 Convertible

[baxsie]

It is a "Millermatic® 211 Auto-Set™ with MVP™":

http://www.millerwelds.com/products/mig/product.php?model=M00245

[Q-Dog]

Nice work. That should make things a bit easier.
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Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle