Ok, I know this conical latch idea of mine is flakey but bear with me. I got some things tacked up today to see what was what. First is the upright that will hold the spare tire. In my last post I said how I had to make an adjustment to get the upright close, but not too close, to the back of the van.  My solution was to cut and bend the upright to mirror the profile of the rear of the van. Here are some pics with the upright (not fully welded out yet) roughly in place. My swing away arm is just clamped to the stock bumper.

I think this might work.

Ok, on to the latch. I tacked welded a bit of U channel onto the upright and I also bored a hole for and tacked in the short section on alluvium tube that you saw in the previous post and that houses the female Delrin part of this cockamamy set up. Here is the latch assembly more or less assembled. But some notes of explanation needed. Of course the threaded rod has not been cut down to size yet, and that metal but you see right against the left most flange represents the back stop I have yet to weld to the bumper. the two flanges meeting (and I think I might slim them down a tad) are the male and female parts in tight congress.. on the right hand side of the box section upright you can just see a trimmed down nut on the threaded rod, the thread rod, then the hand wheel. See the collar in place inside the “cage”? I need to make a set screw for it. The collar does two things, keeps the hand wheel from falling out of the cage when it is unscrewed from the rod, and when the hand wheel is turned to unscrew from the rod the collar pressed against the cage and pushes the upright away from the back stop.

I really am not doing a good job of explaining this. You’ll have to wait for a video or something.

Face on view. Aren’t I a clever fellow making 5 holes in the hand wheel reflecting the five holes in the vanagon wheel? It’s this attention to useless details that distinguishes my crazy ideas from other crazy ideas. 🙂

(Here’s something educational.  Click on the pic to bring it up in a new tab, then zoom in on the tack weld on the left side of the fully visible seam.  You can just make out a hairline crack on the tack. This happens because the heat sink of the thick walled box section tubing draws heat away very quickly from the cooling puddle of the tack weld. To reduce the chance of this happening I should have warmed up the tubing, it was pretty well dead cold. )

Male and female separated. Time for a smoke.

I think I can weld out everything now, and trim down a few of the moving parts.

Update: 21/02/2014.

Dirk over on the IG16 syncro forum expressed some concern that the upright being made of aluminum would waggle back and forth like one of my dog’s tails. Any time a German engineer gives advice it behoves one to listen 🙂 . So today I welded up (not very well, i was rushing) the upright and tacked it to the swing arm, and I cut out a reinforcing piece to weld in (3/8″ thick 6061 stock).  I am almost positive now that things will be wedding night stiff  when finished.

I’ve been amusing myself (!) by attempting to make a latch for the swing away tire carrier that’s going on my aluminum bumper. I have this almost unreasonable desire to make sure the horizontal arm of the carrier is fixed hard against a back stop on the bumper. I know other designs use an over the centre draw latch mechanism, and I am sure they work well. But I got in my head that I wanted to try another approach.

The back stop mentioned will be a sturdy bit of aluminum plate welded vertically to the forward top edge of the bumper. Something like a 4″ X 6″ bit of 3/8″ plate. It will be positioned at a point on the bumper were the end of the swing arm end up when the arm is “closed”. Now imagine a truncated cone projecting horizontally back from that plate that fits into it’s female mate that is in the swing arm. The cone arrangement will, I think, locate and secure the arm to the back stop.

Instead of a draw latch I decided to have a captured screw handle on the swing arm. This screw handle will engage a threaded rod projecting out from the male cone.

Yeah, it doesn’t seem very clear and I don’t have a sketch of my idea. But here are the parts I have made so far.

From left to right: hand wheel/screw handle, male cone (will be attached to back stop), female cone partially inserted into bit of tubing that will be welded into the swing arm.

The cone couple. 10 degree included angle, made from Delrin. It is a tight fit into the aluminum tube that will house the female cone. A bit of glue and a couple of countersunk screws on the flange will hold the Delrin in the aluminum.

The hand wheel (going to call it that from now on) is made from scrap aluminum with a centre section of stainless steel pressed in. I mean really pressed in, a shrink fit. I heated the aluminum and drove the stainless into, the somewhat enlarged by heat, hole. Then I fancied it up with a turned recess and some holes. The stainless centre is threaded for 1/2″ NC.

The other side. The narrow section will be inside the “cage” that I have yet to make that will hold the hand wheel to the swing arm.

Arranged in order.

I had to make a collar to put on the narrow portion of the hand wheel to stop it falling out of the cage when unscrewed from the threaded rod. Of course I broke the damned tap when i was threading a set screw hole.

Grr.

I didn’t want to make another collar so i ground down the stuck tap (carbide burr on die grinder) and drilled for another set screw.

I was so pissed that i broke a tap I didn’t get the new hole exactly centred on the collar. Too bad, thats the way it is.

Enough of this for today.