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Rotisserie Takes Shape

December 15th, 2011

Shiny Metal Good Mask for Cluelessness

I made a lot of progress on the pig motor today.

I decided not to use welds for all of the fabricating. I had a steel plate scrap I planned to use as the mount, and it turned out it had some holes in perfect locations for bolts, so I decided to bolt it to the steel-tubing upright that will hold it up. It also has a couple of curves that make it fit snugly against the tubing, and they should add rigidity.

I took a piece of square tubing Val Prieto gave me, and I cut it to length using the grinder. I have faster cutting tools, but the grinder was handy, and it’s a little more artistic. Then I put a wire brush on the grinder and cleaned the metal. Wire brushes on drills and drill presses are pathetic compared to the ones that fit on grinders. Take my word for it. The only problem is that they throw bits of sharp wire all over the place, and they can actually fly in curved paths, so you really need a face shield AND goggles.

I opened up the holes in the plate. They were too small for 5/16″ bolts. This was not fun. Holes in sheet metal don’t like being opened up with drills. My drills kept catching. Surprisingly, they also caught when I drilled a fresh hole. I have no idea why. I ran the drill slowly and used pipe threading oil.

I used the drill press and my snazzy South Bend vise to drill holes in the tubing, and then I mated the tubing and plate, and it was beautiful.

I realized I needed reamers. That’s what you use to open existing holes and make them round. I’m trying to find out what kind to get.

Incidentally, I found out there’s an amazing tool called a bridge reamer. You’ll love this. If you’re doing what I did tonight–drilling a bunch of holes that have to line up and take bolts–a bridge reamer is what you need. Apparently it takes your crappy, misaligned holes and makes them pretty and makes them line up. I think. Anyway, that’s what the Enco catalog implies. I need a couple of these things. If they work as advertised, they would be incredbly useful. Making holes line up is not easy.

I only put one hole in the plate. I installed the motor and tightened the nut, just to see how it would look. I can’t put the other holes in until the bearing is installed. The bearing will tell me where the holes have to be. If I do it now, I could be off by an eighth of an inch, and then I’d have to commit ritual suicide.

Here are some bad phone photos.

The bearing will rest on a horizontal piece of square tubing perpendicular to the motor shaft. The tubing will be welded to the side of the upright tubing.

You can’t see it, but there’s a lot of room to the right of the motor. I’m going to get a light switch and put it there, in a nice box. That will allow me to turn the motor on and off.

I’m working on the charcoal pan. I found aluminum sheets today for about $14 each. They’re only 24″ by 36″, so I may have to use two. I would prefer this to galvanized. They won’t rust. I keep reading that aluminum will take the heat of barbecue charcoal. I hope that’s right. I can do a test tomorrow with a small piece of aluminum.

The motor shaft is a little loose in the 1/2″ hole in the hub I made. On top of that, it has a key instead of a flat spot. That means I have to make a keyway. I plan to do that by sticking a ground tool in my lathe tool post and pulling it in and out of the hub. But I think I need to make a new hub, because the looseness will be a problem. Unless the bearing allows some movement (search me; I haven’t seen it yet), I think any eccentricity in the pole’s fit will cause problems when the motor operates in its rigid mounting. If there is play in the bearings, I’m fine as I am.

I love the way that polished steel looks. I want to paint it, but that’s pointless because the burro will gouge it up. I think I may season it like cast iron. I’ll throw it in the oven with oil on it. It will look good, and it won’t scratch like paint.

The steel plate has to be shaped a little, because the bottom edge is rough from plasma cutting. I think I’ll use the bench grinder. Then I’ll clean it up and blast it with truck bed paint, which should last forever.

The other end of the apparatus will be a joke. A bearing, a T-shaped piece of metal, and some bolts.

It looks like this is going to work, and when it’s done, the whole thing will fit in a very small space. The burros go back to Val until the next pig event.

Stay tuned for more updates.

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This is really sad. Someone just suggested I use step drills for enlarging holes. He’s absolutely right. And I already have them! I can’t believe I didn’t think to use them.

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2 Responses to “Rotisserie Takes Shape”

  1. Ed Bonderenka Says:

    I don’t have a broach kit for key-slotting a hub, so I plunge mill with an end-cutting mill. This leaves a radius where a square edge would be left by a broach, but the key won’t rise into it, especially with a set-screw tapped in to the hub to hold it down.

  2. greg zywicki Says:

    I was going to express some doubts about aluminum and charcoal, then I remembered that cast Al dutch ovens are very common, so there you go. As long as you don’t supercharge it with a fan.

    When are you going to move from all them sissy cutting and forming tools and cast your own metal to-shape? Just a notion.

    In an unrelated area – there’s a game availlable know that hooks a real guitar to a computer…Seems like a must-have.