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View Full Version : Converting fixed position rotisserie to adjustable height



chevynut
12-31-2014, 02:39 PM
I bought a rotisserie a few years ago from a fellow tri5 enthusiast for less than the steel and parts to build one myself. When I assembled it, I realized it was awfully tall so I decided I needed to do something about it. The center of rotation was about 62" off the ground, and with the arms around 14" below that my car would have to be at 4 feet off the ground to load it onto the rotisserie. I don't like having it that high off the ground. So I wanted to drop it as far as possible while still being able to raise it up or 360 degree rotation. The answer is to modify it and add hydraulic jacks.

I don't know the brand of the rotisserie, but it seems really well built and has a nice safety feature in the rotating head assembly. There are two locking bolts, and one of them goes into a groove so the head can't come apart when the bolts are loosened to rotate the body. I don't know if all rotisseries have this, but I thought it was a good idea.

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The problem with this rotisserie is that the rotating head is on TOP of the vertical post. This means there's no way to lower it as I'd like to without locating it forward of the post. So the first order of business is to cut off the heads from the posts.

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After cutting through the welds with my horizontal bandsaw, I ground the remaining weld beads off of the posts and cleaned up the underside of the heads. The posts are only 1/8" wall but they're 3" square tubing. Since a bare tri5 body only weighs around 600 pounds at the most, that's only 300 per end and I think the 3" x .120 tubing should be sufficient. I think most guys over-build rotisseries anyhow. :)

Now I need to pick up some 3 1/2" x 3/16" wall square tubing to slide over the posts. I already have the two 3 ton HF jacks which only set me back about $100 for the pair.

I found out that you need a minimum of about 41" between the pivot point and the top of the rotisserie legs, and I plan to make this one go to about 44".

chevynut
01-01-2015, 04:47 PM
Got some 3 1/2" square 3/16" wall tubing yesterday and slid it over the vertical post. Looks like it's going to work out well. Still trying to figure out the heights but I'm getting close. I tacked the rotating heads to the sliding tubes. Made some brackets to bolt the upper part of the jack to the sliding tube and still have to make the lower brackets. The way it's put together it makes it a bit of a challenge to get the jack mounted.

Rick_L
01-01-2015, 07:56 PM
The uprights on mine are 1.5" square tube with 2" x 3/16" wall fittings that fit over the 1.5" tube. No problems structurally.

The only problem with my setup or yours is that you may have a friction problem with the outer tube "cocking" on the inner tube if you try to use a jacking setup. The weight of the body will only let it go up easily, or down easily, depending on the geometry.

I have considered building a "bearing box" with UHMW for sliding bearings for such a setup. The "box" would probably have to bolt together. So far I've lived with what I have. It's adjustable, but without the body on it.

chevynut
01-01-2015, 08:48 PM
Rick, I was wondering about the friction myself. My outside sliding tubes are pretty long, almost 30", so that should help to keep it from cocking. I had to put the jack on the opposite (back) side as the arms because there was no room under the rotating head to get it as low as I wanted to since the jacks are 22 1/2" compressed. So there is added force pushing it the wrong way. I noticed that some rotisseries have the jack quite a ways inboard of the upright, and I assume that's to help with the friction.

At Goodguys I saw the Auto Twirler booth and they had bearings on their sliders on one model they showed me. I don't remember what they looked like. I may consider some kind of bearing if friction is a problem.

I ended up going with 42" from the center leg to the center of the pivot. I really want this thing to be as low as possible when it's all the way down, to make it easy and safe to load the body. The jacks have 20" of stroke, so the center of the pivot is 22" above the leg at the lowest point. Then the mounting point should be 12-15" below the pivot or 7-10" above the leg. The top of the leg is 9 1/2" off the floor so I'm looking at 16 1/2 to 19 1/2" loading height. That seems pretty good.

Rick_L
01-02-2015, 05:39 AM
I think my outer tubes are only 12" or 15" long, so 30" tubes will really help with the cocking of the tubes.

Putting the jack on the outside will just reverse which direction the tube cocks when you try to move it. I doubt if that's a big deal.

chevynut
01-03-2015, 08:51 PM
Well HF sure has some screwed up specs for their long ram jacks on their website. :( They say they're 24" minimum and 44 1/2" maximum height with a 20" stroke.

http://www.harborfreight.com/3-ton-heavy-duty-long-ram-hydraulic-jack-36396.html

Those dimensions should lead you to question the specs from the beginning. I measured them at 24 1/2" minimum height out of the box and assumed the stroke was 20". So I set up my mounting brackets with the rotating head at 22" and tacked them on. The extended height didn't come out right and I didn't understand why. Come to find out the box says the stroke is 19 1/4" with a minimum of 24 7/8" and a maximum of 44 1/8". So in the end I set the bracket so I got 42 1/2" to the center of the pivot with the jacks all the way up and didn't worry about the stroke or the minimum height.

First I fabbed some 1/4" thick brackets to go on the bases of the uprights and welded them on. Then I attached the jacks with 5/8" steel pins.

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Then I welded the rotating head assembly to the 3/16" wall sliding tube, welding completely around it. I fabbed some brackets out of 1/4" steel plate and located them to get the right height at full jack extension.

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Here's the jack at full height of 42" at the center of the pivot.

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And here it is at the lowest point....I believe it's 22.75" above the leg:

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I don't think it's needed, but I'll probably weld a gusset under the rotating head "just in case". There's a fair amount of leverage there and I'd rather be safe than sorry.

So a little work on the attachment arms to the frame, probably adding some more locking pins, and I think the rotisserie will be ready to haul my frame to the paint shop. Hopefully that will be in the next few weeks.

chevynut
01-16-2015, 10:20 AM
They're finished! Installed 1/4" steel gussets and squirted a little paint on them.

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