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davit advice needed

I am making a davit for a hoist. The davit (imagine a figure 4 with a long leg) will be about 14' high, with about a 3' crosspiece. A diagonal will go from the top down to the crosspiece. An electric hoist will be put on it.

At the bottom, I want to pour a SonoTube concrete base. The top will be attached to a roofing timber.

My question is about the base. I had imagined just welding a large washer to the base of the 2" x 2" x .250" tubing. Then, in the SonoTube, I would place a round rod post with a washer welded on there. Attach it by welding to a rebar frame to distribute the load. The washers would rub face to face, with some lithium grease on them. I figured I would stack at least a couple of spacer washers on there to keep the welded ones from wearing.

This will be out in the weather 24/7. Snow, rain, sunshine.

I was wondering if I should use some kind of bearing, and if so, what kind? Mounting a round bearing to a square tube would require some kind of adapter unless I could weld it on direct.

This is going to get minimal use, only turning 90 degrees, and being used maybe half a dozen times a month. No heavy wear.

What would you do? The simple washer thingus, or a bearing? Somewhere I could get a baseplate/bearing combo?

OR?

Advice appreciated.

Reply to
SteveB
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Make the washers yourself and make them thick enough to drill and tap for Zerk fittings so they can be greased. Turn a small grove in the washers face for grease distribution. Sandwich a thick bronze washer between the two fixed washers. Should last pretty much forever with periodic greasing.

Pete C.

Reply to
Pete C.

To be legal you must use a davit approved by the American Flange Institute, known as an afidavit.

Sorry, couldn't resist it.

In more of a helpful vein, don't trust welded rebar. Rebar can have fairly high carbon content and become brittle with welding. Use mild steel or HRS bar. Some HRS also has some carbon content, but usually less than rebar; it'll be OK if not quenched after welding.

Reply to
Don Foreman

Snip , I would place a round rod post with a washer welded on there. Attach it by welding

Welding to re-bar=BAD. The heat weakens it right at the joint. There is no need to weld to the reinforcing . The load will be distributed though the concrete. Be sure to circle the vertical bars with hoops of thin re-bar. If the verts are #5's the stirrups can be #3's. If the verts are 6's or larger the stirrups should be 4's. I'm not an engineer, just passing along what I've seen and tied for 30 years in the commercial construction business. Tom

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Reply to
Tom Wait

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