A-frame for lifting

[cdhd2001]

I am going to build an A-frame to attach my 3-ton chain hoist to for lifting miscellaneous stuff, but primarily my 500 pound Miller welding machine. I am basing the design loosely off of one my dad built and uses. It will be made from a 4"x4" square tube 1/4" thick and 10 ft. long with legs built out of 2 7/8" sch 40 pipe. Cross braces on the legs will be 2 3/8" pipe. I want to build the A-frame 10 ft (maybe 12 ft.?) tall.

So, my only uncertainty is how far apart do I set the legs at the ground? Closer to vertical is stronger, but will tip over. Angle them too much and the pipe legs will bend. Any suggestions on the "perfect" width or angle?

 

[George2615]

I have an A frame style gantry with a chain faul and an 800 lb electric winch I use for lifting just about anything. I've attached some pics though they may be hard to see details with all the junk in the way.

The I-beam on top is 6" H x 3" W x 11'6" long and is bolted to a 10"x20"x3/8" steel plate on each side. (6 bolts per side) Top of the I-beam is 10'7" from the floor. the overall 11'6" width lets me put a car or truck under it for pulling motors.
The base on each side is a piece of 6"x2"x 4'8" long rectangle steel with 6" steel swivel wheels welded on to roll it around.
The uprights are 2"x2" angle steel (4 per side) and are welded to each 10x20 plate on top and the base on each side.
The whole thing is built kind of like a big heavy duty swing set on wheels. My Dad bought mine used many years ago and I inherited it. It says it has a capacity of 1 ton but its held a few more pounds than that at times.

Hope this gives you some ideas how to build yours.