Fishing for Tubing/Pipe Cutting/Welding Info for a Project

I have quite a bit of large diameter, fairly thick-walled pipe and about 20 feet of big C-channel. I want to make a shop hoist. I've cut the pipe to length. I need to make a few joints where I need to make a perpendicular joint with a pipe butt welded onto the pipe tangentially.

I'm hoping that the pictures come through.

One picture shows the pipe fresh off of the chop saw; so you can see the wall thickness. The white stuff is whitewash. These pipes are from some barn demolition. They were used as uprights; until the bottoms rotted out from acids on the barn floor. (manure and such)

Another shows a test cut made with the torch. Note. When I make the real cuts, it seems that I should do more grinding and wire brushing to get the old whitewash and possibly old galvanizing off of the pipe to cut more cleanly.

Another picture shows the rough layout of one side of the hoist. The longest piece is the bottom. The two pieces perpendicular to it are the uprights. The short piece between the uprights at the other end is a brace to hold the frame square.

This is what I'm thinking about. I want to use a torch to cut the butt ends roughly into the properly rounded "bird's mouth" to mate perpendicularly. I can finish the shaping with a grinder/file. Then I can weld.

How do I minimize making the joints brittle?

Will the torching make the end of the butt brittle? If so, would that be helped by torching to a rough shape and leaving more metal to grind off?

What about quenching the actual weld. Should I just let it cool naturally? Try to heat it a little? Try to cool it faster?

Maybe I'm just worrying about nothing, but...then again...maybe I should at least think about it. Dropping an engine would be sort of a disaster...ya know?

Hello, first off, I doubt the wall thickness is heavy enough. And I wouldn't be using old
pipe! If it were me I'd go to buy/find a cherry picker,new or used and be SAFE! You can buy
a decent one at Harbor freight. Just my .02 Cents worth...Jim in New Mexico

If that's galvanized pipe, it's going to be difficult to work with. It's not intended for structural use. The galvanizing is going to cause problems both cutting and welding. Don't want to breathe the smoke!

But if that's what's going to be used, try grinding the galvanizing away first. If you can find a plasma torch, that will make the best fish mouth cuts without all the heat spread.

I understand the caution about the pipe. If you look at the cut end, you have to remember that the pipe is four inches in diameter. The diameter and wall size is comparable to 4" schedule 40 plastic.

What you see on the ground is the frame for one side of what I'm making. It will have another whole frame on the other side that's just as heavy. It will be spanned by two C channels.

So, in the end, the weight of a 2.0liter Kia Spectra engine will be held aloft by 4 pieces of 4" diameter steel pipe. I'm feeling pretty confident about that.

The reason that I'm avoiding the cherry picker is that my first job is dropping the engine cradle from a Kia so that it can be replaced. Gotta love NY state winters. The cradle on a 10 year old car is getting too rusty to hold up the engine.

Anyway, the "legs" of a cherry picker go right under the engine. I need space under there to work. I had all of this large diameter tubing and two pieces of C-channel just laying around. I've seen other types of small engine hoists that are gantry crane style. They usually have a single upright on each side and a heavy I or C beam spanning the engine, along with some serious diagonal bracing on the sides to prevent spreading.

I figured that I'd give it a shot with all of this scrap that I have around. I'm confident that there is enough metal in the design to do the trick, but I want to make sure, as best that I can, that the welds aren't any weaker than they could be.

I've attached another picture to show the C channel that's going across the top. Remember, two uprights on each side. Two C channels going across. Everything welded together to form a box on the ground and in the air.

Are there still worries about the size of the metal? (I'm asking seriously) I've looked at the little harbor freight lifts. The wall of this tubing is at least as thick as what they're using. The C channel over the top is way, way, thicker than anything in those cherry picker types that I could pick up for maybe a couple hundred bucks.

Another shot at getting that photo up.

I think you'll be OK, didn't realize that was 4".

Sounds like you have a plan!

I hope so.

I do have some 2" pipe as well. I was thinking about how to best use that to add some strategically placed "spines" to the 4" stuff to improve flex strength, as well as diagonal bracing for sideways racking.

I will grind all surfaces to be welded, though, like you said. There's no reason to take the risk that there's some galvanizing zinc in there to foul the weld.

I'm working at my garage door on warm days for ventilation.

That's the biggest pain for this project. We had about a week of 30 degree highs and rain and snow and crud recently. I've had to wait until this past weekend for the type of weather where I could work with what I would consider adequate ventilation.

Next week, I'll probably be sweating so much that I can't see. Such is spring in good old Upstate NY.

I'll post some pictures of the completed assembly to get critiques.

I would fish mouth the uprights. That way the cross piece is setting in a saddle. The weight of what ever you are lifting pull the cross piece into the saddle. The welds are not holding the load that way. They are just keeping it together.

You could also turn the chop saw 45 degrees and make mitered joints. Easier than trying to cut fish mouths into the pipe ends.

Another thought is to take some of the waste cut off ends and try and weld them together. Make sure you can make a good solid weld. Look inside and make sure you have penetration.

You can cope the pipe with a hole saw . or get it close with the torch and grind in the cope. Use a 7018 for fillet welds. Never quench any weld ,let it air cool . Good fit up before welding and you won't have any weak spots.

Read my mind on that one.

I was thinking of doing the same thing.

As for the cross piece on top. It's strictly bracing. I'm going to set the C channel right into the end of the uprights. The cross piece won't have to hold the weight. I'm thinking of adding some additional "spines" with 2" pipe to help transmit the load down from the top and spread it on the bottom pieces.

I know that I could buy a hoist, but I have all of this metal. I'll also admit that I wanted a project for a cutting, welding and design exercise.

Grinding the galvanizing back is great. You also might consider preheating before welding since you don't know the metallurgy of the pipe. Doing a test weld as suggested is a good idea. If you only have an AC welder you might do just as well with 6011 rod. It does well with poor fitup. If you are unsure of your joints you can apply some plate gussets to reinforce them. Also a good idea to proof load before you start using it. Hook it to your truck bumper and pick it up a little ways. You'll know if something starts to bend or warp. Then let it down and check all the welds. You'll have more confidence when lifting something lighter.