Hi all,
Trying to tap here the collective wisdom. There is this kind of wrench I will need to use to open up a large hydraulic cylinder and it takes a 3/4 in drive breaker bar, which I don't have. Looked around and they're not cheap; now I don't mind forking out for a good tool that will be useful in the long run, but I'm afraid this will be a one time use most likely.
Question: have any of you tried to make a square 3/4 in drive out of 3/4" or 1" round bar? I guess it won't be as tough as a proper Chrome Vanadium bar, any other issues you see with going this route?
I also modified my biggest adjustable wrench to give it a pin wrench capability. It's an 18" x 2.5" adjustable wrench and it can remove the glands on any cylinders up to around 4.5" OD.
My understanding is that on old large cylinders (like 4" diameter) some excessive forces might be needed to open them up. Just because the pins coulde span the 4" it does not always mean you can actually open up a large cylinder. Also, the pins must have a good firm grip on the holes, otherwise you'll deal with something a lot worse if the pin holes in the cylinder cap get damaged.
In any case, I wasn't going to risk that, and ordered the wrench in the picture above, but it needs the 3/4 in drive.
Bob, I considered an adapter, but I'm not sure it would be strong enough to take some big forces (i.e. long extended pipe on breaker bar).
I have a long 3/4" breaker bar and even with the big equipment it doesn't get used much, so I get what you are saying. I think you can make something. A handle from something that doesn't bend, maybe some square tube. The right square stock to go into socket, hard enough it doesn't twist under load, but not so hard it would shatter.
Timj wrote: ↑Wed Jul 20, 2022 3:44 pm
I have a long 3/4" breaker bar and even with the big equipment it doesn't get used much, so I get what you are saying. I think you can make something. A handle from something that doesn't bend, maybe some square tube. The right square stock to go into socket, hard enough it doesn't twist under load, but not so hard it would shatter.
Yeah, that's the idea Tim. As for the right stock, that is the bigger question for me now, what to use. I have a long 1.5" pipe that could be the handle. Thinking of welding a square stock onto it for the drive, but not sure even if my welding would hold. I'd have to be really careful, as sketchy home made tools like this are one way of getting hurt. but then again, I wanted to be more of a red neck and shed my city slicker skin so how better to do it than this?
If the pipe is galvanized, then you'll want to grind the zinc coating off before you try to weld to it. You can weld through the zinc coating but it gives off noxious fumes and will make the weld very porous and weak.
Meanwhile if it's regular black pipe then it probably has a pretty thick coating of varnish and/or mill scale on it. And you'll want to sand/grind that coating off before you weld it.
Either way if you get it down to clean shiny metal then a weld should hold without much trouble.
Bob
"Never be afraid to try something new. How hard can it be?"
Hehe. Here is my un professional ramble. I would take an old socket of big enough size that you could grind down to the 3/4 opening. This would be done on the 1/2” drive end of the socket. I would then set a hard bolt in the 1/2” drive opening. Weld it in good. Then cut off the opening that goes on to the bolt or nut. Then weld that end on to a piece of heavy flat bar. Then slide a pipe over that and away you go. Or cut the socket off to fit the pipe and weld it on there. And away you go.
Update in ramble ! I would maybe put the bolt in 1/2 hole first and weld it in. Then shape to the 3/4 opening you need.
Another update in ramble. Maybe better to use an impact socket.
Another ramble update: Maybe use a 3/8” drive socket. A little more meat there to work with after welding 3/8 drive in.
let's go, it's finally time to blow. 
but then again, I wanted to be more of a red neck and shed my city slicker skin so how better to do it than this? 
make sure weld is good and when you start pulling, ease into and pull like you know it's going to break. 
I would maybe put the bolt in 1/2 hole first and weld it in. Then shape to the 3/4 opening you need. 