Couple questions- what is the straightness tolerance? What strength do they need to retain? At the plant I work at, it is very common for some form of handle to be welded to them. Everything from Allen wrenches to round stock. I personally wouldn’t do the copper tube filled with weld. I personally would make some kind of jig to hold the stock being welded on. Out of morbid curiosity, what is the end goal of the project?

 

Yep, similar. They'll be specialized screws with something other than socket heads. And not a standard that I can purchase. I may just end up single-pointing new ones from scratch on the lathe. I've got about 30 to make...I just figured copper tube filled with weld was the quickest and simplest.

 

If you described the situation, the need, better, someone might have a better solution. It also helps to know what equipment you have and have access to, for example a lathe or mill.
Suppose you bought some longer bolts and slipped a circular long spacer under the head? Even a bunch of washers JB'd together.

 

What sort of a head do they need? Could you cut the head off the right type of bolt and just weld that on? Or weld on a piece of square or round stock to save all the build-up time? Maybe a couple other options. The more info you give, the easier it is for people to help.

 

Not really sure what you are after? You could machine the threads of another cap screws or hex to fit dethreaded end into the first cap screw, then weld or braze together. You can machine on a drill press with a file and time.

Brazing works well for this application

 

I will echo that any details/sketches you can share would help. How I would approach doing it on a 1/4” bolt would be different than if it was a 1” bolt, and not knowing roughly what the added portion does/is expected to do. And I agree with tapwelder, brazing or silver soldering might be the best choice. Anything you can share would help.

 

I'd start with a cut-down allen wrench and weld a sleeve on.

 

"Copper tube" and "welding" just don't sound right.

 

It sounds to me like his thought is to use it as a form.......think concrete in a sono tube.
If my thought is correct I doubt he would have much luck getting the weld to penetrate.

 

If there are not super length sensitive put a short sleeve on or some machine washers. I might find a longer bolt with stock head and do the same.

 

I've never used them personally, but it seems to me there are some special rods for building up on top of a broken bolt so you can get vice grips on it to get it out. Would those rods help in this application as well?

 

IDK, just make the shape and weld it on. I don't understand all the drama.

 

I do not completely understand. How do you intend to hold/tighten them. I saw you mention it so I know you realize that. Drop in and use the nut to snug ?

I like the allen shank in the head and weld around it then machine it down idea Denis G posted above.

Machine steel plugs with a round pilot to just go into the socket heads and weld them on and then machine back to tolerance.

Just get threaded studs and put machined round coupling nuts at one end will easily make heads however tall you want them and have the same thing with no welding. Put the lathe to work. You could machine the head flat or back off the stud a little and put setscrews in the end then you could hold them again too and could machine it off flat to look nice leaving just the allen head hole. Lock the stud into the coupling nut using the setscrew. JB weld all the threads if you wanted them to not.

 

The bolts are standard 1/4" black oxide socket head cap screws. Whatever hardness those are...Grade 8, maybe? The heads need lengthened, because a special head with be made (ground, or machined) on them to be used with a special wrench.

Again, I figured adding weld to the existing socket head would be the easiest and quickest to get it done. I've only used copper a couple of times to limit weld, and not in this way...by making a tube and filling it. I'm wondering if the head will get stuck. If it could work, without leaving voids, I'm assuming that I'd have to work quickly...do the fill, and promptly smack the bolt out before it gets stuck.

This probably is out of the ordinary. I thought with all of the welding experience on here someone was bound to have done something similar.

 

The bolts are standard 1/4" black oxide socket head cap screws. Whatever hardness those are...Grade 8, maybe? The heads need [(sic); to be] lengthened, because a special head with be made (ground, or machined) on them to be used with a special wrench.

Again, I figured adding weld to the existing socket head would be the easiest and quickest to get it done. I've only used copper a couple of times to limit weld, and not in this way...by making a tube and filling it. I'm wondering if the head will get stuck. If it could work, without leaving voids, I'm assuming that I'd have to work quickly...do the fill, and promptly smack the bolt out before it gets stuck.

This probably is out of the ordinary. I thought with all of the welding experience on here someone was bound to have done something similar.

Getting a completely homogeneous new section of the same alloy by welding to an existing bolt, then machining it and finally heat-treating it for the needed strength properties sounds like much more work than just starting with a blank of the right alloy.

Will the new socket be something like an oval 8-sided star, so standard wrenches won't fit it? What about people who'll use soft, chewed bubble-gum to make an impression and then use modern technology (scanning>CNC machining, or 3-D printing)? Is it really worth the effort?

 

The head does not exist? I have always just brazed the appropriate head to the bolt. However, if proprietary, you can still braze a chunk of steel and machine to the desired dimensions.

 

Or a couple nuts and machine them down.... welded or brazed, 1/2" isn't a whole lot to gain on a 1/4" bolt...

 

Like others above, I would also suggest using round coupling nuts (available on McMaster-Carr)
Nice round body, available in a few lengths. This with a 1/4" threaded rod.
Cut to length as needed. Easy, and will look professional.
This will be easy to replace if the need ever occurred.
I get this is a welding site, but sometimes...
Geoff