Made a screw earth clamp for welding

Hi all,

Following our discussion about screw earth clamps, I decided to make one for the following reasons:

  1. I thought I could build a stronger one.
  2. If I made one from a G-cramp, I could use it to clamp the work too.
  3. Making stuff is always more satisfying that buying it.

So here it is. Perhaps I went overboard with the photos for such a simple project, but those of you who are bored will probably enjoy them:

formatting link
Comments are welcome!

Chris

Reply to
Christopher Tidy
Loading thread data ...

Reply to
RoyJ

That's a neat clamp! One question, is the ground lead just soldered in, or is there a setscrew to secure the lead? I just finished putting the Miller lead connectors on the pigtail for my Readywelder. They are brass with a ferrule for the lead, and a big setscrew bearing on the ferrule at right angles.

Pete Keillor

Reply to
Pete Keillor

It's held by two socket head set screws. The solder was just to help the lead keep its shape and make it a snug fit. You can see the set screws in this picture:

formatting link
Chris

Reply to
Christopher Tidy

I took another look. It looks like you have two screws bearing on the lead. Is that correct?

Pete

Reply to
Pete Keillor

Yes, you can see the socket head set screws in the last picture. Glad you like it.

Chris

Reply to
Christopher Tidy

One comment/suggestion I have is to install some type of strain relief. As it is now, the stress is transfered directly to the internal lead itself, instead of o the entire cable. One possible (and relatively easy) solution would be to drill two small holes in the G-cramp, just large enough to insert two wire ties, which would hold the entire cable securely to the clamp.

Jon

Reply to
Jon Danniken

RoyJ wrote: > A bit of overkill but nice. You will find that the brass deteriorates > over time. The clamp is heavy enough that you can just clamp it over a > piece with mill scale and it will work. But htat leads to some internal > arcing at the interface.

I guess I tend to go for overkill, but stuff you use for welding gets thrashed. I figure that if the brass deteriorates there's enough metal to allow me to remove the contact block and skim the surface on the lathe. I reckon it should be more secure and less prone to arcing than my crocodile clamp, anyway.

Chris

Reply to
Christopher Tidy

Thanks for the suggestion. It didn't occur to me to fit a "cable grip" because the cable is so fat. I don't know if it'll pull out from the grubscrews with use or not, but if it does I'll do you as suggest.

Chris

Reply to
Christopher Tidy

It looks like the other end of the cable has a crimp on type of connector. Yes?

I don't like the idea of the solder. Solder tends to cold flow and gives way even faster around hot welding work. I suspect your connection between the contact block and the wire will deteriorate fairly quickly. I would suggest a crimp connector (properly crimped) on the wire bolted to the side of the contact block. Could you tap the hole the wire is in for said bolt?

I notice the can of 3 in 1 oil at the lathe. Were you using it for cutting oil? Ernie L. recommended d-limonene. I got some and it works extremely well on copper and copper alloys - far better than anything else I've tried.

Ted

Reply to
Ted Edwards

It isn't actually soldered to the brass block. The solder just stiffens to end of the cable, and there are two grubscrews which clamp it tight. I copied the arrangement from my stinger, which seems to work fine.

No, it's for the bearings. It's my father's lathe and apparently it's the recommended lubricant. It's only a small machine (4" centre height I think). But I do admit that sometimes I use it as cutting oil if I can't find anything else.

Chris

Reply to
Christopher Tidy

itself,> > instead of o the entire cable. One possible (and relatively easy) solution

Not so much pulling out, but breaking. By installing a strain relief, you transfer the stress of the inevitable flexing of the wire onto the wire and it's insulation, instead of the wire all by itself, which will eventually harden and break off.

Of course, you could always just wait until this happens and then restrip, re-tin, and reinstall the cable. :)

Jon

Reply to
Jon Danniken

Yes, that might well happen. Do you think drilling a hole in the clamp frame would weaken it significantly? These are cast steel clamp frames. My guess is probably not, but I'm not certain.

Chris

Reply to
Christopher Tidy

Neither am I. Perhaps a more judicious approach would be to use a hose clamp around the G-cramp, instead of drilling through it. Not the most elegant approach, though, but it would serve the function without weaking the G-cramp.

Jon

Reply to
Jon Danniken

Yes, maybe I could figure out a neat solution along the lines of a hose clamp. Interestting thought.

Chris

Reply to
Christopher Tidy

Actually -- the solder increases the chances of flex failure right at the point where the solder ends. A good crimp terminal is far more reliable for long-term service. (Of course, for a *good* crimp terminal, you need to have a good crimper to fit. I'm currently covered from about 26 gauge up through 3-0 gauge, and still looking for the dies for 4-0. All crimpers, dies, and terminals made by AMP.

The *good* crimp terminals have an insulating sleeve around the crimp area and back over the wire insulation, and the sleeve is designed to offer support at the insulation to minimize flex failure.

Enjoy, DoN.

Reply to
DoN. Nichols

The main reason I used the solder was to fatten up the end of the 25 mm2 lead and keep it round. I wanted the option to use 35 mm2 lead at a later date if necessary. Perhaps I should have used longer set screws, but it would have made the clamp clumsier and 10 mm were what I had.

I'll use the clamp and see when the lead breaks. My guess is not soon. My stinger has this kind of connection (minus the solder) and it hasn't broken yet. Anyway, it's only five minutes work to fix when it does.

Chris

Reply to
Christopher Tidy

Nice looking work!

Reply to
Eide

Looks very nice! I will make sure to make something like that also. A great idea. I think that I will do it a little differently, by drilling a home on the side of the C clamp (approximately where you have numbers stamped on it), threading it, grinding the area flat for better contact, and inserting a bolt to serve as a terminal.

How is your phase converter project?

i
Reply to
Ignoramus21796

Nice job Chris, it certainly suits your family name. :-)

Somewhere along the way I missed learning the etymology of clamp names. I wonder if there's a specific reason why what we call a C-clamp in the USA you fellows call a G-cramp.

Was there once a subtle difference in their shapes so ours looked more like a C and your's like a G?

Jeff

Reply to
Jeff Wisnia

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.