Thread: A woodie with a metalurgy question

Hi Jim,
You cant do that, (well unless you have special wire, which you wont get for a gasless MIG as far as I know). You wont be able to harden the weld beads.
Got a drawing of what you are trying to do?

Stuart

Originally Posted by Stustoys

Got a drawing of what you are trying to do?

How's this Stuart?

Blue represents original steel. Red is new built up steel.

Attachment 202901

I have tried it already, and managed to lay down beads where I wanted them. Also managed to grind & file away the excess and got the angle I wanted, but took FAR too much off in the process and buggered up the angles the two heads need to match each other.

Its sitting on my bench at present waiting for a free half hour or so to present itself at the same time as my having the right frame of mind to take things more slowly and concentrate on what I'm doing.

In the meantime, my mind is ticking over. Thus the question on hardening.

Cheers
Jim

I think you need a stick welder and some hard-facing electrodes. Or a mate with same.

Hi Jim,
Whats wrong with grinding the side off like this?
The problem with using normal mig wire is its just MS, you cant harden it. The wire you are trying to cut will likely be tougher than the jaws(still it might work as a test).
There are ways to harden MS but they certainly arent cheap.

Hi Bryan,

Is there a amperage limit on hard-facing electrodes? I remember reading some where for hard-facing MIG you need 175amp min. tempering could become tricky also?

Stuart

Stuart, I haven't used them myself. I wasn't aware they had amperage requirements, or that they needed tempering. Going back to the first few posts I see they were mentioned then. I think if you grind the jaws down that far you will create other problems. If I remember when I go out I'll have a look at mine.

Originally Posted by Grandad-5

This is the opposite scenario which is what happens when the horizontals are on the outside of both panels. I can't avoid having this situation altogether so I try to just minimise the occurances.
Attachment 200840
You can see that the horizontals no longer line up. This means the end of the panels are out by 4mm in relation to each other.
I've tried a couple of different techniques but none so far are what I'm looking for.

Wouldn't they fit together if the stub-ends of the wires ... sitting on/under the verticals and flush with them ... were beveled at 45 degrees?
It would sit together like a (woodwork) mitre joint.

You could get that with a bench grinder and a jig ... bit like making a jig to grind a plane iron ... but on a larger scale. Maybe you could get there with an angle grinder also. Or ... painfully ... with a hand-file.

Cheers,
Paul McGee

Originally Posted by Bryan

I think if you grind the jaws down that far you will create other problems. If I remember when I go out I'll have a look at mine.

I can save you a trip out to your shed, it does throw the geometry out on the other plane.

Originally Posted by pmcgee

Wouldn't they fit together if the stub-ends of the wires ... sitting on/under the verticals and flush with them ... were beveled at 45 degrees?
It would sit together like a (woodwork) mitre joint.

You could get that with a bench grinder and a jig ... bit like making a jig to grind a plane iron ... but on a larger scale. Maybe you could get there with an angle grinder also. Or ... painfully ... with a hand-file.

Scratch the handfile Paul. I'm not into pain.
I like the idea of a jig. I wonder if a 4" woodworking belt sander would take a metalwork type of belt? Sortof a handheld linisher.

Definitely going to mull your idea over.
Thanks.

Ok, so I've learnt a couple of things today. The metal left by my MIG is mild steel.
You cannot harden mild steel.
I think that just about puts the kibosh on the whole deal.
Does everyone concur?

Thanks guys.
Jim

Jim, just to clarify your last point about hardening mild steel.....it can be done by several methods and there are different applications for each.........but for what you want to achieve most would be too involved and expensive to set up just for that job........on the other hand, if you have the jaws separate and in my reading of your posts, then maybe you only need to harden the cutting edges???, provided your work is small enough, ie it can be placed into a small tin say the size of an old tobacco tin etc... then perhaps it may be worth looking into the case hardening process for them......here's a quick link to have a read....it's not that complicated nor expensive to do.....on the other hand, you are probably best off doing it right first up to get what you need without having to resort to "add on" processes to get the result.....this is just another way ..........the product mentioned is no longer readily available but others similar on the market are - they all use the same process and it does work with differeing results....I use it now and then and know it works for me.........hope that helps a bit..........Lee

Case Hardening with Kasenit

Wow, thank you for that Lee. It helps more than a bit.

That one article cleared up quite a few things I didn't understand. For one thing, I thought case hardening was the same as hardening.
I'm going to need to read that article a few more times before it sinks in, so leave it with me to study at my leisure.
One question though, it mentions different types of steel and their relative carbon content.
The jaws of these boltcutters are marked Cr-Mo which I assume to mean Chrome Molly.
An expression I recal from my bike riding days. A Chrome Molly frame was top end. Light weight and strong.
How does this type of steel enter into the discussions?
Does it change anything or do I still think of it as mild steel?

Actually, after reading that article, let me see if I can answer my own question. It tells me that heating it to cherry, (as happens when welding) and then allowing to cool slowly softens metal. A process called annealing, which is a term I've heard in relation to copper pipe but never knew what it meant.
Would I be correct therefore to say that even if Co-Mo indicates a harder steel, welding it has just negated that. Am I on the right track?

Jim

Hi Jim,
I'm not sure the case hardening as explained in the link will give you a deep enough case.(but then I'm not sure it wont either, of course there are ways to get a deeper case but they just add to the cost)

The jaws might be Cr-Mo but the weld bead will be mostly mig wire(with some % of Cr-Mo thrown in). How well case hardening powder will work on it I have no idea.

I think even fully annealed Cr-Mo will be tougher then MS.(but I havent looked it up)

I'm still not getting why you cant grind the side off(only the first 10mm or so) the blades an leave the factory cutting edges alone? How does the change the geometry? (it will give you a weaker cutting edge though)

Stuart

Originally Posted by Stustoys

I'm still not getting why you cant grind the side off(only the first 10mm or so) the blades an leave the factory cutting edges alone? How does the change the geometry? (it will give you a weaker cutting edge though)

Hi Stuart,
That's because I was misunderstanding what you meant.
The line on the pic shows it clearer.
Grinding it off there, wouldn't upset the geometry at all.
I've got family matters to deal with right now and it might be Sunday before I get any shed time, but I'll look at it again now that I understand what you were suggesting.

Thanks
Jim

Worn gears, can be rebuild with an arc welder and the appropriate rod. I've done it for years when I worked as a factory fitter. I have rebuilt rather large stuff like the worm gears for a dripping press some 2 meters long and one foot in diameter, the teeth on the blade of a 20 ton bulldozer and also smaller stuff like the gears in the gearbox of a cultivator.
So your little bolt cutter can be rebuild no problems at all. Just get the right rods.

A welding supplier will be able to help you if you tell them what sort of welding machine you are going to use.
And yes, you will have to grind it back with a grinder and not a file.

PS
As far as your job is concerned though, to cut with a bolt cutter and then grind the wire ends seems a lot of work.
Can you cut the wire mesh directly with the grinder, a blow torch or a plasma cutter?

Originally Posted by Marc

As far as your job is concerned though, to cut with a bolt cutter and then grind the wire ends seems a lot of work.
Can you cut the wire mesh directly with the grinder, a blow torch or a plasma cutter?

Hi Marc,
Yes, I can and have done so. But I've found I can cut them very quickly with the bolt cutters and equally quickly clean the sharp ends up with the grinder.
Using the grinder alone, I found was awkward and I didn't feel comfortable.
I have neither a blow torch nor plasma cutter.
The ends must be neat when I'm finished.

Really, the modifications to the bolt cutters is for use on site when I'm installing. I just feel it would improve things.
Its an experiment.
The bulk of my work is done in my workshop and goes quite well.

I was under the impression that the correct rods were rather pricey for this little job. Is that not correct?

Jim

Originally Posted by Grandad-5

I was under the impression that the correct rods were rather pricey for this little job. Is that not correct?

Thats what I would have said, but I just had a quick look on ebay for "hard facing rods", there is a guy selling some 3.2mm rods(about the biggest I would guess you could use for $20(hrc) or $30(hrc55) for 2kg. "It has a HRC (hardness of deposited metal) of roughly 55"
55 what? I have no idea.

Stuart