Repair cast iron?

[Tim Wescott]

These are two of the four jaws from an old Taig (I think) 4-jaw chuck that I've been abusing by using it on a much larger lathe than it was intended for. As you can see, I broke the tab off of one.

I've got a new four-jaw chuck on order, but before I repurpose the chuck adaptor for that chuck -- is this jaw really all the way broken, or is there hope for it? I'm thinking that someone really talented could maybe braze that jaw back together and put it back into service after some fettling.

Mostly, I'd hate to chuck that chuck and then find out that there was a reasonable way of fixing it.

 

[SmithDoor]

Tig weld and hand grind to fit.

Dave

These are two of the four jaws from an old Taig (I think) 4-jaw chuck that I've been abusing by using it on a much larger lathe than it was intended for. As you can see, I broke the tab off of one.

I've got a new jaw on order, but before I repurpose the chuck adaptor for that chuck -- is this jaw really all the way broken, or is there hope for it? I'm thinking that someone really talented could maybe braze that jaw back together and put it back into service after some fettling.

Mostly, I'd hate to chuck that chuck and then find out that there was a reasonable way of fixing it.

 

[Master]

Had a boat cast iron starter housing break. Man brazed for me. Worked great.

 

[Badhippie]

Why not drill it and countersink the hole and bolt it back together. That is if you don’t have access to a tig rig or stick welder. Or braze it
Thanks Tom

 

[Badhippie]

Oh ya forgot a step drill, countersink, and tap hole
Lol Tom

 

[ajoeiam]

These are two of the four jaws from an old Taig (I think) 4-jaw chuck that I've been abusing by using it on a much larger lathe than it was intended for. As you can see, I broke the tab off of one.

I've got a new jaw on order, but before I repurpose the chuck adaptor for that chuck -- is this jaw really all the way broken, or is there hope for it? I'm thinking that someone really talented could maybe braze that jaw back together and put it back into service after some fettling.

Mostly, I'd hate to chuck that chuck and then find out that there was a reasonable way of fixing it.

You were asking about repairing cast iron.
I'd bet that the jaws are steel and the back is cast iron.
Any one of the listed repairs should be workable.
Which one you use will depend either upon your 'friends' (smile) or your own skills.

 

[awake]

Personally I would try brazing or TIG brazing rather than welding. But as small as that part is, and if it were me ... I would probably not have much hope that I could achieve it - my skills are too ham-handed.

 

[xtal_01]

I am always worried about "location" when welding (tig or brazing).

I would consider bolting it together first (as someone said, drill, tap, countersink or counterbore ) ... it would not have to be a huge screw since it is more to pull them together into the right spot.

Then "V" the edges and braze or TIG.

If you only have access to a stick welder, I know I used special nickel rods years ago to weld cast iron.

 

[Tim Wescott]

You were asking about repairing cast iron.
I'd bet that the jaws are steel and the back is cast iron.
Any one of the listed repairs should be workable.
Which one you use will depend either upon your 'friends' (smile) or your own skills.

It sure broke like it's cast. I didn't see any sign of plastic deformation, just a brittle break.

Which doesn't mean it's not steel with a rather high carbon content, I suppose.

 

[Tim Wescott]

It sure broke like it's cast. I didn't see any sign of plastic deformation, just a brittle break.

Which doesn't mean it's not steel with a rather high carbon content, I suppose.

A file just skates on it -- so I'm guessing it's really hard steel. Or something weird like white cast iron - but you're probably right.

 

[kuhncw]

You might try silver brazing.

Chuck

 

[mayhugh1]

Those jaws are hardened steel (real hard). You would have to anneal before drilling any holes and likewise before welding. Brazing will destroy the heat treatment which will need to be redone, and then re-grinding will be needed afterward. I don't think a repair is practical. - Terry

 

[Charles Lamont]

Tim, you said you have a 'new jaw on order' but then talk about scrapping the chuck. Did you mean you have a new chuck on order?

 

[Tim Wescott]

Tim, you said you have a 'new jaw on order' but then talk about scrapping the chuck. Did you mean you have a new chuck on order?

T'oh! Yes -- I've edited my post. I'm just assuming I can't get parts for a 40 year old chuck.

 

[deeferdog]

Once the jaw is repaired and spinning at 1600 rpm with me very close, I would have difficulty in keeping my mind from recalling those pictures of weld failures I have seen over the years. Cheers, Peter.

 

[Tim Wescott]

Once the jaw is repaired and spinning at 1600 rpm with me very close, I would have difficulty in keeping my mind from recalling those pictures of weld failures I have seen over the years. Cheers, Peter.

Killjoy!

It's a 3-inch chuck, and now that I'm getting a bigger one it would only be used for small, light jobs. And besides, if it breaks again in the same place it'll jam in the slot the same way.

 

[deeferdog]

Born to worry, so I like to share!

 

[L98fiero]

Those jaws are hardened steel (real hard). You would have to anneal before drilling any holes and likewise before welding. Brazing will destroy the heat treatment which will need to be redone, and then re-grinding will be needed afterward. I don't think a repair is practical. - Terry

I can't imagine the jaw being made out of cast iron, it basically has no tensile strength, it's probably a tool steel or at least a fairly high carbon machinery steel. Even if it's on a small lathe, imagine the excitement when the jaw breaks again, comes out part way and hits the lathe way while turning at 1000 rpm.

 

[Charles Lamont]

Rather than a repair, I think it would be easier to make a new jaw, an interesting exercise. As it is only going to be for light jobs, if you made one out of some fairly good steel you should get reasonable life without hardening it. OTOH, if you wanted to harden it, the brittle failure tell us that case hardening would probably be better than through hardening. UK model engineers suppliers offer a case hardening compound that will produce a case that is thin, but better than nothing.

 

[Tim Wescott]

Actually I found out that the Taig brand is still alive, and the chucks they sell on their website look like the same design to the one I have -- so I just sent them an email asking if they might have spare parts that would fit.

I expect the answer will be "no" -- but, nothing ventured, nothing gained.