Damage from welding

[Tiggy_dorset]

Scenario :
At work-300kg billet placed in a lathe chuck for turning. Being a little on the heavy side, it doesnt really want to stay in the jaws. I welded extensionsto the jaws no problem, but there were still obvious concerns regarding spinning such a lump. We toyed with the idea of extra security by welding the billet to the jaws in its position. This idea was scrapped as we were unsure of the effects to the electronics/electrics to the lathe if we start to pump amps through it.

My question :
Im sure most of us know to disconnect the battery when welding a car. What would be the effects if the battery was not disconnected?
Would We have caused damage the the lathe circuitry if we had attempted to weld to it? What would be the method to prevent damage?

Thanks guys

 

[Pete.]

You welded extensions to the hardened jaws? I hope you priced up replacements first coz they are £££!

Why can you not hold the slug against the chuck using the tailstock and a revolving center?

 

[Tiggy_dorset]

I do what the boss requests, Pete That is what they done with the tailstock but they were feeling extra safety concious by considering welding the job to the jaws. 300kg isnt light which needed an engine hoist to get it to the chuck.

Its the issue regarding welding and electronics which got me thinking about doing some research on it, hence the question to you guys

 

[Drains]

Er, lathe not up to the job then? Get a bigger lathe mate. Might not be helpful, but I've had it up to here with engineering comanies saying they can do jobs that their machines simply can't.

Depending on the shape of your billet, it might be better to do it on a vertical lathe.

TiggyD, I don't mean to be rude or unhelpful. If you really want to go for it, weld lugs between the chuck and the job. Cut them off when the job's complete. You'll cause less damage that way, as the jaws will (as mentioned) not be worth much after. If you have to turn the job, weld it back on once it's centred, although I doubt you'll be able to centre it too easily.

And to answer your question.... earth the lathe and the work, and isolate the lathe from the mains. But don't blame me

 

[series2]

As drains said, the lathe isn't big enough. I don't think I would want to be near a 300kg spinning lump that wasn't perfectly secure.

 

[chap]

Earth the chuck, so you don't get the current path through the bearings (second hand advice).
Can you not drill and tap, bolt to a face plate? I've done this with lumps that wouldn't fit in the chuck (admitably ali).
Run the lathe slow and wear a suit of armour

 

[series2]

Earth the chuck, so you don't get the current path through the bearings (second hand advice).
Can you not drill and tap, bolt to a face plate? I've done this with lumps that wouldn't fit in the chuck (admitably ali).
Run the lathe slow and wear a suit of armour

I'd go one further and call in sick, let someone else start the lathe

We are the Knights that say 'Ni', and we demand a risk assessment

 

[madkayaker]

long stick extension on the switch would be my way! sounds like to small a lathe to me and welding on a high presion item would not be idea of fun

 

[michael1703]

300kg will have a lot of momentum if the lathe gets its turning, really wouldnt do it or go anywhere near it

 

[mr migwire]

I FORESEE PAIN IN YOUR FUTURE!!!!!!!

300kg i for one would go with series2 on this and throw a sicky for sure,

 

[mike os]

I believe my approach would be "you can **** right off if you think I'm going anywhere near it"

 

[Tiggy_dorset]

Thanks for the advice guys, I will bear it all in mind if I decide to take up lathework.
The chuck seemed to big enough for the job, the problem was the recess in the jaws wern't deep enough for the job to sit in securely enough for peace of mind. The extensions welded to the jaws were not for extending outwards, but horizontally along the outside face of the job. Im just the welder who gets shoved into his cubbyhole out of the way, the lathe turning I leave to the machinists, thank god.

As for my question regarding damage to electronincs and such, I have done some more research and found the answer I was looking for.

I still appreciate all the feedback I got, thanks.

 

[mike os]

I would think if they are electronic... seems likely these days then I would not want to weld with them connected.

If simple old electro-mechanical stuff then I dont think it would be an isssue

 

[outofthefire]

At work we connect surge protectors to the wagons batteries before any welding is done even so the other day someone fried a starter motor so i'm not sure i'd risk the electrics in a lathe.

 

[rich8000]

outofthefire +1 on vehicles disconecting the battery will only protect the battery, you have to to use surge potection or isolate all the electrics to be safe.
As far as the wieght of the billit, if the lathe is man enough and your not going over the spec of the chuck / jaws the tail stock will hold it.
Vibration is the bigest enemy, especialy with an intermitant cut.
Don't forget to use appropriate PPE to ensure you get max payout in event of an accident

 

[mike os]

My £2mn payout got me a wheelchair just like stephens

I even got the same voice

 

[RapidResponse]

One thing that may be worth considering. Chuck jaws are usually Case hardened. If they are and you try to weld with that much carbon in the surface, the weld will most definately fail anyhow. Machining that in a Lathe with the correct capacity and enough throw should not present too much of a problem. 4 jaw chuck in tail stock and low carbon faceplate to weld to and drive it. Periferal speed will not be too high. Just make sure the Lathe will handle the capacity.