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View Full Version : Bummed out- lathe broke



Dave Anderson NH
10-03-2004, 4:52 PM
I was making progress in turning marking knife handles and awl handles yesterday and today. I needed to get restocked due to a large number of sales in the last three weeks. As I was cranking the hand wheel on the tailstock of my Jet JWL-1236 to tighten up on the end of a blank, things went South. Suddenly the crank turned easily without any pressure and the handwheel retracted to the right about 2 inches. Looking down I noticed that the casting had snapped at the end flange. Does anyone have any experience with this happening? I couldn't help but notice that the section of casting is VERY thin here, about 1/16". I've already emailed Jet with the same pictures I've posted here and asked for their help. This lathe is about 5-6 years old and out of warranty, so I don't know what their response will be though I hope they'll make good on it. If they don't, I'll just buy the replacement which I'm sure will be white rather than the blue of my lathe. Since it's Sunday, I won't here from them until tomorrow when I get home from work. Not exactly a happy ending to a day in the shop.

Bob Smalser
10-03-2004, 5:12 PM
Poor design or bad casting. We could silver braze a replacement sleeve or bushing in there easy enuf, cutting back to some better meat in the casting....and it'd likely perform better than a stock replacement part.

Have a machinist pal with mill and lathe?

Dave Anderson NH
10-03-2004, 6:29 PM
I don't think silver braze would have the strength in this case since the thrust is against the inside machined face of theat little disc. It was a tensile strength break. I went down to the shop a few minutes ago and put the dial calipers against the wall thickness which broke. It actually measured .035". My calipers aren't cheapies either, they're a pair of Starretts I broke the bank buying new at $49.95 "some years ago" when I was in engineering school. I take them to work every 6 months for recalibration by the contract calibration house who does all of our recertification.

It is either a design flaw (the wall and the disc should both be thicker) or the casting was machined too deeply leaving the wall and end face too thin. I'd be curious at seeing one of the new tailstocks on the white Jets of the same model.

John Shuk
10-03-2004, 6:45 PM
Dave,
I feel for ya. I have the same lathe and will be a little more attentive to that. I did have an issue with the post on my tool rest getting holes in it from the set screw and they made good. It was just at the end of warranty though. As to the sales of those marking knives I think I am interested in one if you e-mail me the info at LEVUK@optonline.net

Wes Bischel
10-03-2004, 6:56 PM
Dave,
Sorry to hear about the problems. If Jet doesn't come through, and the replacement cost is high, just another thought - File or machine off the remaining flange. Then add a steel plate to thrust against. The plate can be bolted to the tailstock by drilling through the plate and tapping the face of the tailstock. (with a hole for the ram of course)

It sounds like a lot of work, but it shouldn't be too difficult (famous last words). I would think cutting the steel blank would be the hardest part.

Just food for thought.

Wes

Bob Smalser
10-03-2004, 8:28 PM
Silver braze of the 1100 degree flavor is 40k psi and plenty strong enuf.

Welding cast iron is very, very difficult and thin cast iron is of an unknown flavor is a complete crapshoot, whereas you can braze this yourself at home.

For strength, just make the base of the flange/sleeve/bushing large enuf to cover enuf cast surface....wrap it around the corners if you have to.

But the larger area of the casting that requires heat, the greater potential problems of warping and cracking.

The piece should be preheated in a kitchen oven as high as it will go....brazed...then stuck in a bucket of garden lime for a day or so so it can cool slowly.

I'm not the machinist...my neighbor is...but if we can fix all the local shipwright's cracked Stanley 10's...guys who really use the things hard...and have them hold up, betcha your local equivalents can fix your tailstock easy enuf. Or, if Jet tells you to kiss off, machine the repair piece and you can braze it on yourself. Depends on what a new Jet replacement parts costs.

Another alternative is to prowl the old machinery shops for junk lathes an adapt another tailstock to your Jet...you can paint it any color you want to.