Lathe clutch

My current lathe has a clutch, my previous two didn't. I would never own another lathe without a clutch. John

I have 3 lathes. All superb. But after using the Lodge & Shipley with a clutch and brake, there is no comparison.. Try threading up to a shoulder without a brake! Steve

When I got my 15" Sheldon, I thought that not having a clutch would be a problem. I ran it just quickly with a static phase converter, and the coast-down was quite long. When I got it all set up and running, I used a VFD with a braking resistor. I get the spindle to stop from any speed in about 3/4 second, which seems just about right without making the machine slam to a halt. I think this is just about perfect for this size lathe. I have also added a jog button that runs the motor at 6 Hz, I think. This is nice to turn the chuck to a particular position or engage gears that won't quite slide in without motion.

Without a VFD, I would think that the clutch/brake would be a must-have.

Jon

The (late) Father's ML7 has a clutch. My ML7 has an invertor with braking. I would say that one or the other is extremely useful to have. Braking needs to be approached with caution on lathes with screw mount chucks. I find with mine that if I've got the braking too sharp, the invertor will normally trip before a well mounted chuck will unscrew itself. This, of course, can lead to problems if one is relying on the braking (but it served me right for seeing how fast I could go with that 35lb lump of cast iron :-(.

Mark Rand RTFM

My ML7 can run in reverse (as can many) and I have, on occasion, used it in reverse. The trick is to ensure that the chuck is on harder than the expected cutting torque. The current Connoisseur model has a groove turned in the mandrel nose, into which a grub screw on the chucks can locate, to prevent 'unwinding'. I may investigate this as a possible modification one of these days.

Mark Rand RTFM

This is why I changed out the spindle on my Clausing 12x24" to have a L-00 spindle nose, instead of a 2-1/4x8 spindle nose.

He was allowed to continue the class after doing this the first time? Aside from the damage to the chuck (and probably to the lathe bed as well), the danger to the others in the class would seem extreme. Your wording sounds as though it was a frequent occurrence.

Enjoy, DoN.

THANKS all.

Not quite Irrelevant thought.... Would case hardening be of use in a situation like this?

Mark Rand (no opinion, just curious) RTFM

Case hardening tends to make things soft on the inside, brittle on the outside. Not a good combination for a pressure vessel that takes dynamic pressure loading measured in milliseconds and in 10s of thousands of psi.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

What if you pack the barrel with carbon and stuff instead? Case harden the inside.

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

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Then the stress fracture (just before bursting) starts on the inside.

A firearms barrel is a dynamic item. If you ever watch one under ultrahighspeed photography, you can see it bulge as the round goes down the barrel. The round and the gas load.

Case hardning makes it hard, but brittle. Once you crack the surface layer..it tends to migrate through the metal IE stress fracture as it cleaves the grain structure. Even with a soft core. There are some heat treats that work well with the proper alloy. Springfield rifles come to mind, but even the early serial numbered double heat treats were known to KaBoom or to break. Springfields up to serial # 850,000 IRRC were known for this. After this, a different nickle alloy and heat treating was used.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

I suppose. It ought to start at a much higher pressure than plain mild, in any case. I'm assuming a judicious draw of temper after the hardening.

Nice.

Ya, I'm quite familiar with stress raisers. One of our cars has a small crack in the windshield that's slowly progressing, glass is wonderful stuff for stress concentration... More on topic, I've cold forged copper and aluminum a bit too much without annealing, causing it to split and (eventually) crumble from the stress. Although I suppose the rifling doesn't help much... say, is that usually round or square cut?

Hm, I would think something like 4140 would work nicely. High ultimate tensile strength, when annealed has a lot of ductility and can be hardened to give up some of that to remain in shape to pretty high loads. Correct me if I'm wrong with any of the engineering terms or use thereof...

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

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Was going to add, does the high speed of the event affect it much structurally?

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

- - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting and Games:

Thats not doable with case hardening. If you are talking about proper heat treating, yes indeed.

In a properly rifled and head treated barrel, there are no stress risers inherent with the rifling. Same as splines on a shaft. Most rifling is square cut, or square button broached, but there is a fair amoung of polygon rifling out there as well.

you might enjoy this article. Im not an expert on the subject..just an advanced amateur.

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

Yes, indeed. both in the friction of the bullet, and the gas cutting effect of the very hot and high pressure of the expanding gases. It wears out the barrel over time.

As to the dynamic loading..indeed it does. The thinner the barrel, the more movement due to harmonics of both the bullet travel and the pressure wave. This is a critical part of barrel design and bedding.

Which is why most rifle barrels have a significant gap between the stock and the barrel. The movement of the barrel may touch the stock several times during the process and affect exactly where the hole in the end is pointing when the bullet comes out. If it is consistant...the sights may be adjusted to compensate..but its seldom consistant due to a host of factors, from ambient temperature to the consitancy of the pressure generated from shot to shot.

Ballistics is fascinating.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell