Lathe clutch

I was talking with someone yesterday regarding the relative merits of the
Myford Super 7 and Harrison M300 lathes he owns. His view is that the
Harrison is the better lathe but that the absence of a clutch is a
disadvantage. I would be interested to have the views of others on the
importance of the clutch.
Ian
Reply to
Ian Robinson
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My current lathe has a clutch, my previous two didn't. I would never own another lathe without a clutch. John
Reply to
John Kunkel
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
Reply to
Steve Lusardi
I have a Kerry 1140 which has a clutch/brake and a Harrison M300 with brake but no clutch. The M300 has taken the place of the Kerry as it is a much newer machine in much better condition but I still have the Kerry and use it for dirty ops and metal spinning as the kit I made was for the Kerry. The clutch allows gentle take up and nudging the piece round whereas the M300 starting seems a bit brutal and is all or nothing, I am sure a soft start would cure this. The Kerry clutch arm is on the back of the headstock so one has to reach for it past the chuck to stop the lathe. I never thought much about it until I got the M300 but that could be a risk in some circumstances. Probably modern safety regs require the M300 to have a full length foot brake as well as the forward/reverse control on the end of the carriage which the Kerry doesn't have. Both these lathe are comparible in size and features but I prefer the M300 but if the Kerry were in equal condition it would be an interesting comparison. I did consider fitting a clutch to the M300 but now i'm use to it its not worthwhile. My neighbour has a Myford which is a nice lathe but too small for my needs.
Ian Rob> I was talking with someone yesterday regarding the relative merits of the
Reply to
David Billington
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
Reply to
Jon Elson
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
Reply to
Mark Rand
My neighbours Myford has a clutch and can run in reverse, which is not much use with threaded chucks. Maybe useful with drawbar and collets. Reminds me of a chap in my metal shop class who used to delight in spinning up the southbends then switching to reverse. It amused him the way the chuck would unscrew and dance across the floor.
Mark Rand wrote:
Reply to
David Billington
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
Reply to
Mark Rand
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.
Reply to
DoN. Nichols
It happened on a number of occasions and was intentional. I just stayed well away when he was about one of the lathes. The guy left the class I think but the class was not well disciplined. Luckily most of the students had no interest in using the any of the 4 lathes, it was mainly me and another chap who made a 10" barrel for a 12 bore shotgun. A blind eye was turned to that, the lecturer didn't want to know. The guy said it went down a very well blowing away targets at the local NRA meet. I was worried as it was only mild steel.
D>>
Reply to
David Billington
THANKS all.
Reply to
Ian Robinson
Not quite Irrelevant thought.... Would case hardening be of use in a situation like this?
Mark Rand (no opinion, just curious) RTFM
Reply to
Mark Rand
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
Reply to
Gunner
What if you pack the barrel with carbon and stuff instead? Case harden the inside.
Tim
-- "I have misplaced my pants." - Homer Simpson | Electronics, - - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting and Games:
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Reply to
Tim Williams
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
Reply to
Gunner
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, - - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting and Games:
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Reply to
Tim Williams
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:
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Reply to
Tim Williams
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.
4140 and 4150 are the most common steels used for barrels in firearms.
you might enjoy this article. Im not an expert on the subject..just an advanced amateur.
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This has pictures of the rifling process
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And an T-Nut article
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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
Reply to
Gunner
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
Reply to
Gunner

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