lathe brake& spindle lock

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dgoddard
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lathe brake& spindle lock

Post by dgoddard » Fri Mar 09, 2012 10:18 am

I have a typical Chinese 12 x 36 lathe. It lacks two common lathe features, a brake and a spindle lock.
Has anybody come up with a fix for this or will I be the first if I design one.
I never met anybody that I couldn't learn something from.

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Dave_C
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Re: lathe brake& spindle lock

Post by Dave_C » Fri Mar 09, 2012 11:32 am

Don,

I can see the advantage of having a brake but since your lathe is a D-4 cam lock, what is the purpose of having a spindle lock?

Dave C.
I learn something new every day! Problem is I forget two.

lakeside53
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Re: lathe brake& spindle lock

Post by lakeside53 » Fri Mar 09, 2012 11:50 am

My lathes magnetic brake is also a spindle lock (locks it from rotation). Very usefull when manually tapping or doing anything else when you want your material "held".

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Richard_W
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Re: lathe brake& spindle lock

Post by Richard_W » Fri Mar 09, 2012 12:31 pm

I don't know of any after market fixes. Those that have a brake usually have the brake on the motor shaft. I have seen very few lathe with a spindle lock other than using the break as a spindle lock. Like the Clausing has a button to release the spindle break for changing the gears or dialing something in. Once you turned off the spindle in either forward or reverse the brake automatically came on and stayed until you pressed the button to turn it off. Some electro mechanical setup like the Takasawa had a weight that dropped and locked the motor shaft when ever the power to the motor was turned off. Kind of like a drive-line brake the 60 Chev pickups had only electrically operated. I have seen the same type setup on 20 ton over head cranes built in the 40's.

I know you can lock the South Bend lathes by leaving the back gear pin in and engage the back gear. This locks everything up but you can only do it with the power off or evil things happen. I know most use that feature to change chucks, but is a bad idea because one day a few gear teeth will fatigue and break over time.

I did a conversion of a 36" Sidney lathe to a dedicated pipe bender to make the coils for steam cleaners for Landa pressure washers. We used a disk brake caliper, master cylinder and rotor from the front of a Chevrolet for the modification. It involved makeing an intermediate shaft between the motor and the input shaft of the lathe. We had room for this since the original electric motor was replaced with a smaller one because we used low gear and never used the higher speeds. It was also built so when the power was turned off to the motor the brake went on to keep the coil from unwinding for tack welding in the spacer bars. I wasn't involved in the electrical set up. I did however make all the other components. That was about 20 years ago so I may be rather vague on the details. Basically a motor connected to an intermediate shaft by Love Joy coupling supported on 2 pillow blocks with the brake in between the pillow blocks, then the original motor pulley mounted on the far end. You can see some of the details in the pictures, since there are no prints and this same setup would be an over kill for a bench lathe. But may give you some ideas.
Sidney mod1.jpg


Richard W.
Last edited by Richard_W on Sat Mar 10, 2012 3:39 pm, edited 1 time in total.

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dgoddard
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Re: lathe brake& spindle lock

Post by dgoddard » Fri Mar 09, 2012 1:40 pm

DrDavo wrote:I can see the advantage of having a brake but since your lathe is a D-4 cam lock, what is the purpose of having a spindle lock?
Holding the spindle still while I hand tap the work piece.
I never met anybody that I couldn't learn something from.

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Dave_C
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Re: lathe brake& spindle lock

Post by Dave_C » Fri Mar 09, 2012 3:04 pm

Don,

That makes sense I guess.

I do it differently. I hold the tap in the tail stock and rotate the chuck while out of gear. That way I have the tap perfectly straight. I don't lock the tail stock and I let it creep as the thread deepens. I even power the chuck to back off on deep holes sometimes.

Works good for me.

Dave
I learn something new every day! Problem is I forget two.

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SteveM
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Re: lathe brake& spindle lock

Post by SteveM » Fri Mar 09, 2012 9:56 pm

The motor on my Atlas is a dual shaft. I suppose I could rig up something like the disk brake on the other end.

There are disk brakes for scooters and bikes that might do the trick.

Steve

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Richard_W
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Re: lathe brake& spindle lock

Post by Richard_W » Fri Mar 09, 2012 11:51 pm

SteveM wrote:The motor on my Atlas is a dual shaft. I suppose I could rig up something like the disk brake on the other end.

There are disk brakes for scooters and bikes that might do the trick.

Steve
What about the disk brake on a lawn tractor? It brakes on the transmission.

lakeside53
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Re: lathe brake& spindle lock

Post by lakeside53 » Sat Mar 10, 2012 1:10 am

They are usually part of the transmission - adapting would be painfull at best. They also have very small plates desiged to stop slow speed shafts.

Some type of motor cycle disk brake would be very nice on a lathe!

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BadDog
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Re: lathe brake& spindle lock

Post by BadDog » Sun Mar 11, 2012 1:26 pm

Putting it in the lowest back-gear should work fine for something like hand tapping something held in the chuck, though I've never tried. Why not power tap?

Any vehicle with a slip off "top hat" style brake disk would be fine. Baring that, most non-slip-off disks separate from the hub easily by pressing out the lugs. Drop by a brake shop, they have "out of spec" pull offs in PILES that they have to pay to get rid off (scrap). See if you can get a small light one that is not warped (sure wouldn't want that) or cut up too badly, that should work fine on a lathe. And frankly, you can get new disks at discount auto parts for surprisingly little. Likewise for calipers and pads. A little research should produce an inexpensive small caliper (motorcycle stuff is NOT cheap). It won't need to be too big really. Again, not a 2+ ton car, or safety/heat issue. Finally, same thing for a master cylinder. Might even use a clutch (or other source) for the master cylinder. With a few brackets, a hub, and a lever/pedal assembly, doesn't seem too hard, though in reality space/details may well change that.

My lathe uses a hub/fly-wheel rig with a wrapped friction band and purely mechanical actuation. Works very well with very little pressure.
Russ
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dgoddard
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Re: lathe brake& spindle lock

Post by dgoddard » Sun Mar 11, 2012 9:10 pm

BadDog wrote:Putting it in the lowest back-gear should work fine for something like hand tapping something held in the chuck,
Not for 1/2 or 12 mm coarse threads.

BadDog wrote:Why not power tap?
I lack any device to stop if the tap bottoms, and most of my taps are not High Speed Steel at this time.
BadDog wrote:Any vehicle with a slip off "top hat" style brake disk
I am not familiar with what design is specified as ' slip off "top hat" style'
BadDog wrote:My lathe uses a hub/fly-wheel rig with a wrapped friction band and purely mechanical actuation.
I have some ideas along this line if I can just get the right kind of friction band.
I never met anybody that I couldn't learn something from.

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GlennW
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Re: lathe brake& spindle lock

Post by GlennW » Sun Mar 11, 2012 9:22 pm

dgoddard wrote: and most of my taps are not High Speed Steel at this time.
Take the money you would spend on a brake and buy good taps.

Fix the problem, not the symptom.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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