Clausing 100 mk3 lathe

COMachinist

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Hi Everyone
Well thought I would start a thread on the 100 mk3 I bought the 3/11/14. I have million questions about the lathe. So first thing I may have spoke to soon about the taper attachment. What have I have is part of an Atlas taper attachment I have not been able to find the cross slide bar or the dove tail block for the cross slide or the block for the taper bar. If I can find the dimensions for the parts I can make them on the mill. So far no luck on the internet. Next I have got tools I have idea what they are we can have a little contest for a year or more where I post things and you can tell us what it is:thinking:. I have ordered a Clausing 100 mk 3 4800 manual from the place on Fleebay that sells reproduction manuals. He says it will cover about 99% of my lathe.
Next up I was playing around with the lathe and it has a forward/Rev switch, and yep you guess it right went to turn it off and rev, and chuck unthreaded. I was able to partly catch it with my free hand. I didn't ding the chuck or the bed ways. but my hand got dinged but good.:angry:
Anyone know a fix for that? I know don't do that any more right.:nono:
So any help for now would be appreciated.
CH
 
I think you have just discovered the major issue with threadded spindles. There are a few things you can do to minimize this:

1) Make sure the chuck is on really tight

2) Make sure the lathe is completely stopped before you reverse it.

The upside is that you chuck is not frozen onto the spindle, so you won't need to soak it in penetrant oil :)
 
One fellow that I know solved his problem as follows:

1. Drill a 1/4" hole in the chuck backplate, drilling it crossways into the spindle thread
2. Tap the hole 5/16"-18
3. Mount the chuck on the spindle
4. Cut a piece of 1/4" diameter nylon rod, 1/4" long
5. Insert it in the newly created tapped hole in the chuck backplate.
6. Put a 5/16"-18 setscrew in behind the nylon rod.
7. Tighten the snot out of the setscrew.

The nylon will press firmly against the threads of the spindle without damaging them and will keep the chuck from spinning off of the spindle. The nylon will even misshape slightly to make a very capable locking device. Care must be used when removing the chuck to keep from losing the piece of nylon, however.

I have not yet tried this on mine as I only have a simple on/off toggle switch on my lathe, no reverse as yet, but I have used the same method to lock adjustment dials on machines. It locks them well enough that they will not move due to vibration, but can be moved with hand pressure if necessary. It would probably provide enough resistance to turning to keep the chuck from coming off of the spindle, too.
 
You probably don't need to spend more money right now but this is another good reason for a VFD - soft start. It's surprising how much difference a 2 - 3 second ramp up time makes, the machine starts much more smoothly.
 
Do you have a 3-phase motor on the Clausing?

Robert D.
 
Do you have a 3-phase motor on the Clausing?

Robert D.

Hi Robert
No I don't have a 3ph on it yet. I do have a 1.5hp 56c frame 3ph and a NES1-015SB Hitachi 2hp VFD. I have this same setup on my mill. I love the 3ph VFD flexibility and being able to change RPMs on the fly. I need to sit down design a lock for that chuck that will work. I was completely thrown off by that little event.:phew: I have been searching the internet and have no seen any thing that would be long term workable solution. The nylon or delron padded set screw looks to be a short term fix, but I can see problem with it down the road. If I use a braking resistor on the VFD, then it could work loose I could really have a problem even with that. So I need to think long and hard able this.
Found some backing plates from shar's 1 3/4x8tpi They have a couple sises for 11-12" lathes made of cast iron for a good price. I Think it would be good to pick some of those up befor they disappear.
CH
 
Hi Robert
No I don't have a 3ph on it yet. I do have a 1.5hp 56c frame 3ph and a NES1-015SB Hitachi 2hp VFD. I have this same setup on my mill. I love the 3ph VFD flexibility and being able to change RPMs on the fly. I need to sit down design a lock for that chuck that will work. I was completely thrown off by that little event.:phew: I have been searching the internet and have no seen any thing that would be long term workable solution. The nylon or delron padded set screw looks to be a short term fix, but I can see problem with it down the road. If I use a braking resistor on the VFD, then it could work loose I could really have a problem even with that. So I need to think long and hard able this.
Found some backing plates from shar's 1 3/4x8tpi They have a couple sises for 11-12" lathes made of cast iron for a good price. I Think it would be good to pick some of those up befor they disappear.
CH

Well, the lock for threadded chucks is going to be a bit of a head-scratcher. The solution the lathe manufactures came up with include the L series tapers (L-00,L-0,L-1 and L-2) followed by the short taper A and D mounts. The D style cam-lock is currently used on most new lathes. One possible solution could be to cut some slots into the threaded portoin of the backing plate and use a shaft collar to compress them down, locking up the threads. But that would only work on chucks that have a threadded boss sticking out of the back.
 
CH,

OK. There was quite a long thread on this same subject on the Atlas_Craftsman Yahoo group recently. The consensus (with maybe 15 different respondents) was that properly seated threaded chucks coming off isn't a problem unless you are threading or turning in reverse or manage to abruptly stop and reverse the spindle by any means other than running the carriage into the chuck.

Although probably not your problem, to properly seat a threaded chuck, you screw it on until it stops, back it up about an eighth of a turn, and spin it to stop. It should ring or clunk. If you then turn the chuck until the tightening socket is at about 12:00 and insert the T-wrench, it should take a good rapid jerk to break the threads loose.

However, if I'm reading your statement correctly, you went to turn the motor off but instead moved the switch past OFF to REV. The motor reversed and the chuck came off, which isn't too surprising even if the chuck was properly seated. The only explanation I can think of is a problem with the centrifugal switch in the motor. A properly working single phase motor if suddenly reversed will continue to smoothly run in the same direction as before with no more than a few milliseconds hesitation.The reason is that with the centrifugal switch open, the motor will happily run in either direction with power applied to the run but not the start windings. If the motor reversed, the switch had to be closed, which it doesn't normally do for at least half a second or more after power is removed unless there is enough load on the motor to stop it almost instantaneously.

If I misunderstood what you wrote, let me know.

FWIW, there are switches that won't let you go from FWD directly to REV without releasing pressure on the toggle or lever as you pass through OFF. Usually only used on 3-phase motors as they aren't normally needed on single phase ones and are quite a bit more expensive. And there are also triple push button motor starters where you can't physically depress the REV button if the FWD one is depressed. If either run button is depressed, the only one that will work is the OFF.

Robert D.
 
However, if you do need to run your threaded spindle machine in reverse and cut while it is doing so, you do need to lock the chuck to the spindle nose. I recently bought a locking chuck that was made in Germany for one of the European built lathes. The threaded nose of the backing plate is split in six places and has a locking collar around it.

Robert D.
 
However, if you do need to run your threaded spindle machine in reverse and cut while it is doing so, you do need to lock the chuck to the spindle nose. I recently bought a locking chuck that was made in Germany for one of the European built lathes. The threaded nose of the backing plate is split in six places and has a locking collar around it.

Robert D.

Damn, looks like somebody had my idea before me again :)
 
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