Anyone tried this?

[COMachinist]

Hi
I have been studying the Meeks dog clutch. I saw a video of Jim Schroeder's G0602 lathe cutting single point threads and he made it look like a piece of cake. G Meeks designed a single dog transmission to add to a lathe and which has movable bidirectional trips that shift the lathe and lead screw in to neutral. so it can be reversed for next threading pass. I would like to make one for my Clausing 100 mkIII. What really makes this all work so well is a quick retractable tool that move the cutter back .150 or so, so you can reverse the lead screw back to the start. You can see it here http://www.hobby-machinist.com/showthread.php?t=20806 If anyone has done one or would like too, let me know. If you have better idea for the clausing I would like to here it. I know it has a tumbler but I'm worried about breaking a gear reversing it while it is running.
Thanks
CH

 

[benmychree]

Hi
I have been studying the Meeks dog clutch. I saw a video of Jim Schroeder's G0602 lathe cutting single point threads and he made it look like a piece of cake. G Meeks designed a single dog transmission to add to a lathe and which has movable bidirectional trips that shift the lathe and lead screw in to neutral. so it can be reversed for next threading pass. I would like to make one for my Clausing 100 mkIII. What really makes this all work so well is a quick retractable tool that move the cutter back .150 or so, so you can reverse the lead screw back to the start. You can see it here http://www.hobby-machinist.com/showthread.php?t=20806 If anyone has done one or would like too, let me know. If you have better idea for the clausing I would like to here it. I know it has a tumbler but I'm worried about breaking a gear reversing it while it is running.
Thanks
CH

Not only you would likely break gear teeth using the tunbler to reverse, but it would not work anyway, as there is no capability to re engage the lead screw in the proper one revolution fashion as the one tooth clutch does. In my shop I had a Monarch lathe that was equipped as described, and it is a very handy feature for short threads and threading to a shoulder, but not so handy for longer threads, as it takes so long to return to the starting point. Personally, I would not even consider trying to build this feature into an existing lathe; too much work for limited benefit.

 

[COMachinist]

Not only you would likely break gear teeth using the tumbler to reverse, but it would not work anyway, as there is no capability to re engage the lead screw in the proper one revolution fashion as the one tooth clutch does. In my shop I had a Monarch lathe that was equipped as described, and it is a very handy feature for short threads and threading to a shoulder, but not so handy for longer threads, as it takes so long to return to the starting point. Personally, I would not even consider trying to build this feature into an existing lathe; too much work for limited benefit.

Humm I'm a hobbyist there is no such thing as to much time. I know guys who have spent a year building tiny little v8 engines to just watch them scream a long. So being retired I have all the hobby time I want. I see why it would not work using the tumblers. But it will work with the Meeks tranny. So if I can come up with a way to put the single dog clutch in place of the tumbler then it will do as Jim's G0602 does for threading. Right?
It looks far more useful than just the threading use it has now. I read, Jim's version will be in The Home Shop Machinist soon so maybe I can adapt it to the Clausing. It would be nice to have trip points to drop the lathe in to neutral at both ends of a cut
Thanks for your input.

Mk100 Tumbler

Meeks Dog Clutch
CH

 

[f350ca]

I saw that article and thought about building his designs into my Colchester but lucked into a Hardinge HLV that has the features. It looks doable. The Hardinge and I think his design uses a double dog clutch one central drive with mating clutches on each side for forward and reverse. The clutch on the Hardinge is geared off the spindle before change gears, it can only drop in in two positions so probably is 2:1 reduction from the spindle, then it doesn't mater where it engages the tread will pick up. The Hardinge drops out within 0.001 carriage travel every time.
You have to run back under power which is slower than cranking it back, but when your threading at 6 or 800 rpm its pretty quick.
Saw plans for his quick retract somewhere, was pretty much the same design as Hardinge used. Works nice.
Good Luck
Greg

 

[Marco Bernardini]

You have to run back under power which is slower than cranking it back, but when your threading at 6 or 800 rpm its pretty quick.
Greg

600 rpm with a normal M6 thread (1 mm/turn) is 60 cm (23"-5/8) a minute: a respectable 0.0223693629 miles per hour, tells Google.
Not quick as an unloaded swallow, anyway

 

[Oscar T]

I built the cross slide retractor, you can find Mr. Schroeder's plans on the Projects in Metal web site. It was a fun project and I am waiting for his article on the threading clutch in the Home Machinists magazine.

 

[mws]

I would like to have seen more details on how he renegages the thread at the right place after disengaging the drive to the lead-screw gearbox. I believe if I did that to my lathe I'd have a hell of a time getting my threading dial re-indexed correctly.

In lieu of such a device, I've seen several simpler mechanisms which only disengage the half-nut at the bottom of the thread, which is a nice feature, and really takes most of the worry out of threading.

I've gotten very quick at threading using the adjustable stop on the cross slide to reset the tool for each pass and just use the compound for additional depth as usual without having to worry about the cross slide position.

If I have a difficult shoulder to thread up against I've also taken to turning the tool upside down and threading in reverse, moving away from the chuck.

 

[hermetic]

You guys might be interested in "screwcutting in the lathe" by Martin Cleve. It is No3 in the workshop practice series of "Special Interest Model Books" ISBN 978-0-85242--838-2 He goes into detail about the dog clutch and retractable toolpost he built for a converted Myford which he used to earn a living cutting small batches of special bolts and threads. If screwcutting is your thing, I think this is one of the best books out there.
Phil.
UK

 

[benmychree]

I saw that article and thought about building his designs into my Colchester but lucked into a Hardinge HLV that has the features. It looks doable. The Hardinge and I think his design uses a double dog clutch one central drive with mating clutches on each side for forward and reverse. The clutch on the Hardinge is geared off the spindle before change gears, it can only drop in in two positions so probably is 2:1 reduction from the spindle, then it doesn't mater where it engages the tread will pick up. The Hardinge drops out within 0.001 carriage travel every time.
You have to run back under power which is slower than cranking it back, but when your threading at 6 or 800 rpm its pretty quick.
Saw plans for his quick retract somewhere, was pretty much the same design as Hardinge used. Works nice.
Good Luck
Greg

My thinking is that if you tried reversing the lead screw at 6 0r 800 rpm, that you would break something; I remember a Pratt & Whitney toolroom lathe in my high school / Jr College shop that had a warning plate on it stating that the leadscrew reverse should not be operated at more than so many RPM ---- I stupidly operated it at a higher speed, and sure enough , the clutch was amaged to the point that it would no longer stay engaged, and was not real cheap to repair The teacher (smartly) kept the toopost in hi desk drawer so that it could not be used ----

 

[f350ca]

The Hardinge seams to go forward to reverse pretty smooth, no noticeable noise at all. The manual says the maximum recommended threading speed is 1000 rpm

Greg