Meek screwcutting dog-clutch

I'm sure that I'm not alone in being very pleased to see that Graham Meek has returned to the forum. He will get no peace now...

Please can I ask Graham a couple of questions? I think I recall you mentioning (in your previous, but now missing, posts) that you had considered designing a dog-clutch, for your Emco Maximat Super 11. Did it get done? Also, what about a version for the V13?

Please forgive me for not answering this before. I have only just found this post while searching for something else.

You are right I did design a version of the dog-clutch to fit the Maximat Super 11. Unfortunately health issues have meant I have never had a chance to make one for my lathe. The design requires the complete strip down of the headstock. As the clutch is fitted where the reversing lever for the leadscrew and feeds is fitted. It is the possibility of falling ill for some months and having my lathe in bits, is why I have fought shy of doing this version.

Originally when I started this design back in 1985 Emco were going to loan me a complete headstock, through their UK base. This would have dispensed with the need to strip my own machine. Unfortunately this company closed down about this time and "my loan" promise must have been lost in the ether.

As with all my designs the lathe did not require any other modification. The clutch selector lever even made use of the spring detent holes of the old reverse lever. The design does also require the fitment of an additional change wheel stud. As some of the additional pitches outside the range of the gearbox need the drive reversing. As the reversing lever was no longer there the extra stud is needed.

I have tried an umpteen designs since to try and produce a design to fit externally. After many hours and several designs it was found the switch gear or the change gear banjo gets in the way.

I have no experience of the Maximat V13 lathe, other than standing in front of one at the Machine Tool Exhibition at Birmingham years ago, wishing I had 3-phase and it was mine.

Once again my apologies.

Regards

Gray,

Graham; I've pm'd you.

Having had another look at the Maximat Super 11 dog clutch again, I have come up with the following schematic that I am 90% certain will work.

The main stumbling block has always been the square operating rod for the two speed motor switch. The rod is right where the clutch should ought to go. However in a moment of inspiration I tried fitting the dog-clutch outboard of the rod and hey presto it worked.

While this is just the schematic drawing, certain changes will probably be needed to be made, but nothing significant, (I hope).

Regards

Gray,

I once owned a lathe that had a dog clutch. It was a marvelous tool for threading. I could thread up to about 600 rpm. At that point I could hear the clutch "bouncing" as it engaged.

I bought the lathe, used, here in the US. It was a Pratt and Whitney. It had a 400V 50 cycle motor and a property tag from Buck and Hickman. I assumed it was shipped from the US to England for WW2 parts production. Somehow it was shipped back to to the US. It was badly worn when I got it. Even so, it was a great lathe.

Well finally I have something that works, it has not been an easy machine to add the attachment to. The Mk2 design above has gone through a few more iterations since I last posted. Mostly the design is now more compact and there are less gears in the transmission.

Below is the drawing of the controls of the mechanism, it uses the dead space behind the chuck interface to mount the operating lever, which has a total travel of 45-46 mm. All the rest of the mechanism is out of sight. I hope to start work on the unit next week so I will post more info as the project progresses.

Regards

Gray,

For those following this post I have started work on the parts for this screwcutting clutch. The above photograph shows how the Gearbox Cover plates would fit to the Main body. The output shaft will be on the left Overall length of the unit is 103 mm by 96.5 mm high .Hopefully this week I shall make a start on the main body.

Regards

Gray,

I had hoped to make a post last weekend, but things conspired against me. The Main Body shown below is the second attempt. The first was originally made in cast iron tooling plate, but two operations from the end I noticed a crack in the plate like the strata running through a rock face. Thus it was time to start again.

Here are some more photographs of the project so far.

Regards

Gray,

Edited By Graham Meek on 05/05/2019 13:04:52

Hi Gray

That looks to be a superb bit of machining you have accomplished there.

A pal of mine has just finished a Meek clutch for his Warco lathe, (with a bit of help from myself with 3D CAD drawings and gear hobbing etc. We took the liberty of "enhancing" the design in a few areas. 

It will be displayed on the Bradford MES stand at Doncaster next weekend, after that I will take some photo's before he refits it to the lathe, and send you some copies.

Hope you are well.

Phil

Edited By Phil P on 05/05/2019 14:23:13

Hi Phil,

Thanks for the praise, and the news about your friends Warco unit, I shall look forward to that. I always like it when others add their own twist to my design. I never consider my designs to be the last word on any topic, just a solution that worked for me.

This design for the Maximat has fought me every step of the way, or that how it has appeared to me, but with a bit of luck the end of the tunnel is insight. Most of the major machining is done, just the turning and gear cutting to do now.

I am as well as can be expected, thanks for asking.

Regards

Gray,

For those following the post but are not familiar with the Maximat I thought I would include a photograph of where the unit has got to fit. Sorry for the poor quality of the scan,

Regards

Gray,

Edited By Graham Meek on 05/05/2019 19:33:21

I had hoped to give a more blow by blow account of this project, unfortunately a bout of Shingles had other ideas. For those who have been following this post I have made significant progress despite my infirmity.

John (Slater) has been busy with the 3D views and his help has been most welcome, especially visualising where the parts go.

Hopefully tomorrow will see these parts assembled. There are still the trip rod and stops to make, but this should not take too long.

Regards

Gray.

I forgot to add one photograph the other day showing the Dog Clutch shape.

Over the weekend I have had a chance to fit the unit to the lathe. The Trip Rod and Trips are still to me made hopefully this week will see this project finished.

The unit is very quiet in operation, which did come as a surprise. I thought at the design stage that by enclosing the extra gear train in its own gearbox this might quieten things down but I was pleasantly surprised by how much. The noise is not dis-similar to that made by the Hardinge, even down to the clunk as the dog clutch engages.

The lower bearing was I thought going to give me a lot of trouble as regards alignment. The main bearing block sits on an unmachined portion of the bed casting. The bearing block is held in place by the headstock end hold down bolt. To overcome the roughness of the cast surface I used a 1.5 mm thick Aluminium spacer, which seems to have done the trick.

Hopefully later this week I can post the remaining parts.

Regards

Gray,

This week has seen all the required parts made and fitted. The Stops may come in for a slight design change before I put pen to paper.

What cannot be seen in the above photographs is the keyway running on the underside of the Trip Rod to orientate the Stop. There is nothing worse than trying to set a stop which has a mind of its own due to the eccentric nature of the design.

The clutch was pressed into service to make a new M8 stud for the extension piece. This is required to allow the same range of adjustment as Emco originally intended.

The parts in-situ,

This is the original position of the stud before the extension was fitted.

And after,

I hope you have liked my project on the Emco?

Regards

Gray,

Hi Gray,

Congratulation, excellent job as usual. I'm impressed how you have managed to fit it inside the rear cover.

Thor

Hi Thor,

Thanks for the kind words about my work. I must admit this design has fought me every step of the way. Even fitting the extension piece this morning required an additional modification. In the form of a scallop in the rear face of the extension piece to clear the aluminium casting that carries the quadrant banjo.

Whilst it has been a challenge I have enjoyed every minute of it, back to the Steam Wagon now.

Regards

Gray,

Hi Gray,

I have been watching this with great interest and wonder if you will be publishing a book or drawings etc for this clutch? Is is indeed a very clever design and fitted neatly into the machine, my compliments.

Regards John

Hi John,

I have agreed with Neil to submit this as an article for publication in MEW. I hope to finish the text and update the drawings by the end of this month or early next month.

Regards

Gray,

For those Forum members waiting for further details about the article. I managed the finishing touches this morning and it is wending its way to Neil's desk as I write this.

Regards

Gray,

Edited By Graham Meek on 08/07/2019 16:09:37