Graham Meek Myford Super 7 Screw Cutting Clutch

[Robert ButlerParticipant @robertbutler92161]

[Robert ButlerParticipant @robertbutler92161]

Gentlemen

Having recently re-read Graham's article for the screw cutting clutch for the ML7 in MEW. i am tempted to buy his "Projects for the Home Workshop" which i understand contains the original design for the Super 7 which I have. I have some queries which hopefully the esteemed members of this forum will be able to resolve.

a) I have the custom Machine DRO Sino DRO fitted to my S7 and wish to retain this. Is this possible?

b) Are there any disadvantages when fitting this device or can the lathe be operated normally with the added advantage of easy selection of forward and reversing the leadscrew?

c) Have any worthwhile improvements been made to the original design – if so details would be appreciated.

Thank you in anticipation

Robert Butler

[Chris TriceParticipant @christrice43267]

(a) Yes. The disengaging rod sits neatly, if a little tightly, below the cross slide and above the aluminium housing on the rear of the bed. You may find it advantageous to make the arm the rod attaches to adjustable for length in order to fine tune it. Similarly the block that clamps to the bed that supports the other end of the rod might need tweaking depending on how close your saddle is going to get to it.

(b) No disadvantages. Mine has been fitted for at least five years.

(c) That's a question for Graham. My one suggestion would be to make the groove in the barrel which holds the lever in the neutral position via the sprung ball bearing a bit deeper than the other two locating grooves because sometimes when disengaging manually, the lever skips over the neutral position and goes into the reverse position.

[Robert ButlerParticipant @robertbutler92161]

Chris thank you for your reply, i have purchased Grahams book and await delivery with interest. if anyone else has anything to add i would be interested to hear from them.

Robert Butler

[Graham MeekParticipant @grahammeek88282]

Hello Robert,

I am unfamiliar with the DRO set-up so I cannot comment on this.

There have been a few additions to my original design to suit personal preference. The first being the ability to dis-engage the unit when desired. Using the original Myford tumbler lever location holes. This was done by Ken Willson, (KWIL), and several people I know have added this feature. I have no drawings of this, but I am sure a personal message to KWIL will get you the necessary details.

Another modification which has gone a long way to quieten the device down in use is the fitment of non metallic idler gears in place of the Phos Bronze ones. The materials used so far are as follows, Delrin, (Acetal), a Nylon graphite mix and my choice Tufnol. The flat woven material, not round. The latter is not good for gears as the laminations are running parallel to the gear teeth. Not perpendicular to them as in the sheet material.

The last modification I can think of is the addition of ball races in the idler gears. This mod was down to Phil Proctor and shown on the front cover of MEW which contained the ML7 version of the clutch.

I hope this helps.

Regards

Gray,

[Robert ButlerParticipant @robertbutler92161]

Dear Graham

Thank you for your post, I am grateful to you.

Robert Butler

[john anderson 5Participant @johnanderson5]

hi can anyone tell me if i can fit a screw cutting clutch on a ml7r i don,t have a gearbox and its not big bore i want to buy grahams book if its possible thanks john

[Phil PParticipant @philp]

I can provide a set of PDF drawings if you would find them useful.

Phil

[john anderson 5Participant @johnanderson5]

thanks phil, that would be great, if you need my e mail its johnanderson05 at hotmail.co.uk ,i am hoping you can fit it to a std ml7r. i was looking at your album, i have a clarkson grinder which i,m hoping to do 4 facet drills, and i,m a proud owner of a pultra, i,m a newcommer to engineering , so i must be buying the right gear. cheers john

Edited By JasonB on 10/05/2020 12:55:37

[Brian WoodParticipant @brianwood45127]

Hello John Anderson

Yes, you can fit Graham's clutch to the ML7R

Regards Brian

[john anderson 5Participant @johnanderson5]

thanks brian thats good , i thought you had to have a gear box so that you would have enough room

[Graham MeekParticipant @grahammeek88282]

Hello John,

There is one YouTube video posted which shows a non-QC gearbox installation. While it is on a standard Super 7, there is little difference between this and the ML7R. The video was posted by a friend in Italy who I helped out many years ago.

Thanks Phil and Brian for answering on my behalf, I do not always log-in every day.

Regards

Gray,

[john anderson 5Participant @johnanderson5]

thanks gray that good , just ordered your book cheers john

[Graham MeekParticipant @grahammeek88282]

Hello John,

I have sent you a PM

Regards

Gray,

[Andrew CrowParticipant @andrewcrow91475]

I have read Graham's article on the Myford screw cutting clutch which contains quite a bit of grinding. I don't have grinding facilities and I'm not sure I would want to cylindrical grind on my lathe. Have other builders completed the unit without resorting to grinding?

[Brian WoodParticipant @brianwood45127]

Hello Andrew,

Like you I do not have grinding facilities and I completed my version of Graham's clutch by careful finishing cuts and polishing where it was needed. My lathe is an ML7R with fitted gearbox and the unit has now operated well for several years. It has the KWIL modification so that it can be disengaged

I have though altered the arrangement of sprung ball bearing into grooves in the selector barrel by bringing that detail outside to a more positive spring loaded indenting in the boss that clamps the operating lever to the device cross shaft.

One last point. I tried black nylon gears as idlers, they were quiet but the narrow one suffered from gear smearing and spreading and was replaced with one made from Tufnol. The other, being wider, is still in place

Regards Brian

[Graham MeekParticipant @grahammeek88282]

Posted by Andrew Crow on 22/01/2022 17:39:32:

I have read Graham's article on the Myford screw cutting clutch which contains quite a bit of grinding. I don't have grinding facilities and I'm not sure I would want to cylindrical grind on my lathe. Have other builders completed the unit without resorting to grinding?

Hi Andrew,

The grinding is not required, a good finished turned item will work just as well. I grind because I have a toolpost grinder and I can finish multiple parts quickly. It is one of the traits of being a Toolmaker by profession.

As regards using a toolpost grinder, provided the ways are covered, ( I use a piece of Denim, dark blue up, that way this side always gets the dirt), I have had no problems with my 36 year old Maximat form using a toolpost grinder. It is a genuine Emco product.

Regards

Gray,

[bernard towersParticipant @bernardtowers37738]

Andrew you can do it without grinding just be very careful and get a good surface finish finally finishing with polishing paper. Mine has been running for 6 or seven years now with no trouble except changing the bronze idlers for sheet tufnol ones. Oh and my super 7 has a dro fitted.

[egaParticipant @ega]

Graham Meek:

I have your "Projects for Your Workshop Vol 1" (sic!) and have occasionally wondered if a second volume is in hand?

The denim tip would be useful for those who have jeans they can no longer wear; I would be inclined to spray the upside with light oil.

[KWILParticipant @kwil]

My Super7 prototype clutch version has green nylatron gears (Moly DS loaded) and the wear/use has not caused me to change them. My clutch drives a DAG Brown designed Metric/Imperial banjo arrangement and then the standard Myford Quick change gearbox, so I have all the options available.

[Graham MeekParticipant @grahammeek88282]

Posted by ega on 24/01/2022 10:36:13:

Graham Meek:

I have your "Projects for Your Workshop Vol 1" (sic!) and have occasionally wondered if a second volume is in hand?

The denim tip would be useful for those who have jeans they can no longer wear; I would be inclined to spray the upside with light oil.

Like the first Volume of the Projects Book, that decision lies firmly with TEE Publishing. It was only ever called Vol 1 for a means of having other volumes by other authors if I remember correctly.

This year marks my 11th year of writing and with 50 + articles already done. It is also the year that the Emco machines are going to be retired. It may well be that I shall retire from writing too, as yet I have not made up my mind. While I do have several items still to write about, time is in short supply these days. Plans are afoot to down size to smaller machines and I want to concentrate on getting these to a stage I am happy with. Maybe after then I might pick up the pen again.

If you desperately want to know about a Vol 2 I would suggest you contact TEE.

Regards

Gray,

[egaParticipant @ega]

Gray

Thank you for your informative reply. I think that the process of downsizing would be of interest to most forum members sooner or later; it affects them primarily, but also those others who have to sort things out later on.

I suppose that the ideal downsize lathe would, amongst other things, have a relatively large spindle bore and small footprint.

I obviously misinterpreted the book title and am grateful for the clarification.

I wish you well for the future.

[Graham MeekParticipant @grahammeek88282]

I have for a number of years had an Emco Compact 5. This will be the mainstay of the workshop along with a Proxxon mill, when the table turns up. If the sale of the Maximat Super 11 and the FB2 generate enough funds I might add the larger Proxxon lathe.

I have also been given a well worn Unimat 3 which has had a full restoration and can be found elsewhere on the Forum. (I still have to finish this electrically).

Recently I have been working on a design for a screwcutting clutch for the C5. Once you have had this facility it is hard to let go. This is now ready for manufacture, but it will have to wait for a short while.

 

A few further notes on how I go about grinding in the lathe might be handy for those wanting more info.

A rectangular tobacco tin partially filled with water is place under the grinding wheel. This is kept in place with an Eclipse Pot Magnet, placed inside the tin.

When dressing the wheel the grit goes into the tin, as well as the debris from grinding. Dressing the wheel should not take more than 0.05 to 0.1 mm to clean up the wheel, 0.002 to 0.004" ref.  While grinding I present a cotton pad to the rear of the work. It is made in the same fashion as a French Polishers Rubber. This is soaked in water but not dripping in water. The action of this pad is to trap particles of grit or metal debris which would get imbedded in the wheel and ruin the work. Plus the mass of the pad allows a certain amount of cooling to take place.

The spindle is run in reverse for external grinding and forwards for internal grinding.

When doing internal grinding, like the new ER Spindle for the Proxxon mill, (listed elsewhere & in my album). I usually squirt a drop of water into the hole, but not a lot. This keeps the wheel free of debris and cools the work. Again any debris drips into the tobacco tin.

A toolpost grinder is on the list of items to make for the C5.

Regards

Gray,

Edited By Graham Meek on 25/01/2022 11:33:39

[egaParticipant @ega]

Gray

Thanks for the grinding information which reminded me that there are some helpful photos of this in the book.

[Andrew CrowParticipant @andrewcrow91475]

Many thanks to everyone for the information to my query, lots of useful points which I will try to incorporate. However, one further question has cropped up concerning a disengagement arrangement. I am assuming that this involves using something similar to the existing Myford tumbler arrangement. I would like to incorporate this as it's useful to disengage when using the leadscrew handwheel for milling.

Any information would be gratefully received.

[Author]

Posts