recoil escapement fly cutter drawing needed

[David lawrence 3Participant @davidlawrence3]

Hi all, I am just about to grind a fly cutter tool to make the escape wheel for a John Wilding large wheel skeleton clock. No drawings or measurements are in the book to help me make this hss cutter.. Any help please. JW suggests Thornton who sell a cutter but its around £ 65.00 for one clock use so I was going to make my own. I have looked in other clock making books I have and they are different escapements but all dimensions are supplied. thanks, David

[David lawrence 3Participant @davidlawrence3]

John Wilding clock, need help

[John HaineParticipant @johnhaine32865]

What is the tooth profile? I have made the count wheel (basically a ratchet) for my Woodward Gearless clock using a standard 60 degree dovetail cutter, so that may be a good approach. If you know the tooth profile (and for the scape wheel it's going to be fairly simple) it's just a matter of making a fly cutter to its "negative". JW's "Wheel and Pinion Cutting in Horology" is helpful too.

[Michael GilliganParticipant @michaelgilligan61133]

David,

More questions than answers, I'm afraid … Which of the seven sizes of [Thornton] Recoil escape wheel cutter does JW specify for this clock ?

MichaelG.

 

Edited By Michael Gilligan on 10/05/2016 14:00:12

[David lawrence 3Participant @davidlawrence3]

Hi Michael, its a number 7 thornton recoil cutter, regards David

[Michael GilliganParticipant @michaelgilligan61133]

Posted by David lawrence 3 on 10/05/2016 15:44:08:

Hi Michael, its a number 7 thornton recoil cutter, regards David

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So the cutter is 5.08mm wide … we're getting there

Is there a decent photo of the 'scape wheel in the book ?

MichaelG.

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EDIT: … That's 5.08 according to Thornton

… but 5.80 according to Richards: who also show the profile 

Edited By Michael Gilligan on 10/05/2016 16:13:56

[AjohnwParticipant @ajohnw51620]

As no profile is given I suspect you would be better off buying a book that covers the design of this type of escapement and go through one with the same outside diameter and tooth count.

I'm not a complete fan of Laurie Penman's book Practical Clock Escapements but he does cover anchor escapements pretty thoroughly. He disappoints for me somewhat as there are mentions of numerous types of escapements and he could give more design detail on some. He does cover anchor recoil and graham dead beats very thoroughly.

Wheel and pinion cutting is mainly related to gearing and cutting them so I wouldn't personally suggest that one as I don't think it would get you out of the fix you are in. Penman's should.

If this is typical of Wilding's design books sounds like a good reason to not buy one to me.

John

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Edited By Ajohnw on 10/05/2016 16:10:41

[Bob StevensonParticipant @bobstevenson13909]

Th escape wheel teeth should only be considered in conjunction with the pallet shape as the two are inextricably linked.

All the info is shown in fig.85 on page 40 (the 'photocopied' later edition produced by Wilding himself)

Wilding is indeed a bit sketchy with his info about escapement teeth/pallets and this is one of the reasons his books are unpopular with our members (Epping forest Horology Club) The usual working practice is to NOT buy any 'scape cutter but to make up a basic fly cutter and cut a 'scape wheel and pallet arm. Assemble these in a simple,..ie flat type depth tool and check for fitness of action with the pallets……… The final teeth shape.fly cutter can then be determined (if indeed it needs to be modified at all)

[AjohnwParticipant @ajohnw51620]

Posted by Michael Gilligan on 10/05/2016 15:59:33:

Posted by David lawrence 3 on 10/05/2016 15:44:08:

Hi Michael, its a number 7 thornton recoil cutter, regards David

.

So the cutter is 5.08mm wide … we're getting there

Is there a decent photo of the 'scape wheel in the book ?

MichaelG.

.

EDIT: … That's 5.08 according to Thornton

… but 5.80 according to Richards: who also show the profile

Edited By Michael Gilligan on 10/05/2016 16:13:56

Wild gives the sizes in his wheel and pinion cutting book as well but for type 7E so who knows. That one is 5.8mm thick and has a 12.25mm rad. He does shows shots of Thorton cutters and they do have the E on the end. I visited the original makers some years ago – very happy chap but another story.

Odd as I just got the book out to rifle for any useful information. I don't expect to find much for home type construction. The first 60 pages are mostly on history. Then comes a design for cutter frame for wheels, not suitable for pinions and shots of a milling spindle which is. Plenty of gear math and photo's of this and that on what ever.

I'm not being fair on Penman's book. It more or less does do what it states on the cover. Wild's ????? really.

John

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[David lawrence 3Participant @davidlawrence3]

Hi all, Thanks for all that info, most interesting. I shall have a go at grinding a cutter tomorrow, regards David

[Sam StonesParticipant @samstones42903]

Hi David,

Not much to add compared with these other chaps.

However, back in the 70’s and knowing nothing about clock building, I ground a fly cutter in silver steel, hardened and ground it.

As you can determine from the poorly formed root radius (radii), the cutter didn’t have a full-form profile.

Instead, I approached the locking and clearance faces of the wheel from different angles.

For reference, the wheel was made from silver steel too, hardened/tempered, and the locking faces lapped. The fifteen tooth wheel has an OD of ¾” (19mm) and is 1/16” (1.5mm) thick.

Good luck.

Sam

Edited By Sam Stones on 10/05/2016 21:44:33

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