Basic Clock Design

Not really 'on topic', James, but I think it worth linking this blog

He is covering the build of one of the Peter Heimann Regulators that Ajohnw has mentioned several times.

Obviously an engineer rather than a 'clockmaker' ... it makes interesting reading.

MichaelG.

I must be on commission Michael. I have no connection at all but feel that as clock books go it's very good value and actually does what it states on the cover. Some don't. There are 2 designs in it and as he suggests they needn't be followed slavishly.

The design shown in the blog is unusual in some ways. There are no chimes. It's month going and uses 2 weights which give it a certain amount of symmetry which is usually lacking in regulators. Both designs are aimed to be pretty good time keepers.

John

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This is a rough layout of an "electric remontoire".

S3 locks the remontoire wheel when the solenoids operates. It's driving the escape wheel pinion and the hour and min wheels before it so is intended to be the only source of power.

Harrison used the same style of maintaining spring (S2) on his escape wheel remontoire but used 2 springs rather than one.

Sometime when done mechanically this sort of arrangement is used to cause one of the hands to jump at the correct interval rather than move slowly in the usual way.

Suitable sources of coils and contacts might be relays. The type with clear plastic covers that can be pulled off.

John

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Michael,

Thank you for the link to the blog. I have been reading this for a while and have found it very interesting.

John,

My escape wheel has 30 teeth and the arms of the pallets are at 90 degrees. They span 7 1/2 teeth and have an angle of either 1 or 2 degrees (drop?): I cannot recall which I drew. I know that in the drawing below, one pallet hits the teeth of the wheel. This is because I cannot work out how to rotate the wheel in the CAD drawing.

Edited By James Alford on 30/04/2016 09:07:37

Let's borrow this animation from Wikipedia:

**LINK**

MichaelG.

Edited By Michael Gilligan on 30/04/2016 09:17:59

Michael,

I have found plenty of animations online, but am stuck trying to rotate the wheels in my own drawings. It is possible to animate some elements of assemblies in Onshape, but, so far, my designs have remained stubbornly inanimate. Still, I shall persevere.

James.

James,

Sorry ... I was only trying to provide a convenient illustration, for the convenience of others who might be following the discussion.

I will try not to interfere any further.

MichaelG.

Michael,

I did not think that it was interfering, but that my original post was unclear! I would prefer your contributions to continue, please.

JAmes.

I found the blog interesting too Michael. One thing I noticed was probably a need to take some care when taking a wheel blank from one machine to another but that may just be an impression from shots of making the pinions - sticking a mandrel in a 3 jaw chuck doesn't seem to be very sensible to me. That lead me to understand why some cut the teeth on the lathe.

Reading a bit more on the dead beat angle in 2 books 90 degrees is ideal. One reckons that major departures makes things more critical so manufacturers generally use it. The other reckons it minimises friction but on large wheels using it will add more inertia and hence increase friction that way so on large wheels it's better to increase it. The book I mention states that this area is the most important one in the clock. Another points out that they can be made in two parts and turned to get precise rads - slot to hold each half in a piece of bar. Which ever I would use the spreadsheet for the design as it shows a good way of getting the impulse faces correct.

For a clock I'm going to call John's Folly. Nice double meaning. I'm inclined to use Brocot but am not sure that I have design information where the wheel finishes up looking much like a dead beat one. A Riefler is vaguely similar but I wouldn't be keen on applying the impulses to the suspension as I doubt if I could sort that out. On the other hand I can't see why this couldn't be used in a conventional fashion. This one appears to use a slope to provide the impulse where as the Brocot uses the rad on the pin. The pin pallet also uses a slope and it seems can be rather good if made correctly.

Not too clear on slope - the slope is on the wheel rather than part of the pallet.

Any views?

 I don't want to hyjack the thread but thought some discussion might be of use. It seems to be getting a fair number of views.

John

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Edited By Ajohnw on 30/04/2016 11:35:24

Edited By Ajohnw on 30/04/2016 11:47:35

John, the Brocot escapement is a dead beat escapement. The important design point is that the front face of the escape wheel tooth is radial so that it is tangential to the pallet and thus avoids recoil. It is easy to make and set up hence its use in better quality mass produced mantel clocks, often with a visible escapement and jeweled pallets.

Russell.

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That's probably a very worthy topic for a thread of its own, John.

Yes, its very common for [Watchmakers and] Clockmakers to use the lathe headstock for dividing, and a spindle on the vertical slide for the cutters. ... The arrangement has a great deal of merit; especially when we look at the antics required to put a small dividing head on a small milling machine.

MichaelG..

Thanks Russell. That's what I thought was going on so could work from scratch myself. I have had clock repair periods but haven't had to adjust one but that all started with a book which shows the degree of adjustment that's available even by rotating the pins slightly. My Pultra came with a precision x-y table so no problem drilling the holes either but any miller could do that anyway. The other aspect is that they can be jewelled - not a cheap option but worth it if the clock works. The available pins are a bit thin though, The biggest I can find is 2.35mm dia. I have no idea what the UTS is.

The fact that things meet square on made me wonder about other similar arrangement. I suspect that when I start digging up info on Riefler I'll find it has to impulse via the spring suspension. It's another attractive one though from a making point of view. It uses 2 escape wheels right next to each other. One has a slope for the pin to run on to provide the impulse. Using 2 wheels means that this one could be burnished easily and adjusted by rotating it against the other wheel which has the usual form. I'd guess that's why he chose to use 2 wheels. It seems the pin pallet can offer near similar levels of performance with a pendulum but I suspect it would be a pig to make.

Maybe all OTT but years ago I bought two second hand volumes of the clock maker. One of the articles has a telling point. The lack of very high precision designs. It looks like these must include some sort of remontoire some where to me. A nice simple one. It just means a few more bits to make and probably some trial and error. The designs in clockmaker are far from simple. In fact it turned out that the one initially shown in one article didn't work out..

John

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That will determine the diameter of the escape wheel as the pallet diameter is the pitch of the escape wheel less the drop.

Russell.

I think it's more a case of needing some care when transferring to the miller Michael and being sure things are reasonably line up, square etc.

I came across this site which may be of interest, or reassuring in my case.

**LINK**

Not that the site doesn't have a vested interest.

As these will need rather precise axial alignment I feel that clock makers pins would be a good idea when plates are held together for machining etc. They cost peanuts but there doesn't seem to be any reamers available for them. The pins are tapered. ??????????????????????

I'm pretty sure Burgess found that ball races aren't a good idea on the escapement and used PEEK instead.

I've been looking for jewel holes with a decent bore, say 1 1/2mm plus but PEEK ones are about on the web.

John

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I think there's much more to it than that, John ...

This is the recent thread that prompted my observation.

MichaelG.

My dividing head is home made Michael so it's bound to be supremely accurate. It also has a tongue in the bottom to locate in the T slots to square it up. To be honest I have never really seen a rotary table on edge as a viable option for cutting gears but if needs must I well understand why people do use them that way. I have seen comments about messing up counts - sector arms and plates would be a good idea.

Looks like clock taper pins are on offer all over the place but no reamers to match. Odd really as I have worked on movement that hold all sorts in place with them - even the plates. Just add even the washers needed to do that by the look of them.

There are so many pins about that googling clock pins brings up suppliers I had never heard of.

John

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Edited By Ajohnw on 30/04/2016 17:24:29

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Have you checked the taper against that of a standard 5-sided Broach ?

MichaelG.

M&P reckon that their broache's sizes are given from about 10mm from the shoulder and the taper is 1mm per 100mm. They don't state the length of their pins but a number 10 off Cousin's is 16mm long and tapered from 1.20 to 1.60mm which is 2.5mm per 100mm. They also do a No 12, 16mm, 1.40, 1.75 which comes out at 2.18mm / 100mm. This are Swiss made. The taper is pretty noticeable so no chance of knocking them out from the wrong end. The are available in steel or brass.

The Brocot

It clearly shows the impulse as the pin slides over the tooth. Niel's isn't so clear on the dead beat. Normally a slitted "carrier" like this would normally have push pull screws on both types.

Watching that gif I am wondering if Abbeyclocks comment about efficiency is a load of bull.

John

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Edited By Ajohnw on 30/04/2016 20:29:13

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I think you've lost me there, John

Do you mean this comment: ... "If you consider the displacement (or distance moved) of the pallet in the direction of Fp, and multiply this by the force Fp that rotates the pallet at each instant in time, you get a 'work done' curve. This curve looks very different and reveals how inefficient the Brocot design really is."

... taken from this page ?

MichaelG.

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Edit: I haven't gone through his analysis in detail, but Chapter_11 looks quite thorough.

Edited By Michael Gilligan on 30/04/2016 22:14:08