Woodturning is not my thing but I have managed to clean up my contrate wheel blank. It's about twice as thick as it needs to be which is probably being overcautious but I want to do some work hardening by hammering the cast brass so I am erring on the side of caution.
What are you using as your source of brass? How are you intending to work harden the contrate blank? Which way do you hammer, how much and how hard? Cheers
This chap sells yellow brass for clock restoration and will make bespoke castings, so I was thinking of using him. I have had an initial phone conversation and he said he could make castings either from my models or from wax copies. Brass Foundry Castings For the work hardening I was thinking of hammering the ring from the outside over a stake of similar diameter to the inside. A fair whack is what I intend to give it (can't really be more precise). I have recently been in contact with a professional restorer whom I hope to meet sometime in the next few weeks. I think he recently restored an Etherington and I hope to pick his brains about it.
Delaunce is said to have investigated the hammering of escape wheel blanks before cutting, I wonder if crown wheels were cast like this or turned from blanks that had been hammered. The crown wheels for brackets are not all that deep. The alarm ones are. (did you see my pm with a clock for you?)
Hi Nigel, This is going to increase the diameter, and possibly stretch the crossings, so I hope you've left enough thickness to cater for this. Regards, Graham
The book has inspired me to gather together in one document pictures and descriptions of all the clocks I can find by Etherington. With so much material now on line it's surprising how far you can get without leaving the house!
I have made the models quite a bit thicker and deeper than needed but until I try I won't really know how it will turn out. My tutor is convinced that they would originally have been cast.
Nearly there with my pattern making. Clockwise from top left: swan neck verge bracket, contrate wheel, verge crown wheel (might also be able to use for alarm crown wheel), 1/4 repeat fly, alarm motion work cock, verge front cock, verge back cock, alarm spring barrel, hour lifting lever cock and, in centre, verge potence. All have been made slightly oversize to allow for shrinkage, tidying up etc. I still need to make pulleys for both the 1/4 repeat and alarm, but I might turn these. The bob pendulum could also be turned rather then cast. I have not yet finalised my designs for the apron to go over the backcock or the supports for the alarm pallet arbor but these might also need to be cast.
An aside, my brief foray into making casting patterns always required "draft" on my patterns. I guess how your patterns are used by the mold-making process might allow no draft, but the several ways I have made molds or cast parts have required it — just wondering what I am overlooking. Draft The pattern needs to be removed from each mold it shapes without breaking or distorting it. The draft is a taper that facilitates pattern removal. The exact angle of the taper depends on the complexity of the pattern, the mold type, and surface type.
Jim I guess this depends on the casting method. I was going to make copies of each part in casting wax using two part silicone rubber moulds. Silicone rubber being flexible, tapers should not be necessary but clearly the two parts of the mould need to be planned in such a way that any piercing (such as in the crossings) does not result in the part getting stuck. If the metal caster then uses the lost wax process, getting the wax pattern out is not an issue since it just melts and burns away and the mould is then broken up to remove the casting.
I have still to collect my copy of the recently published tome on backplate engraving Home but in the meantime I have started to think what my new pieces should look like. The apron attached to the backcock (whose shape I have recently changed) and the two pulleys will need decorating (first pic). My instinct is to try to reproduce the style of the engraving and to echo the motifs used. Having collated as many images of clocks by the same maker as I can find, the nearest example to mine in many respects is shown the the second picture (although there are some key differences; the movement only has a single train and the alarm is wound through the dial rather than via a pulley). The apron repeats the basket of fruit motif and the 1/4 repeat pulley echoes the acanthus scrolls of the backplate, but the back of the alarm spring barrel is left plain. My backplate is in the third image and my initial doodlings in the fourth. Curiously, some very finely engraved backplates are accompanied by pulley engravings of less good quality (last pic). I wonder if different engravers were commonly used for these components?
Interesting that Etherington used so many different movement configurations. Each is completely bespoke. Obviously it would have been easier to make them similar allowing for some productionisation. He must have received different commissions from his clients which were all made individually. The bob in the black and white photo has engraved circle so I assume it was turned on a lathe.
I would think that as with longcase at the time (and for most of the 18th century) all clocks were made to order as individual commissions.
Yeah made for individual commissions but longcase clocks are pretty standard movements and dials. Apart from choice of Marquetry, walnut or ebonized case...There’s little variety. These bracket clock movements are completely different.
Is it possible that Etherington, like a number of others, outsourced some of his work? That would make it easy to understand why there are different movement layouts used, which could be the style of his outworkers rather than his style? It seems to have been the case that some of the early makers did this.
It's always been the way here, very well known in pocket watch circles. There was a parts and assemblies supply chain right from the beginning especially for London makers. It probably explains why early provincial bracket clocks can be so whacky.
We are so used to the idea of batch and mass production these days that it's hard to get into the mindset of the early makers. In my Monday afternoon clock session there are two distinct tribes: the "engineers" and the "horologists". The first group focuses on and worries about measurement and precision but the second group is only really interested in whether part A fits with part B and considers measurement to be secondary (I would put myself in the second group). The engineering approach is essential for modern manufacturing methods but the second is, I believe, more efficient when it comes to bespoke work. With some standardisation of components such as castings, it doesn't make much difference to the amount of work needed if each hand built clock is slightly different.
Currently struggling a little to cast my patterns cleanly in wax for sending on the the brass caster. I was a little too cavalier in making my silicone rubber moulds I think, but am hopeful that I will get there soon. Meanwhile I have been working on my lathe tooling. My Cowells CW lathe is a nice little thing but unlike a proper watchmakers' lathe (e.g. the 10mm vintage Pultra at my club - a lovely lathe to work on) switching between the cross slide and the graver tool rest is very tedious. The slide really has to be taken off completely to allow space for the tailstock and graver rest, but this means dismantling the linkage with the lead screw, removing the tailstock and sliding it off the end before replacing the tailstock. A better setup at home I think is to use my Myford for work requiring the cross slide (which is also easier to use) and keep the Cowells set up for graver work. The problem with this is that my Myford only has imperial collets and my Cowells only metric ones. Original Myford collets, especially in metric sizes, are now very scarce and expensive so I have come up with a different solution: generic 2 Morse taper collets plus drawbar (see pic). Collets 2mm upwards in 1mm increments are quite inexpensive. I have now found a German suppler who stocks 1mm collets and up in 0.5mm increments, at twice the price, but still less than original Myford ones and much less than 8mm horological collets.
In the case of watches they seem to have worked in small batches of perhaps four where presumably there would have been some conformity. The difference between the Rolls Royce approach and the Ford approach from the beginning of car manufacture. Ford wanted reproduceability, so precision was required. Rolls just wanted accuracy, so parts were hand finished to fit perfectly but were not then able to be switched to another vehicle. When Rolls were having trouble producing Rolls Royce Merlins in sufficient quantities in WWII both Ford and Packard were approached. Ford wouldn't do it, Packard did take it on but they redrew all the components to meet their higher precision standards. I've been looking at some crownwheels this week on early 18th century brackets, I still think they would have been cut from round disc castings that could be planished first to harden them. They are so shallow there seems to be not much gained by casting the profile and it makes them very difficult to work harden.
Hi Nick, This seems the most practical way to make these wheels. W.J. Gazeley describes cutting a wheel from a flat disc. Regards, Graham
Sending off my waxes to the brass caster today and arranged to visit a restorer who has worked on several clocks by Etherington who I hope will be able to give me some tips. I have also managed to track down a clock by this maker in the Ashmolean museum (it's not on display nor does it appear in their web search). They have agreed to show it to me.
Just heard from the brass caster. Apparently he can't use the same type of brass for lost wax as he would for sand cast yellow clock brass but he has assured me that the colour will still be nice and yellow. I have asked him to proceed and we will see how it turns out. In the meantime a job lot of second hand engraving tools has turned up. They appear to be (from left): 2 lozenge shaped gravers, 3 square scorpers, 2 v-shaped, 2 dotting gravers, 2 spitzstickers and 2 stitch gravers (for cutting parallel lines). Now I just need to work out how to use them.
My sister has a lkoad of those for lino cuts and woodblocks, I didn't realise the ones for brass would look the same
Wood/linocut tools are similar but the tool shapes are different at the cutting edges. Wood and lino tools are generally formed like gouges - i.e. scooped on the top edge - whereas metal engraving tools are not.
My new metric collets have now arrived (first pic). The ones at the top are 2 Morse taper and range in size from 1.5mm to 6mm (the smallest I have found is 1mm and larger ones are available, in increments of 0.5mm). The bottom row are the much more expensive 8mm watchmakers versions which are available in a huge range of sizes. The second pic shows the 2 MT ones in action on my Myford - one in the headstock holding the work and a second in the tailstock holding a 4mm diameter homemade centre. I am making a homemade broach with a one degree taper which I intend to use in boring the brass wheel collets which have to be fitting to tapered arbors.
All my books on how to work on a lathe have hitherto focused on the engineers' lathe but the more I work on my clock the more it has become clear that the techniques used on a watchmakers' lathe are just as important, if not more so. I therefore ordered this book. It's quite expensive but has lots of very clear diagrams and explanations. Reading it has convinced me that I should make my own wheel cutters to match the shape of the old ones. He devotes a whole chapter to the subject.
Here's a useful link to making form relieved gear cutters and a suggestion for a book. Making Multi-Point Gear Cutters "The Clock & Watch Makers Guide to Gear Making" by Robert Porter might be very useful and cheap.... Cheers Dean
Thanks for the recommendations. Bookfinder shows the book available only in the USA at about £50, but I will keep an eye out for it. I thought I would focus first on making a fly cutter. This should be good enough for small brass wheels, but not steel pinions.
Hi Nigel, Yes indeed, the cutting pressures in pinions would be too much for a fly cutter. A good book, (if you haven't already got it), is 'Wheel and Pinion Cutting in Horology' by J. Malcolm Wild, ISBN 1 86126 245 0. Should be less than £20 to buy here. Regards, Graham
Pinions certainly can be fly cut. It is not the best way to cut them, not efficient, but sometimes it might be necessary. What I have seen to work best is to saw cut slots to depth then shape the profile with the fly cutter, carefully and slowly. An award-winning clock/watchmaker by the name of Bill Curtin (Indianapolis, IN) made several of his skeleton clocks using only fly cut steel pinions. I watched him do a couple of them, circa 1978. His fly cutters were razor-sharp and he used a Levin 10mm watchmakers lathe with a Levin milling attachment. He used a stick lubricant by Tap-Magic IIRC. And he cut them in several passes, advancing quite slowly but with more cutter speed than I expected. Photos of some of his work can be found in the 1980 NAWCC Bulletin, Convention Competition, for those who are NAWCC members. Here are some photos for those who are not members.
Highly productive day in Oxford today. First a visit to the Ashmolean Museum to inspect their Etherington table clock which is currently in store and poorly catalogued. It's not in the best shape but it must have been a real beauty in its heyday; small size (6 inch square dial) in a tortoiseshell case with exceptionally fine mounts. Dial spandrels are later and the mechanism has been altered quite a bit, but by how much it was not really possibly to tell without taking it out of its case. Then (after delivering a food parcel to and buying brunch for my son who is studying there) I paid a visit to Wim van Klaveren, a restorer, who had an Etherington movement to show me. He is going to send me pics but I took a few of the alarm, which is the part I am having most difficulty with in finishing the design.
Wim has now sent me some great pics of another Etherington he worked on: Under dial work without the 1/4 repeat, the 1/4 repeat parts, all the parts, the 1/4 repeat in place, the underdial work with the 1/4 repeat installed....
That's sneaky that cock to provide the pivot for the alarm crownwheel so it doesn't interfere with the verge.
The cock is screwed onto the inside of the front plate just underneath the pillar. The support for the bottom pivot of the alarm pallet arbor is riveted to the plate and a small piece of bell metal is dovetailed in to provide a hard bearing surface.
Hi Nigel, Both mechanisms were adopted in pocket watches as well, called potences, (or however you want to spell it, there were a lot of variations). Regards, Graham
yes, that's what I'm saying is sneaky. When I first looked I couldn't see what he had done. In lantern clocks it is usually done with a bridge riveted to either the inside of the back plate or to the side, this approach is also found in longcase and hooded alarms which makes sense as they were often made by former lantern clock makers.
My pretext for going to visit Mr van Klaveren was to collect my copy of this book, which he edited: Its 420 pages, 1,000 illustrations and accompanying on-line database are modestly described by the author as "an introductory study" into the engraving of backplates. It is magnificent.
Is that a good book? I was thinking of buying it as I have seen a few of the clocks before. Are all the clocks on the website in the book? Thanks Dean
I have only just started reading it but it seems very well written - better than the Gretton book - and it is very beautifully produced. Not all the clocks on the website are illustrated in the book but most if not all are referenced. I suspect this will become a classic reference work.
It's time I got back to work on the clock itself. Neither my tutor nor Mr van Klaveren liked the fact that my pinion on the second arbor of my quarter repeat has as many as twelve leaves (horologists in my experience are very polite so it's when you hear comments like "unorthodox" "not seen that before" you know you are very likely on the wrong track). Although I have now made the arbor and pinion I think I should redo it. The second wheel has a locking pin on it. Each time the quarter strike is initiated the run up to the first strike needs to be the same so I figure the second wheel should complete a full rotation for each strike. The gear ratio must therefore be n:1 where n is the number of pins on the main wheel. If the main wheel has 72 teeth (a common number it would seem) then (number of pins) x (no of pinion leaves) = 72. In my current design the numbers are 6 and 12. I chose this because the space is tight and the fewer leaves on the pinion the bigger the wheel and less clearance with the pillar. A while back I concluded that 12 pins and 6 leaves was cutting it too fine. Below is the CAD view with the pillar and main arbor in the same plane, showing the clearance with the 6 pins and 12 leaves. What didn't occur to me at the time was that I could use something in between: 8 and 9, or 9 and 8. The eight leaf would still be a bit tight, so I am inclining to a nine, giving 8 hammer pins on the main wheel.
Nine leaf pinion now cut but nether it nor the arbor is finished or polished. But comparison to the 12 leaf the cuts look a bit shallow. I didn't have access to a nine leaf cutter so I think I used an eight leaf one instead. I think I may need to modify it by filing but I won't know for sure until I have cut a wheel, so I have now switched my attention to making a suitably shaped wheel cutter.
