Horology

I was a hobby clock repairer for about 20 years but since retirement I have made it a pretty much full time occupation. I am using this page to illustrate some of the various techniques I use. specifically on clocks. None of these things are original with me. I have learned these things from other clock repairers, books and various other sources. I also enjoy helping other repairers whenever I can.

This is a brief description of how I make an escape wheel. The techniques are pretty standard even though the equipment used may vary. It may not be the right way but it works for me.

I begin by turning a blank and an aluminum backer to the correct diameter of the escape wheel at the same time. The blanks are mounted on the same mandrel which will be used on the wheel cutting jig so that everything remains concentric. The Sherline lathe is a light duty lathe but is ideal for clock work. Also it can handle ww collets which is a great convenience.

This illustrates the wheel cutting jig mounted on the mill. I am using a jig produced by David Lindow. I have used rotary tables and dividing heads but this is by far the most simple system I have found short of CNC devices. The unit is heavy duty, eliminating chatter and having the convenience of never having to reindicate the mandrel. It just moves from the Sherline lathe directly to the jig. It is fool proof.

I have mounted the old wheel on the mandrel along with the wheel blank. This allows me to align the fly cutter precisely after which I remove the wheel. I am then ready to begin cutting.

The teeth are now finished. You will notice the brass wheel and behind it an aluminum blank. The purpose of this blank is to prevent burs on the wheel as the cutter exits the brass blank. The cutter.will leave the bur on the aluminum blank as it exits.

I use the original wheel as a pattern to trace the spoke outlines onto the new wheel. I used Dykem layout die and scribed the lines with a sewing needle held in a pin vise. A wide tip felt marker is a lot more convenient but I did not happen to have one. The Dykem is pretty messy if you are not careful.

I am crossing out the spokes by hand. Several weeks ago I saw a Heagner scroll saw at a wood workers exposition. It is the finest I have ever seen. It cuts quickly and flawlessly. Hence the $1000 price tag. The blade travels up and down perfectly perpendicular whereas all other saws move the blade in a slight arc. The finish is remarkably shooth. There is no comparison. I kept my hands in my pocket and went home without one. Shucks!

Now this is an operation that could be eliminated with the Heagner scroll saw. It leaves a nearly perfect finish. I am doing the final crossing out on a die filer.

The removal of the old wheel is accomplished by turning off the peened or staked portion allowing the wheel to be removd. Normally I would do this in the watchmaker's lathe with a graver. It literally only takes seconds. However, the arbor has a pinion on the end that would normally fit into a collet. Collets not being large enough to accomodate the pinion I could use a steady rest and jury rig something. The Sherline lathe's three jaw chuck is plenty accurate enough for this job. You will notice I have not chucked up on the pinion but rather on the brass collar onto which the wheel is staked.

This is a great tip for clockrepairers. I wish I could take credit for it but recognition must go to J.M. Huckabee, clockmaker, author and columnist for the AWI Horological Times. The original hole in the wheel is bored to fit a mandrel used on the wheel cutting jig. The wheel must then be bored to fit the clock arbor. The wood blank is screwed from the back to a face plate. A pocket is then machined to a diameter just a few thou. smaller than the wheel. The wheel is pressed into the pocket. It is held securely enough to bore the center yet is easily pryed loose without damage.

Why make a screw? Don't we just buy them? Yes, but every so often when a clock screw is buggered up due to sloppy workmanship (not by me of course) or a screw is missing, or a screw is needed for a special application it becomes necessary to make one. There are many ways to make them but this is one way I do it.

No point in showing the obvious but a blank is turned from appropriate material turning the major thread diameter first and then stepping up and turning the head diameter. The next step is is to cut the actual threads.

In this photo I am using a screw plate for cutting the threads. This is a tool used by clockmakers. Usually I use a more common tool, a threading die held in the tool post. The screw plate is available from most clock material supply houses and are usually metric. For imperial threads I use threading dies. The screw plate is hand held. You can see the handle type shape at the end of it. Most clock screws are relatively short and only eyeball guidance is required. Longer screws would probably require some alignment assistance from the tailstock.

This is a back view of the screw plate. It is an interesting device and is available in various sizes often with accompanying matching taps.

The next step isto part off the threaded screw blank. Much of this can be done on a small lathe like the Sherline which is an excellent small lathe for clockmaking. I prefer a little larger lathe. I can make small things on a big lathe but I can't make big things on a small lathe.

Cutting the slot for the screw head is a job for a slitting blade. I have chosen a blade to match the slot in the screw I am matching. I am doing this on a Sherline mill.

Here is the finished screw along with the screw I am matching. All that is left is to blue the screw. The traditional way is to heat treat the screw and turn it blue. Being this is a for profit job I took the easy way out and used a one-dip bluing solution which I get from Mile Hi Clock Supply which is an excellent product.

Making a ratchet wheel is basically the same as making any other type wheel. The big difference is in broaching the square hole in the wheel.

The blank is indicated in a four jaw check mounted on a dividing head. The blank was turned from brass on the lathe. Then the chuck was removed from the lathe spindle and mounted on the dividing head. Having the same spindle on both the lathe and dividing head is a definite advantage.

I'm using a single point cutter turned on the watchmaker's lathe. There are many ways to create the cutter profile but turning it with a hand held graver and using the old wheel as a pattern works well for me. Besides the customer usually doesn't want to pay $70 to $80 for a multi-tooth cutter. This method is quick and efficient.

I check the first round of cuts. Nothng worse than ending up with half a tooth. Normaly this length of material sticking out of the chuck should be supported at both ends. It sticks out about three times its diameter. Being a bit lazy on this job and trying to pick up speed I cheated. On the final round of cuts I made several passes to compensate for the material flex.

I have moved the chuck from the dividing head back to the lathe and am drilling a pilot hole through the stock. Normaly I would bore the hole to keep it concentric but in this case I use a drill because the hole will be broached out.

Parting off is the next step. The wood stick retains the wheels and keeps me from having to search for them on the floor. My knees scream when I have to do that.

This is the first step in making the broach. I am using O-1 drill rod. The smaller diameter is the same as the wheel pilot hole. The larger diameter is equal to the hypotenuse of the final square.

The flats for the broach are milled next. The blank is moved from the lathe to the mill using WW collets. Rather than using a rotary table or dividing head I use a collet holding block which is clamped in the mill vise. After each flat is milled the block is rotated 90 degrees and the next flat is milled. The block is a Sherline accessory. It is quick and easy to use.

The following is a description of how I replace broken or missing teeth in a mainspring barrel. The technique is pretty much the way most smiths would do it. The photos may be helpfull to those getting started in clock repair.

The first step is counting the teeth. This barrel had two teeth missing but the two adjacent teeth were radically bent over so I will replace them also. Straightening then will more than likely break the teeth off.

The barrel will be mounted on a mandrel for machining. However, the hole in the barrel is larger than the mandrel so an adapter is made to take up the slack. The spacer is made from a scrap of brass rod..

Measuring the inside diameter of a small hole accurately is difficult at best. I make a go no go gauge which is a diameter equal to the mandrel turned on a scrap of brass or steel. The gauge is used to determine when the bored hole is the proper size.

This photo shows the adapter being partd off. This is probably not necessary to demonstrate but it does show the parting tool being used in the upside down position from the back of the work. I have always parted off from the front on small parts without problems but the rear mounted tool really takes the fight out of parting off..

The barrel is mounted on a mandrel and mounted on a wheel cutting jig. A pocket is milled in the area where the new teeth are to be replaced. The jig is shown in other areas of this web site. The jig is manufactured by David Lindow. There are many ways to index a wheel but the Lindow jig is by far the best and easiest system I have used. I have used a dividing head as well as home made indexing jigs and none compare. It is very heavily built which helps reduce chatter and it is specifically made to fit the Sherline mill. It will, however, it will work on any mill without modification.

A brass plug is filed to fit the milled out pocket. I do not fit it to a press fit but I do want the plug to be tight enough to remain in place while the plug is soldered using soft solder. I heat the barrel from the outside and apply the solder from the inside. That means the brass is hot enough to melt the solder and cause it to flow. I do use an acid flux. Be sure to neutralize the flux by washing it with a solution of baking soda and water..

Before machining the teeth the brass plug, which is oversize, must be trimmed to size. The face and top ore machined. The barrel is then reversed on the mandrel and the backside is machined. I reverse the barrel because on the Sherline lathe the barrel interferes with the cross slide so the cutting tool cannot get past the barrell. If you are using a lathe with a little larger swing the cross slide is not a problem.

The teeth are cut on the Sherline milling machine using a single point cutter. I use a fairly high spindle speed and the teeth cut quite cleanly..

After cutting the teeth I use a boring bar to clean up the excess plug and solder. Because of the condition of the barrel (it is out of round somewhat) I turn the barrel by hand making the boring bar work sort of like a shaper.

After the teeth are cut and the inside of the barrel is cleaned up I clean up the barrel face with silicon carbide paper on a paint stick. I start out with a coarser grit and work my way up to 600 grit. The barrel had so many nicks and dings I was only concerned with the area with the replace teeth.

I don't usually work on cuckoo clocks, in fact have worked on very few even though I have a dozen of them sitting in boxes which I have not gotten around to working on. But since this starving clocksmith can use the business I have decided to take them on. Everyone has one and none of them work. "Do you work on cuckoo clocks", they ask? It is all work so I started taking them in. There is no good way to hold the little critters so I spent an afternoon making the above stand. It is not my idea or design. There is a photo of something similar in Kochmann's book, "The Black Forest Cuckoo Clock." Mine is just a crude copy but it works great.

I am often asked when a mainspring should be changed. The photo on the left illustrates a new mainspring and a mainspring that has been "set". (Lost its elasticity)

Here is another example of when I would change the mainspring. It originally was a hole end mainspring. Someone creatively changed it to sort of a loop end. It worked but is considered blacksmithing.

This my version of the Bergeon magnetic bushing machine. I have never seen one except for photos in supplier catalogs. The base is fastened to the moveable drill press base with two flush fitting allen head screws. The base was secured from a local scrap yard and is about 1/8th inch thick. The advantage is that the plate can be moved very easily to properly aligh the reamer to cut to the original hole. Yet, once the plate is in position it holds very securely.

This is the plate holder. It is simply a piece of 1/2 inch diameter cold roll steel with a 10-24 thumb screw to clamp the plate and a rare earth magnet at the bottom. The magnet has a 1/8th inch hole in it and is simply placed over a stump turned at the bottom of the holder. It does not even need to be epoxied as it holds well magnetically. The holder slides very nicely on the base and yet holds the plate firmly in place once in position.

If the magnetic plate holders are a time saver this little device is nothing short of a miracle. It, once again, is not my idea but that of Pat Downey and Jon Hathcock of the Denver Rocky Mountain Clocks. In my estimation the premier shop in Denver. However, I digress. It is simply an arbor bored to fit the reamers accurately with a small rare earth magnet shoved up into the orifice. Dang! It is so fast!

Thesr two photos show how the plates are held and how the plates may be slid around to find the exact center of the original hole. I do this by sight. When I am satisfied I am aligned properly the plate is held firmly.