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How to make a tiny machine screw for an antique French clock

3/30/2014

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PicturePivot steel turned down with a graver
I've nearly had a French crystal regulator done for a couple of weeks, but the rate adjusting assembly has been acting quirky because I lacked a single screw of the right type. I decide to make a screw from scratch to solve the problem. I had an old broken screw that fit the threads, so I knew some of the critical dimensions.

The process started with finding some hardened steel rod of the appropriate outer diameter. In this case, the screw head will be the largest diameter of the part. I chose some steel rod just a bit bigger than the size of the finished screw head. I chucked the rod into a collet in my lathe. I used an antique American Watch Tool Co. watchmaker's lathe, but any small precision lathe for metal would work. Using a carbide graver, I turned the piece down where the screw threads were to be. Using a graver is something like turning wood on a lathe, but with metal on a very small scale.

PictureThreading the end of the screw
Next, I used the screw I had and experimented with screwing it into different dies until I found one in my metric die set that seemed right. I cut threads on a short section of scrap metal to test within the clock. Once I found the size that fit, I installed the die into a handle and cut the threads with the rod still in the lathe. The handle was held stationary, while the I turned the lathe spindle by hand. No power was used during this operation, and I probably should have removed the green urethane belt from the spindle pulley.

PictureUsing a knife-edge file to part off the screw

Once the threads where cut, I used the graver to start a parting cut. I made the cut in from the end to leave room for what would become the screw's head.  Once the placement of the cut was established, I used a Swiss knife-edge file to part away the piece. The file was held with a hand at each end, the end with the handle resting on the lathe tool rest.  I did use power to the lathe for this operation.

PictureA screw slotting file on the filing rest
The screw was then removed from the collet. I found a new collet that fit the turned-down section under the screw head. The screw was flipped around (head out) and chucked into the lathe once again. I filed the head smooth, and added a slight chamfer to the head. I then burnished the head so that it was shiny. This not only looks good, but is important to the bluing process to come. I swapped the lathe tool rest for the filing rest. I placed a screw slotting file on the rest, and adjusted the height until it was in the center of the head. With the headstock spindle locked, I filed the slot in the head by hand.

PictureBefore and after bluing the machine screw
The the screw complete, all that remained was to blue it. This is the appropriate look for a French clock. The blued surface also prevents oxidation. The screw was dropped into my homemade bluing pan -- and old metal spatula with turned up edges and a hole drilled in the bottom. I held the screw over an alcohol lamp until it reached the desired color.  It leaves a lovely blue-black color that's unmistakable.

PictureThe completed screw on a penny for scale
The finished screw has a rounded tip by design. It screws through a solid block of brass into a drilled space through which a threaded rod passes. The rod has a rounded notch in it where the end of the new screw enters the drilled hole. The tip of the screw fits into this notch. This allows the threaded rod to turn freely, but it cannot slide out of the drilled hole. It's a simple and clever arrangement, but it only works if you have a screw of the right size, length, and shape.

I did almost everything while wearing a magnifying eye loupe. I didn't realize how small the screw was until I sought out a penny to use in a photograph for scale. The screw works perfectly and cannot be distinguished from the 100 year old screw right beside it on the clock.

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Restored clock pivot - before and after photos

3/17/2014

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PictureAn American clock pivot, before and after repairs
In my previous post I showed you what a badly worn clock pivot looks like. The pivot is the end that spins in the clock plate. This one had a deep groove worn into it. This not only increases friction inside of the clock, but means the gear was slowly moving away from the gear with which it must mesh. In time, this can cause further damage to other parts. Certainly, it will stop the clock from running eventually.

To fix the worn pivot, I installed the arbor that holds the wheel and pinion into the watchmaker's lathe, and cut off the damaged end -- often referred to as "mushroomed" pivot. Next, I drilled a hole in the end of arbor. I found some special pivot wire the same diameter as the largest part of the old pivot and gave it a slight taper on one end using the lathe. I cut this section of pivot wire to length, then installed the tapered end into the hole I had drilled in the arbor -- making sure that its axis was exactly the same as that of the arbor. Finally, I filed, stoned, and burnished the pivot to a mirror-like shine. This last series of steps happens for all of the pivots in the clock.
This is one important step included in an overhaul that will minimize friction with the gear train and help to keep the clock running well for a long time. 

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Damaged clock pivots - a severe case in need of repair

3/12/2014

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PictureA badly worn pivot at the end of a clock arbor
Perhaps you wonder what I do all day, or why it can take a lot of time, expertise, tools, and expense to repair an antique clock?  Here is one answer to your question: pivots.

Pivots are the ends of the axles (called "arbors" in the clock world) that spin in small holes drilled in the clock plates as the clock runs. These, along with the holes themselves, can become worn. The pivots must have a mirror-like polished surface in order to minimize friction within the train of gears.

The pivot shown here is one of those textbook examples of extreme wear. My mentor, Bob Frishman of Bell-Time Clocks, explains:

"This usually is a result of folks continuing to oil, and not clean, an old clock. The new oil just frees up the abrasive dirt and let's it keep grinding away the steel."

Indeed, he is right. This particular example had a few other factors which caused this wear, and I hope to post about them soon. For now, let's just say that creative home repairs aren't usually a good idea. Also, please don't add oil to a dirty clock! You will be doing more harm than good.

A slightly worn pivot can be put into the watchmaker's lathe, then filed, stoned, and burnished back to a reflective surface. Not this one. I will have to "repivot" this one. This means I will have to carefully cut the remaining pivot off, then drill a hole into the arbor, and fit a new piece of pivot wire into the end. For more on the process, you can read books such as
The Clock Repairer's Handbook by Laurie Penman, Practical Clock Repairing by Donald DeCarle, and Clock Repair Skills by Steven Conover.

The owner of this clock will never hear about all this, but they will be getting their money's worth. Though tricky and time consuming, this is the kind of repair that is covered in the price of the overhaul that I am performing.


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Profile of Dug North Antique Clock Repair in The Lowell Sun

3/7/2014

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PicturePhoto by SUN/ David H. Brow
It's a big day for me. I was profiled by my local newspaper, The Lowell Sun. Do you know how many times the local paper will write a "there is a new clock repairer in town" article about me? Just once. This is it!

Reporter Samantha Allen visited my shop with photographer David Brow. They spent a full hour talking with me, taking pictures, and shooting video. They seemed genuinely interested and it was a pleasure to spend time with them.

The article hit the presses today, though the video version has been available for a few days and can be seen on my About page.  The article does a great job! The only thing that isn't mentioned is the fact that I also sell antique clocks. Many of these can be found on my Clocks for Sale page. Others in the shop, which are in line for the necessary overhauls, you will have to come and see for yourself. These can be secured with a down-payment and can usually be ready in a couple of weeks.

My thanks to Samantha Allen and The Lowell Sun. I'm honored to live in Lowell and to be part of this trade. The two seem like they were meant to go together.


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An old kitchen spatula becomes a classic clock repair tool

3/6/2014

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I have been working on a lovely French clock. These brass movements are accompanied by steel machine screws which are a blue-black color. The bluing process not only makes the screws look nice, but produces a change in the surface of the metal that is less prone to rust.
PictureA French clock, alcohol lamp, and bluing pan
There are chemicals one can use to create the bluing effect, but the traditional method is to heat the metal to just the right temperature until the metal turns that color on its own. I didn't have a "bluing pan" the tool used to perform this process, so I sacrificed an old kitchen spatula for the purpose. Here you can see the French clock movement, an alcohol lamp, and the bluing pan. The screw had become damaged from many repairers going at it with screwdrivers. I put the screw in a pin vise, cleaned the rust from it with a file and abrasive stick, and used a special screw slotting file to dress the slot in the screw head. The screw looked much better, but was awfully shiny.

PictureA homemade bluing pan with a tiny screw
After cutting some notches in the corners of the spatula, I bent the front and side edges up to form sides that would keep small parts from falling out. I also drilled a small hole in the bottom. This hole will allow the threaded portion of a small screw through, but not the head. This leaves the head sitting evenly on the pan's surface.  Here you can see the bright steel screw head in the bottom left corner before I've applied any heat to it.

PictureA freshly blued machine screw
The final step is to use a heat source -- a traditional clockmaker's alcohol lamp in this case -- to heat the screw from below. I read about the process in many clock repair books including Practical Clock Repairing by Donald de Carle.

One has to watch carefully, as the small screw heats quickly. It is easy to pass the point where the screw has reached the desired blue-black color. Here we see the lamp in the background and the blued screw still in the bluing pan. Success!

Sometimes there is a lot of satisfaction in the old ways of doing things. Not only is the screw's finish consistent with the rest of the screws in the clock, but it was fun to do. It required little in the way of supplies and only one old kitchen spatula was harmed in the process. I like to think that it has been given a new lease on life. I certainly wasn't using it much in the kitchen! As time goes on, I will drill more holes to accommodate different sizes of screws.

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Four new clocks soon to be for sale

3/5/2014

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I participated in an online auction this week, and bought four clocks. I'm really excited about  these, because they each bring something new to my clock offerings.
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Ingraham Shelf Banjo
First among the clocks is this shelf banjo by Ingraham of, Bristol, Connecticut. The clock is made of stained birch and features a 4 1/2 inch Arabic numeral dial, brass embellished side arms,  and a black and gold-painted lower tablet. The clock runs for a week on a winding and strikes the hours on a gong. It stands about 8 inches high. A keen observer might notice some striking similarities between this and the Ingraham "Nyanza" banjo clock I have for sale on my Clocks for Sale page.

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Ansonia "Regulator A" Wall Timepiece
It's not called a clock, because, technically speaking, a clock must mark the hours with a sound. This beautiful walnut regulator was made by the Ansonia Clock Co. around 1900. In addition to the walnut case, it features a glazed lower door marked Regulator A and a large 12 inch dial. This will also run for a full week on one winding. Easy to wind and set, this clocks is suitable for areas where hour striking isn't desirable. This one measures 32 inches in height.

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Two Connecticut Clocks
I was thrilled to find these two clocks offered together. The on the right is a E.N. Welch schoolhouse clock in gorgeous rosewood. It runs for a week on a winding and strikes the hours. The one on the left is an older clock known as a "split-baluster shelf clock". We know it's older because it has a thirty-hour (runs for one day on a winding) wooden works movement. This will be the first antique clock with wooden gears that I've owned, and I'm excited to work on it. They measure 32 and 25 inches in height respectively. They will be sold separately.

I will be picking these clocks up this week. Each will need to be evaluated and overhauled before I can let them out the door, but that doesn't mean you can't put a down payment on one and claim it. If  you are interested in these or any of the clocks I have for sale, I will be participating in the open studio event this Friday, March 7th from 6PM to 9PM at 307 Market Street, Studio 411 in Lowell. Here's a map to my clock workshop and studio.
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No clock is beyond repair: a dramatic banjo clock example

3/2/2014

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Picture
Last year, I purchased this banjo clock by the Sessions Clock Co. in lot with two cuckoo clocks.  I was more interested in the cuckoos at the time of purchase, but couldn't turn my back on this clock. The poor thing was on the verge of being thrown out or stripped for its finial, bezel, dial, and movement. I decided I would make an effort to prevent that.

After a complete overhaul of the movement and a lot of casework, I brought this one back from the dead. It is now one of the strongest-running clocks in my shop. It features a large brass eagle finial, bent brass bar sidearms, nautical scences behind the glasses, and a "bim-bam" strike that plays out on two chime rods.

I guess this goes to show that if it was fairly well-made to begin with, almost no clock is completely beyond repair. It just takes tools, time, a few parts, and know-how.

I've had some parties interested in this clock, but still no takers, so it is for sale on the Clocks for Sale page. Come check it out in person in Lowell, if you like -- just make an appointment with me.

Even if this banjo clock doesn't sell for a while, that's OK with me. It's a nice reminder that sometimes there are second chances in life.

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A view of my clock repair workbench

3/1/2014

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Watchmaker's benchMy watchmaker's bench
Welcome to my clock repair blog. I'll be posting here every now and again about things that strike me as interesting. Hopefully, it will give you a sense for the work I do and how I do it.

With that in mind, let's begin with one of the most important things of all: where I do my work. In my case, it's done at this watchmaker's bench. Though it's called a "watchmaker's" bench (and indeed, watchmaker's use them), clock-makers and repairers use them too. It's also quite similar to many jeweler's workbenches.

The key characteristics are:
  • Its height
  • The number of drawers
  • Features designed to catch falling parts

Compared to most tables and workbenches, the watchmaker's bench is quite high. When used in conjunction with a short chair (note to self: get adjustable stool) the repairer's head is fairly close to the surface of the bench. This minimizes the amount of hunching and straining needed to see very small parts on the bench.

This bench has 16 drawers and, believe me, they are all full. I've got almost every tool I routinely use at arm's length. The drawers make this possible. I also have a magnetic tool holder in front of the bench and a small shelving unit on the wall to the left. Really, it's only when I need to use the watchmaker's lathe that I need to get up.

Finally, the bench is designed to minimize the loss of small parts. The side and front edges of the top have a short apron, so nothing can roll off. The font edge has trough routed into the surface. Small object trying to roll off the bench in that direction and likely to roll into this groove and stop. Finally, directly above the stool, there is a fabric-lined tray that slides out. The front edge is pulled close to the body, so that any part that comes that way should drop into the tray, rather than into your lap or on to the floor.

It's a fine bench and I've already become so used to the locations of objects, that I can grab the right drawer handle almost without looking.

More on the workshop, tools, and clock repairs in later posts. Thanks for reading!

-Dug North


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    Picture
    Clock Repairer Dug North

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    Dug North repairs antique clocks in and around Lowell, Massachusetts. He's also known for his mechanical wooden sculptures.

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