Gear cutters

[wow]

I have a Sherline lathe and mill. I have made some fly tooth cutters as per Jerry’s instructions but I would like to buy factory made disk type cutters. Sherline does not sell them as far as I know. Can you folks share what cutters you use mostly in clock work, which are the best, and where to get them? Thanks,
Will

 

[sharukh]

Thornton's seems to still make new cutters for clock wheels and pinions. So does Bergeon I think. Not cheap at all.

And then there is the great auction site; either for used cutters or new ones made in china.

Sharukh

 

[Jerry Kieffer]

I have a Sherline lathe and mill. I have made some fly tooth cutters as per Jerry’s instructions but I would like to buy factory made disk type cutters. Sherline does not sell them as far as I know. Can you folks share what cutters you use mostly in clock work, which are the best, and where to get them? Thanks,
Will

Will
As Sharukh mentioned, PP Thornton and Bergeon as well others occasionally sell horological cutters, Cheap Chinese options are of course tempting if your standards are Chinese inspired.
Purchasing is of no issue for new construction, if purchasing matching wheel and pinion cutters for each desired size from the same manufacturer.

Where the issues start to come into play is when you attempt duplicate an existing wheel or pinion. In Horology, almost all wheel and pinion teeth make contact about mid tooth over a length of a few thousands. The rest of the 99 percent of the tooth profile is unimportant as long as it enters and exits the tooth cavity without contact. As such, each manufacturer has there own version of what they consider the ideal tooth profile. Sometimes wheels and pinions function perfectly with various brands of cutters and sometimes not, but rarely look good if they are not exact profile.

The following is an example.

(1) The first photo shows a spring barrel where the bottom of the teeth are flush with the barrel per the red arrow.

(2) The second photo shows a commercial cutter where it would need to be set much deeper in order to form the top of the tooth thus deeply grooving the barrel itself.

(3) The third photo shows a machined cutter machined to match the existing barrel tooth profile for invisible teeth replacement.

I have many Commercial cutters purchased as I could find them at a reasonable price over the years. Unfortunately I am lucky to find the match I need half of the time, but when I do, it makes the job easier than matching a cutter. Fortunately, I can machine the cutters I need that are unavailable.

Jerry Kieffer

 

[Allan Wolff]

Will,
I have made a few cutters but never got good enough at it to be able to make one in 30 minutes or even get the profiles correct. I purchased a few of the single tooth cutters from Merritt's with mixed results. One cutter works great while the second one seems to want to hammer on the brass like a dull chisel. In the end I purchased a set from PP Thornton, directly through their website and shipped to the US. They work awesome and should last a lifetime.
Most of the work I do seems to be putting new teeth in barrels or great wheels, so I purchased the short form cutters from .5 to .8 in .05 steps (.5, .55, .6, .65, etc.) Some cutters have not been used yet, but I didn't want to pay postage from England for each cutter as I needed it. Anything under .5 module I purchase as needed in the regular tooth form. I have found a few on ebay, but most are purchased straight from Thornton.
Hope this helps,
Allan

 

[wow]

Jerry, thank you very much for your advise. You are always so kind to share your expertise. I used your diagrams and read about your fly cutters and have made a couple. From your comments, it sounds like that is the best way to go. The commercial cutters from Thornton and Bergeron are very pricy and I wouldn’t know which ones to buy for the best usage. I will buy more blanks and make them as I need them. I am grateful.
Allan, I will keep your information in case I come into a pile of money. Thanks for replying.
Will

 

[Jerry Kieffer]

Jerry, thank you very much for your advise. You are always so kind to share your expertise. I used your diagrams and read about your fly cutters and have made a couple. From your comments, it sounds like that is the best way to go. The commercial cutters from Thornton and Bergeron are very pricy and I wouldn’t know which ones to buy for the best usage. I will buy more blanks and make them as I need them. I am grateful.
Allan, I will keep your information in case I come into a pile of money. Thanks for replying.
Will

Will
Commercial cutters are efficient timesavers when they meet the need as Allan mentioned.

However, as you make more and more cutters, you will find yourself reusing the ones you have made and machining process will become less
and less.

Good luck and stay well
Jerry Kieffer

 

[rgmt79]

(2) The second photo shows a commercial cutter where it would need to be set much deeper in order to form the top of the tooth thus deeply grooving the barrel itself.

Thornton do supply "short form" cutters which prevent this.

Richard

 

[wow]

Thornton do supply "short form" cutters which prevent this.

Richard

This is all excellent information. Another question: What other option is there for cutting pinions besides the expensive cutters like those from Thornton?

 

[Bruce Alexander]

This is a very good Thread Will.

Once you're all set, up and running, please post some photos of your typical set up.
I'd like to be able to fabricate gears and do precision repairs/restoration on long spans.

Thanks,

Bruce

 

[Jerry Kieffer]

Thornton do supply "short form" cutters which prevent this.

Richard

Richard
PP Thorntons bread and butter is their standard cutters.

While they will supply long and short forms , they are generally special order and may not be in stock at normal prices.

The barrel shown in the
two photos post #3 is the same barrel and is used as a class example of tooth replacement thus the barrel markings.
However when ordering a special cutter, you still have the " to long, to short, to fat, to skinny issue" with the manufactures profile.

Over the years I have accumulated well over 100 commercial Horological cutters and still do not have what I need about 50% of the time.
The barrel mentioned above is a great example where a Thornton short profile cutter has a profile that is not a perfect match and is to short per attached photo. So neither a standard or short profile would have worked unless a standard was used to cut the depth and a short form the form the tooth.

In this case, the tooth duplication cutter in the third photo post #3 took about the same time to machine (not grind) as it would to order a commercial cutter. Of course I am a one finger plucker giving me more time.

Jerry Kieffer

 

[Jerry Kieffer]

This is all excellent information. Another question: What other option is there for cutting pinions besides the expensive cutters like those from Thornton?

Will
There are always options.

Jerry Kieffer

 

[Jim DuBois]

And I still end up making cutters for a number of jobs....and I have quite a few more in boxes. The discoloration is drying anti rust and lubrication that turns brown and quite crusty. I was originally set up to cut gears for others. I did that for several years but discovered doing commercial clock wheel cutting and being a barber had too much in common. Namely, one's income is dependent on how many heads of hair are cut each day and while other barbers can be found to enhance workflow through the shop, apprentice wheel cutters are few and far between.

 

[wow]

Will
There are always options.

Jerry Kieffer

View attachment 625674

So cutting pinions can only be done using the disk style cutters, right?

 

[Jim DuBois]

Pinons can be fly cut. But to do so you need a very rigid setup, very sharp cutters, pay a lot of attention to feed and speeds. The best way IMO to flycut them is to saw the spaces between the teeth then carfully use the flycutter to complete the tooth profile. Metallurgy matters too. Much easier in 12L14 than in tool steel.

 

[Jerry Kieffer]

So cutting pinions can only be done using the disk style cutters, right?

Will
First, on second thought, I should mention that the photo in post #11 was an attempt at humor. Hopefully no one got the idea it was a proper repair.


High speed steel cutters are the preferred cutter for cutting steel pinions or at least those typically used in horology. Unfortunately, its a tough task to duplicate the toughness of HSS when hardening/tempering is utilized in home shop setting. However, it can be done successfully by slotting as much metal as possible from each tooth cavity in the pinion, and then using a machined/hardened/tempered single point cutter to shape the rest of the form also per Jims description.

However, Sherline now makes a 30,000 rpm die grinder attachment for their milling machine. In this case you can dress the desired stone diameter if required, using a diamond dressing point in the Lathe.
It can then be setup per the following photos and the critical cuts can be ground in a 1/4" HSS lathe blank using the stone in the same controlled manner as with a endmill. The HSS Lathe blank assuming of quality, will perform in the same manner as HSS commercial cutters.

Jerry Kieffer

 

[Shipsbell]

I have a Sherline lathe and mill. I have made some fly tooth cutters as per Jerry’s instructions but I would like to buy factory made disk type cutters. Sherline does not sell them as far as I know. Can you folks share what cutters you use mostly in clock work, which are the best, and where to get them? Thanks,
Will

So a couple of questions, are you going to build a clock or are you going to make clock wheels and pinions for customers. I will offer what I do. First I designed a clock and figured out the modes. Then you only have to buy only 2 cutters. One for the wheel teeth and the matching mode for the pinion. Simple works and affordable. I have purchased from Thornton in England. Patrick

 

[wow]

So a couple of questions, are you going to build a clock or are you going to make clock wheels and pinions for customers. I will offer what I do. First I designed a clock and figured out the modes. Then you only have to buy only 2 cutters. One for the wheel teeth and the matching mode for the pinion. Simple works and affordable. I have purchased from Thornton in England. Patrick

Patrick, I repair clocks for others and I repair clocks that I have bought or traded for. I work on almost any kind made over the last 200 years. I have never made a clock. I cannot do some jobs myself and have to send them out. A few years ago, for instance, I rebuilt the movement in an old Hershede grandfather clock. The customer called about a year later and said it stopped. After detailed inspection, I found a cut pinion on an arbor that had a cracked leaf. I could not cut the new pinion so I sent it out. I have learned how to cut teeth in brass wheels using a fly cutter. I have learned how to make fly cutters on my mill. I am now starting the process of learning how to cut my own pinions on arbors I have turned. Could you post some photos of your work and the cutters you bought? I probably will make my own cutters but also purchase some. As expensive as they are, I am trying to decide what to buy first to best meet my needs on my Sherline set-up.

 

[Shipsbell]

Patrick, I repair clocks for others and I repair clocks that I have bought or traded for. I work on almost any kind made over the last 200 years. I have never made a clock. I cannot do some jobs myself and have to send them out. A few years ago, for instance, I rebuilt the movement in an old Hershede grandfather clock. The customer called about a year later and said it stopped. After detailed inspection, I found a cut pinion on an arbor that had a cracked leaf. I could not cut the new pinion so I sent it out. I have learned how to cut teeth in brass wheels using a fly cutter. I have learned how to make fly cutters on my mill. I am now starting the process of learning how to cut my own pinions on arbors I have turned. Could you post some photos of your work and the cutters you bought? I probably will make my own cutters but also purchase some. As expensive as they are, I am trying to decide what to buy first to best meet my needs on my Sherline set-up.

Hello, here are the pictures you requested. I purchased the equipment over many years and as you can see these are indexing gear cutter and pinion cutter. I purchased the cutters all at once (wheel) and the pinion as needed. The pinion have multiple sizes 8, 10, 12, etc depending on the leaves. Also I have learned through multiple failures that the machines need to be very firm with no flexing. When the blank slips the workis destroyed.
As for making your own cutters I admire you and Jerry's skill. It's just easier for me to buy them as needed.
Patrick

 

[Jim DuBois]

As others have suggested, depending on what you want ultimately to do wheel cutting wise, a time and strike clock can be built with 3 cutters. Of course, that calls for a bit of careful planning. But, one cutter for the wheels, one cutter for the pinions, and one for the escape wheel will suffice. The same cutters can deliver the strike side components also.

Where this falls into the abyss a bit is the need for 6-7-& 8 leaf pinions in many clock configurations/trains. 7&8 leaves are pretty traditional in many trains. It is customary for using a 6 leaf pinion for the motion works idler paired with a 72 tooth hour wheel. So, what to do to do it with only the 3 cutters? Obviously, any clock we might hope to build will have certain limitations as to how large a wheel can be, how much fall do you have for a weight, or how long /width spring is to be used, how long of run time is desired, and so forth. If we are to select say an 8 leaf pinion that choice will certainly limit a bit the tooth counts we will have on our wheels. 6 leaf pinions in the drive train is not a recommended choice, they are quite in-efficient in that sort of work. Using an 8 leaf idler pinion will require a higher tooth count on the hour wheel and since we only have one wheel cutter in one module the dia of that wheel may get to be a bit large, to yield a 12:1 ratio. We can work around all those things, but compromises are required. It is easier on all if we can cut 6,7,& 8 leaf pinions for our work. 5 cutters will give you a ticking clock better than limiting yourself to just 3. But at $150 each for Thorntons' best, it can be painful.

When it comes to cutting wheels and pinions for repair work, or for the trade, one of everything is best. And everything is a moving target you will never completely accomplish. Jerry K's approach of making one's cutters for a specific wheel or pinion would be preferred over mine of buying many commercial cutters. By today's prices I most likely have over $30k in commercial cutters, and I have needed to make several cutters for special clocks in the last year. (escape wheel for a tower clock, 3 different sized cutters for Ives Brooklyn model clock movements, a great wheel for a woodworks, on and on) So, the making of and successful use of fly cutters per Jerry's (and others') approach makes a lot of sense to me.

 

[wow]

Patrick, thanks for sharing. Great work on the clock. I have a long way to go to be able to get there. I worked about an hour yesterday trying to make a small arbor for a Waterbury carriage clock and it broke in two even while using a steady rest.Got to sharpen my cutters. I’ll get it eventually. I like the challenge, though.

 

[Shipsbell]

Patrick, thanks for sharing. Great work on the clock. I have a long way to go to be able to get there. I worked about an hour yesterday trying to make a small arbor for a Waterbury carriage clock and it broke in two even while using a steady rest.Got to sharpen my cutters. I’ll get it eventually. I like the challenge, though.

So for each wheel I cut successfully you will find 5 failures, see some of my examples and arbors bend oops, many failures before I get a good wheel. Patrick