I have an app that gives me a current reading of approx. 8325 BPH on a Gilbert clock. How do I find out what the target rate should be?

It depends upon the pendulum length. 1 meter pendulum is 3600 BPH (typical tall clock) Timepieces (banjo clocks) are 4680 - 4800 BPH Andy Dervan

If its keeping time, you already have your answer. If not, you will need to learn how to calculate the BPH by counting the teeth on the wheels. Willie X

The exact way is to count the teeth on the pinions and wheels between the escapement and the minute hand. Some clock books have a number of common beat rates. You can carefully time is for some length of time using an accurate reference clock ( like for 24 hours ). You then calculate how much fast or slow it is and apply that ratio the the one you measured with the app. Tinker Dwight

If you have or can find an app that simply counts the beats, you can mentally mark a starting place, start the count and let the clock run so the minute hand turns once around the dial. Stop it in the exact place it started. That will be your beats per hour for the clock. It is more accurate if you let it go a few trips around and average the beats by the number of turns.

Gocu, A beat counter isn't much use without a book that shows you the beat rates ... Only thing close in my book is 8277.55 for a Wm. Gilbert Clock Co. Front plate would be stamped 1907 under the handshaft. Need more info on the clock, like a photo or description. Willie X

No missing pendulum. Here are 2 photos from BEFORE cleaning: And one after cleaning. The original measurement of 8325 BPH was after cleaning and running well, keeping pretty accurate time. I have tried adjusting the pendulum rod nut down till the measurement reading was near 8277 on my clock tuner app, but it was losing several minutes per day at that rate. So, I am going back to the 8325 rate and calling it good. BTW several folks have mentioned counting the time train teeth and calculating the target BPH. Can someone point me to the formula? Thanks

There are special cases with idlers that can confuse and even cases where it looks like a wheel but for calculations it is a pinion. I always like keeping track of which way the teeth point. If the teeth point towards the pallets, you multiply. If the teeth point towards the minute hand then you divide. Multiply by 2 when done. No equations just know that one is direction is multiply and the other is divide. If you get it wrong, it will be obvious. Tinker Dwight

Here is a sample of a page from my notes on an Ingraham clock of mine. Hope you can make sense of it. Calculated BPH on this one is 11,232. It is a tambour style mantle clock with a shorter pendulum than your clock. Multiply the gears together and also multiply that by 2. Then divide that answer by the result of multiplying the pinions together. Hope this helps. Like others mention it is important not to get confused by gears that don't go into the equation, like the second wheel in the example. That is why I sometimes sketch the time train like in the example.

LaBounty says: The formula is: Ratio = Mw/Cp x Hw/Mp where: Ratio = # of revolutions of the minute hand for one revolution of the hour hand. Mw = # of teeth on the Minute Wheel Cp = # of leaves on the Cannon Pinion Hw = # of teeth on the Hour Wheel Mp = # of leaves on the Minute Pinion This is explained very well in an article by Archie Perkins, CMW, FBHI, FNAWCC, FAWI, in the September 1988 "Horlolgical Times", pg. 29 - 31. ================== For clarification, is the "leaf" of a pinion the open slot in between the bars? Hudson, I like your drawing since it illustrated the need to bypass the "transfer" wheels. Tinker, can you show us with a photo or drawing how it works for you? I'm a graphic learner and like to see things. Thanks. Paul

First, this particular quote from LaBounty just shows the motion works ratio that is normally 12:1 but is some cases is 24:1. We can use Hudson's drawing. The second wheel acts like an idler in the path from the escapement to the minute hand and could be left out of the equation. Still, for demonstration of my method, I'll leave it in so that the path is complete. The teeth on the escapement point to the pallets. These we multiply. The teeth on the escapements pinion point to the minute hand ( following the train ). These we divide. The teeth on the 4th wheel point to the pallets so multiply. The teeth on the 4th wheel's pinon point to the hour hand so divide. The teeth on the 3th wheel point to the pallets so multiply. The teeth on the 3th wheel's pinon point to the hour hand so divide. Now, that second wheel. It has teeth pointing to the pallets and teeth pointing to the minute hand so for completeness we will both multiply and divide ( a math student would note that these cancel ). The teeth on the center wheel point to the pallets so we multiply. To put that all together: (((( 48 / 7 ) * 42 / 7) * 42 / 8 ) * 60 / 60 ) * 26 = 5616 or a ratio of 5616:1 Now, each tooth of the escapement it used twice so 2 * 5615 = 11232 ticks per hour. So for each rotation of the minute hand of 1 hour there are 11232 beats or BPH. It is easier to do without remembering the formula if you just keep two multiplied list of numbers of teeth pointing each way in the train. It does help to make a drawing. Towards the pallets: 48 * 42 * 42 * 60 * 26 = 132088320 Towards the minute hand: 7 * 7 * 8 * 60 = 23520 if we now do the calculation wrong, by dividing wrong ( 23520 / 132088320 ), we get 0.000178062678..... An obviously wrong number. If we divide the other way, ( 132088320 / 23520 ) we get 5616. A much better looking number. Just don't forget to multiply by two because each tooth of the escapement is used twice, once for the tic and once for the toc. As for leafs, it is just another word for teeth of the pinion. It doesn't make any difference if you count teeth or spaces between teeth as the number will be the same. Tinker Dwight

So, I decided to make a spreadsheet to illustrate this and create a template which can easily be applied to each clock as I work on it. Here is the example that Hudson showed in his drawing: I haven't figured out how to apply LaBounty's formula which seems to come from the opposite direction. Any help in understanding his method would be appreciated. Thanks. And if anyone wants this spreadsheet, send me a PM. Paul

The part you show in your post is not useful for determining the beat rate. Look at the second half of that post by LaBounty. It basically describes what I've posted but slightly differently. Read from where he says: Now, on to your second question of how to determine beat rate...on down and ignore the part above, he was talking about a different problem there. The reason I describe it as I do is because there are often different routing from the center shaft to the escapement. In some clocks, power from the spring ( or whatever ) goes through the center wheel. In other cases, there are more or less wheels in the path. Following the path and noting the direction the teeth point along the path always works and is the least confusing. As I've shown, you don't even need to remember some formulas. LaBounty starts at the center wheel and goes to the escapement. He doesn't state how to deal with idler wheels. He only talk about wheels and pinions while other interesting teeth count sizes exist. If a tooth count is larger than the wheel it is meshed with, is it a pinion or a wheel? Looking at the direction the teeth points along the path always works, with no confusion. The path from the escapement to the center wheel is almost easier to follow. Tinker Dwight

Tinker, we're saying the same thing, only I'm doing it in graphic and table format and you are describing in text form. SumProduct of the Blue Wheels on my graphic (EW to Min Wheel): 2x48x42x42x26 divided by the SumProduct of the Black Pinions on my graphic: 7x7x8 Likewise, LaBounty is the same except he starts at the "Center Wheel" and moves to the EW. I just didn't see that his Center Wheel was what I called the Min wheel. Thanks, Paul

The minute wheel is not the same as the center wheel. The minute wheel is the one on the side as part of the motion works that drives the hour hand. See: https://mb.nawcc.org/showthread.php?39874-Clock-Parts-Terminology Tinker Dwight

OK, here is another page from my notebook showing the Time Train on a grandfather clock of mine. In my notes the "minute" gear is the gear that turns at the same rate as the minute hand (once per hour). Perhaps my nomenclature is incorrect, but my math is correct! Anyway, it helps me to sketch it out the path from the escape wheel to the minute hand.

The math is correct. It clearly shows the reason to draw the path out. Notice that the size at the center wheel, one is 40 and the other is 30. The 40 is what one would normally call the pinion while the 30 is what would be called the wheel. Tinker Dwight

The equation at the bottom of that figure doesn't compute out to 3600 BPH. The figure shows 70 for the wheel but 71 is used in the equation. Just sayin'! Kurt

Good catch guys. I caught it myself when I did the math, but didn't correct my note. The clock does run at 3600 bph. Corrected sketch:

If you want an exact number, that will have to come from a calculation. Electronics can only give you an approximate number, which is usually good enough. The only thing you can take-to-th-bank is what the minute hand says after a 7 day run. â˜º Willie X

Not so, Willie. The modern beat counters are pretty accurate, and counting the beats required for the minute hand to travel once around the dial is also very accurate. Once you determine the BPH, you STILL rely on the electronics to set it, right? No difference. Otherwise, counting the teeth is futile as well.

Uh, there's still another "71" on the page...nearer to the top!! Not that anybody's really making a big deal of it or anything!! Kurt

Beats can be funny numbers. Unless you know what to expect, you might never guess from the method you propose. As an example, I have a clock in front of me with a beat of 11567.02041 and another with 10462.5. I doubt any thing your beat counter would give would not make any sense of these. Tinker Dwight

Bugs, How would you account for the extraneous clicks and pops a movement would make in an hour? Also, your stop/start point will always be guesswork. I will stand by my last post. â˜º Willie X

The start/stop point is compensated for if you allow several trips around the dial and average the beats. The extraneous clicks and pops are eliminated by turning the sensitivity down so that only the "real" beat is detected. It really is quite accurate. Tinker - your fraction measurements are just as hard for you to set at the end as it would be for a beat counter to detect. I don't see a big issue. The bottom line is getting the clock close enough to be acceptable. It takes a LOT of fiddling to get a clock to keep perfect time ..... if possible at all.