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Friday, October 23, 2009

Confusion at TPD calculations

A little while ago I came across a forum in which a watch winder reseller was trying to “educate” his potential buyers in math. I admire his conviction in selling.

In the first part, the reseller says the unit rotates at 6.25rpm, and the total TPD provided is 2340. But in his “math” answer he claims the unit rotates gently at 1.625rpm giving a total of 2340TPD. Very contradicting, isn’t it? I don’t think the reseller has really thought much before he replied. He’s totally confused himself without knowing it.

From here, I have a big question. Is 2340TPD provided in one direction or the total of both directions?

If the watch winder provides 2340TPD in both direction, that is CW 1170TPD + CCW 1170TPD its okay. But in just one direction, I’ll stay away from this unit. My calculation below says why.

Ok, let’s assume the knob setting is at “Mode 1” and the RPM at 1.625, we get: -

Winder rotates clockwise for 2 minutes and rest 6 minutes. (Sequence repeats the whole day; total cycle time is 2 + 6 = 8 minutes).
RPM assumed at 1.625rpm
2 minutes x 1.625rpm = 3.25turns (in 2 minutes)
In a day (1440 minutes), we have 1440/8 minutes = 180 such cycle times
Multiply 3.25 by 180 = 585 Turns per Day in one direction.
TPD is far below any requirements
So the seller’s claim that it winds at 1.625rpm (2340TPD) is NOT true.

Next, let’s assume the knob setting is same at “Mode 1” and the RPM is now at 6.25: -

Winder rotates clockwise for 2 minutes and rest 6 minutes. This means the total cycle time is 8 minutes.
RPM is now assumed at 6.25rpm
2 minutes x 6.25rpm = 12.5turns
In a day (1440 minutes), we have 1440/8 minutes = 180 such cycles
Multiply 12.5 by 180 = 2250 Turns per Day in one direction.
TPD far exceeds winding requirements
But, we’re very close to the “claimed 2340TPD”.

Finally, to get 2340TPD as claimed by this confused reseller, the motor RPM has to be…

Winder rotates clockwise for 2 minutes and rest 6 minutes. Total cycle time is 8 minutes.
RPM has to be at 6.5rpm
2 minutes x 6.5rpm = 13turns
In a day (1440 minutes), we have 1440/8 minutes = 180 such cycles
Multiply 13 by 180 = 2340 Turns Per Day
This is the TPD as stated in sellers claim which definitely exceeds requirements

In his calculation, the unit has 2340 TPD and is divided by 1440 minutes (24hrs) equals 1.625rpm. This means that the unit rotates continuously without the 6 minutes “rest”. To calculate TPD accurately, the rest period has to be taken into account. Obviously, he overlooked this. Always look at the Total Cycle Time of the “turn-and-rest” winding sequence.

Selling any product requires in-depth product knowledge and understanding its Form, Fit and Functions. Only renowned watch winder manufacturers and their respective AD know their products at the back of their hand. For that reason, I think most of the resellers that sell Cheap Watch Winders don’t give full details of winding sequence, motor RPM and the TPD.

Let’s take another example: -

“Winder turns clockwise for 2 minutes, and then stops for 6 minutes, then turn counter-clockwise for 2 minutes and then stop for 6 minutes. Sequence repeats for 12 hours and then stops for 12 hours before starting all over again the next 24 hours.”

Let’s assume this winder turns at 5 rotations per minute (rpm).

So for 2 minutes, it’ll make 10 clockwise rotations; 2min x 5rpm.

Similarly, it’ll make 10 counter-clockwise rotations.

The whole cycle takes 16 minutes; 2 + 6 + 2 + 6.

So in 12 hours, you’ll actually have 45 repeats of this cycle; 720min/16min.

Meaning, it has 450 turns in a clockwise direction (45 x 10) and 450 turns in a counter-clockwise direction. Do you follow? Glad you did!

If you have a Rolex, it requires a minimum of 650 to about 800TPD in either direction to keep it wound. This winder will provide 900 turns (450 + 450) to this Rolex, which is fine. No worries about it.

However, if a watch requires 800TPD in a CW only direction, then setting the winder to bi-directional winding does not do anything. It will not keep this watch wound. The user has to set the winder in a CW only direction.

Some manufacturers adopt a “wind-it-all” technique by providing a much higher TPD. This simply means that they factory-program the winder to wind bi-directionally at 2000TPD, or even higher. This gives 1000TPD in both the clockwise and anti-clockwise direction. Of course it’ll fit any watch’s winding requirements. But this brute-force method comes with a cost of having higher battery drain, higher wear and tear to the motor, stressing the slip-clutch of your watch and eventually your timepiece will make a trip to the service center.

Its better (and safer) to test the winder for yourself and not just take any resellers word for it. After all, it’s your money you’re parting with. Just time the winder to see how much rotations it does in one minute and ask for the winding sequence. From there you can calculate the TPD. Remember, the clutch system in any watch is not meant to be abused/over-stressed in any Watch Winder. It’s like a respirator machine that merely keeps it “alive”.

A Swansea-born professional boxer has a punch of about 3.5tonnes. His opponent would be able to withstand this at an instant. But imagine being hit constantly the whole day. In a similar fashion, would you continue utilizing the slip-clutch of your timepiece for the whole day?

http://news.bbc.co.uk/2/hi/uk_news/wales/6529755.stm

http://www.sciencedaily.com/releases/2007/06/070622090701.htm

http://ideas.repec.org/a/bep/jqsprt/2200723.html

Finally, it’s not how slow, fast or how gently the motor rotates, there’s more to it as calculated above and even more when designing a well-engineered Watch Winder. There’re certain factors and techniques that a true watch winder manufacturer considers in making a good winder besides providing accurate TPD. Most cheap winder units just merely perform R&D (Reverse & Duplicate) without really understanding the concepts of a proper winding system.

So, with this said, do you still think it’s easy making you own (homemade) professional watch winder?

Thinking back,

I would give the resellers mentioned two thumbs-up for bravely giving his/her very best. They’re earning a living.
The resellers need to know their product better
I pity those timepieces on these winders and the people who bought them
To err is human, right? We learn from mistakes…

Labels: choosing winders, rotations, tpd

posted at 9:13 PM by ten10

Wednesday, October 7, 2009

Selecting a Watch Winder

If I ever make a big leap to buy a watch winder, I would make several comparisons on various websites and at my local stores.

I have a few considerations…

At the top of my list is BUDGET! How much am I willing to spend? I’ll put a cap on my spending. With that I have to see the number of watches that I own too. I would look for a Single Watch Winder if I have currently two watches. I would rotate the two between wearing and putting the other on the winder unit. This not only saves me money, but also forces me to attend to my watches daily. I believe after some time I’ll be conditioned to do so and it’ll become a habit for me. When making purchase one must also remember that “You’ll get Monkeys if you pay Peanuts”.

The other important (if not CRITICAL) factor I’ll consider is if the store or company I purchase from has a repair center within its premises. This makes repair faster and cheaper. This will definitely ensure I’ll not pay a dime for repairs during the warranty period.

The next factor I’ll consider is the features the winder unit offers. As long as it has a two direction selection, I’m fine with this because a bi-directional watch winds either way.

The TPD selection is important for me but not critical. If the winder unit has a factory pre-set 900TPD, I’m ok with it. If it comes with a dual selection, let’s say, 650 and 900TPD, it’s then a bonus.

The looks on a winder doesn’t bother me at all. Just something presentable would please me.

I’m also very weary about buying winders online. Several winders look the same, have different foreign sounding brand names but I could not be ascertain if it comes from a reliable source. A search in trade websites show similar designed units but from many different “factories”. Anyway, I’d rather see and test the actual product in person prior buying it. That’s me! I’d rather be safe than sorry.

Here’s my take on buying a Watch Winder

Most Common Questions	My Suggestion/Opinion
If I have only 1 automatic watch and wear it often… is brand X good?	Forget it! Don’t buy…
If I have only 1 automatic watch and wear it only on occasions… should I buy a winder?	Buy one if you can afford it; or just for the convenience…
I have two automatic timepieces and wear them on alternate days… is it necessary to buy a winder unit?	Don’t buy… since most watches have at least 36 hours of power reserve…
I have two automatic watches and wear only one; the other is an heirloom… I keep on display… I saw this model on sale…?	Buy one if you can afford it. But be aware that antique automatic watches would not have a built-in clutch system. So get one with TPD controls; prefer at 900TPD max.
I have a small budget and am looking for a watch winder… which model should I get?	Always pay attention to the TPD that the winder delivers. I recommend 900TPD for older watches and up to 1400TPD for newer ones. Don’t abuse the slip-clutch.
I’m puzzled by why some reputable companies have their winders set at above 2000TPD… isn’t it on the high side?	This is a sure way (brute-force) method to wind one-and-all watches. Most fine timepiece manufacturer specify the minimum TPD required to keep them wound. Add about 50% to this TPD and your timepieces are in good-hands.
If I’ve worn a watch the whole day, should I put it in a winder right after I get back home?	The watch has built-up quite enough torque up to the next 1.5 days. Put it on the winder the next day then, or if you’re forgetful put it on the winder but set it to the lowest TPD setting. Change this setting back to normal after that.
I am thinking of buying a cheap watch winder. Would it hurt my watch in the long run?	Firstly, the word cheap is subjective. Secondly, it’s not the price but the TPD the unit achieves in a day that matters most of all. Thirdly, low-priced units are made with low cost parts and they would not last in the “long run”.
I have a notion that winders are a simple device that has been over-stated and over-priced. Am I correct?	Superficially, it’s quite right. But in a broader deeper sense the unit has some “technology” behind it and the price would greatly depend on where it’s made, A&P spent, parts used, and so on.
A Watch Winder is a very simple product to make… did anyone make one themselves?	In theory, YES, it’s a simple product. In my following post I intend to demonstrate how I made my own watch winders. If you try it yourself, you’ll know the joy (pains?) of designing and fabricating one.
I need help on the winding direction and TPD settings for my new (insert brand) watch…	Come on!… there’s a comprehensive database on the web (and periodically updated) as far back as 2003. Please do a web search…
I’ve seen this model from a seller and the same model also appears on another site claiming to be “foreign” built… why?	Many winders are made in China and many OEM have claimed to be their own. Use your instincts and buy according to what you sense. Don’t be fooled by the price offers. You may end up buying another after the first one breaks-down.
I got a low-cost winder and the motor started making noises after 6 months… should I send it for repairs?	Any electro-mechanical device (motor) has what we call MTBF (Mean-time Before Failure) and most low-cost winders have low-cost parts that have short operational life-span. They are poorly designed and have not been thoroughly tested for “aging”. Sellers usually give a short warranty period of maybe 3~6 months. Just because the exterior is high-gloss, it doesn’t mean the interior matches it!
I’ve got a collection of automatic watches and would like to buy a cabinet winder to keep all of them… but the prices are a turn-off… what can I do?	Get individual winder units and store them in a normal glass display cabinet. It’s also easier that way when any one of the units break-down, you can send the individual unit for repairs; not the whole damn cabinet.
My collection of luxury timepieces is worth lots and lots… I have money to buy a cabinet winder for them… which brand is the best?	Your funeral then… so far I know prices of reliable cabinet winder units go above S$3k. Most AD does not carry out their repairs here, so this means they’ll probably send the whole cabinet to the Country-of-Origin for repairs if needed. I’ve yet to come across any local company now that makes cabinet winders here. If there is, you’ll be assured of immediate attention. Then again, if you’re ultra rich, go ahead!
I’m happy to announce that I got my winder unit from overseas for (insert dollar amount)… can any seller beat this price?	Like all people, we are excited to get the best bargains and want the full functions with all the bells and whistles… they somehow forgot about repairs and the trouble associated with it when buying from overseas resellers. So I guess buying a low-cost winder is part of their disposable income… even the winder unit itself becomes disposable!
Winder brand X is on sale now… it winds 5 minutes clockwise, 5 minutes anti-clockwise and then stops for 40 minutes… buy the first unit for $400 and get the second for half price… is this a good bargain?	Again, look at the TPD it presents. There are many winders with many fancy winding sequences but what’s important are the results… TPD! It is very unfortunate that sellers don’t really know much about watch winders and the treatment it’ll give to the timepieces. They are only profit-driven. Perhaps they only think they know much. I will post some examples on how you calculate the TPD from the winding sequence given. Stay tuned.
Why does my watch lose time on a winder?	First, check the required DIR/TPD and set your winder accordingly. Second, tilt the unit forward enough till it’s nearing 90 degrees to the surface of the table. Third, calculate the actual TPD on your winder, as the manufacturer may have given (programmed) false information about the TPD settings. Fourth, call your timepiece agent on this issue. If all done but still your watch loses time, get back to the winder seller to rectify this problem.
I want my winder unit to run on batteries and last 10 years on a single installment… is this possible?	Sure it’s possible, just connect your winder unit to a car battery and it’ll last that long… I will also post a blog later on how you can extend the life of your battery-powered winder.
I would like to buy a watch winder that fits into my safe. What’s the best choice?	A compact battery-operated winder unit without extra watch slots would be the best choice. Store your other non-automatic watch collection in watch boxes. Another way is to get a customized watch winder that is tailored to fit your safe. I’ll teach you how.
The seller promises that the winder I bought is silent… but when I got home to try it, it sounds like a grinder from a distant. Why?	Your mistake for not testing and listening before buying. Noise is very subjective and each person’s threshold for noise differs. Most manufacturers recommend testing with the lid of the unit closed anyway. So what’s your tolerance level of noise???

Labels: choosing winders

posted at 8:57 PM by ten10