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