Looking for guidance for a watch winder project.

I've done a lot of searching about this subject, and it almost always is a poster asking for help, getting some advice and never following up. I'll try not to do that. I decided to pick up this project because it seems simple enough to build something that rotate an adjustable amount, and I believe that throughout all the tutorials I've actually have all the pieces to do this project.

I've gotten an Arduino kit from Dfrobot.com and I've finally cracked it open this summer. I've gone through all the tutorials from controlling LEDs, various sensors, servo, 130 motor etc. a full list of items the kit has is in this url: https://www.dfrobot.com/product-345.html . Scroll down to shipping list.

My initial plan: I plan on using the below items for this project. It would be neat if I could use electronics solely from the kit , but I am not against buying any missing parts. I am extremely new at this, so my plans might require massive revisions. My initial plan is to mount a cylinder that will hold the watch in place while it turns. Here's an image of what I will try to make: https://www.versawatchwinders.com/images/products/versa/vr001/vr001-black-open.jpg .

DC motor: I decided to use the DC motor rather than the servo because the servo is very noisy and doesn't do more than 180 degrees. I understand the servo is a better option because the servo has ways to track position for counting rotation but the noise and not doing more than 180 degrees makes it a bad choice. Please let me know if there's a better solution for this and I'm willing to buy any alternatives. Also, I have no idea how I will mount this cylinder to the motor and whether it will have enough torque to rotate it.

IR remote + IR receiver: Why not? My kit came with one, and I plan on using it to remotely switching between presets of different turn speeds as well as putting it into standby.

8 segment display: I'll use this to display which preset the winder is currently using. 0 will be standby, 1-4 will be different turn speeds.

Buttons or potentiometer: Alternative to the remote to switch the presets

RGB LED or multiple 5MM LED: Will be used to show Green (on) or Red (off) depending on preset.

USB cable: I have a spare USB -> AC adapter from an older phone I can use to power everything.

My main questions are; which is the best motor to use for this project? How will I mount the cylinder to the DC motor or whatever motor I'll be using? is my usb charger plug safe to use to power? Is there anything big that I'm missing and is this actually a harder project than I'm thinking?

Thanks in advance!

How will I mount the cylinder to the DC motor or whatever motor I'll be using?

You probably need to consider how fast the watch can be wound and how you would avoid over-winding.

The motor will need to run slowly enough, or be geared, so that the the winding takes place at a rate acceptable to the watch mechanics.

Any kind of solid linkage between the watch and the motor might risk damage to the watch and/or motor once the watch becomes fully wound and the winder stops turning.

Maybe you could have something like a pencil eraser on the shaft of the motor. When the watch was pressed into place the winder would make contact with the eraser. As the motor runs friction would wind the watch but once the watch becomes fully wound hopefully the eraser would slip.

Thanks for the reply ardly! I was afraid I was not going to get any word back at all. I think I've might have missed a crucial bit of information about the watch winder. This is for automatic watches (or self winding watches) that has a rotor inside the watch that spins and winds based on movement. The winder I'm planning on building will not be affixed onto the crown (the part you use to change the time on the watch). I've added a link to an image below that should show what I plan on making.

I would buy a battery powered watch :slight_smile:

Does the watch really not mind what axis the rotation is taking place in?
If all you are doing is rotating the watch, as in the GIF, you could use a small DC motor or servo. The servo could move the watch back and forth rather than continuously rotating it.

You're winding an automatic watch, right? Not winding the crown? Then there's no problem with over-winding, although you probably want to keep it less than 10x over.

I always pictured doing this with a stepper motor. You can direct-drive without any gearbox. A normal DC motor has to spin at high RPM, like 5000RPM, to get any reasonable performance. So you need a gearbox to gear that down to the 0.5RPM required by the watch. You can buy lots of different gearboxes at hobby stores. That will also solve a lot of the problems mounting the motor.

With the stepper, you can drive a specific number of rotations per day. With a DC motor, you're just driving it for an hour or half an hour and you don't really know how far it turned unless you add a sensor.

ardly:
I would buy a battery powered watch :slight_smile:

Does the watch really not mind what axis the rotation is taking place in?
If all you are doing is rotating the watch, as in the GIF, you could use a small DC motor or servo. The servo could move the watch back and forth rather than continuously rotating it.

Heh having a watch hobby is has it's drawbacks. The watch has to rotate in the same way as the GIF as there is a rotor in the back of the watch that spins in the same axis. The servo could work for 3 of my watches (clock wise and counter clockwise), but I do have a unidirectional watch that only benefits in 1 direction. I might actually use the servo I have on hand right now because I already have it, and there might not be a huge benefit of getting a full 360 servo when the same thing can work. Thanks for the advice!

MorganS:
You're winding an automatic watch, right? Not winding the crown? Then there's no problem with over-winding, although you probably want to keep it less than 10x over.

I always pictured doing this with a stepper motor. You can direct-drive without any gearbox. A normal DC motor has to spin at high RPM, like 5000RPM, to get any reasonable performance. So you need a gearbox to gear that down to the 0.5RPM required by the watch. You can buy lots of different gearboxes at hobby stores. That will also solve a lot of the problems mounting the motor.

With the stepper, you can drive a specific number of rotations per day. With a DC motor, you're just driving it for an hour or half an hour and you don't really know how far it turned unless you add a sensor.

Since you've put some thought into this subject, do you have a model of a stepper motor you recommend? My only requirements is that it is quiet, can mount a reasonable amount of weight and is easy to set up. Thanks!

Go to Pololu.com. They have a good range. You only need one of the smaller ones. The weight of a watch is not significant. Grab a pack of their shaft collars too, so you can screw onto the motor shaft.

Getting it bedroom-quiet will be a challenge. You will have to use rubber mounts and experiment with different controllers to reduce the "whine" noise from the controller. The noise specification may end up forcing you to use a DC motor with an optical non-contact sensor to count the rotations.

A unidirectional watch will still work on a servo. You just need to make sure that you wind far enough (90 degrees is often enough) and then it idles on the return stroke.

Thanks MorganS for a hardware source, I'll start looking through it for parts to find one that has enough torque yet is quiet enough to be in my bedroom at night. I was considering buying a heavier duty one as I plan on building something that can up to 4 watches at the same time (think Ferris wheel, or a cross with post to put watches).

Is it possible to use time rpm to measure a DC motor? I know that it won't be precise but (Time)(RPM) would give me a rough estimate how the revolutions. However, for a more elegant solution I will take you up on the non contact sensor to measure revolutions.

An issue that I should find is the magnetic field. Mechanical watches are susceptible to magnetic fields, and even a weak one over time will cause a watch to run faster. Will a hobby motor be an issue or do they sell MF shielded ones as well?

Thanks again!

How old are the watches? Magnetism is not usually an issue with a modern watch. If you're worried, put a steel plate between the watch and the motor. Use steel as the backplate of the watch holder.

Yes time and RPM can be used. An automatic watch is very tolerant of over-winding.

They range from the 80's to modern. I'll include adding metal plates to try and fix this issue. Also, you've gone above and beyond helping me, so I feel bad asking you for one more favor. I'm looking at the Pololu site, and there is soooo many different motors that I'm spoiled for choice. Is there any particular model you recommend for this project? There are various gear ratios and I'm not experience enough to know if I want a high ratio or low. Thanks once again!

A stepper motor will make more noise but you can step it slowly so you could mount the watch directly. You can also count the steps so you will know exactly how much you have rotated. Since the weight of the watch will be acting along the shaft of the motor the weight is relatively unimportant, you just need enough torque to overcome inertia and get the watch moving.

DC motors run at high speed so you need gearing so that the high speed motor turns the watch slowly. The attached image should make gearing clear. You may need a train of several gears to slow things down enough. When you know the rpm of the watch table you can just use timing to work out rotations as you don’t need an accurate position for this application.

It might be an idea to use a timing belt so that the connection between the motor and the watch table has some play in it. That way as you mount the watch onto the table any pressure will not act directly on the motor (this applies to using a stepper as well).

gear.gif

All of these will work I'd pick one of the cheaper ones around $12-$17 to start with. The pancake motors at around $50 may be convenient to fit your project into a smaller box.

Belt drive is a great idea to get the motor's magnetic field away from the watch. I expect most 1980s watches will be OK with the motor but there may be exceptions. (In my book anything since the invention of the quartz crystal is "modern".) A friend of mine has a mechanical watch from the 80s which is specifically marked "non magnetic". He used to work with motors in the megawatt range in underground coal mines where battery-operated equipment is forbidden, including battery watches.

The DC motors with gearboxes at Pololu are worth a look. Most of them are intended for driving wheeled robots so they will be vastly overpowered for your application. The smallest of them will be fine.

ardly:
A stepper motor will make more noise but you can step it slowly so you could mount the watch directly. You can also count the steps so you will know exactly how much you have rotated. Since the weight of the watch will be acting along the shaft of the motor the weight is relatively unimportant, you just need enough torque to overcome inertia and get the watch moving.

DC motors run at high speed so you need gearing so that the high speed motor turns the watch slowly. The attached image should make gearing clear. You may need a train of several gears to slow things down enough. When you know the rpm of the watch table you can just use timing to work out rotations as you don't need an accurate position for this application.

It might be an idea to use a timing belt so that the connection between the motor and the watch table has some play in it. That way as you mount the watch onto the table any pressure will not act directly on the motor (this applies to using a stepper as well).

The image actually does show how the gears would slow down the DC motor. I assumed I could control the amount of voltage and it could slow the DC motor itself. The timing belt does seem like a great solution, however I am trying to make it fit in a box and I'm not sure how much space is taken with the belt setup. Although since this is my first project, I might go big and have a large setup and leave the optimization of space for round 2. Thanks for all this information!

MorganS:
All of these will work I'd pick one of the cheaper ones around $12-$17 to start with. The pancake motors at around $50 may be convenient to fit your project into a smaller box.

Belt drive is a great idea to get the motor's magnetic field away from the watch. I expect most 1980s watches will be OK with the motor but there may be exceptions. (In my book anything since the invention of the quartz crystal is "modern".) A friend of mine has a mechanical watch from the 80s which is specifically marked "non magnetic". He used to work with motors in the megawatt range in underground coal mines where battery-operated equipment is forbidden, including battery watches.

The DC motors with gearboxes at Pololu are worth a look. Most of them are intended for driving wheeled robots so they will be vastly overpowered for your application. The smallest of them will be fine.

User ardly also mentioned a belt drive and I think I'll start thinking in that direction. The pancake motor may come around in a later stage when I have the basics figured out and when I start making a more compact version. I guess I'll pick up something that requires less than 5V as that's what my Uno puts out. I might pick up 1 stepper motor and 1 dc motor from Pololu to test.

Also, non magnetic watches either uses a magnetically shielded case made of non ferrous metals or they uses a lot of material internally that are non magnetic.

Thank you once again for the advice!

The 5V output from the UNO cannot power any motor, except perhaps the motor in a car fuel gauge needle.

You need to power the motor driver directly from the power supply.

I was able to power a "130" motor using the UNO's power output. I assume that it is closer to a fuel gauge needle motor than a "real" motor?

Depending on the input voltage, that can burn out the UNO's voltage regulator.

No, I don't know what a 130 is. Where did you get it? Do you have a datasheet?

This is the one that came with my beginner kit. I used it in the tutorial that it came with to start and stop a fan. The tutorial had me adjust the PMW to control the speed. I was initially planning on doing the same instead of using a gearbox to step it down as you and ardley suggested

With appropriate gearing, that will drive a watch winder. It may even be quite happy on the Arduino 5V supply, but once again, that will depend on input voltage.