Replacing the bearings in a Copal motor

[Johan de Jong]

The rotor of a Copal motor runs in brass bearings/bushings. After a few decades of continuous running the wear of these bearings can start to give problems: the motor becomes noisy or friction becomes too large and the motor (intermittently) stops.

For a while I’ve been looking for a solution. My first attempt to replace them with ball bearings was not satisfactory (too noisy). But now I think I may have cracked it: I replaced the bearings with new porous metal bearings similar to the original. The first clock I did this way has been running perfectly silent for more than two weeks.

Here is how I did it:

First step is to open up the gearbox like described here.

Second step is to remove the pinion gear. With a wooden block for support I used a flattened nail and a hammer to push the axis out of the pinion gear. I also bought a small pinion puller, but that did work out since the gear sits in a recess in the motor (may though still useful to remove the pinion from the axis if the gears give way before the pinion does).



As you can see there is a tiny washer on either side of the motor and also some black stuff. That is I think the remains of old lubrication and wear of the bearings.

Third step is to remove the bearing. This I also did by hammering but using a larger bolt to push the two bearings and spacer out of the motor.



(story continues in next post...)

[Johan de Jong]

The replacement bearings I found here on AliExpress. They measure 1.5 x 3.5 x 1.5 mm (ID x OD x L). That is quite a bit smaller than the original (1.5 x 6 x 2.5) but these were the only ones I could find with an inner diameter of 1.5 mm.

To fill the gap I use a spacer tube that a friend was so kind to 3D print for me. It measures 3.5 x 6 x 11 mm (ID x OD x L). A final refinement using a drill and sandpaper was needed to make it all fit. As an alternative I ordered these spacers but these are still on their way, so I can’t tell yet whether this is a good alternative.



The two bearings then need to be well aligned to let the rotor run smoothly. For this I used the smooth end of a 1.5 mm drill. By grabbing it at both sides and wiggling it around I made the bearings align.



I then added a drop of oil to each bearing and did a test run before pressing back on the pinion gear and reassembling the gearbox.

As said, one clock is running silently for over two weeks now. The second on I have just finished and is also running smoothly. Let's hope it stays that way for a few more decades

[gschmidt958]

Fantastic job, thanks for sharing!

[Johan de Jong]

Small update: that pinion puller I bought is not a good fit for the Copal motor. The pin is a little too thick and the fork is also the wrong size to get a good hold on the gear. That's a pity, but maybe it is handy some other time.

[Johan de Jong]

I was notified that the link to the bearings did not work (anymore).

Here are two new links to the bearings:
Kaifa Electronics Co.: https://www.aliexpress.com/item/33046865723.html
MSM Parts Store: https://www.aliexpress.com/item/1005002302288903.html

I used the bearings from the last link (1.5 x 3.5 x 1.5) but I think they are the same article.

[Johan de Jong]

Update : I tried to remove the bearings from another Copal motor, but these were so firmly stuck that I was afraid my hammering would destroy the motor

So I tried this alternative method that I think is a lot safer.
As shown below I used a small vice, a nut and a bolt to press out the bearings.



This Copal motor also had a little surprise in store: instead of the two bearings and a spacer that I saw with the other motors, this one had four bearings in a row and no spacer. Maybe that explains why they were so badly stuck.

[Johan de Jong]

Another update:
The spacers I ordered from AliExpress (3 x 6 x 12) have arrived and they work very well and are easy to work with!

The outer diameter is exactly 6 mm and fits nicely in the motor.
The inner diameter is 3 mm, but after drilling with a 3.5 mm drill the new bearings fit perfectly.
The length is 12 mm. That is about half a mm more than the original but no problem.

[flipoclock]

I was finally able to do my first successful repair with new bearings and a plastic sleeve, it has been running now for a few hours and it is as silent as Copal motor should be, which is not 100% silent but it has a very soothing and calming running noise, I can't really describe it but when I hear that when a Copal clock is running, it makes me happy because it is an indication that all is well.

I had to wait for my 1.5mm and 3.5mm drill bits to come in, I could not get them locally and had to order them from further away. The final adjustment to the bearings with the 1.5mm drillbit takes some practicing and is a bit tricky but it is the most important bit. Once that is done, you might want to manually adjust the flywheel to ensure it is as balanced as manually possible to prevent the new bearings from wearing out again too soon because I suspect the new bearings are not the same quality as the original Japanese ones but if these last anywhere from 5 to 20 years, essentially I will be happy.

This clock will run for some time to ensure it is ok again and in the meantime I will done one or two more for a test and when they all are running fine, even after a couple of week, I am happy.

At the ends of the bearings I tried some new stuff that I bought, for a bit of lubrication, it is called Molykote DX ( https://www.ebay.de/itm/125795194114 ) and from what I have read it should work well with a situation where you have a small shaft spinning in two bearings but time will tell I guess.

[flipoclock]

I have been tinkering around with a few more motors and found that you have be careful when swapping parts between motors. You would think that the flywheel essentially is always the same, it is not! The length of the shaft can differ.
I was having trouble getting a flywheel to balance nicely and quietly on the new bearings and decided to try another flywheel I had lying around and this worked like a charm but I ran into an issue trying to reassemble the gearbox, it would not fit as a whole, I ended reworking the original flywheel and putting that on (and it now works like a charm).

[Johan de Jong]

Good you got it done! And good to know that there are these differences in the rotors. I have seen so many variations in Copal motors. Finding which parts are exchangeable will always be a matter of trial and error I'm afraid.

BTW: the motors I fixed until now are still running fine

[Sebastiaan]

I tried a different approach, because I was not too happy with ordering from Ali (1), the bearings/bushings construction (2) and I expected that real ball bearings would be more precise and durable (3). Also, alignment is not an issue with the correct bearing size .

I discussed my idea with Johan, who said he already tried this with AliExpress ball bearings but it was too noisy. Ali was already no option, so bought Japanese quality stuff. I ordered the 601-H X-ZZ from the reliable manufacturer EZO with dimensions 1,5x6x3mm. Double sided covered, so (re)greasing should never be a problem anymore. They are quite expensive for their size, I paid €6,50 a piece plus shipping. Maybe they are expensive because they are so ridiculously small.

So, my experiences with the replacement which I did according to Johan's description (thanks for that!) but with different bearings:

1. I opened the rivets of the gearbox by drilling them. Pushing the rivets had no effect, and I hammered quite hard. Afterwards I put a bit of superglue on the drilled rivets to reassemble.
2. I removed the pinion gear by putting two small flat screwdrivers underneath each side of the gear and lift it off its axis. Piece of cake.
3. Getting the bearings out of the motor with a hammer seemed to much violence. I pushed them out with a bench vice, socket wrench on one side and a 5mm bolt on the other side. Johan's post #5 explains it.
4. Between the bearings was a spacer. I reused it to maintain a decent spacing between the bearings.
5. Pushing in the new bearings in the motor was a piece of cake and they seemed to fit exactly. Unfortunately, they were a just a little too loose to not worry about them moving. Despite my initial restraint, I put superglue on the edge of the bearing and then pushed them in the motor. My restraint was justified, because the bearing was stuck, but not completely inside the engine. Fortunately, I ordered 4 bearings, so I hammered the glued ones out. My advice: put in the bearings in their right position first. Then a teeny tiny tiny drop of superglue just between the outer edge of each bearing and the motor will suffice.
   If the bearing doesn't fit, you can use some force on the outer ring of the bearing, but if you push on the inner ring, you ruin the bearing. So be considerate or use the oven-freezer method as stated below with the motor in the oven and bearing in the freezer.
6. The flywheel slided easily in the bearing with minimal to no force. If it doesn't with yours, don't try to push! You will definitely ruin the bearing. With bearings, you can always use the oven-freezer combination. So for this step, put the flywheel in the freezer for an hour or so, and the motor with bearings in the oven. Watch for molted wiring and burns, so not too hot, probably around 75-80°C would be good without melting the wires. Then try again.
7. Don't order PRC bearings or other cheap junk. If you make this effort for your valuable clock, buy quality stuff. EZO is available at several web shops. Watch for the ZZ code, only these are double shielded and thus pregreased for eternity.

At first, the motor was a bit noisy but that disappeared in a few minutes. Now, I can hear the engine rolling with my ear on the clock and maybe a few centimeters away, but that's it. It is very quite, especially compared with the old bearings. Unfortunately, I don't have other flip clocks to compare (yet). My flywheel is a bit unbalanced, so I expect noise level should be even lower to almost zero.

Thanks everyone on this forum for the good work!

[Johan de Jong]

Great work and thanks for the detailed description!
Not the cheapest solution, but you're right: a good clock deserves it