Fibre wheel in old mains clocks. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Darren-UK · 12th Aug 2011, 5:33 pm

That's more of a Starburst rather than Sunburst clock.

It certainly isn't ugly but is somewhat peculiar. The counterweights on the hands represent the sun and the moon, rather odd because with such hands one would expect a little flag appearing in a window to indicate day and night. I suppose it's just a decorative novelty, with the sun and moon passing each other every hour.

I'd think it's a 1960's clock, especially as the field coil former appears to be of white plastic.

The movement looks to be a neat little effort. What size is the fibre wheel? smaller than I'd imagined by the look of it. Some modern, rubbishy, alarm clocks contain wheels of nylon, PTFE or whatever; may be one of those could be adapted by turning down the diameter and cutting new teeth by using the fibre wheel as a template if you don't have gear-cutting equipment.

Another, rather drastic, option would be to replace the movement with a Smiths, Metamec or whatever effort. Problems may arise there with hand-arbor length and diameter though.

This is all shot-in-the-dark waffle though. If you can show us the fibre wheel, or describe it dimension wise, perhaps we can suggest something more definate.

EDIT...just seen Michael's post; his suggestion seems a good'n if costs aren't prohibitive.

Top Cap · 12th Aug 2011, 6:48 pm

As I think you suggested, it might be possible to make a small gear infill as it is just a couple of cogs. I tried (miserably) to draw something in MS Paint but you cannot draw anything with less than 90deg rotations. However, if you look at the small attachment and stretch your imagination a little I am certain you will catch the idea. The two gear cogs would of course be manufactured with dimensions to match the circumference of the fibre wheel. Made of very thin material and glued to the original to fill the small space in the cog wheel. Would have to be done with good precision as those clock motors do not have much power and any excessive load from cog mismatch may stall it. I think super glue may set too quickly to enable a good position of the infill patch to be established. Another possibility would be to fill the missing part with Araldite then file the missing cogs into the Araldite. Not a job for my ancient eyes and shaky fingers though I would probably have a go using a large bench magnifier.

Mike Phelan · 12th Aug 2011, 7:40 pm

Dennis

Seeing the number of teeth (poles) on rotor it's only running at about 200rpm, so the wheel in question isn't running very fast at all.

Don't worry about wear as there's no load on the wheel train on this sort of clock.

dennishoy · 12th Aug 2011, 9:46 pm

Quote:

Originally Posted by Top Cap

As I think you suggested, it might be possible to make a small gear infill as it is just a couple of cogs. I tried (miserably) to draw something in MS Paint but you cannot draw anything with less than 90deg rotations. However, if you look at the small attachment and stretch your imagination a little I am certain you will catch the idea. The two gear cogs would of course be manufactured with dimensions to match the circumference of the fibre wheel. Made of very thin material and glued to the original to fill the small space in the cog wheel. Would have to be done with good precision as those clock motors do not have much power and any excessive load from cog mismatch may stall it. I think super glue may set too quickly to enable a good position of the infill patch to be established. Another possibility would be to fill the missing part with Araldite then file the missing cogs into the Araldite. Not a job for my ancient eyes and shaky fingers though I would probably have a go using a large bench magnifier.

This was exactly what I was considering as an option to get it going.
I would make four teeth exactly as you have drawn them 1 - 2 - 3 - 4 where teeth 2 - 3 are missing on the fibre wheel. I would then align teeth 1 and 4 with the undamaged fibre teeth and then 2 and 3 in the middle must also be in the correct position.

dennishoy · 12th Aug 2011, 9:54 pm

Quote:

Originally Posted by Mike Phelan

Dennis

Seeing the number of teeth (poles) on rotor it's only running at about 200rpm, so the wheel in question isn't running very fast at all.

Don't worry about wear as there's no load on the wheel train on this sort of clock.

Mike, quite right. The clock runs for 6-8 seconds (one part rotation of the fibre wheel) then stops when the gap with missing teeth meets the rotor.

Another clock expert off this forum has told me that the second hand is screwed on and the minute hand is mounted on a square cutout on these clocks. He has said that any attempt to force the hands round to the right time too quickly puts stress on the fibre wheel and is probably the reason for it failing. You are supposed to use the little winder on the back to set the correct time.

Interestingly, he also told me that this clock has a 50-50 chance of starting in the correct direction. If it starts in reverse, there is apparently a brass lever and rachet device which stops the rotor and it will then restart in the correct direction of travel. So when it is powered up, you may see the second hand go backward for a few seconds before stopping and then changing direction. Clever eh?

Darren-UK · 12th Aug 2011, 10:45 pm

If power is disconnect when you move the hands directly it shouldn't harm the fibre wheel providing the rotor isn't partially, or even fully, seized. This is sometimes the case when electric clocks have stood disused for a long time. If, however, you try to move the hands directly when the motor's running then damage is likely to occur - especially if the teeth on the wheel are already quite worn.

The directional starting device isn't unusual. Smiths used a similar idea, but with a coil spring that kicks back instead of a lever. Metamec used a lever device, operating in conjunction with a manual starter.

12th Aug 2011, 5:33 pm	#21
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Fibre wheel in old mains clocks. That's more of a Starburst rather than Sunburst clock. It certainly isn't ugly but is somewhat peculiar. The counterweights on the hands represent the sun and the moon, rather odd because with such hands one would expect a little flag appearing in a window to indicate day and night. I suppose it's just a decorative novelty, with the sun and moon passing each other every hour. I'd think it's a 1960's clock, especially as the field coil former appears to be of white plastic. The movement looks to be a neat little effort. What size is the fibre wheel? smaller than I'd imagined by the look of it. Some modern, rubbishy, alarm clocks contain wheels of nylon, PTFE or whatever; may be one of those could be adapted by turning down the diameter and cutting new teeth by using the fibre wheel as a template if you don't have gear-cutting equipment. Another, rather drastic, option would be to replace the movement with a Smiths, Metamec or whatever effort. Problems may arise there with hand-arbor length and diameter though. This is all shot-in-the-dark waffle though. If you can show us the fibre wheel, or describe it dimension wise, perhaps we can suggest something more definate. EDIT...just seen Michael's post; his suggestion seems a good'n if costs aren't prohibitive.

12th Aug 2011, 6:48 pm	#22
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: Fibre wheel in old mains clocks. As I think you suggested, it might be possible to make a small gear infill as it is just a couple of cogs. I tried (miserably) to draw something in MS Paint but you cannot draw anything with less than 90deg rotations. However, if you look at the small attachment and stretch your imagination a little I am certain you will catch the idea. The two gear cogs would of course be manufactured with dimensions to match the circumference of the fibre wheel. Made of very thin material and glued to the original to fill the small space in the cog wheel. Would have to be done with good precision as those clock motors do not have much power and any excessive load from cog mismatch may stall it. I think super glue may set too quickly to enable a good position of the infill patch to be established. Another possibility would be to fill the missing part with Araldite then file the missing cogs into the Araldite. Not a job for my ancient eyes and shaky fingers though I would probably have a go using a large bench magnifier. Attached Images __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way!

12th Aug 2011, 7:40 pm	#23
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: Fibre wheel in old mains clocks. Dennis Seeing the number of teeth (poles) on rotor it's only running at about 200rpm, so the wheel in question isn't running very fast at all. Don't worry about wear as there's no load on the wheel train on this sort of clock. __________________ Mike.

12th Aug 2011, 10:45 pm	#26
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Fibre wheel in old mains clocks. If power is disconnect when you move the hands directly it shouldn't harm the fibre wheel providing the rotor isn't partially, or even fully, seized. This is sometimes the case when electric clocks have stood disused for a long time. If, however, you try to move the hands directly when the motor's running then damage is likely to occur - especially if the teeth on the wheel are already quite worn. The directional starting device isn't unusual. Smiths used a similar idea, but with a coil spring that kicks back instead of a lever. Metamec used a lever device, operating in conjunction with a manual starter.