Advice and guidance on repair and restoration techniques.
geofflove
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Repairing a cog

Postby geofflove » Sat Sep 12, 2020 9:25 pm

Topic moved to Tips & Tricks - Site Admin.

I’m about to start in reviving a Williams Spanish eyes pinball machine. An early inspection shows a missing tooth on a sprocket in the ball count unit. See pic. It’s the tooth at about 10 o’clock, the flat at about 9 o’clock is meant to be like that. Has anyone got any advice on repairing the tooth? Thanks
558BBFEC-AA1E-4727-9990-E54DFBDEA459a.jpg

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pennymachines
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Re: Repairing a cog

Postby pennymachines » Sat Sep 12, 2020 10:13 pm

A keystone cut behind the missing tooth, for a good mechanical join to the soldered-in piece, which you then file down to match the existing teeth.

This one has straight teeth, but gives the idea:


livinginthepast
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Re: Repairing a cog

Postby livinginthepast » Sun Sep 13, 2020 8:19 am

Replacing a tooth as Pennymachines describes is a good repair, but as this is a ball count unit which will use limited steps , you may be able to reposition the stop stud and the switch actuating post ..maybe half a turn? and then the unit can work on a different set of teeth.

geofflove
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Re: Repairing a cog

Postby geofflove » Sun Sep 13, 2020 9:17 am

livinginthepast wrote:
Sun Sep 13, 2020 8:19 am
Replacing a tooth as Pennymachines describes is a good repair, but as this is a ball count unit which will use limited steps , you may be able to reposition the stop stud and the switch actuating post ..maybe half a turn? and then the unit can work on a different set of teeth.
I had wondered about that. Unfortunately, with 5 ‘holes’ in the wheel there’s nowhere to put the post at 180 degrees which would have been the easy solution. I might be able to move the switch it hits to compensate for this though.

I have a clockmaker nearby who sorted me with a spring for another project I was working on. I’m going to try him for a repair first before I resort to more drastic measures. Nice to see there are some options though.

And thanks for the cog repair info. I may resort to diy but if a pro can do it I may take the easy way out on this one!

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special when lit
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Re: Repairing a cog

Postby special when lit » Sun Sep 13, 2020 12:27 pm

It's supposed to be like that, it stops the unit counting past a certain amount. If I remember from mi S/E, it's convertible to add a ball, so the unit should step up to 10, then stop.

geofflove
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Re: Repairing a cog

Postby geofflove » Sun Sep 13, 2020 12:37 pm

special when lit wrote:
Sun Sep 13, 2020 12:27 pm
It's supposed to be like that, it stops the unit counting past a certain amount. If I remember from mi S/E, it's convertible to add a ball, so the unit should step up to 10, then stop.
Here it is out of the machine. The flat spot is the one which stops it going past 10 I think. The missing tooth sadly stops it going past 6 so I’m pretty sure it’s not a ‘feature’ in the case. It also causes it to step 2 steps down if you do manage to get it to 7 manually.
8B100893-6691-4572-B30A-21FA432D8D2Aa.jpg

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dickywink
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Re: Repairing a cog

Postby dickywink » Tue Sep 15, 2020 7:07 pm

Hi Geoff
Here is something you could try ...
if you have a bit of scrap thin aluminium you could make up a small 2mm thick plate that screws through the existing holes and fits to the side of the cog, as long as you have clearance for the plate to rotate,

it looks as some tight operator was trying to prevent the Add a ball going up to 10 :D
tooth.jpg
all the best ... Dicky

geofflove
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Re: Repairing a cog

Postby geofflove » Wed Sep 16, 2020 7:26 am

dickywink wrote:
Tue Sep 15, 2020 7:07 pm
Hi Geoff
Here is something you could try ...
if you have a bit of scrap thin aluminium you could make up a small 2mm thick plate that screws through the existing holes and fits to the side of the cog, as long as you have clearance for the plate to rotate,

it looks as some tight operator was trying to prevent the Add a ball going up to 10 :
That’s a great idea. Not thought of doing it like that. I’ve actually got someone nearby who specialises in horological dentistry (who knew that term existed?!) to do a fix on it. We will see what he makes of in a couple of days time. He helped me out a couple of months back when I needed a clock spring replacement so looking forward to seeing his work. And he charged very little!

I think you are right about it being deliberately sabotaged. It’s not general wear as all the other teeth are fine and they are pretty tough - I just can’t see it snapping off without some help. I concluded the same that someone didn’t want anyone on there all day long getting free balls...!


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