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Clock Wheel

This topic has 12 replies, 8 voices, and was last updated 2 January 2017 at 17:43 by Mark Bus.

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29 December 2016 at 16:56 #274258
Mark Bus
Participant
@markbus97330
Hi,

I cut the center wheel on the clock I'm currently building and one of the teeth is narrower than the rest ; something must have slipped. Its 1 Mod. , the teeth are about 61 thou. except the narrow tooth which is about 46 thou. Is this going to cause any problems with the operation of the clock? The perfectionist in me is screaming in agony while I scourge myself with barbed wire for making the error, but the rational man thinks that it won't matter.

Thanks,

Mark
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29 December 2016 at 16:56 #3746
Mark Bus
Participant
@markbus97330
29 December 2016 at 17:03 #274261
Anonymous
If something slipped you'd expect one tooth to be narrower and one tooth to be wider. If one is too narrow and all the others are equal then there must be something wrong in the orginal calculations. I've no idea if it'll run, but personally I'd make it again.

Andrew
29 December 2016 at 17:09 #274263
John Haine
Participant
@johnhaine32865
I had a similar issue making a ratchet wheel. It turned out that the blank had not been firmly enough clamped to the mandrel, so every time a tooth was cut it slipped slightly. Overall it lost more than a tooth but every tooth looked OK. Next time I put more wellie on the clamp nut and all was OK. You might also check that you have the expected number of teeth…?
29 December 2016 at 17:15 #274265
Bob Stevenson
Participant
@bobstevenson13909
Welcome to 'wheelmakers angst'….

There's good and bad news;…it'll probably work,…but you will always 'KNOW' every time you look at the clock!

If you have already crossed out the spokes etc then keep going…if it's just the blank with teeth then do it again….clockmakers can prefer one or the other methods for various reasons .
31 December 2016 at 08:50 #274585
john carruthers
Participant
@johncarruthers46255
can you scarf and solder in a new tooth?
31 December 2016 at 09:12 #274593
Michael Gilligan
Participant
@michaelgilligan61133
Posted by john carruthers on 31/12/2016 08:50:17:

can you scarf and solder in a new tooth?

.

John,

I would be interested to understand how you see this working:

I have inserted teeth to replaced damaged ones, but I honestly can't see how one under-size tooth could be successfully replaced.

MichaelG.

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Mark wrote: Its 1 Mod. , the teeth are about 61 thou. except the narrow tooth which is about 46 thou.
31 December 2016 at 09:26 #274598
john carruthers
Participant
@johncarruthers46255
I am assuming there are comensurate wider spaces either side, or on one side, of the narrow tooth? if not then it's a non starter.
31 December 2016 at 09:37 #274602
Michael Gilligan
Participant
@michaelgilligan61133
Posted by john carruthers on 31/12/2016 09:26:55:

I am assuming there are comensurate wider spaces either side, or on one side, of the narrow tooth? if not then it's a non starter.

.

Thanks, John … understood.

I guess we need a photo to clarify.

MichaelG.

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[Mark] Could you put the wheel on a flatbed scanner, and post an image, please?
31 December 2016 at 11:08 #274626
Neil Wyatt
Moderator
@neilwyatt
I've had this happen if the wheel isn't held 100% securely. What happens (I hypothesise) is that the vibration from cutting is slightly imbalanced and the wheel creeps imperceptibly and it's only at the final cut taht the error is visible.

Neil
31 December 2016 at 19:40 #274725
Mark Bus
Participant
@markbus97330
Hi,

The wheel has the correct number of teeth. The spaces on each side of the narrow tooth are the same. Tooth tip to tooth tip distance is equal. The mistake occurred when i was cutting the first two teeth when I was going back and forth to get the right depth of cut. It dawned on me to mount it on my depthing tool to see if it would work with it's respective lantern pinion. I set it at the correct theoretical spacing. Well , I did that and I didn't notice any problems. I got to thinking that if it was the opposite problem, i.e. a wider tooth, then there might be a jamming problem when the pinion pin was engaging with the tooth but with the narrower tooth things should be OK. The only problem I can think of is that there might be a slight gap or pause in the timekeeping when that narrow tooth comes into engagement with it's pinion?

Mark
31 December 2016 at 20:02 #274726
Bazyle
Participant
@bazyle
If you think about it the tooth to tooth spacing on one side of the teeth is the same for all, but the thin tooth makes the spacing on the other side off for the last tooth. With a lantern pinion one side of the wheel teeth never touches in a clock that only goes one way, So just mount it the right way round and it will never miss a beat, the other way round might give a problem at the lowest driving weight.

edit Hummm, I'm not sure if that is right.

But if you cut all the teeth again making them as thin as the thin one then you could get them all the same but weaker which would be ok else the one thin tooth is already a fatally weak point.

Edited By Bazyle on 31/12/2016 20:07:41
2 January 2017 at 17:43 #275168
Mark Bus
Participant
@markbus97330
Hi,

I looked at the bad tooth again and the space is bigger on one side then the other. But it turns out I made another mistake. I made some multi tooth wheel cutters earlier this [2016] year and the first wheels I cut I used my .125 thick cutter . Then I went to cut the 1 Mod. third and center wheels with my .186 thick Thornton cutter. Unfortunately I forgot to adjust the height of the cutter and I cut the teeth too low. Having tried them out on the depthing tool I still think the wheels would work even with all the errors but I know if I use them I'm going to be thinking about it during the whole construction process so I've decided to make new wheels. It"s just easier.

Mark
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