Blick clock

I have a Blick clock which I have raised from the dead by dumping its synchronous motor and gearbox and fitting a stepper motor. It is the sort of thing which used to drive factory hooters, school bells etc. There is a big gear with 288 teeth, from which I want to drive a small pinion to trigger an hours chiming device. The OD of the gear is 7.375, so add 2 to the teeth and divide and I get 39.3 dp, or 0.65mm module. It is definately not 7.25" OD (40 dp) I can't believe either of these. The original design was American, so I'd suspect it should be dp. Any one got any better information? I daresay it will work with 40 dp, or I could make a lantern pinion with the odd dp, but it would be good to be sure I'm doing it right

bump

Could it be that the gear was specified in terms of its circular pitch? From your numbers the gear has a circular pitch very close to 0.08.

Mike

Is it an involute gear or a cycloidal one?

Neil

Posted by Neil Wyatt on 25/07/2017 17:01:15:

Is it an involute gear or a cycloidal one?

Neil

Dunno, does it make much difference? Here's some photos

I think Mike has got it, 0.08 circular pitch. I'm not likely to find a matching gear for that am I, but I can make a lantern pinion. Good job I bought Ivan Law's book last week.

Looking at the photo of the teeth, particularly near the number 16, they do appear to be cycloidal rather than involute. 0.65mm module could well be the right size.

Blick Time Recorders was a marketing company rather than a manufacturer, many of its designs where made by the National Time Recorder Co. in the UK. Have a look at WorkClocks.co.uk website for more information.

Neil