Strange behaviour from wall clock

[Cespain]

I recently bought an unnamed wall clock which came without a pendulum and after some advice in another post in this forum managed to make one which seemed to work fine. I've now gotten around to testing the clock more extensively and have observed some very strange behaviour. When I set the clock to the correct time and start it, after about 45min or so it has lost 7 mins. The strange thing is that it remains the 7 mins slow for days, i.e. it is not really running slow but just seems to lose the 7 mins initially. So I thought that I would set the clock 7 mins fast but in this case it stayed the 7 mins fast instead of what I thought would happen , i.e. lose the 7 mins initially and then stay at the right time. I have done several other adjustments, setting it both fast and slow but it never settles at the right time. I have dis-assembled, cleaned, oiled etc and re-assembled it many times but can't figure out what is wrong. Any suggestions would be appreciated?

 

[Uhralt]

Possibly the clutch that allows you to set the time by moving the minute hand is too loose. I have found this kind of behavior: The clock will seem to lose time until the clutch catches in a position that provides more friction. After that it will run properly. Tightening the clutch will solve the problem.

Uhralt

 

[Cespain]

Thanks, I'll give it a try and report back.

 

[R. Croswell]

When you set the clock, turn the minute hand to 10 minutes (at least 7+ minutes) beyond the correct time, then turn the minute counterclockwise to the exactly the correct time and let go of it. When setting any clock, if the last movement is counterclockwise it will take up any slack or backlash in the works. Then see how it behaves.

RC

 

[Cespain]

Thanks RC, I'll try that one first as it will save me disassembling the clock again.

 

[Cespain]

So far RC's suggestion seems to have worked but I'll try it few times just to make sure and perhaps in the interest of completeness I should examine the clutch as Uhralt suggested.