Gallery, Projects and General > Project Logs

DTI Challenge 2022

<< < (3/6) > >>

vtsteam:
Hmmm......... Despite the fact that the dial said "Full Jeweled" uhhhhh, I didn't see any. Maybe I don't know what I'm looking at, but those just appear to be holes in the brass plates. There were no bushings of any kind, jeweled or otherwise.

vtsteam:
I've been watching John and Bob on clocks:

awemawson:
'Fully Jewelled' refers to the lying salesman who marketed it - they were on his fingers  :clap:


Nowadays in the UK we have something called the 'Trades Description Act' that prevents that sort of lying but no doubt the dial gauge pre-dates that by many a year. Is there anything similar in the States Steve?

vtsteam:
Federal Trade Commission Act, Andrew. In this case it would have been the manufacturer since it's marked on the dial. Or it could have been a repairer somewhere along the line if this was a mix and match Frankengauge.

Anyway it's back together, cleaned and carefully oiled (lightly as per Bob's video -- though only with 3-in 1 since I don't have instrument oil).

Results, it is much easier to read, it sounds "proper", and smooth.
Problems: still yellowed bezel, return to zero is not consistent.

On the return to zero -- it was losing about a tenth of a thou, every time it was pushed to full reading and released. This, I believe turned out to be the plunger end screw, located at the top of the clock. It's housed inside a removable cap. It sets the zero limit. It was turning itself loose ever so slightly every time the DTI was cycled. That is easily remedied with a tiny dab of paper cement on the screw threads. I don't believe this screw is supposed to be bottomed out tight, but allowed to float and provide that zero adjustment. But I might be wrong......Bob, any idea?

Second problem with the return to zero: once the screw setting was remedied, if pushed to full limit, the pointers would return to zero fairly consistently, but if turned to say a quarter rev of the pointer, would not return all the way.

I'm not sure of the cause here -- could be friction/wear, or weak return string, or mis-assembly.

For wear/friction, I'd guess that the most likely suspect is the tiny pointer pinion. It seemed a little worn, by eye. It revolves the most of any shaft in the movement. It gets a lot of end pressure also, when the clock hand is pressed on, or pulled off. Or maybe its bearing hole was supposed to have a jewel in it....??? The pinion shaft fits into a brass block bearing that looks to be hand made. Is this block original?

For mis-assembly, i'm not completely sure how to set the backlash spring to "2 revolutions" or where on the rack I'm supposed to start engaging its pinion -- fitting this part up is tricky -- you have to rotate the rack clear of the pinion to get the spring post screwed into it, and attach the spring. Then push and rotate it back to engage the pinion. It doesn't always engage in the same place on the rack (invisible, done by feel) so the range of motion varies, as does the amount of pre-tension on the backlash spring. Maybe I haven't got that all proper -- and maybe the zero position is varying because of it.

I do wonder how important the insistent zero is -- is the gauge useful even if it never gets figured out? I guess I could only tell by using it on a gauge block to see if I get consistency past zero....

Well, of course I'd like to get it working perfectly to begin with, but if that tiny pinion is the cause -- there's no way I can make another, or if the movement is really missing a jewel there, nothing I can do about that either....

awemawson:
"but if that tiny pinion is the cause -- there's no way I can make another"


Of course you can make another - you just haven't worked out how  :lol:

Navigation

[0] Message Index

[#] Next page

[*] Previous page