A7750's do they "bed-in"?

[mikerblade]

I've had a look through the board but can't seem to find anything so excuse the noob question.

I've had my Slevin for a few days now & It seems to be changing how much time its loosing per day, 1st day it was 45 secs/day slow, 2nd 35secs/day and so far today 10secs over 12hrs.

I'm hoping to get it serviced by The Zigmeister in the future(although I'd imagine I'll be very lucky to get a slot once his PM's open) but I was wondering if the movement "beds-in" over the 1st week of so of use or am I just wishful thinking.

many thanks,Mike

[RWG Technical]

A correctly serviced movement wont' bed in like a car engine will that's new. The reason is that once it's oiled correctly, there is nothing to wear out or bed in against.

The timing of any mechanical watch will vary as it's being worn. There is always positional errors, dial up and down typically run slower than crown down (side load on the pivots).

On an unserviced movement, or one that is over oiled, the friction varies quite a bit between positions, and the timing will also vary.

What you see is quite normal, and even once serviced you will see variations in the timing, a 7750 that is serviced typically is withing a few seconds on the timer in all the positions. But even so, while being worn, and the activity that the watch is put under (sitting still, leaning on your writs, walking etc), can cause the rate to vary 30 or more seconds per day.

RG

[mikerblade]

Many thanks The Zigmeister. so much to learn

[Pugwash]

Another thing ... when you receive a watch, it's just been punted around your local postal depot wearing nothing more than a Jiffy Bag. I'd take a few days to settle in after that, myself.

[92tru]

But even so, while being worn, and the activity that the watch is put under (sitting still, leaning on your writs, walking etc), can cause the rate to vary 30 or more seconds per day.

Hey zig, thanks for this tid-bit of info. something like this made all the difference in my quest to obsessively adjust my TY-2530 mov't in my PAM222. I figured it would always be fluctuating time and being a few seconds fast or slow, to the point where I just concluded it was something in the fact its a poor quality-control mov't - it is a REP after all!!

Spent the whole weekend trying to calibrate with a quartz seiko and after getting pretty close to it being spot on with my iPhone, I can now rest-assured that these little variances in accuracy are just attributed to motion AND poor quality control...........

one question tho, with the motion of the wrist throwing off the accuracy, does the mov't ever correct itself? or does it just continue steady beating, but now with just being off accuracy?

[RWG Technical]

one question tho, with the motion of the wrist throwing off the accuracy, does the mov't ever correct itself? or does it just continue steady beating, but now with just being off accuracy?

Overall the movement averages out, after servicing if you check and adjust the watch on the timer, it's normal to aim for +6 to 10 seconds per day. For the average user, this tends to even out the rate while being worn.

Position errors are a result of the design of the movement and the quality of the parts, which is why the genuine Rollie's are clearly marked "Adjusted for temperature and 5 positions". Were not so lucky, our movements don't have anywhere near the quality or design.

The only real way to get an accurate mechanical watch, is to have the wearer use the watch for a day, then measure the error and correct it.

For example, if you wore the watch for 24 hours, and at the end of the test, the watch was +20 seconds, you would put it on the timer and adjust it - 20 seconds to remove the error.

Also keep in mind that as a watch unwinds, it speeds up, adding to the problem... Anything in the + - 20 seconds per day for an ETA and I'm happy...more of an allowance for the Asian models.

RG

[92tru]

hey zig that last reply really cleared things up, UNTIL!

i have a TY2530 pr pam222. Its time-keeping accuracy actually speeds up when i wear it on my wrist, esp when walking........ not that i swing my arms like a maniac or anything!! It only speeds up say 5-15 seconds, after a brisk 20 min walk or so.... i thought it should be slowing down? after sitting for 30 mins, the movement seems to regulate itself back.. but i haven't nailed down exactly how much it will retard if i leave it idle indefinitely - esp since you mentioned it should 'speed up' as it unwinds!?

in this case, it seems i have to aim for -5 to -15 seconds/day in hopes that it stays somewhat accurate after wearing it on my wrist...

clear as mud? uh help, yoda?

[RWG Technical]

It speeds up because it's crown down (crown up is the same), when it's crown down, the pivots have side loads on them, side loads have more friction than up and down loads, more friction = less balance wheel swing, less swing = faster ticks and tocks...think of a pendulum, move it up it goes faster, make it longer it slows down.

RG

[92tru]

Hey Zig,

that was perfect. When I read your first response above, I just couldn't figure out how friction would make time pass by FASTER? friction always slows things down, but when you reminded me about the balance-wheel and pendelum analogy, it all fit together! thanks again!

[Pugwash]

When I read your first response above, I just couldn't figure out how friction would make time pass by FASTER? friction always slows things down, but when you reminded me about the balance-wheel and pendelum analogy, it all fit together! thanks again!

I explained it to the missus one day as an escapement's job is to slow down the uncoiling of a spring. If it's not working well, it can't slow it down enough.