Gruen 452ss mainsprings and timing

[Levine98]

Hi, 

I have a Gruen Caliber 452ss that I've been working on and am having trouble getting it to keep time at full wind (snowflakes and ++++ss on the timegrapher watch makers side up). However at reduced wind, say 2/3 or less, it times fine. I've checked the mainspring specs in my bestfit book and on the pink pages (bestfit is listed Gruen 452ss in the pink pages under Pierce 105, the base movement). 

Unfortunatly all sources give different specs for the mainspring. The Bestfit gives 150/10/11.5 while the pink pages give 150 x 9.5 x 11.

I'm using a NOS mainspring spec'd from the Bestfit book, i.e., 150/10/11.5. Could this small difference cause this kind of sympton?

 

Thanks

[mikepilk]

The GR Mainspring catalogue gives 1.50 x 0.11 x 300 x 9.  The Best Fit also gives 1.50 x 0.11. 

 What do you mean by 150/10/11.5 - 1.50 x 1.0 or 1.15 ?

[Levine98]

25 minutes ago, mikepilk said:

The GR Mainspring catalogue gives 1.50 x 0.11 x 300 x 9.  The Best Fit also gives 1.50 x 0.11. 

 What do you mean by 150/10/11.5 - 1.50 x 1.0 or 1.15 ?

Sorry for the confusion. I've been mixing up Dennison and metric measurements in my communications.

If I stick to metric, the pink pages (http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&Gruen_445SS) states 1.50 x 9.0 x 0.10 x 290mm for the Pierce 105 (which is what this movement is based on according to Bestfit reference).

The one I installed, based on the Bestfit reference, measures metric 1.50 x 9.5 x 0.11 x 290mm (the Bestfit reference I have states mainspring requirements in Dennison format 6x10x11.5). So to your point, when you convert it to metric the Bestfit also says the dimensions for the Gruen 452ss mainspring are 1.50 x0.11.

Does that make sense? And my question, I guess, is regarding the 'strength' number, would a difference of '0.01' be enough to cause the symptoms I'm experiencing? 

[mikepilk]

The thickness effects the stiffness more than the height, but I've used springs 0.01 mm thicker without problem. 

As it's a NOS spring I'm surprised you have re-banking, but it sometimes happens. Modern oils with old movements and you can get too much amplitude. 

You can try thicker oil, and oiling the pallot arbor jewels to dampen things down.

[Levine98]

Super, thanks for the advice. I normally don’t oil the pallet jewels in these old movements and old pocket watches, but will try this. Regarding amplitude it is very high indeed, well above 300 at full wind watch makers side up

[mikepilk]

No one (apart from Seiko) suggests oiling pallet jewels, but it is an easy way to reduce amplitude. A bit of HP 1300 on one or both jewels.

The Omega Workshop manual suggests :

In most cases, knocking is detected in horizontal positions when the movement is completely wound, and when the amplitude is over the maximum amplitude tolerance levels:
- 310° for self-winding watches
- 325° for hand-winding watches

How to eliminate knocking:

If the knocking continues: Replace the lubrication on the bridle facing the dial (or the movement if the dial is already installed) with colourless Moebius SYNT-HP-1300 oil. This will reduce the amplitude by approximately 10-15°. If this operation is not sufficient, the bridle on the other side may be lubricated with colourless Moebius SYNT-HP-1300 oil.

I'm not sure what is meant by "bridle", I guess the pallet jewels ? (unless it means the balance? - I've never tried HP1300 on the balance) 

(We need one of the "pro's" to help - if I mention @nickelsilver x3 he magically appears !)

Edited August 9, 2022 by mikepilk

[clockboy]

They thickness (strength) does a make difference for sure. However .5 is not a massive amount. It certainly seems it’s over banking.  I presume there is no wear with the barrel or barrel bridge. My GR ref book shows a strength of .11 for the 452ss.

By any chance have you the original spring if so measure the strength 

Edited August 9, 2022 by clockboy

[Levine98]

Can you sort out one more question? Regarding strength of the mainspring, is the higher Dennison number mean a thinner (weaker) spring? I'm still not clear on this since the Dennison to metric conversion chart I'm using shows the Dennison strength number inversely related to metric strength (thickness)?

[mikepilk]

30 minutes ago, Levine98 said:

Can you sort out one more question? Regarding strength of the mainspring, is the higher Dennison number mean a thinner (weaker) spring? I'm still not clear on this since the Dennison to metric conversion chart I'm using shows the Dennison strength number inversely related to metric strength (thickness)?

I agree, the higher the Dennison number, the thinner the spring.

Ranfft does give the spring thickness for the base movement 455SS as 0.10 mm, but there can be errors. I'm more inclined to believe the GR Database for mainsprings, and BestFit agrees with the thickness of 0.11 mm 

[JohnR725]

On 8/8/2022 at 12:06 PM, Levine98 said:

I have a Gruen Caliber 452ss that I've been working on and am having trouble getting it to keep time at full wind (snowflakes and ++++ss on the timegrapher watch makers side up). However at reduced wind, say 2/3 or less, it times fine.

Can we have pictures of the timing machine. Plus timing and more than one position like dial-up and dial down and then crown down as it's a wristwatch. Also when you wind it up wait about 15 minutes before you take the pictures.

Also when the watches wound up what does it sound like?

 

Then here's the mainspring information I found for the watch

MS-610K

 MAINSPRING 1.50-.11-300 9

 GR 4149

 

 

[nickelsilver]

I have no idea what Omega is saying from above (I'm here!); does sound like they're suggesting oiling the fork pivots though. Not how I'd do it.

 

As one source is saying 0.10, and OP is at 0.115, and getting rebanking there at full wind, I'd say the spring is too strong. Increases in thickness is like cubed regarding power increase- just going from 0.10 to 0.105 can give rebanking in a really top condition watch.

 

But on a different track- some U.S. makers used flat tipped balance pivots. This brought the amplitudes of flat closer to vertical positions.* Gruen was made in Switzerland but assembled and hairspring counted in Cincinnati... I think they used "normal" rounded balance pivots but hoping John will jump in with more info.

 

*and was an issue when using Swiss made aftermarket staffs with rounded pivot- they rebanked-- especially if coupled with the new "Whitalloy" or whatever mainspring. Which is another possible contributor- some modern springs have up to 15% more power for a given cross section compared to blue steel springs.

[Levine98]

Thanks for all of the replys. First, I should point out that I'm a hobbyist with less then 1 year experience. For the first 4 months I worked on Elgin Grade 291 pocket watches to learn the basics and figure out what I needed to build a decent workshop.

These past 3 months I've focused solely on 1950s vintage manual wind Bulovas, Gruens and a couple of odd Hamiltons, Wittnauers and Benrus thrown in for good measure. 

All of these movements (some with cases, most without) were in pretty rough shape and cost on average $25 or less on eBay. I got a couple to run pretty well, a couple that don't run so well (mostly low amplitude)  and a bunch that have been put in to my "salvage for parts" drawer (usually I've fouled the hairspring or lost a microscopic part somewhere).

No matter--I figure this will take me, along with on-line coursework, at least 2 years to get decent at. I look at each movement as a learning platform..the exercise with the Gruen 452ss has forced me to really focus on and understand mainsprings in a way that I had not up until now and to get a better understanding in practice seeing overbanking.

Anyhow back to the Gruen 452ss......

I did try lubricating the pallet jewels with D5 (the only thick oil I have). Unfortunately it didn't help and if anything, caused the timing to worsen (actually the beat error went up some too). So I'm going to strip the movement again, reclean it, and have purchased a weaker mainspring. I'll report back later if/when I get it all put back together and re-timed (this time with pictures and in multiple positions).

Again, thanks

Levine98 

Edited August 10, 2022 by Levine98

[Levine98]

Quick update. Received a new mainspring for a Gruen 445SS movement. Both the 452SS and 445SS are based on the Pierce 105 movement. However the 445SS mainspring is just a slightly narrower than the one I was using (the 445SS movement is smaller).

So far the results are great--dial side up and down about 280 amplitude and in other positions anywhere from 200 to 220, which in my experience is fine for an old manual wind watch.

Most importantly, at full wind it doesn't knock anymore.

My only complaint is these are old blue steel mainsprings--very brittle and hard to handle. But at least it solved the problem.

Thanks all for your input--I'll post a picture once I get the watch cased and ready to go,

Cheers -- Levine98

Edited August 25, 2022 by Levine98

[clockboy]

Great news, onto the next project then