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Gruen 460 Auto Bumper [message #5328]

Wed, 25 March 2015 00:44

Timeticker
Messages: 568
Registered: June 2013
Location: Somewhere in the world

Gruen Master

Soooo, whilst restoring a 460 bumper, I ran in to a bit of a quandry! Posted next are the questions "bumping" me!

1.) What is the power reserve for a bumper? Meaning, being that you really can't wind it like a conventional watch in that it has a bridle to keep it from being over wound, then how long should it last?

2.) Installed new mainspring, the watch started perfectly, and keeps excellent time, but on first attempt, watch ran for 6 hours and shut down.

3.) Re-wound the watch, but it would seem to me that the auto bumper should be keeping the watch running while you're wearing it, and should keep running throughout the night when the watch is off the wrist.

4.) Any comments are more than welcome.....please feel free to pitch in your 2 cents, dollars worth, or a brick through my window.

People you thought were your best friends will stab you in the back to your face!

Love them anyway.
A "Paradoxical Commandment"

[Updated on: Wed, 25 March 2015 00:44]

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Re: Gruen 460 Auto Bumper [message #5329 is a reply to message #5328]

Wed, 25 March 2015 01:44

Gary
Messages: 2165
Registered: May 2013
Location: Seattle

Gruen Authority
Cheerleader

Out of the Gruen course in wristwatch repair, the New Gruen Auto-wind technical bulletin states: "The complete winding will be executed through the natural movements of the arm in 3 to 4 hours' time-". "Once thoroughly wound the watch is provided with a power reserve of approximately 32-35 hours' running time."

There are some really good testing scenarios for auto-winds in this book, too much to type out here.

Hope that helps.

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Re: Gruen 460 Auto Bumper [message #5332 is a reply to message #5329]

Wed, 25 March 2015 12:27

Thojil
Messages: 650
Registered: May 2013
Location: Concorès, France

Gruen Master

I keep mine on a winder all the time, but I will take it off tonight and check for how long it will go.

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Re: Gruen 460 Auto Bumper [message #5343 is a reply to message #5332]

Fri, 27 March 2015 19:33

JackW
Messages: 1977
Registered: May 2013
Location: Denver

Gruen Authority
Head Janitor
Site Admin

When you say "Installed new mainspring" did you use a vintage Gruen blued-steel spring or a new white-alloy spring? If blued, then it is possible it is also set. What size/length did you use? Could be too long and thus not fitting the barrel correctly.

All I know is based on hard work & writing by others. I can only aspire to augment this body of knowledge. If I am wrong it is because of my own failings. -me

"If I have seen farther it is by standing on the shoulders of giants." - Newton

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Re: Gruen 460 Auto Bumper [message #5345 is a reply to message #5343]

Fri, 27 March 2015 20:19

Gary
Messages: 2165
Registered: May 2013
Location: Seattle

Gruen Authority
Cheerleader

Just a thought, if it was the old type blued-steel did you oil it down? I use that Mobile 1 all synthetic or some Vaseline.

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Re: Gruen 460 Auto Bumper [message #5348 is a reply to message #5345]

Sat, 28 March 2015 00:44

Timeticker
Messages: 568
Registered: June 2013
Location: Somewhere in the world

Gruen Master

I used an authentic Gruen blue steel, cleaned it and oiled it. I have been wearing the watch for a few days now, and it seems to be running very well. I'll eventually post the photo of this one. Really nice for original age. Thanks for the information, Gary!!! Greatly appreciated! I really do love this bumper.........it has now become a favorite!

People you thought were your best friends will stab you in the back to your face!

Love them anyway.
A "Paradoxical Commandment"

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Re: Gruen 460 Auto Bumper [message #5349 is a reply to message #5332]

Sat, 28 March 2015 00:45

Timeticker
Messages: 568
Registered: June 2013
Location: Somewhere in the world

Gruen Master

Hey Thojil,

So, what was the final reserve time you got on your bumper?

People you thought were your best friends will stab you in the back to your face!

Love them anyway.
A "Paradoxical Commandment"

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Re: Gruen 460 Auto Bumper [message #5350 is a reply to message #5349]

Sat, 28 March 2015 18:00

Thojil
Messages: 650
Registered: May 2013
Location: Concorès, France

Gruen Master

Forgot

Took it of the winder today 18:30 CET.

[Updated on: Sat, 28 March 2015 18:00]

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Re: Gruen 460 Auto Bumper [message #5352 is a reply to message #5350]

Sat, 28 March 2015 22:36

Timeticker
Messages: 568
Registered: June 2013
Location: Somewhere in the world

Gruen Master

That's ok....give me the next run.

People you thought were your best friends will stab you in the back to your face!

Love them anyway.
A "Paradoxical Commandment"

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Re: Gruen 460 Auto Bumper [message #5358 is a reply to message #5352]

Mon, 30 March 2015 18:06

Thojil
Messages: 650
Registered: May 2013
Location: Concorès, France

Gruen Master

It stopped running after 35 hours & 50 minutes, so in line with Gruen's claimed power reserve.

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Re: Gruen 460 Auto Bumper [message #5375 is a reply to message #5358]

Fri, 03 April 2015 23:17

Timeticker
Messages: 568
Registered: June 2013
Location: Somewhere in the world

Gruen Master

Sounds good! I actually haven't wound it now in 4 days, (wearing constantly) but will mark the time tonight, and take it off to see what happens. Thanks so very much, Thojil!!!

People you thought were your best friends will stab you in the back to your face!

Love them anyway.
A "Paradoxical Commandment"

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Re: Gruen 460 Auto Bumper [message #5401 is a reply to message #5375]

Tue, 07 April 2015 00:07

Timeticker
Messages: 568
Registered: June 2013
Location: Somewhere in the world

Gruen Master

I got nearly 35 hours out of mine. Will probably run a bit longer as it seats in. To be exact, I got 34 hours 50 min, out of it.

People you thought were your best friends will stab you in the back to your face!

Love them anyway.
A "Paradoxical Commandment"

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