# Adding an On-Off Switch to Fowler Digital Caliper



## old toolmaker (Jun 25, 2017)

Hi,

I want to add an on-off switch to a 6" Swiss made Fowler digital caliper.  I acquired this caliper from my father when he passed away about 14 years ago.  It is really a nice measuring tool that has seen little use.  It has one annoying issue that I would like to change and that is the caliper has no shut off switch and you guessed it; the battery goes dead too soon.  I searched the active topics of this forum and have not found an answer for what I want to do.  Does anyone have experience adding an on-off switch to one of these calipers?  Or am I wanting to do something that is not worth the effort?

Dick


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## Bob Korves (Jun 25, 2017)

I think I would make a thin plastic shim to fit one side of the battery if it could be easy enough to get in and out.


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## extropic (Jun 26, 2017)

I'm curious if the caliper has auto-off that isn't functioning or if it's designed to be ON all the time.

The latter seems so unlikely to me, especially for a Swiss made tool.

Are you saying that digits display all the time, until the battery dies, even when the caliper is unused/unmoved overnight?

In the past, I've seen a chart that showed the capacity of various button cell part numbers.
There are some (different PN) button cells with the same physical size but not the same capacity.
You might do a little research to verify that you're using the best battery PN option. 

From Wikipedia: "Cells of different chemical composition made in the same size are mechanically interchangeable. However, the composition can affect service life and voltage stability. Using the wrong cell may lead to short life or improper operation (for example, light metering on a camera requires a stable voltage, and silver cells are usually specified). Sometimes different cells of the same type and size and specified capacity in milliampere-hour (mAh) are optimised for different loads by using different electrolytes, so that one may have longer service life, than the other if supplying a relatively high current."

https://en.wikipedia.org/wiki/Button_cell

Anyway, my recommendation for a switch is to simply remove the battery at the end of the day.


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## Tozguy (Jun 26, 2017)

If you have found that the battery goes dead then can we rule out an auto-off feature?
Maybe check with Fowler to confirm the right battery to use and how to improve battery life.
If it really does not turn off somehow Fowler would have fielded this question many times over the years.


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## Groundhog (Jun 26, 2017)

Seems to me that I've read that most calipers do not completely turn off, they just turn off the display (which is likely the biggest battery user). Don't know what this has to do with your situation though !?


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## old toolmaker (Jun 26, 2017)

There is no auto off function that I know of.  The unit never turns off until the battery is completely dead.  This is the only caliper I have ever seen that does not have auto off or a switch.
I may check to see if I could cut a little slot in the case cover to allow me to insert a thin plastic shim over the battery contact.  I know this would be pita to do every time but short of getting another caliper it might be the best solution.
I might also try to contact Fowler.
Dick


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## markba633csi (Jun 26, 2017)

Of course you can add a tiny switch but it may not be pretty.  You might be able to make a "wafer" that would insert between one side of the battery with two very thin wires trailing out to a tiny switch.  That would probably require the least amount of modification to the caliper itself.  Like a small piece of thin double sided fiberglass circuit board.  I might have some of that around here somewhere...
Mark S.


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## markba633csi (Jun 26, 2017)

There are very small switches available like this:
	

		
			
		

		
	




	

		
			
		

		
	
I think I have some of the slide type I can send you if you want to experiment-  cost of postage
Mark S.


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## Tozguy (Jun 26, 2017)

old toolmaker said:


> There is no auto off function that I know of.  The unit never turns off until the battery is completely dead.  This is the only caliper I have ever seen that does not have auto off or a switch.
> 
> I might also try to contact Fowler.
> Dick



It just occurred to me that the turn off might be a press and hold feature on the zero button or mm/inch button, or maybe press twice or something like that.


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## higgite (Jun 26, 2017)

Tozguy said:


> It just occurred to me that the turn off might be a press and hold feature on the zero button or mm/inch button, or maybe press twice or something like that.


It wouldn't surprise me if that works. I have some digital indicators that you turn off by holding the "on/zero" button down for a few seconds.

Tom


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## old toolmaker (Jun 26, 2017)

Guys,
I am going to check that caliper out tomorrow to see if it will shut of with a press and hold or something like that.  It is definitely worth a shot.


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## old toolmaker (Jun 26, 2017)

I don;t have a user manual so I went online and did a search and got the scoop.
This is a high class caliper but it has no ON OFF switch and the battery life is stated as one year.  I guess that will have to be good enough for me although it seemed to me I was replacing the battery more often that that.
Maybe that was caused by the fact that my shop was unheated during night hours here in Minnesota during the winter months.  Most batteries don't like cold.

Dick


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## Tozguy (Jun 27, 2017)

Shucks, no off switch. Thanks for the feedback though.


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