# Sunnen setting fixture for bore gages



## Brain Coral (Sep 28, 2013)

Hello all,

I picked this up at a garage sale today. I tend to be a little impulsive with buys like this, but I thought that it may be useful, although I don't know much about it. I understand that it would be used to very accurately set a bore gage, but if any of you have used these before, I wouldn't mind a bit of a detailed explanation. With the range between 2" and 8" I assume that this would not be as desirable as the smaller versions.

Heres a few pics...













Cheers...

Brian


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## Tony Wells (Sep 29, 2013)

Well, you're missing a couple of the setting rods, and this is made for a particular style bore gage. Suunen bore gages are built with a pair of small "wheels" mounted on a pair of spring loaded fingers that are spaced off center on the movable contact end of the gaging head.  Their purpose is to press outward so that when sweeping the bore gage through the bore, it is self-centering. That setting fixture uses those centering wheels, or rings, to duplicate the actual measuring conditions in a bore and allows the centering pressure to balance itself and hold the actual contact distance just like it would in the bore. Think of it kind of like an adjustable set ring. 

Many people set their bore gages with an OD micrometer, or with a Jo block accessory. These both present parallel surfaces, and do not allow the Sunnen style bore gages to see the effect of the centering wheels/rings/rolls....whatever you want to call them. I don't remember what Sunnen calls them, although they are wear parts and I have had to replace them more than once on a couple of gages. 

Unless I am mistaken, Federal actually makes (or did) the bore gage for Sunnen, and markets their own as well, identical save for the brand markings.


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## Brain Coral (Sep 29, 2013)

Hello Tony,

Thank you for that detailed explanation. It was cheap enough and I did notice that a few of the ground rods were missing. It looks like I might have bought a pig in a poke ?

Brian


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## rgray (Sep 30, 2013)

If you got it cheap you did good. I see these sell for $500.00 up to $1000.00 on Ebay.


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## Brain Coral (Sep 30, 2013)

Hello Russ,

Wow... !!!  So $40.00 was REAL good !!!  But, it is missing some of the setting rods and by the instruction sheet that I found under the wooden storage block, circa 1966.

I'll have to see if I can find a use for it.

Brian


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## rgray (Sep 30, 2013)

I'll give you $100.00 anytime. 
You accidently did real good. 
Check out Ebay # 281176004502
It's compleate and looks a little fresher but yours is still worth alot of money.
This should be in the tool gloat catagory.)


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## Brain Coral (Oct 1, 2013)

Hi Russ,

That one on Ebay looks brand new... !!!  Well, it's good to know that I didn't spend too much money and that it has some value.

Brian


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