Setting Bore Gages
I have several different types of bore gages around the shop, anything from Interapid, Mitutoyo, Fowler, you name it.
Ideally, the very best way to set these gages is with a ring gage. I have several different common sizes that I use to set my gages, but it's just not practical to buy a ring gage for every size that you may need to check.
I have a shop made holder that holds a gage block stack up between two ground fingers.
The holder has a lock and a fine adjust to tighten the stack up..........but I've had problems with this. It just doesn't seem to be 100% accurate all of the time. I have set a bore gage to the gage blocks and then checked a known ring gage size and resulted in .001 difference which is unacceptable.
What do you use to set your bore gages ???
Oh how I wish I had a set of Sunnen bore gages and their masters. The very best set up for measuring holes made, in my opinion.
We use a micrometer, a stand can be used to aid in shaking hand syndrome. This method has been tested against setting rings and works very well.
The sunnen gages come up on ebay all the time.
I use a mic stand for the two point type gages, like Mueller and IPD. I scrunch a bit of rubber or soft plastic tubing on the mic anvils to help keep the points where they belong.
Agreeing with the previous 2 replies, micrometer very lightly clamped in a Mitutoyo weighted holder, have also checked against ring gauges & found no significant disparity.
Perhaps a little fiddly at first with a fine reading gauge but once the technique is mastered not much difference in setup time to using a ring gauge.
I used Standard gages for decades and liked them, so when I was exposed to Sunnen, I just didn't care much for them. Back in the day, I used rings to set the gage, (and they had to be within .002 of size, I think it was a mil spec or aircraft thing). Now I have a setting fixture from Standard for the larger sizes, or I set up a gage block stack with fingers and a cage when I don't use the fixture. I have a few rings, and pick up additional when I can- I still thinks rings are the best.
Originally Posted by rockfish
I've set a lot of bore gages with micrometers, finding it relatively easy to do, but I've heard that this isn't recommended because of backlash issues ???
Any thoughts on that ???
I ALWAYS set the micrometer to a stack of gage blocks first, lock the anvil with the mic clamped to the stack, and then slide the blocks out. Just setting the micrometer with nothing between the anvils can possibly lead to error.
Originally Posted by rockfish
I always cross check as well by setting the mic with gage blocks and locking it while in a stand, then setting the bore gage, then setting the gage blocks in a cage with fingers, and then checking the mic. All should, and most often do agree.
I do this for Sunnen gages for use in honing and have not had parts rejected.
I use a short phenolic bushing sized to fit over the fixed gage point on the Sunnen that locates it on the fixed anvil of the micrometer on the larger bore gages. That locates the fixed point so you don't need to have your hot little hands hands on it. Takes the "fiddliness" out of setting it too.
2 Canadian cents worth
You got it, rings are ideal. Buy new if possible. Overall they are inexpensive (for their longevity)and usable forever without extreme abuse. Buy used for cheap, have them lapped and calibrated.
Micrometers are perfect for 2 point bore gauges, but, know the micrometer.
Dont set with a Fowler, Chinese, offshore, or borrowed instrument.
I have read many of your threads folks and just out of curiosity, why are you folks so impressed by Sunnen instruments? They are infact Mitutoyo gauges with a different facad.
Let me know about the SUNNEN. We only fix a few of these per year, but, there seems to be nothing special. Mostly we use Mitutoyo parts to fixem because their are no Sunnen parts.
You gave part of the answer already...
Originally Posted by peschi34
They seem very accurate
They are dependable and rugged
The various lengths available suit the job
Ergonomic and easy to use
Nice size ranges
Not made in Asia
But I also can't say that I've used a lot of others. I liked them so I stuck with them
Do you mean the dial indicator is Mitutoyo, or the whole gauge is Mitutoyo?
Originally Posted by peschi34
That is one of the advantages of a Sunnen dial bore gage. The tube you hold has nothing to do with the shaft that holds the bore gage together so the heat from your hand has no effect on the size.
Originally Posted by pistonskirt
Intriguing....I have used plenty of Sunnen mandrels & stones but never any of their measuring equipment (though I seem to remember a Sunnen air gauge, that was decent, many years ago)
Originally Posted by gappmast
The "master" for setting Sunnen bore gages is GREAT. The gage almost plugs in to the
master and there is a knob for rotation adjustment to rock the gage to the correct spot.
The "master" comes with a large tenths micrometer head with magnifying glass to set your size with.
I haven't found anything faster or more accurate to set bore gages with.
Do any of the big catalog houses carry sunnen bore gages. I have checked MSC and Mac master car and haven't found them
Sunnen bore gages for some reason can only be leased from Sunnen. If you find one on EBay, it's because someone forgot they were owned by Sunnen. They periodically have to be sent back to Sunnen for recalibration and refurbishment if necessary.
I did not know mine is leased.....I have never paid any rent.....I sent it back for overhaul a while back, they charged me about 300.00 but never said anything about catching up on the rent.
Rent and lease are not the same thing.
Originally Posted by moonlight machine
Rent is usually paid by the month; leases may be paid fuily in advance, or periodically.
Hmmm. I've been buying them at auctions for years. You'd think something like that would be common knowledge, like compressed gas bottles.