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Tool Hole probe measuring tools

Tool
jcdammeyer

jcdammeyer

John
Premium Member
These arrived today.

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The tiny one for 3-5mm is a bit touchy but it appeared to give consistent dimensions a number of different holes all drilled at the same time with the same drill bit.

Then I enlarged one to 5.5mm and reamed with my my Chinese 6mm reamer (WD-40 for lube). Measured the outside of the probe at 6.01mm. Close enough I think. It's a feel thing too. Tighten too much and it jams in the hole. Too loose and the measurement isn't right.
 
jcdammeyer said:
Close enough I think. It's a feel thing too. Tighten too much and it jams in the hole. Too loose and the measurement isn't right.
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I've got a set like that in my house shop and another in the barn. The set in the house is so old that the plastic case cracks just looking at

You are right, they are fussy, but they are also quite good. I keep a calibrated hole with them so I can tune my "touch".

PRetty sure I got the second set with a Kijiji haul and the first set from Grizzly. But I know for certain that Accusize and Amazon have them cuz I just saw them.
 
IMHO, Ali usually has great prices, sometimes has good shipping, and almost never has top quality. I'm not sure I'd be willing to buy metrology stuff at Ali. On the other hand, if it's not much to lose then why not?
 
Susquatch said:
IMHO, Ali usually has great prices, sometimes has good shipping, and almost never has top quality. I'm not sure I'd be willing to buy metrology stuff at Ali. On the other hand, if it's not much to lose then why not?
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The shipping was more than the item. But since I don't have a set of pin gauges and some of the steps in drill bit sizes are too large this seemed the ideal for boring a hole on the lathe mostly. Drill to almost the right size. Then bore to clean up with multiple spring passes. If one can fit in say a 10mm drill shank or for that matter ream it then great.

In either case, my work isn't super high quality for the most part so these are just peachy for me.
 
Susquatch said:
kings random
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I assume that they vary in price a lot? :p

Bore gauges are easier to use, but the smallest I've seen is a Mitutoyo .7 inch.
3 point mics take skill to use accurately. As much as a telescoping gauge, but waay more expensive.

With a little practice and instruction, telescoping gauges can get you to half thou. (an expert can get to 2 tenths reliably) A 3 point bore mic can get you a lot closer, to a tenth, IF you have the right touch.
 
I looked up the current Mit catalog. They have a 'small hole bore gauge' - .95mm - 1.55mm (wow).

Things just keep getting better! ;)
 
Dial bore gages are direct reading, pretty much accurate to whatever dial is mounted. Tenths is common. This one starts at 1.5mm (0.059") internal diameter. That's kind of the $$ issue though, usually a set is is comprised of 10 anvils or so. To encompass a wider the measurement range, more sets are required. I've been eyeing some used euro models which seem like really good value. Sets go for a fraction of the cost of dial itself. But 99% for sale are metric not imperial. Not insurmountable, just need to switch mental gears. Another option is just get a digital dial & toggle units. But that's where you have to pay attention to stem size as they can vary.

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PeterT said:
Dial bore gages are direct reading, pretty much accurate to whatever dial is mounted. Tenths is common. This one starts at 1.5mm (0.059") internal diameter. That's kind of the $$ issue though, usually a set is is comprised of 10 anvils or so. To encompass a wider the measurement range, more sets are required. I've been eyeing some used euro models which seem like really good value. Sets go for a fraction of the cost of dial itself. But 99% for sale are metric not imperial. Not insurmountable, just need to switch mental gears. Another option is just get a digital dial & toggle units. But that's where you have to pay attention to stem size as they can vary.

View attachment 41000
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Outside my price point.
 
Dabbler said:
I assume that they vary in price a lot? :p
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My bad. I missed it when I proof read my post. But good outcome since you joked about it!

Dabbler said:
I looked up the current Mit catalog. They have a 'small hole bore gauge' - .95mm - 1.55mm (wow).
Click to expand...

I have to look these up. I would dearly love to be able to measure bore size more accurately.
 
Small hole gauges, next bore measuring purchase after telescoping gauges imo. My view is a quality set is preferred as like telescoping gauges, there is feel involved. I've found Starrett, Lufkin, Mitutoyo, PEC, Suzuki and Helios are all excellent but like most things buy used as they can be pricey.

Brown & Sharpe has an interesting version of this that used two balls instead of the split stem. I have a set and they go down to a 1/16 which is sometimes handy

For even smaller, a 0.010" - 0.060 pin gauge set is handy

Using small hole gauges should be accurate in use to a thou or better. Do a few iterations until you get consistent results.

Dial bore gages are direct reading, pretty much accurate to whatever dial is mounted. Tenths is common.
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I've got them in tenths and microns. A micron is damn near impossible to hit, just the variance in surface finish (even when grinding) seems to create tiny variances that will flicker the needle. otoh, if less than tenths, not a lot of advantages over just using telescoping gauges.

DBG probably the most accurate way to measure a bore, but not really direct the way a mic is in that you have either zero them with a mic (or gauge block stack) or use a mic to measure them after. i.e. measuring across the bore gauge anvils or zero in the indicator is slightly fidgety, I do it between anvils of a mic held in stand that has be set with gauge blocks. There is a setting rig that would make it easier, but I don't have one, and I concede ring gauges might make them pretty much direct reading.

I picked up a set of borematic gauges awhile ago....now that is luxury! Just need a few more setting rings and that'll be the go-to.

My conclusion is bores are always a challenge to measure accurately and I've collected a ton of stuff to make the job easier.....but.....98% of the time its reach for the small hole gauges or telescoping gauges. The other stuff more comes into play doing really fussy stuff, like fitting a TS quill to a lapped bore or bores for expensive match bearings etc. 10ths fits that just don't confront us with most stuff we do.
 
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My primary interest is in measuring rifle bores. I have pin gauges in 10ths for the calibers I play with. But they can only measure from land to land in the rifling and cannot measure the bore diameter between lands. The bore gauges that are the subject of this thread are pretty much useless for that. I do cerasafe castings on occasion, but that is very time consuming doesn't guarantee tenths precision, and sometimes the casting gets stuck in the bore and has to be melted out. I tried making an air gauge once, but the results were all over the map. A more direct accurate measurement would be very useful to me.
 
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