Common Methods of Measuring the Diameter of a Hole
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- čas přidán 15. 07. 2013
- Various ways to measure the diameter of a bored hole demonstrated on an actual part. Methods shown include the inside calipers, small hole gauges, telescoping gauges and gauge pins.
- Jak na to + styl
![How to Measure a Hole or Cylinder [HOLE GAUGE]](http://i.ytimg.com/vi/QXAckHGRCyI/mqdefault.jpg)
That is nice to hear. I am a former shop instructor but haven't taught for many years (35). It feels good getting back to it, especially since my videos have been so well received.
Thank you for the compliment.
Tom
Once again Tom you taught me another basic: I was using the telescope gauge wrongly and was never sure of what I read. Your method takes all the guess out - Thanks!
Knowing the "why" makes it easier to understand the "how".
Glad you liked the video.
Tom
Nice Video ! Thank you for taking the time to demonstrate and explain the different methods.I found your explanation of the proper technique to use with the telescoping gauge very helpful.
Here I am in 2020 going over and revising again all these years later. Tom's techniques are the videos I go back over a few times.
Very nice.
Some people are just born to teach others.
You Sir, are the teacher and have our attention.
Thanks Tom
You have an excellent knack in providing a concise and a well articulated explanation. Thank you very much.
For others watching this, Tom does a great job explaining these devices;
I agree that Pin gauges are best, some are exact and some are marked a few tenths under on purpose. The tele and hole gauges are more affordable for the home machinist, those pin gauge sets can be pricey for the novice.
Thank you sir,, once again I have learned some thing I’ll take with me for the rest of my life…
Keep up the good work Tom..👍
Every time I have a rookie question you have a video that's just right. Thank you!
+Poncho likes bacon
It's good to hear that the topics are helpful.
Tom
I understand your thinking on "the spring pass", and I've seen other CZcamsrs make several passes to account for it. My father taught me to use the spring tension on that pass to my advantage. Make one pass, then check for for
fit, and only if the fit was too tight would he make a second pass without adjustment, and usually nail it. We routinely held .001 tolerances using this method. Let the pressures between the tool and surface allow you to sneak up on your desired minimum dia is what I'm saying.
Absolutely. There are lots of little tricks like that in machining. I usually just reverse the feed and take the spring pass if needed for a super finish.
one of the benefits of having a crappy small non rigid lathe
very informative you do a great job teaching, thanks for making great videos
Nice job. Thanks for showing us.
Your South African, English, Dutch, and Chinese toolmakers and machinists have taught you well. That is the proper technique for using a telescoping gauge, exactly the technique I am demonstrating in the video and have taught for years. Maybe you should watch the video again.
Thank you for your input.
Tom
I liked it. Good way to explain us of tolerances. Which side of the exact size well work. Nothing is exact.
in toolmaking in which i'm qualified in, i was taught to, and teach to rock the telegauge out of the hole gently the larger diameter of the gauge will automatically find its center and continuously drag itself out naturally, simple dragging the gauge could result in one end of the gauge being pushed through creating various accumulative errors... this is the preferred method i have been taught by south african, english, dutch, and chinese toolmakers and machinists, love from new zealand
Thanks! Use of the telescoping gauge is commonly misunderstood which is why I decided to make this video.
Tom
Great vid! The only thing I missed was the insertion of the bushing!
Nice work Tom another great video keep it up.
Denis
Great vid thanks! Doing this for a new shift knob on my Jeep =D
thank you so much! super informative
That's what I get for doing the math in my head while shooting a video, I should have taken off .005, not .006. Looks like I got lucky because the bushing did press in fine. I'll add a note to the video.
Glad you enjoyed it.
Tom
How does one apply the telescoping gauge with sophistication?
always informative thanks
+Dorian Charles
Thanks for watching.
Excellent!
Nice video, thanks. I don't quite understand though how 494.5 and you added 6 thou, still you got the hole less than 500. How come?
Thank you Owen.
You are very welcome.
Thank you!
I think you'll find that a second sweep won't change anything, one sweep is all it takes. The biggest factor in getting consistent measurements is getting the drag right. The best way to learn is to set down and try it over and over until you consistently get the same reading.
Inside mics require a 1" hole or larger, so that will be a different video.
Tom
Trying to figure out how you measured .4945", cut .006" and wound up with .499". Thanks for the demonstration
Looking at the video, I guess I got lucky. The final cut should have been .004"- .005", not .006". It's hard to do math and make videos at the same time. :) The reason the hole didn't go oversize is probably because the tool was getting dull and required a few more spring passes to get to size.
5:28 Why is it important to rock the telescoping gauge over center only once? Even if it's unnecessary, I don't see how rocking it back and forth would cause any problems.
Rocking it once will force the guage to find the exact center of the hole. Doing it multiple times accomplishes nothing and increases the chance of it drifting off center and producing a false reading.
Also, I'd like to know what are the other methods of measuring an inside diameter are. You mentioned "fancy methods", but what are those, please.
+Gort Newton
A dial bore gauge was the other method I was thinking of, but they are a bit pricey for the hobbyist so I didn't bother to elaborate.
Tom
Thanks
can a vernier caliper scale be used to measure diameter of hole ?
It can, but not very accurately. A telescoping gauge would be a MUCH better option.
Tom
Thank you Sir
I just got my first ever set of small hole gages. How much drag am I looking for? Just a touch, or a bit more positive than that? Should the gage slide out of the hole in the same way as a block slides out of a micrometer? I've used pins until now and would like to gain more accuracy. Thank you.
Ream a hole to a known size and use that for practice. The key is to develop a feel so you get the same reading every time.
@@TomsTechniques Thanks very much. Will do.
@@TomsTechniques As you were so kind as to give thoughtful advice, thought I'd update this. Started with reaming .250 and .3125 holes. All by hand. None were accurate when I was done. Figured, user error. Ordered a couple of brand new reamers and kept practicing with what I had. Today, I popped and reamed 25 .250 holes, 5 of which were relatively accurate as gaged with pins. Progress. That's better than yesterday. I'd also picked up a used Starrett round small hole gage set that's significantly nicer to work with. As such, I'll keep practicing reaming and using the gages until it all comes together. I'm looking at it as killing two birds with the same stone - learning how to ream well (I thought I knew how) and getting a feel for the gages. Thank you again.
Cool!
Thanks Jack.
Unfortunately, dial calipers are commonly used to measure holes but next to a machinists rule they are the least appropriate tool for it.
Tom
The way in which you applied the use of the tele guage was kind of crude in my opinion but still far superior to using a vernier like I see many people do
Vernier=very-near
I wonder how accurately you can measure the diameter with the edge finder.
I haven't tried it, but probably within a couple of thousandths, provided you have a DRO on the mill.
They work. Have to find center of x an y axis then you can center the two up to find center.
Plug gauges or bowers mic's will always be my favorite, but i've never had a problem with the telescopic gauges.
Hi, what is the name of the tool?
Which one?
I don't think they make them with short sleeves.
classic trick especially if the hole has a chamfer is to machine a punch that is undersize by 2x the thickness of some copper sheet and press the copper through. your hole is the diameter of the copper cup minus a couple thou. this is completely impractical but it's how i sneak up on dimensions when actually making dies.
This is particularly when I'm doing the final polishing. Often when obtaining your final finish you end up removing potentially like 3 thou of material. just from sanding with ~400 grit paper until the peaks are as tall as the valleys. it's better now because i have an actual cylindrical grinding attachment for my toolpost but it can be pretty tricky.
"How does one apply the telescoping gauge with sophistication?"
Maybe he thought your fingers were too dirty -
Its so easy to make an error when you trying to film and machine something.
+Bob Cartwright
Yup. It's a LOT easier to do these lessons in a classroom setting.
Tom
You could wear a Tux. :)
Rocking it over center works?! Whaaaaaa
My dumb ass has just been getting it true straight up and down, then tightening, flailing it to the loose spot, loosen tighten, flail to loose spot, tight loose until there's no more loose spot.....
Yes, that's the only way to get precise readings.
do people actually use these? I've been a machinist for 11 years and I've always used gauge/deltronic pins to measure a diameter of a hole. Or a dial bore gauge for really big diameters.
I use both. Small hole gauges are quicker than gauge pins for low tolerance holes. I'll also use them to get close to the finished diameter on a tight tolerance hole and then use a gauge pin to finish up.
Tom
samwjohnson - that's the trouble: you are a MACHINIST with REAL (costly) tools at your disposal. We metal butchers don't have the time to accumulate the years of experience or the budget for the high-end gages to do it "right" 🤑
I'm lost as to why you need to measure a hole you drilled with a drill press. The size of the drill bit is the size of your hole.
The hole was bored in a milling machine, not drilled in a drill press. But even a drilled hole can be larger than nominal, depending on how well the drill bit was sharpened.
You should have ran your indicator down the side of the hole. Looks like u have some taper. A .498 pin will go in but not slide all the way through??? Bad burr on the bottom side or what? It also looked like the .500 pin started going in at the top of the hole about .01 deep. In my opinion you might be over the high limit at the top!!!!
+Esteban Chavez
No taper. You can't see it in the video, but the slot in the part wasn't deep enough to clear, so the bore created a step in it. That is what was keeping the gauge from going through. The part went into a successful fixture and is still in use.
Tom
:-)
novice here . why not just use a drill bit instead of the bit that you are using
Good question. First, a drill won't drill a round hole, it'll drill a triangular shaped hole. Second, a drill won't drill an accurate hole on location. If the diameter is critical, but the location isn't, you can use a reamer. If you need both, a boring bar like I used in the video is the only way.
Thanks for watching.
Tom
Jinliang Liu Good video! Or we could use reamer as a hole size of whole number.
Yes, if the hole was a nominal diameter. But a bored hole is still more accurate in size and location.
Thanks for watching.
Tom
Intrimiks
That is another option, but if I'm going to spend that kind of money, it would be on dial bore gauges. Just my preference, they both do the same thing.
Tom
Yeah I'm a noob. I was just trolling. Taking my year 1 millwright right now lolol
Sounds like fun. Good luck.
Thanks