Best way to measure an inside bore, very exactly and cheap
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- čas přidán 28. 08. 2016
- This video will show one of the best way to measure very accurately an inside bore that will be used as a future reference, using cheap inexpensive gauge blocks and endmill stubs. Not every hobby shop or small machine shop can afford expensive measuring equipment, this should help in getting very exact readings.
By being creative there is always a way to resolve a problem in the simplest manner, I think this one of those things that will inspire other people to look for the alternative way to do something with the least investment possible
Thanks for watching, hope you enjoy.
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Thumbs up and constructive comments are welcome.... ;)
Pierre Beaudry - Jak na to + styl
lots of useful info there. thanks for taking the time to show us, Pierre
Hi Emma, glad it serves as ideas on how to get something done...
Cheers, Pierre
Great tip. Wish I could give two thumbs up. Practical, simple and accurate...home shop trifecta.
Hi Alan, there is only a limited choice for thumbs direction, glad you chose the "UP" direction... lol
Thanks for nice comment, Pierre
Great video, Pierre! Thanks for sharing the method.
Hello Herb, Glad you enjoyed, cheers, Pierre
U give me a lot of very good information so once again thank u . I calkulate the difference between 4.9224 and 4,9225 inch and it is 2,54 micro or My as we say. In 1986 I bought a new Ford Orion and measured the ticknes of the paint. On the roof and upper side it was 80My on the hod and in the front it was between 90 and 110 My. And that is not much. 2,54 My compare to that is so little it har nothing to say.😊
Happy to help, thanks for your comment....
Excellent video Pierre! Very creative way to measure. Thank you for sharing it! Fred
Hi Fred, glad you enjoyed, thanks for nice comment, Pierre
Thanks Pierre, another interesting video. I'm new to machining and very much enjoy this type of video. Best regards. Bill
Hi William, glad you get something from my videos, even I learned lots of new techniques watching some fellow machinists that share their knowledge on the internet...
Thanks for watching and for comment, Pierre
Nice set up and great measurements.
Thanks Randy, I was looking for a simple way to get close to real measurement, I think this comes close...
Great video!
Glad you enjoyed it and thanks for your comment... 🙂
Thanks Pierre for another interesting and entertaining video. I learnt something more today. :-)
Thanks for watching and for a nice comment, Pierre
Nicely done Pierre! keep them coming,
ATB, Robin
Hi Robin, glad you like, your videos are also a treat... ;)
Thanks, Pierre
That was interesting. I was surprised again at the mastercrafts accuracy. The guage block setup was something tht I wanted to see more of, thanks for that.Danylo
Hi Danylo, That Mastercraft is a little treasure, it's pretty accurate for the price, it served me faithfully for a while now, even I'm surprised sometimes... ;)
Thanks for comment, Pierre
Magnifique, Pierre. I have taken notes. I need a set of gauge blocks and I work in metric but the principle is the same. One thing I have found is that it is very difficult to find the true diameter and very easy to measure somewhere else in the hole so you are measuring a chord rather than the diameter. The two end mills are really neat because they make it hard to do a chord -- the cylinders will slip off if you are not exactly on the diameter. Very useful!
Hi Juan, glad this method will help you to get better measures in your work, if you have them you could also use some adjustable parrallels, close to be as good as gauge blocks.
Thanks for comment, Pierre
Hmm. Adjustable parallels = poor man's (or retirees) gauge blocks. Noted!
Something some viewer suggested, great input...
thanks for the upload, useful idea.
Glad it can help someone get better accuracy on their work...
Thanks for comment, Pierre
Great video! thank you.
You're welcome...
Thanks for comment, Pierre
Very interesting video (again). I had not thought of measuring with gauge blocks and pins. Learned something new here, and had not seen this method on any other video! Thank you for your very fine programs. Enjoyed. I'm still thinking about getting my vise jaws ground by you, but right now am negotiating with my pocketbook to see if I can afford a new Kurt vise. We'll see.
Hi Jim, since I don't own an inside 3 point bore micrometer or a CMM, and needed the highest possible precision, I looked for a cheap way to get it..... This is what I came with..... ;)
Whenever you're ready for the jaws, money don't come easy those days.
Thanks for nice comment, Pierre
Now that was an interesting video. Keep on keeping on.
Glad you enjoyed,
Cheers, Pierre
Really excellent!
Glad you enjoyed and thanks for comment, Pierre
We need to grind a flat on some rounds and polish it so that it can work with the cheaper gage blocks. Thank you for the video and the creative ideas. I have an optical flat coming and the mono-chromatic light idea is perfect (and cheap) :).
For the price it's working great, not as precise as the real halogen light but at least you get a real close estimation...
Thanks for nice comment, Pierre
Great info...thanks
Hi Chuck, glad you liked and thanks for comment,
Cheers, Pierre
Thank you very much!
Thanks for taking time to comment, Pierre
Nice technique.
Two pins plus an adjustable parallel or a planer gauge, measured separately with an outside micrometer would do something similar. Snug the adjustable parallel or planer gauge between the pins and measure all three for a total inside dimension. I've used something similar for making comparative measurements inside dovetails. (I didn't need to know the exact dimension of the new dovetail slot, just whether it was the same size as one that was known to be good.)
Hi Peter, I'll give a try with the adjustable parallels just to test how it compares with direct measurement, cause that will involve tranfering the measure to the micrometer... to be continued...
If someone is good with trig. it's not too hard to calculate the dovetail problem, first choice, mostly if the reference dovetail is near one of the upper/lower limit of the established standard, I admit that the compare method works in most cases... ;)
Thanks for the input, Pierre
Hi Pierre
Nice subject there and very well communicated !
Hi Keld, always nice to have you visiting, glad you enjoy, I'm getting my dementia therapy started and it seems to work... ;)
Cheers, Pierre
Pierre's Garage
Ha, ha, ... yeah, I noticed that too ;-))
very interesting video. your cheepo calipers got close enough for average work. i just purchased a set of cheepo calipers at our local grocery store of all places. i intended to use them on wood since they have a fractions function. when i checked them against my micrometer stds i was amazed to see them within a half thou on every std to six inches. most were dead nuts. well i paid eight bucks for them and they are stainless. needless to say i went back and bought a couple more sets.
Those stores should give me royalties for all this publicity... :)
There is one area where any caliper will be more thrown off a little more is when you have length that is in between thousand ex. 1.0044", 1.0046", 1.0048" it could be anything but the right measure, within it's tolerance, but if we use them as what they're intended we'll be satisfied with the performance... $8 is even a better deal!
Thanks for your input and comment, Pierre
Hi Pierre, Wish I had your gauge block accessory set. I went with Mit. digital mikes as well. But a caution about those non brand name gauge block sets. Mine were a lot more than $100 when I bought my grade 2 set. They came with a "test certificate" showing the blocks deviation from the true dimension. Despite that there were two blocks of the exact same size in the box. Penn Tools didn't even question that and sent me a Mitutoyo of the correct size as a replacement. So one could start to think the included test certificate might even be bogus. (fwiw I do) I then bought a proper set of grade 2 Mits. and the cheap set is now used as shop blocks. But I never trust there exact accuracy and always measure the gauge block stack as a double check and use the Mit. set only when I need as accurate as possible. There's also quite a noticeable difference in the holding force between the two sets and a visible difference in the surface lapping quality as one should expect for the price difference.
I certainly agree a cheap set is almost more accuracy than most home shop guys will usually need. My Mit gauge blocks have always measured 100% to the limits of what my mikes can repeat to, but a time or two the cheap set has shown some small differences. If the work needs a real accurate measurement I think I'd make sure and measure the stack as a double sanity check. I now no longer blindly trust any shop equipment unless I check it myself as well as my equipment will allow.
Very good video and an excellent well explained demonstration. A consistent and a very gentle but educated feel is required even more so when getting down to those accuracy levels for those who haven't done this before is about all I could add.
Nice input in your comment, those cheap certificates, yap photocopier is a great invention... lol
For a machinist, the word should be: measure twice machine once.....
Double checking is always the first thing to do, mostly with closer tolerance parts, even the method of getting there parts machined is as important as the result, even the slightest heat change is working against you in the process, you need to let the part stabilize before any final cuts...
Most hobbyist will be more than satisfied with less expensive tools and metrology units, since money is a major object in their search to fill a tool chest... ;)
Thanks for comment, Pierre
The guys at the calibration lab I visited told me that the blocks which are used when calibrating a 1um accuracy micrometer are accurate to 10th of a micron. And the blocks are calibrated with equipment that is good to 10 nanometers. That's sub millionth of an inch. I don't recall which grade the blocks were, but the 10 nanometers was the most accurate measurements they could do at the lab. The 10 nanometer device was compared to the national standard when it's getting calibrated.
Neat trick measuring.
Hi Mike, glad you enjoyed and thanks for comment, Pierre
Hi Pierre, I'm thinking of measuring bores by setting calipers with nib jaws for ID measuring by feel and locking the screw and then measure between the nib jaws with a micrometer. Any thoughts? I'm sure it would get more reliable reading than telescoping gages, at least. My goal is to be able to measure well within a hundredth of a millimeter.
I might actually ditch that idea or try it later, since yesterday I scored a 0,0002mm (8 millionths of an inch) resolution micrometer head for cheap, I'm going to make it into a very accurate tube wall thickness micrometer and subtract the wall thickness x2 from the OD which I can measure accurately enough. The caliper method could be used when the wall thickness is over 25mm or there would be runout in the OD (still doable if measuring from 180° apart 2 times) then but that's rare for what I've seen. I am a hobby guy and a cheapskate if it wasn't obvious by the way. But the lathe is super precise and so should be the measurements
Hi Pierre, just a thought if you measure the outside diameter marking the two contact points of the micrometer, take a measurement of the wall thickness on the two marked places using a known pin size on the inside, deduct to two wall thicknesses from overhaul measurement and there's the answer, good videos keep up the good work.
Hi Tony, when measuring there is a principle that the best results are the most direct reading and operations possible, also transposing measures will introduce some degree of error each time, but, this always depends on the circumstances and also what is available at the location at the time the job is done.
Your method is ok for times where the outside is a mostly regular diameter, in other times if it's a single bore in the middle of a plate it gets a little more complicated...
Thanks for the input and comment, Pierre
Great innovative video. Could you also take the two end mill stubs, using small clamps to affix them to the inside of ring, then use your mic, or even caliper, to measure outside to outside of stubs.
The problem with this is you can't control the position of the two pins. They have to be exactly on a opposite ends of a diameter. With Pierre's nice gauge block method (or with a telescope gauge or an inside mic) you can feel when you are on diameter because you can no longer wiggle from side to side.
It's exact about finding the widest part of the inner circle, the accuracy resides in the precision of that measure, it would be possible to make an expanding device that could hold the pins in the bore and take the measure just like mentioned by Morris, interesting idea also, that would be another possible method... ;)
Nice demo Pierre! The tenth variation between the gauge blocks and mic may have been due to temperature since you were handling the blocks more.
Hi Jeffrey,
Or it's possible that a slight calibration error from the micrometer, the chances of affecting the blocks with the little handling they got are close to nothing, or it can also be a handling error during the measure, be aware the tenth are pretty hard to chase....
Thanks for input and comment, Pierre
Indeed! The variables are incredible.
I would have liked to see how close the telescopic snap guage would have been, compared to the Gage blocks. most home machinists have those for bore measuring.
Hi Marcel,
Didn't measure with the telescopic gauges, I'll try to find the rings and see if there is something I can do about it, shouldn't be very far, the gauge blocks is surely the best, though... ;)
Pierre
Pierre's Garage In the video, you were talking about the most direct is the best, which I agree. Working on the lathe, with the part inside the Chuck, we don't want to pull the part out to check the measurement because then you have to re-indicate it. I have a dial bore Gage, inside mic, and telescopic snap gauges. Out of all of them, I prefer the telescopic snap gage. There is a technique to using them though. Abom79 has a great video on using them. The snap gauges will automatically find the largest dimension in a bore provided they are used the way abom shows. I don't particularly like the inside mic because it is truly difficult to find that largest dimension inside a bore. I never compared a snap gage to the gage block method that you used. It would be interesting to know how close it actually is to the Gage block method. Probably a whole new subject for a video!
Great tip, now I just need some jo blocks and a surface plate. :-) That being said there would be a lot of "feel" required to get the right measurement as it would be pretty easy to distort that bore a tenth putting the blocks in. I am sure with just a bit of a firm grip i could distort it that much. When you start working tenths it is a tricky world.
Hi Brian, you'll need to lighten up on the fitting the finishing blocks or all you'll do are ovals, large and small... lol
Just like you say tenths are the undergroundd of machining, normally tolerances in the 5" fits are not that close, and, the bigger we go the more slack they get... So, it only gets to be another kinda challenge...
Cheers, Pierre
Pierre's Garage
Sometime I need to show just how easy it is to mess measurements up on large items. It is fun to put a snap gage in the bore of an engine block and then squeeze the block by hand and watch the gage fall out. All to often when doing critical work the holding and clamping is more important to the finished piece than the machining.
Over clamping is sometimes not any better than under clamping... Just different issues... lol
But how did the other gauge methods compare? The spring load and the inside micrometer? Just a thought, what about temperature, if you measure tenths doesn't it show, match temperature to what you want to insert..
To address your question, this method is for the lowest possible investment, the most precise so far...
The telescopic gauge is kinda better when I deal with smaller bores, not always as reliable and doesn't repeat as well as this, as for the inside micrometer it does better than the telescopic, quite good as a matter of fact.
As temperature is concerned, when it comes time to measure I got to make sure that all the instruments and the samples have been at the same temperature for a while to avoid the effect of different temperature effects.
Those effects will be much more noticeable if you measure different materials that react very different to temperature changes as you measure far from the standard lab temp i.e. 20 degC Example aluminum and steel,
that day the temp in the shop was about 72 F (22 C) not to worry about...
Thanks for comment, Pierre
In this example, what were the results with the other methods, 5, 10 ths or more. I know feel is unique, just trying to see if my snap gauge is adequate, meaning worth my time to be proficient with or I am off by several thousandths from the get go.
*****
Telescopic gauge can go off by sometimes near a thousand of an inch at this range, like you say touch is everything...
Someone not used to it could be catastrophic...
Inside micrometer is closer, but there touch is important...
Using gage blocks for direct measurement in the open shop is almost an art form because of the many variables you have to juggle. In this example you can see the wiggling, tweaking etc necessary to insinuate the final block. All this time your hands are warming the block stack an unaccountable amount. Simplify the ID as 5" exact. The coefficient for linear expansion for steel is 6.5E-6 (0.0000065") per inch per degree F over a wide range of low alloy steels. If, by handling, the gage block stack warms 10 degrees F then 5 x 10 x 6.5E-6 = . 0.000325" error but this figure is far from certain because of unequal heating and unavoidable contact with the ring. It may be more or less.
Direct measurements like this must be allowed time to reach thermal equilibrium and then checked for quality of fit before final size determination. Another complication is raised when the shop environment temperature departs from the international standard of 20 degrees C (68 F). In steel work pieces and steel gage blocks departure from environment temperature is of no importance because work and stack expand at the same rate. If the blocks are steel and the work bronze or aluminum (or some other alloy or material) shop temperature poses another complication - surmountable by use of a simple pocket thermometer and some shop math. This way raw direct measurements may be compensated to 68 degree F.
Direct measurements to five significant digits using gage blocks are incredibly time consuming, fiddly, and fraught with sources of error. Such readings are greatly simplified by use of dial indicating transfer gages; in this case bore gages. Handling the gaging end is unnecessasy once the gage is set up and calibrated from a gage block stack so comparative readings are quick and easy to read. Any departure from the setting is displayed right there on the dial. A cheap set of import dial bore gages is not too expensive (you can eat some other time) and once bought last a lifetime of intermittant use. My Mitutoyo set is over 50 years old and the gaging surfaces are the only places showing wear. Since the tool is adjustable, gaging surface wear is moot.
Gage blocks may not be needed in most home shops for part measurement. That decision is driven by your customary class of work and the need for fits with components made by others. Bearing races are only one example. Outer races are typically fitted 0.0005" to 0.0010 loose and the bores, if shouldered, are shallow. Measureing these bores efficiently on a one-sey two-sey scale is a toss-up between telescope gages and dial bore gages. If I had a hundred parts to check, I'd set up the bore gage. If three, the telescpe gage every time. YMMV.
The main application for gage blocks in my shop is as a transfer reference. If I need to turn a bearing fit on a shaft, a gage block stack is handy to reference my mike to. Once when I was flush with cash, I splurged for a cheap set of Metric blocks. Since ball bearings have mostly Metrc dimensions, I need only select the 35 mm block, for example, instead of assembling half dozen into a stack.
And of course (until lately) annual inspection and calibration of my micrpmeters and other measuring equipment.
You got all of this absolutely right, in my videos, I'm addressing the hobby up to smaller shops, not the high tech or aerospace labs, just like you said, there are many more variable to include in the measurements.
Depending on the tools available at the moment some machinist will have one or more creative solution to get the part out the door with "Required" accuracy. Most of those situations will require at most a few tenths of a thousand precision, this is achievable with quite some care taken and some minimal feel and experience, this takes time and lots of practice.
You sound like some person that works in high accuracy parts making/controlling. Not easy to a beginner to understand all those parameters involved in the making of really accurate measurements, even further parameters in the behaviour of those same parts in the actual operation like when a bearing starts to get to operating temperature, etc...
Thanks for your comment, it adds to the discussion, Pierre
Hi Pierre, I couldn't figure out how to just send you a message so figured I'd just do it here. Thanks for telling me how to cancel that thumbs down I'd put on Joe Piecznski's post. You kids know how do do all that kind of stuff ,lol.
Hello Dale, Joe doesn't deserve thumbs down, you probably need glasses to call me a kid, but, youth is a great feeling.... lol
Thanks for comment, Pierre
Very useful video Pierre.
What's a tenth between friends! :-)
Uhmmmm....!!! VERY close....???
ATB, Pierre
I found you can't measure roundness with a standard (2-point) gage, like a standard micrometer, etc.
I came across some Asian boring bits for boring heads that measured 0.4984 diameter, precisely, all the way around. They wouldn't fit the holes in my Erickson 50 boring head, which were 0.5030 to 0.5050 diameter.
I discovered they were 3-lobed and would measure the same no matter where the readings were taken with a micrometer. I put them into a 90 deg V-block and remeasured with an indicator on the top while rotating the shanks in the vee. I got a deviation of about 0.004 to 0.006 thou. These were probably ground on a centerless grinder that was not set up properly and were so out of round as to be useless. You need three simultaneous points or a zero run-out rotating fixture (like the air bearing in a roundness testing machine) to measure roundness.
Be careful what you assume to be a valid method.
Now show me how to do that while it's still in the lathe! ;) But seriously, Good stuff!
Hi Matthew, easiest way to make the apparel stay stable and make the measure easy, is to get the lathe standing up on it's end.... lol
It can be installed or measured while in the lathe, but, I agree it would be a little more awkward, this method is for really precise measures, something we don't do every job in most cases, even in the best conditions, it takes more care and time to perform than more common methods.
Thanks for comment, Pierre
Hi mate, I reckon if you need a more accurate reading than that you are not in a home shop. Well done.
This is already better than lots of pro shops... Many of them don't even get that close... ;)
Don't tell uncle Don that, he might have something to say about that ( o;
Like Keith Fenner would say "Just saying"... ;)
best way to measure an id ,, on the machine? don't like taking the part out each time
It will be a little more awkward to perform this in the machine, but, with some fancy handling you could do it, this is really to the last step of machining the part, also very important to make certain that the part has time to normalize in temp and stresses before taking real precise measures... At that stage, you're chasing tenth.... ;)
Thanks for comment, Pierre
I figured you out. The left side of the brain controls the right side of the body and the right side of the brain controls the left side of the body. I see you writing left handed. You are in your
right mind.
If everything is "Left" all "right" it should work no problems..... Or, maybe I got it all wrong and turn this all around...??? lol
Thanks for viewing and for comment, Pierre
Where to get super accurate gauge pins? Then measure w calapers and rule out subtle errors, look for an integer that would make since with the make, whether its metric or standard. ? Dont tou habe to suspent the pins from touching the wood base, to avoid cosine error, thwy look like they were cut of with an angle grinder.😑
In order to get "Very accurate gauge2 pins, you would need to spend a fortune, another way to go around the problem is to have your set calibrated, then, you have the individual measurements on the certification paper. There is no way to get something very accurate with a caliper since the tolerance of a good quality caliper is about +/- 0.001 thousand or 0.025mm.
Hope this addresses your concerns, thanks for viewing and for your comment, Pierre
Cringing at you jamming and scraping those precision blocks against a carbide tangential contact! You lose precision each time a block is abused.
The purpose of the plastic label on the Mitutoyo 5-inch micrometer is for you to hold it in hand there. This isolates body heat from distorting the measurement, which can easily be tenths.
Your practice reminds me of Connely's _Machine Tool Reconditioning_, which deals with generation of precision gages and surfaces without a more-precise tool. One example is precision dividing of a circle using a circular stack of equal pins. It's more feasible to generate multiple pins of mutually equal diameter than it is to fit a predicate diameter. Or how the tool and die trade managed tenths precision in rectangular positions with nothing more than a lathe and dial gage.
Hi Richard,
You're quite right about the plastic plates, I've got some micrometer stands that I should always use, bad habits and wanting to expedite the work are not the best practice... ;)
Thanks for sharing your experience, Pierre
That takes a lot of time
Making real precise measurements without the perfect set-up requires to be creative...
It's easy to get quick and efficient with all laboratory tools, but, those are very $$$$, rarely accessible to ameteurs or hobbyist, this method, even if it requires more time will give you good and very results with minimal cost.
Thanks for viewing and for comment, Pierre
@@pierresgarage2687 thanks for replying I appreciate it you definitely right we always seeking accuracy besides minimum time to done the job some times the time is$$$$$.thanks again