ฝัง
- เผยแพร่เมื่อ 25 ส.ค. 2024
- Various research and testing of low cost Chinese gage blocks or jo-blocks against their certificate of calibration and traceability using a comparator stand with both a Fowler .001 dial indicator and a precision .00005 digital indicator.
![ถามตรงๆ กับ อาจตุพร ทำไม ประเทศไทย ใครเป็นนายก ก็โดนด่า พอออกเเล้วคนคิดถึง!!?? l [Nickynachat]](http://i.ytimg.com/vi/3YFLMXxBGAs/mqdefault.jpg)
Very analysis of the block. I just use a Grade B set myself. They only time I try to work in tenth's is if I am surface grinding.
Non of my machines except my grinder can Work in the tenths zone. So I only use the blocks for comparison and angle setups. I can measure in the micron range and have compared my blocks to one another and against the certificate. I found the certificate to be close, but temps and dirt is always an issue and my shop is far from a controlled environment.
Enjoy the video.
It looks like I bought the same set. 81 pcs Economy from Shars a little while back.
When I got them, I mic-ed them all up & every one appeared to be right to the tenth of a thousandth of an inch.
The box was coming apart at one spot when they were first delivered. A little wood glue
& a clamp fixed it good. I was happy. They're as accurate as I need to be.
Hi
I have been watching you for a couple of months now and you're pretty good for someone who is self trained.
You seem to have a bee in your bonnet about 10th of 1000. Factories that produce work to this standard is heated to 68 degrees Fahrenheit or 20 degrees Celsius and everything is kept at this temperature.
One of the things a tradesman learnts is specifications, and most machinist only work two 2 thousands of an inch, probably 95% of the time, going smaller than this means higher cost and everybody tries to keep costs down.
Class B is more than adequate for your work and mine, working to size exactly, doesn't mean that it is better.
Tolerances should be the first decision on a new Project. Being too tight is probably one of the biggest faults for a amateur.
Keep up the videos I enjoy watching them and don't get too uptight on size, enjoy yourself, I do.
It depends on what tolerances you hold on parts. If you have .0005 or less tolerance, you would want Blocks that measure within half a tenth or less I would say. For home use, or more open tolerances at work, these economy Blocks are fine. You don't need Mitutoyo Ceramic Gauge Blocks which are 3k for 81 pieces
I picked up a set of cheap gauge blocks and they all measured way better than any of my instruments could measure. Temperature will cause more error than the blocks might be off by. More than good enough for any home shop.
Also the blocks are lapped finish after grinding. Its likely coming off a totally automated line. One in 10 blocks might hit right on the number and those are the A blocks. The further they drift from the target the lower the price. It's as simple as that. The machine prints off a certificate automatically. The cheap ones likely get a stamped signature. The brand name blocks likely get another inspection before the name goes on there. Very little man power used either way.
Not so much with ceramic gage blocks.
@@rufusleers Ceramic gage blocks would be a waste of money for a home machinist.
40 years in the trade…
The gage blocks sets I’ve used all had inspection certificates with them.
Various grades of blocks will have different levels of accuracy.
The certificate supplied with the set will tell you how much each block deviates from its’ nominal size.
Those numbers you think are “bogus”, are indeed valid. They tell you how much each block deviates from the nominal in units of a millionth of an inch.
So, if a particular block has the number 24 assigned to it, it means that the block is 24 millionths (larger or smaller) than the nominal size of the block.
A good shop grade of blocks need not be any more accurate than “plus or minus” 50 millionths of an inch.
Grade A inspection blocks will have typical tolerance of +.000004/-.000002 (millionths). They like to supply them on the “fat” side so that when they wear, they wear towards the nominal size.
I can’t imagine a hobby shop machinist ever needing grade A blocks.
Hi Dave, I recently purchased this same set of blocks. Like you, I was confused by the "large" deviation described on the certification sheet. Converting microns to thousands would have one of the blocks as much as 1.4 thousands high (unacceptable even for grade B set) so I got out the micrometer to verify the deviations and found that they are all spot on with their actual size. SO, the certificate is wrong...which is nice!! Good to see another guy who enjoys exploring the limitations of his tools. Keep making videos, Dave!!
There zero on the veneer side of a mic is redundant. It's also the reading on the main scale. The human eye and brain combo is pretty good at quartering up the difference between .101-.102 the veneer helps with splitting it up to the 1/3rds and 1/8ths and finer.
The tolerances of gage blocks are given in microinches. One microinch equals one million of one inch! Even grade B gage blocks are more accurate than any measuring equipment found in the field, the only place that one will find equipment accurate enough to check gage blocks for accuracy is in laboratories.
If it just dawned on you after three years that your micrometer has a vernier scale, I would say you probably are still an apprentice.
No, he would have washed out of an apprentice long before three years.
or a woodworker AYE!
I’m a retired machinist/toolmaker… 40 years in the trade.
It took about 10 years before I felt comfortable calling myself a journeyman.
3 years ?… you barely got your feet wet.
As far as gage blocks go… grade B for in-shop use.
Grade A for inspection ONLY! Grade A blocks should never see the shop floor. They are only used to validate other inspection devices and/or direct validation of the work piece, in a separate clean environment (away from the machines).
Hobby shop machinists should never invest in anything better than grade B, unless you happen to be doing some very precise work.
Hope this helps.
There are a lot of factors in calibration and use of gage blocks. Everything has to be taken into account, and for steel blocks, temperature variation is kinda sorta accepted as 6 millionths of an inch per inch per degree C, standard temperature 20 C or 68 F. Also, any error in the measuring equipment has to be known, as well as the uncertainty of the equipment, in millionths of an inch, I don't know the metric standard, probably microns. Also for calibration, the equipment used should be accurate to one tenth of the gage tolerance. It gets hairy, I retired our of a gage lab. Been a long time, but I think 50% humidity was standard also, could have been a little higher or lower. The anvil pressure of the instrument is controlled, from 16 to 48 oz depending on what's being measured. One of the methods I used to like was monochromatic light and optical flats. Lets you know how far off that supposedly perfect surface was.
Measuring a 10th consistently is very hard with most mics. Temperature of materials and your hand warming the mic change the reading. Also the rigidity of the mic itself comes into play, your clutch or ratchet needs to be properly tensioned to slip at the correct torque to ensure that you arent spreading the anvil from the spindle, as they get used the threads also wear and create slop so its not consistent across its range. The carbide faces last a long time, but the steel wears relatively quickly and need frequent adjusting
In meteorology we took 5 readings tossed high and low and averaged the 3 left
I got the economy set which for me is fine. I machine at home and not as a fine production shop. These serve me perfectly well for what I do. If you're in a situation where you have to QA parts to ultra high tolerance, probably skip the economy set. If your making parts at home where most of your machining is really just thousands of an inch or your learning, these will work fine. Also, if the products you manufacture are only moderate precision by design, these will still be fine and less depressing if you drop or loose one.
It's no big deal but the word "vernier" is pronounced VER - KNEE - ER. No, I'm not an english teacher I just live on the online dictionary's because I either am not sure how to spell a new word someone utters, don't know what the new word means or both. I hear you on the certificates like a computer + printer & anyone can certify anything as legit from Martian pine cones to Hitler's dentures & anything & everything inbetween. Real Journeyman/Experts do not exist as we are continually learning, meaning we are ALL apprentices... just @ different levels in our lifelong apprenticeships. Great video like home machinists is where it's at!
Great video this week , all ways looking for the next one to good information we never stop learning. i know that most home shops don't work in the tens mostly in .001 + or- but .0001 very hard see if you can turn it to a certain .0001 like .2501 sorry not picking on you Dave i know i cant :(
Many times there is a warning in small print in the ads which says the picture is representative only. That means the ads for sets shown at the end of the video may be for different sets after all.
I'm late to the party (it's March 26, 2019) there's some things you should know.
It's common in Asia countries to take a Western name when working as a rep, tech, manager, whatever when in contact with US or European customers. There's good reason for this: many Asian names are difficult for oxidentals to pronounce correctly.
You're entirely correct that import calibration certs are a "trust but verify" document. If tenths accuracy is important to your work you should at least either calibrate your import gage blocks yourself using borrowed equipment or bite the bullet and have them calibrated at a real metrology lab.
When you get into gage block calibration, you discover the process is tightly controlled by specs and standards. Which means it's usually expensive to calibrate an entire 81 PC set - about $300. However, I see a granite base comparator on your bench. Find a gage head and gage amp with one setting graduated to 10 millionths per division, you could spend a evening trying equal length stacks against each other to determine self-consistancy. If you have a good tenths (0.0001") reading dial indicator you can interpolate the graduations and estimate difference between comparative readings to fractions of tenths. You still can't assert with any authority your gage block set is in calibration but you can by process of elimination determine the probable error of most of your blocks and make notes on the calibration sheet.
I have a set each of Shars blocks in Imperial and Metric systems. I spent a couple of after hours calibration sessions comparing my block sets with my employer's sets under bi-annual calibration. I then used the noted deviation on the cert sheet to correct to a presumed absolute value so my new calibration sheets for my cheap Shars blocks could be claimed accurate to single digit millionths if not certifiable under FED SPEC GGG-G-15C and ASME B89.1.9-2002. Should I need a reference length to millionths I can select the appropriate blocks, consult the (home made) cert sheet for the relevant error, work the math and certify in my own mind the length I assembled was corrected to +/- small millionths - in fact closer to assembled length the set grade would certify. If you know the error accurately, you can correct for it.
Mitutoyo's "Gauge Blocks Catalog" E12014 has a world of gage block information. It's free on the internet in PDF format from Mitutoyo's website. There is also a NIST publication: "The Gage Block Handbook" as a PDF.
Ours is a very technical trade. Large parts of it deal with critical systems of aircraft, nuclear power, military materiel, precision manufacture, foreign trade, etc. Accordingly, our trade is hedged about with specs, standards, and restrictions. "Machinery's Handbook," the bible of our trade is pretty much a compendium of the most commonly used machine shop standards connected by narrative. It doesn't end there. If you've been in the trade for a while your handbook collects slips of paper, items torn from catalog tables, margin notes, etc. Every good small shop has a library of handy references.
A dial test indicator is not really suited for data collection. Because of the variable angle of the contact tip lever to the plane of reference, the indicated reading is subject to "cosine error." Look it up. Also look up "dither" in connection to mechanical metrology and "stiction."
Another point is close tolerance measurement is affected by temperature. All mechanical measurement is referenced to 68 degrees F (20C). A micrometer measurement in the 3" range can be in error by 0.0005" merely from handling the mike frame with warm hands. Related is the differences in thermal expansion in metals. A warm aluminum part may contract to out-of-tolerance/undersize when at room temperature.
Appreciate you sharing this, will definitely save me research time in the future as well.
Take Care.
You can sometimes find a "Mahr Supramess" that has 0.00002" or 0.0005mm resolution for $100. used in workable condition. Beyond that you would need a "CEJ Mikrokator" which are hard to find for less than $300 (used in workable condition). A non-working or stuck Mahr might be repairable. while a "CEJ Mikrokator" is most probably not. I own both.
I had a Mahr for a bit and returned it. I don't really have a need for that kind of accuracy. But never heard of a CEJ and will be looking to see what it is. Thanks!
I recently picked up a set of the Shars economy grade blocks, and they will probably be fine for what I will be doing with them. Seeing how much more the higher grades cost, I will be sticking with these for quite a while.
Funny sometime later I did a video saying I never used these blocks the set I do use most are square gage blocks for a lot of different things. Be interesting to know if you use them...
@@TheMiniMachineShop I used them to line up drawer slides for my kitchen cabinet. I spot checked a few blocks with a micrometer, and were basically spot on.
@@JasonTHutchinson Hi Jason, basically spot on? The average shop doesn't have the equipment to measure the error in a grade B set. But what you can do, if interested, is create a 1" stack from many smaller blocks then you can see the accumulated error in the stack maybe .0001 at most. But each block has to be super clean.
@@TheMiniMachineShop My Starrett micrometer is only accurate to a tenth. I currently do not have anything in my shop that is more accurate than that. I will try making a 1" stack.
Love my set of cheep blocks. I use them for spacers and set up blocks. Got a good set but I seldom use them.
I mainly use them to check indicators, calipers, etc...
What are you making that has to be with in .00001? a few degrees in temp could make more than that.
Slip, zero and interference fits.
Gage blocks are NOT finished on a surface grinder. They are “ruff” machined on the surface grinder, and then finish to size by the “lapping” process.
scratches in surface plates and you are concerned about tenths?
sorry if this is harsh but I do appreciate many of your shop tips and enjoy your channel
I am looking to get a set of grade B blocks, +0.25 -0.15 microns definitely doesn't bother me, I don't know what you all are making in the home shop to require such high precision.
This is a shop grade or grade B set. They don't sell anything less accurate.
@@TheMiniMachineShop Yeah, I was just wondering what people here are making, when grade B isn't precise enough.
Lol, it took 3 years to figure out how to read the vernier scale on a tenths mic? Yeah bruh, you're still an "apprentice". Don't take it too hard though lol. I'm not even an apprentice yet. I just turn good metal into scrap metal. So not a jab, just thought that was funny and had to mention it. 🤣🤣 Nice vid btw, I like the sleuthing on the shars "traceability certs". I had a feeling they were bogus and i think you confirmed that pretty well. Cheers!
One old video and I still have yet to use those blocks..
Dave,
Those Shars blocks are more then adequate for any home shop. If you really want to test Jo gauges, you should test them with a comparator that measures to a 1/1000 mm (roughly a quarter of 1/10 000").
You can do this...it really isn't beyond the realm of the home-shop, providing one works clean and you keep your head in the game.
The question is why would you want to (besides for lulz) ?
You will find out that, if you would make such measurements, that even holding a block for a short while (and thus warming it up) will change its size.
And unless you are about to make a precision microwave cavity resonator, for your next doomsday satellite..... this could be called 'overkill'!
Toodles!
Paddy
PS the high and mighty Starrett, praised in to Heavens by everyone has sold out to the Chinese.... There entire 'International line' is made out of the same 'Chineseum' as all the rest of the imports. Prices are slightly lower than the few things they still produce in the US.... but still inflated for Chinese imports.....
It may be the better grade of China-special......it is China-special nonetheless....
China gets a bad reputation because they are willing to make anything to a price point if you are willing to pay for it they can make quality like Iphones and fighter jets etc. The real issue is that the US MBA's and purchasing agents push too hard on price without verification quality. The other issue is that a lot of parts get farmed out to cottage industries.
Lets look at things logically. If it wasn’t for Chinese imports half the guys out there wouldn’t be able to afford to get into the machining hobby. If you want the best there are US, European and Asian brands that are excellent, so let’s not put down the Chinese for providing workable solutions for the rest of us.
I stopped at 17:16.
If you use an indicator to measure the differential thickness of gage blocks, you probably didn't understand very well the correct use of the two tools...
Explain!
@@TheMiniMachineShop Indicator is not a measuring instrument. It is "precise", but not "accurate". What you read on the dial is just a rough indication of deviation from a reference position, not a measure of this deviation. An indicator has to be used for comparing two things of the same height, not to measure the difference in height among different parts. You can use different height gage blocks to check the accuracy of an indicator, not the opposite!
It is not pronounced "veneer" but "vernier"
that would be 'Ver Knee Air'? At least that is how I pronounce em
@@Scallisgaming nope, .... Ver Knee Ear
It's pronounced Vair-Knee-Aye
Actually my Boss in the 70's refered to them as
Very Near. Just a Tool he used for roughing out.
Me mon-ee-aye!
Arrrrg argargarg!
It's "vern-ee-er" not "vern-ear"
test indicators are only accurate reading from a loaded state
I hate to say it but unless you are capable of measuring to microns you are wasting your time bottom line even Chinese gage block errors of 25 to 50 microns which is in B range is well beyond the measuring equipment in your shop. There is a guy on utube who was measuring gage blocks from a China made set compared to a $3000 Starrett-Webster set and could not detect any difference with a Starrett 0.0001 reading indicator and could not detect any measurement difference between the $3K set and the budget asian import set. No home machinist has any need for a higher grade set unless they are doing aerospace work or toolroom gage work for ISO or automotive work witch needs to be traceable. Look at the tolerances on your gages and micrometers and you will see they are far looser than B grade economy gage blocks. Spending a few hundred or even a thousand dollars will not get you any closer. Another couple of issues are temperature and operator factors even quality labs often notice measurement errors between inspectors with the same measuring tools. Any home machinist who can hold plus or minus .001" is doing great without a surface grinder. Only with good grinding equipment or hand lapping are you likely to do better. Even large high tech companies struggle with 1/10,000 and micron level tolerances.
1 micron =.00004 and x 25 is .001 not within B range and not beyond either of my Mitutoyo mics spec'd to .0001.
@@TheMiniMachineShop He probably meant 2.5 to 5 microns or 25 to 50 millionth of an inch? A Generic 25 mm micrometer is specified at around +- 2 microns.
The tenth of a thousandth readout is via a "vernier" scale. This is not pronounced like "veneer" as in hardwood veneer plywood. The emphasis is on the 1st syllable and the word rhymes with the made-up word "burnier". So it's pronounced "Vern" like the name, and "...ier". It reduced your credibility if you don't even know how to pronounce the words. Unfortunately lots of people get this wrong, not sure why since you can just look it up on Google and click to get the proper pronunciation...