An interesting method of calibration:groucho:
Calibrating Vernier Calipers
Calibrating Vernier Calipers
Calibrating Vernier Calipers
- Thread starter claymont
- Start date
Yet another three minutes of my life that I’ll never get back …. THANKS!
What he destroyed was actually a Dial Caliper not a true Vernier caliper. A Vernier caliper has only one moving part and can be accurate if used correctly they are normally used for larger size calipers like a 24"-48".
In a recent class about machine shop measuring instruments I asked the instructor who is also the director of the school what level of precision he would attribute to a dial caliper and he said without hesitation .015 would be about the limit he would put on it. Now I understand some people will not agree with that number but remember that dial calipers get dropped and knocked off benches all the time. They are also very dependent on the amount of pressure the user puts on them.
A couple years ago my trust Mitutoyo calipers were giving me trouble and sure enough the jaws where sprung. I use Mitutoyo digital calipers for general work but for everything else I use a Mitutoyo digital Micrometer as I just don't trust a caliper anymore. I also have a 0-6" set of Mitutoyo vernier micrometer set not much use for cue making but nice to have for machine shop use and when I want to make parts for machines and fixtures. I would also recommend a cheap set of gage blocks and gage pins (I don't have a complete set of pins but its on the list).
Most of the import measuring tools are simply JUNK. You also have to watch as some of the more trusted names as they have started to have parts and tools made in China and even the old stand by Starrett and Brown & Sharpe have started to offer a line of import made tools.
Here is a link to some great reviews of metrology tools and has some great info on their quality and origin.
http://www.longislandindicator.com/index.html
In a recent class about machine shop measuring instruments I asked the instructor who is also the director of the school what level of precision he would attribute to a dial caliper and he said without hesitation .015 would be about the limit he would put on it. Now I understand some people will not agree with that number but remember that dial calipers get dropped and knocked off benches all the time. They are also very dependent on the amount of pressure the user puts on them.
A couple years ago my trust Mitutoyo calipers were giving me trouble and sure enough the jaws where sprung. I use Mitutoyo digital calipers for general work but for everything else I use a Mitutoyo digital Micrometer as I just don't trust a caliper anymore. I also have a 0-6" set of Mitutoyo vernier micrometer set not much use for cue making but nice to have for machine shop use and when I want to make parts for machines and fixtures. I would also recommend a cheap set of gage blocks and gage pins (I don't have a complete set of pins but its on the list).
Most of the import measuring tools are simply JUNK. You also have to watch as some of the more trusted names as they have started to have parts and tools made in China and even the old stand by Starrett and Brown & Sharpe have started to offer a line of import made tools.
Here is a link to some great reviews of metrology tools and has some great info on their quality and origin.
http://www.longislandindicator.com/index.html
cheap calipers
I agree with this and I have several of these too, but the one by iGaging is of even better quality with a proper Old Guy display with big numbers. Also, it's VERY smooth. It's more money but still dirt cheap.
Robin Snyder
I agree with this and I have several of these too, but the one by iGaging is of even better quality with a proper Old Guy display with big numbers. Also, it's VERY smooth. It's more money but still dirt cheap.
Robin Snyder
Hey.... that's the first I heard of that brand. I like the big display.... I will try a set of them.
Kim
Just because a caliper is zeroed with the jaws closed doesn't mean that it will measure accurately across its range it would have to be checked with gage blocks. I use digital calipers in the shop to but when it comes time to do something that needs accuracy the mics have to come out.
I only used calipers for years but after starting school and seeing what is needed to make precision parts I have limited their use in my shop.
Most large machine shops don't even allow machinist to bring in their own measuring tool because of the QC states that all measuring instrument must have a certification sticker on it and be calibrated at regular intervals.
Now before everyone goes off about how its only wood and only a pool cue let me say that when people want to know why certain cuemakers cues sell for many times what the average cue goes for (think top 50 cuemakers in the world) it's small things like this that make the difference.
I only used calipers for years but after starting school and seeing what is needed to make precision parts I have limited their use in my shop.
Most large machine shops don't even allow machinist to bring in their own measuring tool because of the QC states that all measuring instrument must have a certification sticker on it and be calibrated at regular intervals.
Now before everyone goes off about how its only wood and only a pool cue let me say that when people want to know why certain cuemakers cues sell for many times what the average cue goes for (think top 50 cuemakers in the world) it's small things like this that make the difference.
For precision, a mike is the only way to go. My 50 year old Starrett 1" mike (the nice one with the carbide tips and friction thimble) has never needed to be zeroed, and it reads in tenths. I think I paid about $35 plus a few extra for the case when it was new..
I only own one gage block, a 1", and my cheap-ass digital caliper which like most measures in thousandths, measures it as 1".
Robin Snyder
I only own one gage block, a 1", and my cheap-ass digital caliper which like most measures in thousandths, measures it as 1".
Robin Snyder
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Hi,
Mics are truly the most accurate of the two choices.
I have 5 20.00 digital calipers in my shop and use them for various tasks before landing at final dimensions. I test my calipers with my .850 carbide sanding mandrel and they are right on. When they are not, I toss them in the garbage.
When I do an A joint or other boring operations I have "go" gauges that I use with precision reamers to tune in my fit.
JMO,
Rick
Mics are truly the most accurate of the two choices.
I have 5 20.00 digital calipers in my shop and use them for various tasks before landing at final dimensions. I test my calipers with my .850 carbide sanding mandrel and they are right on. When they are not, I toss them in the garbage.
When I do an A joint or other boring operations I have "go" gauges that I use with precision reamers to tune in my fit.
JMO,
Rick
I wish I had taken notice of your advice. You were spot on.