Woodpeckers or Bust?

tvrgeek

Scott
User
Inherently, I don't think one can calibrate a digital gauge. It is based on a two phase capacitive strip. It works, or it does not. Initial calibration verifies it works. I think if you had a gauge block, you could verify yourself, but contract requirements may dictate all tools be traceable to NIST standard.

With the exception of Starrett and Mitytoyo, every single caliper user feed back runs about 10% with serious issues. They track to the same issues I have had. One killed batteries. Three erratic readings, one dim and erratic display. I will probably buy a Mitytoyo ( $120 ) but wish it had a fractions function.

I have had a General digital protractor and a WIX angle gauge for several years with no difficulties. My height gauge recently started to act up and my digital calipers are erratic. Fortunately, both when they are off, they are way off.

For woodworking, what would be slick is a dial caliper that read in 128ths. Maybe I need to buckle down and just start working in metric. It is a shame we did not convert back n the 60's when it would not have been so expensive.
 

Gotcha6

Dennis
Corporate Member
I think that I first saw this site here, but they have blemished tools for decent prices (including PEC):

Thanks for the link. I have several cast iron try square heads that need new pins and the prices they have are very reasonable.
 

tarheelz

Dave
Corporate Member
Count me among those who believe the modern mythology of square to sub-fractional decimal is not worth the effort. It's modern conceit of the woodworking hobby.
 

BKHam

Bradley
User
i think trying to get as square as you can is worth the price and some time, especially if you fit drawers (without slides) or work with miters in your work.

i have a starrett 12 inch and 6 inch combo square and love them. that being said, they can get out of square due to the head and the blade being of different hardnesses. Also just general wear and tear. so even they need checking. i think the fixed blade of the woodpeckers maybe a nice reference to have in your shop.

don't be afraid to give yourself some luxury in the shop. you likely worked hard for the money funding this purchase.
 

tvrgeek

Scott
User
Count me among those who believe the modern mythology of square to sub-fractional decimal is not worth the effort. It's modern conceit of the woodworking hobby.
Guess you don't make picture frames. :)

Ordered a Shars 303-1554 caliper. Shars does make a fractional dial caliper. 1/64 resolution. That would be a good WW tool. I wonder if I could attach one to my planer rather than a Wixy?
 

ShortRound84

ShortRound
User
eBay is a great place to find used Mitutoyo calipers. I picked up a used 24" Mitutoyo vernier caliper for less then $100. Came with its original wooden case and calibration certificate from 1962.
 

Mike Davis

Mike
Corporate Member
Count me among those who believe the modern mythology of square to sub-fractional decimal is not worth the effort. It's modern conceit of the woodworking hobby.
This is not possible without perfect machine set up. Only possible with perfect measuring tools.
E4699603-799D-450A-BFAF-765BEEF1F793_1_201_a.jpeg
 

tvrgeek

Scott
User
Then you don't know anything about gauging standards or gauge control!
My metrology was all electronic equipment, but I am thinking about how digital calipers are made. I do not believe there is any adjustment. I guess if you drop them, you could bend the head. If you used them enough, maybe enough wear the head rocked. ( one $12 set yu could feel the rock new) You could test for that by holding it to the light. Other than that, they are what they are. As I mentioned, contract, ISO, and so forth may require verification that is basically meaningless, but verifiable to NIST. It lets Chinese companies advertise " made in an ISO 9000 facility" but of course, that only means if their spec is a mile wide and it is within a mile, then they have maintained process control. The specifications are a bit miss-leading as they do not reference temp. As we know a 6 inch strip of stainless does not stay the same length. No different from a dial or vernier. Maybe it is within the .001" over 6 inches. I would have to look up the specific alloy.

I would be afraid of used Mitutoyo or Starrett from e-bay. They make "old" counterfeits too. I guess a vernier would be safe.
 

Hmerkle

Hank
Corporate Member
My metrology was all electronic equipment, but I am thinking about how digital calipers are made. I do not believe there is any adjustment. I guess if you drop them, you could bend the head. If you used them enough, maybe enough wear the head rocked. ( one $12 set yu could feel the rock new) You could test for that by holding it to the light. Other than that, they are what they are. As I mentioned, contract, ISO, and so forth may require verification that is basically meaningless, but verifiable to NIST. It lets Chinese companies advertise " made in an ISO 9000 facility" but of course, that only means if their spec is a mile wide and it is within a mile, then they have maintained process control. The specifications are a bit miss-leading as they do not reference temp. As we know a 6 inch strip of stainless does not stay the same length. No different from a dial or vernier. Maybe it is within the .001" over 6 inches. I would have to look up the specific alloy.

I would be afraid of used Mitutoyo or Starrett from e-bay. They make "old" counterfeits too. I guess a vernier would be safe.
so when you "Set-up" and verify a digital micrometer or caliper, you have gauge block at varying lengths and you check that the tips measure that accurately. yes, this is a "go or no go" because there is not a lot of "fix" to a digital device, but, there are some electronic "fixes" to set "True zero" (not with just the "Zero / ABS" button and verifying that the "Flats" of the caliper match the "tips" (if you didn't know, only the tips are certified accurate - using the "flats" of a caliper is not per the standard...
a "master gauge tech" CAN pull the head on a caliper and "Adjust it" for an accurate reading over the length of the caliper, but most trash them and buy a new "calibrated" device... as @Mike Davis mentioned most of these devices are double or triple the cost of one you or I would purchase with a COC (certificate of conformance)
 

Rick Mainhart

Rick
Senior User
You might want to look at Taylor Tools (taytools.com) ... they have seconds (blemished) tools at fairly reasonable prices.
 

Tarhead

Mark
Corporate Member
Sorry guys! My acrylic drafting triangles are as good or better than any metal square. If I drop them or run over them there is nothing to worry about. A .001 feeler can't get under them on a certified granite reference plate. One is 24" long.
 

Rushton

Rush
Senior User
Totally agree with the value of architectural drafting triangles. But, my drafting triangles stay carefully wrapped between use. I consider them delicate and to be reserved for drawings/layout and verification of other squares. Their acrylic edges are easily scored or chipped so they simply can't replace my steel combination square blade for knife scribing accurate cutting marks on my wood stock.
 

tvrgeek

Scott
User
so when you "Set-up" and verify a digital micrometer or caliper, you have gauge block at varying lengths and you check that the tips measure that accurately. yes, this is a "go or no go" because there is not a lot of "fix" to a digital device, but, there are some electronic "fixes" to set "True zero" (not with just the "Zero / ABS" button and verifying that the "Flats" of the caliper match the "tips" (if you didn't know, only the tips are certified accurate - using the "flats" of a caliper is not per the standard...
a "master gauge tech" CAN pull the head on a caliper and "Adjust it" for an accurate reading over the length of the caliper, but most trash them and buy a new "calibrated" device... as @Mike Davis mentioned most of these devices are double or triple the cost of one you or I would purchase with a COC (certificate of conformance)
I understand the "tips" but even my cheap ones are darn square when up to the light. As far as accuracy over length, that is defined by the pattern of the etched strip under the scale just as a dial is based on the accuracy of the tooth grind and a vernier based on the accuracy of the etching. Unlike a dial, a digital that is dirty could get a false trigger or skip across the scale as the basic technology is a 2-phase capacitive sense. Any de-lamination will cause a localized error. A dial could drift due to gear wear. All of them can only be accurate at a given temperature. The biggest error is more likely any play in the jaw against the body as the tiniest rock will be amplified at the tip. Basic a reason a mic is more accurate than a caliper. A simple go-no block can identify that. I wonder how many of those high end brands folks claim to use for 50 years daily have worn enough to cause a bit of head rocking? Do they verify every now and again with a gauge block set?

The "zero" button only changes the display in the processor. It does not change the sensor position, so maybe, maybe there could be some adjustment for the first half a thou, but I would need that explained by the design engineer of the technology. The one I tore apart was glued in place. This initial position could be the difference between low end, accuracy of .001" ( but should really be +/- and digit to be an accurate spec) and the mid to high end reading .001" but accuracy .0005.

A possible feature low end are venerable to is as a battery just starts to fall off, epically an alkaline that drops slowly vs a silver or lithium, you might get processing or sensor error smaller than when you notice it getting flakey. My Wixy (CR2023) went from reliable to erratic very quickly so I noticed it, but my cheap calipers with L44 were harder to identify when they got funny. I guess the S44s would be more obvious but they have half the energy of an alkaline.

From the mid-price up, a NIST traceable cert looks like it costs about $60. I don't know what annual verification costs. When I was in industry, we had our own met-lab so the cost was not identified to the project or contract. I would hope that from mid price up, they are verified to a standard at end of line. I doubt the $12 ones are though I could imagine an automated process with optical reading and a little bit of AI could do the job if one were to build millions, Too expensive for thousands. Next time my Fluke battery goes dead, maybe I'll use it as an excuse for a new one as the range switch is wearing out. Come to think about it, one of few electronic devices I have had that works fine for 30 years and on only the second battery. Yea Fluke.

For my uses, consistency and relative difference are the measures that are most important. Not absolute. The one I ordered, due to day, is a CR2023. I buy batteries in 10-packs from Amazon. Had good luck with their brand big packs of AA and AAA too.

Hmmm. My tringles are probably 50 years old and don't have chipped up edges. Good Post ones. Just tossed in my desk drawer. It may depend on the material. Mine I think are Lexan, not plexi. But for setup, as they are clear, not as handy as metal machinist squares as backlight is easier to see.

I found another measurement error last night. I bought a flat tip for my dial indicator to make setting up my jointer knives more accurately. ( but put in a Byrd head anyway). Used it to verify my TS. It is not flat! As I slide across the corner of a tooth , it changed by half a thou. Cheap tool. Back to the conical tip.
 

tarheelz

Dave
Corporate Member
I'm definitely willing to tolerate all my joints being half a thou out. 1/200 of an inch.

Heck, I just try to keep my gaps under 1/32. Any larger than that, and I might have to use too much wood dust (formerly sawdust) to hide them. (I use the term "wood dust" now to signal just how expense the stuff is).

Heck, this is North Carolina. The wood is all gonna move, shrink, etc. anyway. ;)
 

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