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digital calipers giving pain


Horton
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I am sure some machinist is going to shake his head when he reads this….

 

So I own maybe 4 different sets of digital calipers. I have a set of slot calipers, I have a set of Mitutoyo and at least 2 other random calipers. On hot days I often find they all give CRAZY readings. I am getting ready to invest in some old school dial calipers.

 

Does anyone have a clear idea what goes wrong with the digitals on hot days. Is it moisture / grease on my hands getting on the back of the rail?

 

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Incredibly expensive calipers are only as accurate as the conditions they're used in. You do have to remember that metal expands and contracts with temperature. The aluminum fin probably changes the most but I doubt you'd get more than 0.001" or 0.002" difference. The caliper jaws themselves won't move much but all the chips, capacitors, and other fancy electronics built into these things can start going nuts when they're outside of their calibrated temperature zone. Dial calipers use tiny gears and teeth to count revolutions but even those can give bad pretty dimensions in the wrong environment.

 

We use a lot of fancy measuring devices at work but at home I rock the harbor freight calipers. Say what you will but when measured inside my house where I keep my ski's and never more than 5-6 degree swing, I've never been more than 0.0005" off of my starting measurements even after 3-4 weeks of using the ski. If I'm more than 0.001", I'll double check and reset the zero and it'll give me a perfect dimension again.

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@Horton usually it's either moisture or the battery. My slot caliper is very sensitive to moisture and Mitutoyios work well only with SR44 battery. The cheaper LR45 batteries are good for generic or the slot and all work better with the SR44.
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I have problems with my slots in high humidity when we ski in Louisiana, Houston or Florida. I upgraded to Mitutoyo harsh environment calipers a few years ago and haven't had the issue. Try not to use the slots for anything but DFT anymore. Each set of them measures depth differently too it seems so they just confused the issue when communicating with others. I think I got them from Mcmaster Carr. Can possibly get a better deal somewhere else.

 

http://www.mcmaster.com/#digital-calipers/=14g6gy6

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My digital slot goes crazy when the battery starts to fade! Ive been a toolmaker for 40 tears and I hate digital! The only reason for having digital on the slot cal is so you can zero it when you check the dft! If the gosh darn ski companys would just make the tail of the ski square we wouldnt have all the fuss! And you guys that are posting numbers to the half thousandth need to get a life!
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@Horton I would be pretty hesitant to use a digital caliper outside surrounded by water. I think a good ole mechanical is what you want for that application.

 

@bbruzzese @teammalibu Denali has solved the DFT issue. On any Denali starting from the 3.4 (main production run), there is a flat spot that makes it trivial to repeat to 0.001" without any special maneuvers or equipment.

 

Harbor Freight El Cheapo digital calipers are pretty darn good for indoor usage, but don't have the range and handy appendages of a decent mechanical caliper, and both are "required" for measuring a fin.

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Dials are fine if the rack gear is not exposed. Verniers are way too hard for us older guys to read. For those who do not know , a vernier measurement is made by seeing which lines line up on the stationary and moving parts of the calipers. Hence the name " very - near " calipers.
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Agreed....cut your own slot calipers. It's not hard. I took a die grinder and a semi-steady hand to mine. The slot is a little wider than the fin but I tried measuring straight on and at a slight angle and got the same reading. $10 for the calipers and I keep those custom slot calipers zeroed at 1.583". These slip off that zero every few times I use them but if you used the real slot calipers as your primary set, you'd have to zero them every time so not a big deal in my mind.

 

A little ugly but they've been working great for over 3 years.

 

bb9c3c1lcz0f.jpg

 

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@Horton , these are Verniers , they pre - dated the dial calipers. Out of habit , people call dial calipers " Verniers " The top numbers are imperial , bottom is metric. You look to see where the zero of the moving jaw ends up , look at how many lines ( each one is .025 ) it is past the number then try to figure out which line is lining up on the scale of the moving jaw. This measurement is .462 , maybe ? Sure glad they invented dial calipers before I started needing them at work.

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So accuracy wise you have really 3 things going on.

 

Technique - measuring fins is horrible compared to the proper use of calipers - so you get a lot of difference between two people measuring the same thing. So if you and someone else can use the same tool over and over and get the same number you both probably have great technique.

Actual accuracy of the tool.

Ability of you to read the tool.

 

Only the vernier type is a direct reading of the measurement, there is no "mechanism" of converting the position of the caliper into a measurement.

 

A dial caliper however has a long rack gear along the back, a small pinion on the dial mechanism turns along the rack and moves the dial. But you can get additive errors - 0 the dial and measure .743" and not a lot of error - but 0 the dial and run out to 7.5" and you can have increased error. If you needed to get a really accurate 7" you could 0 on a gauge block and read from there.

 

Digital use a circuit board to count ticks as you run the dial out instead of a rack.

All are fine - but if you want something that can be left in a ski bag or truck - the vernier really is the most durable, and often they're heavy duty compared to the dial/electronic versions.

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I swear it is like someone is pulling a prank on me. I am adjusting my ski yesterday and suddenly my digital Mitutoyo is doing strange things so I reach for a cheap pair and they are also acting up. I start getting out fresh batteries but I keep getting strange readings. I have 4 pairs of calipers and none of them inspire confidence. I give up.

 

New Mitutoyo Dial Caliper will be here tomorrow.

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Mitutoyo has the IP66/IP67 Coolant Proof Caliper which incorporates a new length measuring system that provides a protection level. So the calipers can be used even in environments where large amounts of cutting oils are being sprayed from various directions (only vernier calipers could be used before).

• No need to wipe off water and oil from the main scale during use.

• Built-in ABS (absolute) scale means that these calipers are ready to use immediately after power-on. The Mitutoyo Digimatic depth gage series 571 is an option and very easy to use.

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@Horton try opening caliper to full and wiping down the groove with alchohol (this may be foreign to some not consuming it =) ) I have had luck doing this before, cannot give you a reason why but it worked, maybe oils, sweat sunscreen etc??
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@Horton what @Butte-Ski ski says, with an ip66/67 caliper you can measure your fin even with your wet gloves on. The non coolant proof Mitutoyo is better than My slot caliper against moisture but still not proof. When I put my Goode tool bag close to my wet staff even without touching I often have issues with my calipers. Wet fin/finbox/hands will give you pain. I would need reading glasses for dial calipers though.

A microfiber cloth/towel to wipe fin area and keeping calipers dry is my way of non issue measurements. B)

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