Stainless steel Digital Caliper $15 at Harbor Freight

[PedroDaGr8]

Was at HF for their v sidewalk sale. Came across this digital caliper. It's had an all metal body (stainless steel). It's no pro unit but it has 0.01mm/0.0005" resolution (+/-0.02mm/0.001" accuracy). 

You may wonder why the dimensions for the resistor body is so strange. Here is why:



Here it is measuring a lead on the resistor:


I have had the cheap HF all plastic digital caliper for years. It annoyed me greatly, it would slip, the plastic was annoyingly not flat between the jaws, etc This one does not appear to have these problems. I have no means to measure precise dimensions. It also comes with a foam lined storage case and a spare battery.

One thing I noticed it appears to have some sort of data port on the side:




I have no clue what that is for.

Now like I said before this is not a professional unit but at $15 still seems like a good deal. I have priced similar units on DX and units like this one tend to run around $22-30. It would be interesting to see if someone capable of evaluating the accuracy could weigh in. Also would be interesting to find out what the data port does.

 Link:
http://www.harborfreight.com/6-digital-caliper-with-metric-and-sae-fractional-readings-68304.html

The price is $20, use the attached 25% of coupon to get the price knocked down to $15. My cashier only asked for the number below the barcode.

   

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[PA0PBZ]

If it is a bit like mine (they look identical) don't forget to take out the battery when not in use for some time, they are a bit power hungry even when switched off. The port is RS232, and if I remember well it spits out the measurements in 9600,n,8,1.

[Bored@Work]

One thing I noticed it appears to have some sort of data port on the side:

These ports have been extensively hacked and reverse engineered. There are a few different protocols, details should be all over the Internet.

[saturation]

Thanks for the find.  Those calipers look very similar to many sold on eBay for about the same price, free shipping.  But at HF, you needn't wait and you can return it should it snafu.

http://www.ebay.com/itm/6-Inch-Stainless-Steel-Electronic-LCD-Digital-Vernier-Caliper-Micrometer-150mm-/380777357464?pt=LH_DefaultDomain_0&hash=item58a8196098

They are so cheap, its often the same price as an analog vernier scale caliper made by others.

Pros
They are accurate to their rated digits
Can be zeroed with each use to compensate for caliper deformation
good linearity
Low cost
good construction

Cons
The electronics can die without warning
The soft switch is not electrically off; if you don't use it for x period, it will kill the battery.
More fragile than a pure mechanical caliper, don't drop it from too high a height.


To do a DIY check of accuracy, measure US coins.  They have very precise dimensions down to 0.01mm, they have also very precise weights for testing scales.  New coins better than used, as used many have wear and tear on its dimensions.

http://www.usmint.gov/about_the_mint/index.cfm?action=Coin_specifications

For other countries, you can check with your national mints.

[deth502]

if youre on their mailing list, youve got a coupon for $11.99, limit 7

One thing I noticed it appears to have some sort of data port on the side:

These ports have been extensively hacked and reverse engineered. There are a few different protocols, details should be all over the Internet.

well, that would save me a lot of time. i was thinking of hacking that port, figuring there HAD to be a measurement output there, and hopefully a power in to eliminate the battery, to turn them into dirt cheap dro's for my lathe. 6" would be plenty for 3 out of the 4 axises in need, with the thought of making a "floating" one for the bed travel, and having them all be powered by and read on a single large display.

[PedroDaGr8]

Thanks for the find.  Those calipers look very similar to many sold on eBay for about the same price, free shipping.  But at HF, you needn't wait and you can return it should it snafu.

http://www.ebay.com/itm/6-Inch-Stainless-Steel-Electronic-LCD-Digital-Vernier-Caliper-Micrometer-150mm-/380777357464?pt=LH_DefaultDomain_0&hash=item58a8196098

They are so cheap, its often the same price as an analog vernier scale caliper made by others.

Pros
They are accurate to their rated digits
Can be zeroed with each use to compensate for caliper deformation
good linearity
Low cost
good construction

Cons
The electronics can die without warning
The soft switch is not electrically off; if you don't use it for x period, it will kill the battery.
More fragile than a pure mechanical caliper, don't drop it from too high a height.


To do a DIY check of accuracy, measure US coins.  They have very precise dimensions down to 0.01mm, they have also very precise weights for testing scales.  New coins better than used, as used many have wear and tear on its dimensions.

http://www.usmint.gov/about_the_mint/index.cfm?action=Coin_specifications


For other countries, you can check with your national mints.

That's a badass tip, the mass in particular is useful as I've seem a few people ask about mass standards. Anyways, the only new coins I had were pennies. I tested five and they pretty much all matched the reported values exactly. One was off by 0.01mm on the diameter. So this this seems quite good for the money.


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[tjb1]

I've had a few Harbor Freight digital calipers but have since upgraded all to Mitutoyo.  The 12" I got was absolutely terrible...battery always dead, temperature change of over 10F and it went on the fritz, move the head too fast and suddenly you are reading negative or are now out at 300". 

I don't really like how they made the trailing digits real small on the one you got, makes it difficult to read at a quick glance and that .0005 resolution is completely worthless on this level of caliper and really on any of them and just makes it even harder to read the display.  If you're not working with precise stuff, I'm sure it will work out fine for you.  Just don't move the head too fast when taking measurements.

Just an FYI, you can usually pick up a dial Mitutoyo for around $80 I believe from Enco if you watch for sales.

[krivx]

If you don't mind used you can get a Mitutoyo for much less on eBay, I think I paid something like $30 from a machine shop that was closing.

[saturation]

Not too many makers of fine calipers left, Mitutoyo is one of the best there is, as well as Starrett. 

But before one spends more than $20 on a caliper, what is your intended purpose?  How much accuracy or precision do you need?  How durable does it have to be?  I think if you are a machinist of any sort, you already own one of the better brands or your work won't be up to par, and you'll own what you need, not what is cheap.

http://www.amazon.com/Vernier-Calipers-48-0-001-Grad/dp/B0078S07N2

But for us folks predominantly working in electronics and using mechanisms mostly for packaging and instrumentation layout on an infrequent basis, if you had to own only one caliper at any grade of quality, accuracy and precision, you really can't go wrong with a non-battery operated vernier caliper, as the vernier is rugged, proven by centuries of use and will work as designed for your lifetime, and probably your heirs too.

http://en.wikipedia.org/wiki/Calipers#Comparison

As described above, the pros and cons of each design.

The only reason I own a digital is because it was so cheap, I could experiment with it, but I wouldn't trust it as my only caliper because it has too many failure points.  When in doubt, I check its measurements against my venier, but at least the digital scale keeps me from making errors from eyeball fatigue looking at the vernier  .  However, 90% of the time, I use the vernier as I don't use it to measure that often; getting used to the vernier is a skill worth having anyone can do as the calipers are cheap.

You're welcome Pedro, also in a pinch, if you need less precise weighs to check a scale, weigh measured water.  Recall 1ml ~ 1 mg, 1 L ~ 1kg etc.,

http://www.engineeringtoolbox.com/water-density-specific-weight-d_595.html

[Frost]

Not too many makers of fine calipers left, Mitutoyo is one of the best there is, as well as Starrett. 

Mahr and Tesa not to forget.

[jolshefsky]

I had one of those and rewired it with an AAA battery dangling off when the batteries kept dying. It worked great for a while but then I started noticing flaky readings. The trouble is, how long before I noticed were the readings inaccurate? Now I have another piece of Chinese shit to throw out. In the U.S., we pay to send shipping containers full of electronic waste to China so their kids get cancer, but they turn around send it right back and make us pay for it.   

I picked up a used mechanical Vernier caliper and it has yet to give me bizarre readings. The original battery is still good too. 

[TorqueRanger]

Not to be mean but you guys got ripped off ... You can pick them up for $9 on sale and they work pretty good ..

[deth502]

I had one of those and rewired it with an AAA battery dangling off when the batteries kept dying.

lol, i have one at work with an AA battery rubber-banded to it.

and afa the vernier caliper argument, i hate them. but  i also hate the digital ones. all but one of mine are dial calipers. only reason i have the one digital is because of the easy switch between sae/metric/fractional, and i rarely use it.

[mrflibble]

One thing I noticed it appears to have some sort of data port on the side:

These ports have been extensively hacked and reverse engineered. There are a few different protocols, details should be all over the Internet.

Indeed. 2 transistors + 2 resistors and an msp430 (or whatever's your poison) and you're good to go. See for example: http://43oh.com/2010/12/interfacing-ti-launchpad-to-digital-caliper/

I vaguely recall I used that one as inspiration. There's also mention of a fast mode, but I've never been able to get that to work. The best "fast mode" I got is to use a supply voltage higher than that of an almost empty battery.

And $15 is a bit overpriced. I got mine for ~ $9, but they go for even less than that on ebay these days.

[danielhans]

You're welcome Pedro, also in a pinch, if you need less precise weighs to check a scale, weigh measured water.  Recall 1ml ~ 1 mg, 1 L ~ 1kg etc.,

http://www.engineeringtoolbox.com/water-density-specific-weight-d_595.html

Yeah, that's true, if you are interested in density of water you can also look and read about it here https://amazingconverter.com/density-converter/density-of-water-lb-ft3