So I bought a cheap polycarbonate igaging digital caliper on ebay and... - Page 1
Forum section: electronics / general

author: cdev
author_rank: Super Contributor
timestamp: October 06, 2017, 04:01:10 am
content: it was $14 and it came with two 3v CR2032 lithium batteries -and it appears to use up the batteries when its off.Being plastic I can tell right now the little door over its battery case is not going to last very long with my putting the battery in every time I need to use it and then taking it out afterwards.It also appears to have a little four conductor data port.EDIT: It appears that data can be extracted from it. I probably will be able to power it externally..Photos added below...Thinking out loud: I wonder what I am likely to have that has a "precise" measurement that I can check its calibration with?maybe a CD/DVD? ..I want to see if its measurements of things like that are accurate.It seems quite accurate and repeatable considering. But - verify..I know, I should have gotten the metal one... But $38 is a lot more than $14BTW, this one also has "absolute origin".. (settable to zero in the middle of its range)

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2017, 05:38:09 am
content: iGaging does not make plastic calipers. They also don't make anything for $14.The real iGaging tools are excellent at a very good price. I can highly recomend them.Do you have a link? I'm not finding anything cheaper than $25, and majority of listings start at $38 - the real price basically.I've had the real ones for couple years with moderate use, and they are still on the first battery.

author: ciccio
author_rank: Frequent Contributor
timestamp: October 06, 2017, 02:19:40 pm
content: I've seen some "no Brand" for about 10 Euros, and even less:http://www.ebay.it/itm/like/272848836819?chn=psI bought a similar one years ago for 18 Euros, labeled "Borletti" that was a well known manufacturer of caliper and measurement tools (they made also sewing machines and military things). It is still availble:https://www.amazon.it/BORLETTI-CDJB15-CALIBRO-DIGITALE-150mm/dp/B00FF8KA02Well, it was supplied with a spare battery for a good reason: the battery lasts about 6 months of "no use" in the toolbox..

author: cdev
author_rank: Super Contributor
timestamp: October 06, 2017, 04:08:10 pm
content: Ataradov,I added some photos. Other than being plastic and killing batteries it seems to take "repeatable" measurements, which I understand is a sign of good construction quality.Quote from: ataradov on October 06, 2017, 05:38:09 am

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2017, 04:29:29 pm
content: Quote from: cdev on October 06, 2017, 04:08:10 pmActually no, even $6 (or free with a coupon) Harbor Freight calipers are pretty repeatable, but they will miss steps on quick movements requiring periodic re-zeroing. My iGaging calipers were re-zeroed exactly once.There is a very simple test if they are absolute origin or not - close the jaws, power of the calipers (and remove the battery), move the jaws, insert the battery. The reading should reflect the actual position. So AO calipers hold their zero and measurement even without a battery (which is pure magic, if you ask me).

author: cdev
author_rank: Super Contributor
timestamp: October 06, 2017, 05:47:07 pm
content: Ataradov,Removing the battery resets it to zero.But, here is the thing. The caliper was sold to me as igaging brand, but not as "absolute zero" (although an "abs" is visible in the pic.)The feature works if you leave the battery in.

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2017, 06:01:47 pm
content: Quote from: cdev on October 06, 2017, 05:47:07 pmThis is not iGaging, for sure. And I would say, it is just a more advanced version of typical cheap calipers. Or they are some giveaway promotional goofy item, but even then I would expect the color scheme and branding to match.Here are legit oneshttps://www.amazon.com/iGaging-ABSOLUTE-Digital-Electronic-Caliper/dp/B00INL0BTS/ref=sr_1_2?ie=UTF8&qid=1507312717&sr=8-2

author: cdev
author_rank: Super Contributor
timestamp: October 06, 2017, 07:43:53 pm
content: I think they are just their ultra cheapest model..Just now went looking at igaging.com for sellershttp://igaging.com/page15.htmland found a link to one of their US dealers.. there I found ithttp://www.igagingstore.com/Electronic-Digital-Caliper-0-6-Display-Inch-Metri-p/210250.htmAs i said it seems to be precise- for a plastic caliper..It will do OK for now, I just wish it didn't eat batteries.

author: sleemanj
author_rank: Super Contributor
timestamp: October 06, 2017, 08:19:34 pm
content: That is relative positioning.Absolute - the device knows where it is because that (distance from origin) is physically encoded in the construction (of the bar) by some means.Relative - the device knows where it is because it keeps track of it's movement. Hopefully. Most of the time. The button just means the same as the rel button on a multimeter - this is zero, report your movement relative to here.The relative devices, if they miss a step, they never know and the measurement will drift. That is why they must always be powered, because even with the screen off they have to keep track of movements.The absolute ones do not have steps to miss.

author: sleemanj
author_rank: Super Contributor
timestamp: October 06, 2017, 08:28:20 pm
content: PS: the rel (or whatever the call it on yours, abs) button is for more than just resetting :-) It is especially useful for measuring pitch, hit the button while measuring the width of 1 pin, so that is zero, then measure across the outside faces of 2 adjacent pins, that is the pitch (because your calipers subtracted half of each pin for you). Same with pitch between holes using the inside measurement teeth, measure one hole and call that zero, measure the outside distance between 2 and that's the pitch.