Author Topic: Rubbish Digital Caliper  (Read 4257 times)

Offline simplyloco

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Rubbish Digital Caliper
« on: November 13, 2017, 12:32:08 PM »
I needed to replace my ageing digital caliper as the repeatability was getting iffy. I bought this shiny silver one from Amazon and tried it on a known dimension, i.e. some workshop grade gauge blocks at 1.75". You can see the result in the picture. In addition, the tips are rough, still with burrs on and it feels very cranky! I know it was only £20, but that is twice the price of the one it was intended to replace! BTW it got 64 five star reviews on Amazon: perhaps they aren't as picky as me! I wonder what these people are making...
I'm doing the returns note right now! :Mad:
John

WP_20171113_12_16_41_Pro[1] by inkaboat, on Flickr

https://www.amazon.co.uk/gp/product/B01N7CW7LQ/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Offline Gas_mantle

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Re: Rubbish Digital Caliper
« Reply #1 on: November 13, 2017, 12:52:31 PM »
John,

It looks very similar to the one I have that cost about the same price.

On the one I have I can zero it with the jaws closed take a couple of measurements then when I recheck the reading with the jaws closed it can be out by +/- 0.05 mm. To be fair though it is fine as a cheap instrument for getting a rough measurement to let me know when I'm closing in on the size I want.

Offline AOG

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Re: Rubbish Digital Caliper
« Reply #2 on: November 13, 2017, 12:54:04 PM »
The cheap ones are rubbish in terms of repeatability, durability and battery life. Even the low end Fowlers aren't that good. I would spend the money on a good set of mitutoyo digital calipers and be done with it.

Tony

Offline simplyloco

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Re: Rubbish Digital Caliper
« Reply #3 on: November 13, 2017, 01:14:19 PM »
The cheap ones are rubbish in terms of repeatability, durability and battery life. Even the low end Fowlers aren't that good. I would spend the money on a good set of mitutoyo digital calipers and be done with it.

Tony

Agreed: I'll be going that way.Trouble is, there is an alarming number of 'Mitutoyo' calipers out there of dubious origin!
I'm with G_M in that I confirm all my serious measurements with micrometers.
John

Offline ShopShoe

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Re: Rubbish Digital Caliper
« Reply #4 on: November 13, 2017, 01:29:03 PM »
"BTW it got 64 five star reviews on Amazon"

I believe that there are people who will write positive (or negative, for that matter) reviews for anything for a fee, whether they know anything about the product or not. I tend to only skim through reviews and take them with a grain of salt. Just my opinion.

Offline MMan

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Re: Rubbish Digital Caliper
« Reply #5 on: November 13, 2017, 01:32:07 PM »
It is a risky road to go down but I tend to wait for a compelling discount at MSC and take the plunge. No arguments on whether it is genuine then. The risk is of course that you buy more stuff.

Martin.

Offline simplyloco

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Re: Rubbish Digital Caliper
« Reply #6 on: November 13, 2017, 11:32:02 PM »
It is a risky road to go down but I tend to wait for a compelling discount at MSC and take the plunge. No arguments on whether it is genuine then. The risk is of course that you buy more stuff.

Martin.

Thanks for the link. I found this discontinued SPI caliper reduced from some £57 odd to £18.00!
John
https://www.mscdirect.co.uk/CGI/INSRIT?PMPXNO=103805887&origin=DIRECT:HISTORY_ORDER

Offline cheepo45

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Re: Rubbish Digital Caliper
« Reply #7 on: November 13, 2017, 11:56:45 PM »
I take gauge blocks with me to Harbor Freight and check all the calipers until I find a good one - so far so good!
I do have a set of Mitutoyu's that I use for close dimensions, and micrometers for really close!

Offline Mike R

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Re: Rubbish Digital Caliper
« Reply #8 on: November 14, 2017, 02:59:41 AM »
I noticed that the MSC one looks identical to the ones I can buy locally from the local hardware store chain (Canadian Tire for the canucks reading). Repeatability is =+/-0.001 if I had to guess from experience.  That and the motion is not very smooth.  I've bought several due to the extremely low cost ($15 Canadian on sale) and for most things they are acceptable but definitely not quality. 
I recently wanted something better so I decided to try out the Aventor brand by Shars as I was putting in an order with them anyways.
I am pleased with my purchases - I got both a 6" and a 12" caliper, both with DPS which is there naming for absolute positioning (behaves the same a Mitutoyo).  Much higher quality than the standard Chinese stuff, the reviews online are accurate - the action is much smoother - I would say almost as nice as the Mitutoyo I use at work but at less than half the price.  I did have some very sharp edges and a tiny burr on a couple of edges of my caliper (not easily visible but could be felt), but not on any of the surfaces for measuring so I simply stoned them off very gently, that was slightly disappointing but at $42.95 US for the 6" I think they are a good deal, and they are claimed to be IP54 (waterproof), so should be safe around coolant (I have a cnc that uses flood - this is important to me!)
Top it off - looks like you could maybe get 20% off that with their Black Friday deals...$34.36 US for a decent set of calipers is a very good deal.  Sorry if this comes off as a sales pitch, just a satisfied customer (seems to happen rarely these days...)
Oh, and accuracy is claimed at =+/-0.001 (can't verify), but the repeatability is definitely much better than the cheap ones, seems to be worst case +/-0.0005 but I'd say probably better than that most times as long as you are using it the same way consistently (same pressure).
Attached are a few pics the new calipers and the old for comparison purposes (the old one has a dying and lose battery too...)
Forgot the link:  http://www.shars.com/products/measuring/caliper/aventor-6-dps-ip54-electronic-caliper  note there are ones same brand but cheaper - those don't have the absolute positioning, which I'm starting to get addicted to.
One last edit - they are at least good enough that you can pay a bit extra and have them calibrated - I didn't go that far but at least its comforting that there is confidence that they are hopefully built well enough to calibrate...
Mike
« Last Edit: November 14, 2017, 03:08:09 AM by Mike R »

Offline Stuart

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Re: Rubbish Digital Caliper
« Reply #9 on: November 14, 2017, 07:06:45 AM »
My view

Calipers are at best a poor measurement device yes they get you near but please get the micrometer out for final


As to Mike R IP 54 is not water proof it may be drip proof. You need IP65 for water proof and the price goes up

See here for IP explanation

https://www.mpl.ch/info/IPratings.html

Stuart

My aim is for a accurate part with a good finish

Offline sshire

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Re: Rubbish Digital Caliper
« Reply #10 on: November 14, 2017, 01:24:45 PM »
Agree on the spotty quality.
My Mitutoyo 6” have been in constant use for over 5 years and work perfectly. It’s one of those things that are a bit expensive but work.
Best,
Stan

Offline simplyloco

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Re: Rubbish Digital Caliper
« Reply #11 on: November 14, 2017, 01:42:23 PM »
I noticed that the MSC one looks identical to the ones I can buy locally from the local hardware store chain (Canadian Tire for the canucks reading).
SNIP
One last edit - they are at least good enough that you can pay a bit extra and have them calibrated - I didn't go that far but at least its comforting that there is confidence that they are hopefully built well enough to calibrate...
Mike
[/quote

I agree: this MSC/SPI one is available with a calibration Certificate, but at £23.83 a pop I can do without it!
John

Offline Admiral_dk

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Re: Rubbish Digital Caliper
« Reply #12 on: November 14, 2017, 10:04:35 PM »
Regarding Ratings on Online shops - I got some stuff from AliExpress and some of it was rubbish, so I tried to contact the seller without any luck => gave bad review, with comments about why, so other could decide for themselves => it did NOT appear on AliExpress and I did still not get any response ...!... will not be very surprised if this is the case on other sites too ....

Offline Dreeves

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Re: Rubbish Digital Caliper
« Reply #13 on: November 15, 2017, 02:44:32 PM »
I only use calipers to get me close and then switch to my micrometer. I don't trust the calipers to give consistent readings

Dave

Offline bent

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Re: Rubbish Digital Caliper
« Reply #14 on: November 15, 2017, 11:33:39 PM »
I found a pair of calipers that were perfect for me - no more dead batteries, and an IP rating beyond any pair I've ever had before (I think I could use them under water!). 

https://www.amazon.com/Fowler-52-057-004-Stainless-Vernier-Caliper/dp/B00B5HOJNQ/ref=sr_1_1_sspa?ie=UTF8&qid=1510788787&sr=8-1-spons&keywords=fowler+vernier+caliper&psc=1

It's a little tough to read the vernier  ;D, but they are pretty darn accurate for calipers (checked against gage blocks here at work).

Offline Don1966

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Re: Rubbish Digital Caliper
« Reply #15 on: November 16, 2017, 12:34:48 AM »
A while back I wanted to update my calipers and bought Mitutoyo 6” one from Amazon. They didn’t work so sent them back and got another that one didn’t work so got my money back.

Don

Offline b.lindsey

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Re: Rubbish Digital Caliper
« Reply #16 on: November 16, 2017, 12:47:44 AM »
That is surprising Don. Makes you wonder if they were genuine. I've had a pair of Mitutoyo's for probably 15 years and still going strong.

Bill

Offline derekwarner

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Re: Rubbish Digital Caliper
« Reply #17 on: November 16, 2017, 02:08:01 AM »
I can set my 30 year old expensive Polish Vernier caliper to 25.4mm or 1.0"......[so easy to read] and the repeatability of my el-cheapo digital caliper to display the same dimension over the blades of the vernier is faultless

it is important to understand the latter are only an expensive G Clamp with a non adjustable TV box in the corner, however checking the accuracy and repeatability of a digital caliper [through comparison] will provide confidence in their use especially for high rate of finished component back checking

Modern component manufacturing Drawings will normally provide a dimension then a +/- tolerance or any requirement beyond that......many older Drawings offer whole number...eg., a 1" bore.....so is the bore machined & reamed with a 1" parallel reamer?......do you confirm the bore dimension with telescopic gauges...then measure these with external micrometers?

If the piston was nominated as 1", is it machined to provide 0.001" per inch clearance?

How many home workshops have test pieces to enable the calibration of these micrometers @ 20 degrees C?, in Industry ...the :old: person  conducting the checking and calibration of all measuring devices must be qualified in the work

Just a few thoughts......... Derek

« Last Edit: November 16, 2017, 04:06:10 AM by derekwarner_decoy »
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Offline 10KPete

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Re: Rubbish Digital Caliper
« Reply #18 on: November 16, 2017, 03:30:22 AM »
Well, it all depends on the dedication of the craftsman, doesn't it?

Pete
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Offline MJM460

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Re: Rubbish Digital Caliper
« Reply #19 on: November 16, 2017, 08:55:15 AM »
Another factor in the performance of digital callipers or any digital scale for that matter is the batteries.  For any given size and voltage standard, there are two types of battery chemistry available, alkaline and silver oxide.  Both are fine in the suitable application, but the silver oxide has a much more stable voltage characteristic, so is preferred for measuring type applications.  I know that the first sign of low batteries on my Measuremax instruments is poor repeatability of the readings, and the silver oxide work well for much longer than alkaline batteries.

I don't know if the top quality instruments have circuitry that compensates better or are just normally supplied with the silver oxide type anyway.  I am sure that better batteries will not bring a cheap device up to the quality of the better instruments, but they reduce some of the frustration in the range where they are adequate.  It may be worth trying a better battery before consigning them to the bin if you have already bought them.  Of course better to buy the best you can afford rather than the cheapest available.  But for final cuts and best accuracy, I am another who resorts to the traditional micrometer, a beginner lesson learned the hard way.

(The alkaline ones are fine for less critical applications, such as LED lights and music devices, but the voltage drops off with use more than the silver oxide, so not good for accurate measuring instruments of any kind.)

MJM460
The more I learn, the more I find that I still have to learn!