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View Full Version : A not bad cheap 12" igital caliper review



Forrest Addy
11-28-2013, 06:59 AM
I just bought over eBay a $40 12" import digital caliper. Cheapest of the PRC cheap. I just held my nose and bouight it as a throwaway. I needed a caliper larger than 6" at my CAD system to model existing parts. My 6" Mitu worked great but it was only 6" besides I wanted to park it at the turret mill. Whenever I needed the Mitu for the mill, it was in the house and vice versa - you know how it goes.

The caliper comes in a fairly nice foam lined molded plastic box slipped in a printed cardboard sleeve. This is no less than "Precision Measuring" brand (really??) made in China. The sleeve has text and pictures listing its features. No calibration slip, dessicant bag, VPCI paper, no nothng inside but the caliper, a spare battery, and the instruction sheet; which was a repeat of the cardboard sleeve info.

Anyway my my new caliper made a good superficial impression. It's well finished, pretty much a dimensional duplicate of the Mitu, accurate within one display increment over the dozen points I checked with gage blocks for OD, ID, step, and depth. And I discovered it has an undocumented auto on-off feature. Move the slide and the display wakes up. Ignore it and it shuts off. Actually it's a cool feature. I'm always leaving the Mitu on for weeks.

Claimed accuracy was English 0.0005" least digit and 0.01 mm. There was no mention of the auto off-on. I lucked into that for myself. One mystery is the back of the slide which has an aluminum sticker listing ISO and Whitworth fastener thread data. No Unified. I haven't checked but I think the Whitworth info is fishy.

I haven't checked hardness of the gaging surfaces and that's a vital point having a profound effect on durability.

I knew it was gonna be a kit when I bought it. Sure enoigh, there seems to be a lack of jaw parallelism unless the roller adjust is used to bring in the measurement. I've isolated the problem - the spar has a little bulge in it - and it took only a couple hours of TLC to stone it out. Now it works pretty good over its entire range. Still cheap even when you consider the time to tune it up.

This particular caliper seems to be acceptable but the jury is still out about the long term verdict. I will keep you posted. I wouldn't recommend it for use in any commercial shop. However it's well suited for a low budget home shop under light usage. If you have to use it for work made to fit third party parts better use it as a comparative gage. I have a mental cert limit of +/- 0.002" for now.

Weston Bye
11-28-2013, 07:57 AM
Keep an eye on battery life. Had one, of similar pedigree(?!) auto-on and all, mine a Fowler brand, and heard other reports of short battery life whether turned on or off. Apparently turn-off only blanked the display.

EVguru
11-28-2013, 09:10 AM
Keep an eye on battery life. Had one, of similar pedigree(?!) auto-on and all, mine a Fowler brand, and heard other reports of short battery life whether turned on or off. Apparently turn-off only blanked the display.

Yes, they only turn off the display. They're typically shipped with an Alkaline (LR44) which don't last well. An LR44 will last fine in a Mitutoyo, but are more prone to leaking and ruining your caliper.

Use Silver oxide cells (SR44). I can't remember the last time I had to change one because they last so much better.

Stern
11-28-2013, 10:23 AM
Thanks for the post, as I find myself needing a large than 6" a lot. The price is right and since I work in less than shop tolerances (hell since I do sprinkler work, +/- 1" is a good tight spec LMAO) Im sure it will be accurate enough for me. I did notice the last digital one I bought had a big note stating "if you're not using it for extended periods, remove the battery" Guess I should check it out sometime as i still haven't used it yet (like my vernier one better lol)

Forrest Addy
11-28-2013, 12:02 PM
The on/off button makes the display go away as though the tool was shut off but it wakes as soon as you move the slide.

Wish there was a way to measure battery current. Maybe a couple pieces of foil with plastic between slipped under the battery. Do they make copper foil?

dp
11-28-2013, 02:17 PM
Interesting timing - I just bought an 8" digital caliper yesterday at Harbor Freight for $9.00 and so far it works fine. The awful documentation claims it comes with SR44 batteries but they're actually LR44. I bought it as a candidate for a CA (cheap assed) DRO for my mill's Z axis. HF has the 12" for just under $40.

Weston Bye
11-28-2013, 05:28 PM
..... Do they make copper foil?

Yep, McMaster-Carr stocks it, but kinda pricey for just a casual test as you describe. If you decide you need to do such a test, I can send a scrap few square inches, if I can find it in the shop.

PStechPaul
11-28-2013, 11:07 PM
I measured my ultra-cheap calipers at 16.5 uA. The LR44 has a capacity of 150 mAh with cell voltage of 1.50, and the SR44 has 200 mAh with cell voltage of 1.55. I think the silver cells have a flatter discharge curve, so the low battery setting may result in several times the usable capacity with SR44. The lifetime of an LR44 should be 150/0.0165 = 9090 hours or about 1 year.
http://en.wikipedia.org/wiki/LR44_battery

I was able to remove the battery and clip onto the (-) terminal in the caliper and connect through an inexpensive meter. The caliper turned off when I opened the battery cover because the battery lifted up and lost connection. But it's easy enough to remove the battery and it's a good idea to do so if not planning to use it for a while. My other HF calipers may have been damaged from the battery leaking and corroding.

flylo
11-28-2013, 11:56 PM
The 1st H-F I bought ate batteries. The last one does not. I buy the one with the silver rule, not the black as it's easier to see. My last battery lasted over a year.

JRouche
11-29-2013, 02:37 AM
Thanks for the post Thrud... Hmm? I mean Forrest :) I was reading some old emails on my old yahoo account yesterday. They were old ones with some old friends. Art Volz was another friend with old emails. So many folks gone by the wayside. Errrr....

I like calipers. I have a few. Some of my most useful prolly say General or some other name. Lemme go see....... Oh! I forgot, here it is.. My best and very first caliper, had it for years but most of you old buzzards prolly have grandkids older :) :) It says Craftsman in the "Craftsman font". No mention of Sears. Made of Stainless and fairly heavy which I like for the size. And it says made in Germany. That's a plus. Prolly why it has survived all these years. Very useful.

Then I got some Dial Calipers. Woo-hoo! They are a nice tool. Its convenient if you want to watch a changing stroke or diameter when the work is moving. Dials are great. The Vernier (my old craftsman) and the Digital dont show a great picture for moving measurements like a Dial will. Still have my first dial caliper also. A cheap one but still works out.

Then the Digitals. Was difficult at first. I was already in the digital world and I knew digital systems drop "bits". Trust factor wasn't high. But eventually I really came to like the digital calipers and micrometers. Still have the HF cals on hand, work just fine. Have some other no name sets also and some once upon a time Fowler sets. I have a mitu 500-752 6" caliper that is very nice, and again, heavy for its size. Sharp points too! Hurts... Some SPI and more Fowler. Fowler 12" and 24".

Another favorite caliper for me is one a dear friend and machinist used and inspired me. Del Fronteras. Outside and inside calipers. The old ones. He used them as transfer calipers for Well pipe on the lathe. Takes some control to use and stay within the 1-2 thou for some rough pipes.

The multi stage brass pumps? He was King. He was turning alot of brass. Had a blanket for the chips. Had to be clean.

And yes HP ruled with the pump stages. The brass was being chewed off fast. His main lathe was the reed prentice. It was only about 15hp. Swung a 24" plate when needed, he kept the 18" four jaw on the spindle. It was 12 foot to the end. He liked to grind his bits at the pedestal grinder. He would bring this lil tiny HSS bit back and mount it in the massive lantern tool post type tool holder and eat hard brass to spec.

Nice to see a lil tool bit eating metal like it should. Time was money so use the 15hp. Miss my friend Del :(

Solly Addy for the side track. I love to read your posts,,, JR

GEP
11-29-2013, 07:24 AM
I bought 3-8" I-gage verniers for around $8.00 the battery's are junk that come with them don't last at all. The one thing i like about I-gage it goes back to the original setting where HF don't does that mean I-gage stays on all the time. I also got a 12" verier for $ 40.00. Don't you all forget where this stuff comes from.

DATo
11-29-2013, 09:10 AM
A History Lesson Learned First Hand

In 1977 I bought my first NEW machinist instrument, a Mitutoyo dial caliper. It was purchased from a hole-in-the-wall retail shop owned by a German who had moved to the USA. He was trained as a tool and cutter man back in his home country and I got to know him well. He had a very small storefront and in addition to selling a few tools he also had two retirees in the back sharpening end mill cutters. They have since built a huge building in the suburbs and were among the first to have computer controlled cutter grinders. The last I heard this company is now the largest industrial supply retailer in my state and the largest retail supplier of Kennedy tool boxes in the USA.

So back to 1977 - I bought the caliper and a 6" set of Mitutoyo telescoping gages for a very affordable price. But the Mits were not selling well at that time because their specs did not conform to Federal requirements. I didn't need 50 millionths accuracy on a mic but apparently the Federal government did. This was probably because my state is heavily dependent upon defense contracts and were thus forced to comply with the regulations. Also, because there were still a lot of old timers who wouldn't buy foreign tools (especially from Japan ... think WWII). I still have these tools and they have always served me well. The Japanese learned to bring up the quality of their products incrementally over time and as you probably know they have become one of the dominate players in that market.

I believe the same will happen with China. Back in the day there was an expression that many of you younger people have never heard and many of you older geezers like me may have forgotten. it was ... Made In Japan ... this was a derogatory expression used to express disdain for ANYTHING made by ANYBODY which was shoddy and very cheaply made. Now the term Made In Japan can actually help sell a product in this industry. The Asians are copiers. The Japanese copied us and the Chinese are copying them. I have learned that there is something in the Asian mentality that does not readily take to innovation but they excel in, first, stealing what others innovate and then striving to improve it and make it cheaper. About 12 years ago, when I was running a home-based business I bought a 24" height gage which was made in China. I bought it for one specific job. It cost $100, was made of hardened stainless steel, weighs about 25 pounds and is far more accurate than I would have expected comparably vying with the Starrett I use at work .. and that was 12 years ago. They still have a long way to go but get ready to duck when they arrive.

The Point:
In both the illustration of the German retailer and the Chinese the lesson seems to be that if you offer REASONABLE quality for a VERY reasonable price you will capture the market, as the German guy eventually did. People want the best bang for the buck today whether it be with automobiles or machinist tools and the days when a machinist tool HAD to have Starrett, Lufkin or Brown & Sharp on it to be worthy of purchase by the average machinist are long gone.

Forrest Addy
12-01-2013, 09:05 AM
New developments. I did a litle handwork on the spar and the slide. Now the spar is straight witnin 0.0002" (at thermal equilibrium) over about 14" and parallel to 0.0002". It's much smoother in action and a bit more accurate.

BUT!! Every for dozen or two slide reversals the display jumps 0.200" or 5.08mm. There's no consistant count; 27 one tine 14 another, 21, 13, 31 etc: random. I can't fix capacitive scales nor micro electronics. I don't have the know-how or the equipment. A measuring tool has to be consistant. No display jumps allowed.

I notified the seller his caliper while mechanically acceptable, its scale and/or electronic faults render it useless as a measuring tool. Then I asked what he would suggest as a remedy. No message back - it is Thanksgiviing weekend.

I expected some problems because after all is said and done it is a cheap POS. If it can be reworked into a usable POS, well and good. If not and I get my money back, also well and good. If after a round of messages and ultimately a denial of remedy and a roud of argely ineffective eBay solutions I will have learned a $40 lesson - and probably be more sympathetic to the wanton import bashers.

Stay tuned for the next episode of (dunh da da dah!) Captain Old Fart in: "The Import Trade" or "The Caliper Caper"

Mike Nash
12-01-2013, 09:11 AM
The 0.200" jump has plagued ShumaTech DRO users from day one. Very scary if you don't catch it while milling. Seems to be electrical noise related. Try yours again outside sometime.

GNM109
12-01-2013, 10:01 AM
The Harbor Freight digital calipers are OK for rough mearurement, as when I visit my scrap rack and want to check sizes. Beyond that, they have proven to be nearly useless. They may work nicely when new, but after a while they begin to act oddly. The problem is that you can zero them and make your measurement and then when you close the caliper, it reads anywhere from .001 to .005. That removes all confidence in any measurement that you might make. For that reason, I won't be buying any more of them. For accurate outside measurements, I simply use micrometers. I will have to get a Mitutoyo caliper for anything else.

I have two of the Harbor Freight units that do the same thing. Neither has been dropped nor mistreated. They started doing this after about a month of use.

I haven't had any problem with battery life, however. I use the Energizer 357/303 and they last a long time.

PStechPaul
12-01-2013, 06:31 PM
These calipers use a counter to totalize transitions along the length of the scale, and have a maximum count speed, so you might try moving the head more slowly to see if it improves. My cheapo all-plastic calipers hold zero even when I move the head as fast as I can to the end and back to zero. BUT, if I use them close to a CFL light, the readings jump all over the place.

You might see if the head from a cheap 4" or 6" caliper will work on the 24", but the display might not be able to show a reading beyond 9.999. However, if it just rolls over to zero, then you can just add 10 or 20 to the reading. I have disassembled and reassembled the HF 6" caliper several times, as you can see in the photos of my other thread. But I had to peel off the metal label on the back to access the screws, although I might have been able to punch openings and avoid the difficulty.

http://enginuitysystems.com/pix/Measurement_800x600_0665.png

http://enginuitysystems.com/pix/Measurement_800x600_0666.png

Forrest Addy
12-01-2013, 07:37 PM
I dunno about speed PSTechPaul. I deliberately zipped the slide rapidly back and forth and most of the time the display returned to zero with the jaws closed. The 0.200 display error recurred about the same average rate that is randomly between 10 to 30 back and forth slide cycles: fast or slow.

EMI is another story. I have two CFL lights near my work station. Same test with the light off results in roughly double the cycles between errors. That tells me the CFL's interfer somehow. But the error recurred. I have a number of low level EMI sources in the shop. Flourescents, VFDs, welding, motor starts, etc. My DRO's, my Mitu caliper, ect all work flawlessly in this mild and very typical EMI environment. I'd guess 90% of the shops in the US have roughly the same EMI environment; all electronic equipment should function normally in it be it doorbell or DNA replicator.

While it may be interesting to track down the exact condition that triggers display error that's the maker's job. It's especially his job to fix it, to male sure all his production models are free of defect. This capacitive scale technology has been on the market for 30 years to my knowledge. You''d think even the bottom feeders would have the wrinkles worked out by now.

Screw it. I'm asking for my money back.

outback
12-02-2013, 12:53 AM
Forrest;

I would try a new battery in your calipers. Hard telling how old the battery really is. We know for sure it had a long boat ride.

I bought a 12" Chinese digital caliper about ten years ago. I checked it just now and of course the battery is dead and I never keep spare batteries for my digital tools. Hardware store with cute checkout girls is only 4 blocks away so I only use fresh new batteries.

I found a place in Rockford Illinois that repairs Mitutoyo digital calipers for a reasonable price.
Instant Gage Repair
(815) 877-2555

Jim

J Tiers
12-02-2013, 08:46 AM
I might throw in here the comment that EMI doesn't bother a dial or vernier caliper..... And the rare tooth skipping complaint for dial calipers is easily detected by checking zero.

Not to mention that if you are any sort of a workman, you will likely notice the feeling if the thing DOES skip a tooth. It usually changes the feel of the slider moving, there is a "bump" in it when it skips.



[b]
Iand the days when a machinist tool HAD to have Starrett, Lufkin or Brown & Sharp on it to be worthy of purchase by the average machinist are long gone.

The quality guarantees the brand. The brand does not guarantee the quality.

Starrett (B&S, etc) is only high quality so long as they PRODUCE high quality product.

There is a tendency in larger corporations which make an acquisition to "milk the brand" they bought by cheapening it, and collecting the high price for as long as it takes the reputation to disappear, then dumping the brand for low sales. Makes the exec look very good for profitability, and throws the blame on his successor.

The customers get HF quality at premium brand prices while it lasts.