Metric micrometer what t buy?

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Good decision, Nigel

Incidentally; I don’t think the manufacturer does anything to lend credibility by publishing drivel like this in the description: [per your second link]

• Display Type:Digital
• DIY Supplies:Metalworking
• Accuracy:0.001mm
• Micrometer Type:Micrometer Set

MichaelG.

Oh dear, sorry to hear that you have a pile of junk mgnbuk, that really is in the G clamp category.

I bit the bullet as I was offered a 0-25 and a 25-50 by someone I know. They are made by Linear (Chronos) and Kennedy (Mitutoyo) and both check out against my slips. I will strip, clean and oil them when I get a few minutes but for £21 I'm happy.

"like" button pressed for this post.

I also like the price on the first item linked - $0.1 minimum 1 piece. That's 10 cents for a mic....

I expect the non-rejects would cost a little more.

I wish you would make an old man happy and do the accuracy checks! Whilst visual inspection strongly suggests this £6.29 treasure can't be as accurate or precise as a better made micrometer, just how badly does it perform? How far off, and how repeatable are its measurements of standard sizes?

My granny taught me to "Never judge a book by it's cover ", and she was right about everything. In engineering and science, opinion alone is untrustworthy, only evidence matters. Accurate experimental evidence best of all.

Be interesting to compare several examples of very cheap, and the £30-ish type, and the £200+ micrometers. In particular, are mid-range cost micrometers 'good enough' for hobby purposes. Mine is, but I work mostly at the rough end.

Dave

There’s a bit more to it than that, Dave.

It might give respectable readings today, but how long will it last?

How easy is it to get any consistent results?

Do you have to be an expert at metrology to get the correct result?

Does the operator have full confidence in the tool?

You say you work at the ‘rough end’ of the spectrum of users (so do I, mostly), but the required precision may change - even if only on odd occasions. I don’t like it if I get differing readings from different measuring sticks! Sometimes one can get round the limitations but I would be peeved if my shrink fit was a loose one, even before heating!

If that item was purchased on the basis of a false description and it does not comply, then it should be rejected - particularly if it is of lower, less merchantable quality. Some epay suppliers try it on - they don’t need many acceptances of these cheaper items to be making a large profit (possibly at that 10 cents per item purchase price).

I have some kit which, while it may work satisfactorily, tend to eat through through cells or batteries. It is annoying, too, when cells do not perform as they should, but stand-by current is an important issue for me - as I don’t necessarily use the items enough to warrant having the digital read-out available - and removing and replacing cells every time of use is a pain! Leaking cells is a potential nightmare with tiny items, too.

If, indeed, it was £6.29 I suppose I could afford to just despatch it to the scrap bin but I would be cross with myself for not getting a more expensive (and better quality) in the first place. I would prefer to buy a secondhand older item from a reliable local ebayer than risk having to return the item to china.

I wish you would make an old man happy and do the accuracy checks!

Oh alright then Dave.

Given the state of the contact points on the Chinese "micrometer", I really don't want inflict these on the calibrated slip set at work. But I have an assortment of "out of spec" Imperial slips (failed calibration by a few millionths of an inch), a small ground parallel set & some ground HSS tool blanks to run comparison checks against, if not absolute checks. I have second hand KS 0-25 and NSK digital 0-25 micrometers to compare against the misrepresented Ebay purchase, which I have yet to parcel up and return (to a UK address with an Ebay supplied pre-payed returns slip). All have been retrieved from the garage & are coming up to room temperature at the moment.

I'm not writing off all Chinese measuring equipment on the basis of this one sample. As with many other Chinese products, they seem quite happy to make items to suit the buyer's cost expectations as well as quality requirements - theChinese supplier website I linked to has a great many examples from several manufacturers that appear noticably better than the item I bought, including the manufacturer of the "cheap" item. The difficult bit is determining what will turn up, as the same mic I bought is available from several suppliers on Ebay (for example) at widely differing prices. Buying a known, respected brand (new or used) should remove that particular uncertainty & even a well used named mic should be better than this particular new item longer term.

Nigel B

I like a bargain, and look for them, BUT

Sadly, in so many cases, You get what you pay for.

If it's too good to be true, it probably isn't

This is about what I would expect for that price.

If a M & W, Starrett or Mitutoyo is priced at £20+ I would expect reasonable quality

Turn back through MEW to read the comparison of digital callipers. Most of the cheap ones could not match the £20+ ones, even for battery life. Which is why I bought the M&W one at £24. The £70+ Mitutoyo is no doubt, Industrial quality and will last for many years of daily and frequent use.

And yes, I use a cheap LIDL calliper for rough and less demanding use!

Howard

Prepare to be bored ! As requested by Dave, I have run a few comparative test checks on the Ebay micrometer, 3 other metric micrometers I either own of have borrowed and, just because it was to hand, an Aldi 150mm digital caliper.

The test artifacts were variously some inexpensive 4"x1/8" parallels of unknown parentage, some out of spec gauge blocks, a piece of ground HSS and a previously unused 25mm setting block from a KS 25-50 micrometer. All had been in the house since yesterday afternoon to come up to the same temperature.

The 4 micrometers - top LHS my ex-industrial NSK Digitrix II. Unfortunately I found I had no new SR44 cells, so this was checked using the barrel markings only. Top right is my ex-industrial DDR KS, with a new, unissued Insize borrowed from work bottom left. The Ebay mic is bottom right.

I checked a variety of sizes from 0.128" (smallest) to 25mm (largest) - now comes the boring bit !

0.128" slip (3.2512 mm) Aldi caliper 3.25 KS 3.25 NSK 3.25 Insize 3.25 Ebay 3.28

0.145" slip (3.683mm) Aldi caliper 3.68 KS 3.682 NSK 3.684 Insize 3.682 Ebay 3.715

5/16 HSS (7.9375mm) Aldi caliper 7.95 KS 7.977 NSK 7.99 Insize 7.98 Ebay 7.97

1/2 parallel (12.7mm) Aldi caliper 12.70 KS12.715 NSK 12.715 Insize 12.719 Ebay 12.74

5/8 parallel (15.875mm) Aldi caliper 15.87 KS 15.855 NSK 15.86 Insize 15.868 Ebay 15.875

3/4 parallel (19.05mm) Aldi caliper 19.05 KS 19.062 NSK 19.062 Insize 19.06 Ebay 19.085

0.8" slip (20.31mm) Aldi caliper 20.31 KS 20.315 NSK 20.312 Insize 20.312 Ebay 20.345

7/8 parallel (22.225mm) Aldi caliper 22.23 KS 22.255 NSK 22.25 Insize 22.255 Ebay 22.28

0.9" slip (22.85mm) Aldi caliper 22.85 KS 22.86 NSK 22.858 Insize 22.859 Ebay 22.89

25mm gauge Aldi caliper 25.00 KS 25.00 NSK 24.999 Ebay 25.035

The 3rd decimal place numbers are "best guess" interpolations of the markings.

As you can see, the results show that while the Ebay mic isn't great it isn't terrible either. But the results are only half the tale - the Ebay mic was not as easy to use for a couple of reasons - the lousy finish to the spindle and anvil faces and the very "easy" thimble action. The narrow parallels wer difficult to get a feel on, as the striations on the spindle face cuaght on the edges of the parallel. This was not as noticable on the gauge blocks. I should have checked something round as well, I suppose, but didn't think of that till after I had packed up.The thimble just felt loose compared to the others. The ratchet was fine, though.

Other random comments :

The Ebay and Insize both had etch graduations, the KS & NSK were engraved and filled and were noticably easier to read.

The Insize scale was "upside down" compared to the others - the millimeter markings being below centre rather than above.

The KS is by far the heaviest and is decidedly chunky compared to the others. Nice ratchet & easy to read.

Only the NSK & Insize have serial numbers. The KS states it meets TGL10546 Grade 1 specifications (DDR norms) & the Insize documetation shows it is to DIN863-1 & comes with a test certificate. As the NSK & KS were bought used, I have no paperwork for them.

The Insize has by far the best case. The Insize mic came from Cutwel and is not the most basic model in the range (they were out of stock of those when I ordered it). IIRC it was around £22 - £23+Vat (the basic one was £20). Insize don't say exactly where it was made just state Asia.

Having checked several Aldi / Lidl calipers before, I wasn't too suprised that the sub-£10 caliper acquitted itself pretty well - probably nearer overall than the Ebay mic & quite adequate for general checks.

Pics below of the markings of the KS, NSK & Insize mics :

Hope that was of interest Dave !

Nigel B

Very much so Nigel, and thanks for the detail!

Here's the results graphically.

I deliberately didn't label which line represents which instrument. Makes ranking the instruments fairer when only the numbers are available. The figures suggest instrument 'O' is best, and instrument S is the worst.

Note that PQ&R are all close to each other in following the same zig-zag pattern. I suggest the zig-zag emphasises the need for standard blocks to be properly calibrated themselves; the instruments are all detecting the parallels are not spot on. (Which is OK, parallels don't need to be accurate, only parallel. Just don't trust them as measurement standards!)

That instrument O isn't following the zigzags with the others is suspicious. O looks good, but I think the instrument isn't detecting variations in the test objects as sensitively as the others.

Measurement is hard to do!

I wonder why people buy these very cheap micrometers? I own an inexpensive one because even though it's workshop class it outperforms my digital calipers when I need better accuracy. If I did a lot of accurate work, it would be worth me going for an up market micrometer, and if it really mattered I'd buy a set of gauge blocks to make sure it wasn't a liar! Don't see much point in owning a wonky micrometer that's only equivalent by a more convenient caliper.

What I've noticed about expensive tools is that they don't automatically do better than cheap ones. Rather they feel better, get results faster, and need less skill to operate. Expensive kit isn't essential - it's amazing what can be done with unlikely tools, skill and patience. Gosh, before milling machines, cold-chisels and big hammers achieved marvels.

Thanks to Nigel I shall sleep easy tonight!

Cheers

Dave

I’m with Dave, I don’t understand buying cheap Micrometers. I’ve got a Mitutoyo and a Moore & Wright 25mm which were both under £25 some years back. I’ve also got an old 1” Moore & Wright somewhere that cost me a tenner from a tool store that was closing down. I’ve got a 50mm Draper somewhere, no idea how much that was or how good it is but I’ve never used it.

Buy Brand name.

Buy S/H.

Ebay has a plethora of high end top quality mics for less than 30 quid.

I’m not too keen on the axes on Dave’s presentation of the results.

For a sensible graph, I would suggest that the true measurement of the part should be taken as zero error. That basically means that other than for the slips, the true dimension has not been used.

A quick glance at the results indicates a +0.02mm to +0.04mm bias for the micrometer tested. That could simply be a 0.03mm zero error, which is not exhibited in the results.

But that does not make it an acceptable item. I’ve seen outwardly identical items (perhaps only differentiated by a slight difference in the shade of plastic) which have very different innards - very much related to the purchase price, of course. Buyers beware - some suppliers do cheat!

“I should have checked something round as well, I suppose”

Yes, I think that might have been more revealing, Nigel

The appalling surface finish on the anvils of the ebay micrometer would presumably produce different readings for a wire measured in various orientations [according to whether, or not, it was lying in a gouge].

MichaelG.

Perhaps worth mentioning in the context of this thread that this week Zoro have a "black friday" promotion and the 0-25mm Kennedy micrometer is reduced to £16.99. Mine arrived this morning and whilst it is still at the bottom end of the price range, it feels nice to use, has clear markings and gives repeatable results. Having said that, the £10 "Whale Brand" micrometer I was using was as accurate (using the ratchet, I couldn't get repeatable results with the thimble as it felt rubbery, unlike the Kennedy which comes to a solid stop), but I do this for pleasure, and it just didn't feel as natural in the hand as those I used in industry. The Kennedy does, so I just ordered the larger sizes to make up a set.

Brian G

I'd noticed that Zorro had the promotion on Brian, looks a good buy. Just out of interest did you get the little adjusting spanner with your 0 - 25 mic?

Yes, mine came with the double ended spanner for the barrel and ratchet. Cromwell/Zoro don't seem to be very good at descriptions as they don't mention either the spanner or the setting standard that is shown in the picture of the larger micrometers.

Brian G

Edit:  I suspect from the markings and the fact that zoro.com sell Insize in the US that Kennedy micrometers now come out of the same Chinese factory as the Insize 3203 series.

Edited By Brian G on 28/11/2019 08:59:04

Ok, thank you Brian.

The 2nd hand 25-50 I bought recently didn't come with a spanner and, of course, the M&W one's I have don't really fit. I was using the 0-25 yesterday and it's ok but I noticed the 1mm graduations on it are on the other side of the datum line to the 25-50 Kennedy! I think I'll invest in a Kennedy 0-25 from Zoro as I could do with a 12mm end mill so that will qualify for free delivery. I've bought a few cutters from Zoro, sometimes via ebay as I find their website is slow and confusing - always cross referencing the price of course. They generally have good prices and are very good on delivery.

I've no doubt you're right about the Insize connection, Incidentally, it looks like Zoro are the mail order arm of Cromwell in the UK.

Cheers, Henry.

I watched a youtube video a while ago in which a Chinese digital caliper was shown to be changing the indicated value as the battery depleted. This was an eye opener for me. Since then I have decided to buy only Mitutoyo’s (or similar) and would prefer a decent second hand quality mic to a new Chinese made one.

That being said I do buy my milling cutters from Banggood which I have found to be excellent, generally. That is more an aside just to prove I’m not a complete tool snob

Mark

Just a quick update, I actually made an ebay purchase recently of a cheap Chinese digital micrometer, which looks very similar to the to the one in my second link; the only difference seems to be mine's in a wooden box the same as the Silverline one in the first link.

It arrived today, very promptly, Royal Mail tracked 48 for the princely sum of £15.08 all in.
It was originally priced at about a tenner dearer, but the seller offered an auto discount, so I thought I'd try it as an experiment.

Well for the price, I'm most impressed, the paint finish is nothing special, and the wooden box is one of the normal tacky varnished ones.
Initially it didn't turn on, but that was because of a dirty battery.

The anvils are carbide tipped and nicely ground and polished; they appear to be flat as well, as I've tried measuring a ball bearing at a good number of points on the surface.

I've a couple of M&W manual, ones 0-1" and 1"-2", the latter of which has a 1" round standard with it.
I used said standard to check both manual micrometers with respect to each other, and as expected they both show 1" dead as far as my eyes can tell.

I then tried various feeler gauges, ground rods, and the 1" standard, in both the smaller M&W and the new digital.
Everything seems to concur throughout the 0-1" range. This of course is only reading the LCD display as the thimble is graduated metric. The new one is adjustable and supplied with a suitable C spanner.
The ratchet seems smooth and the results are repeatable at each of the readings I took.

I don't possess any slip gauges, but from what I can tell, the results are spot on compared to the kit I've already got.

Looks like a bargain for £15

I'd add a link to the seller, but I got the last one, though it looks very similar to the other ones out there

Bill

Edited By peak4 on 21/12/2019 20:37:14