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View Full Version : interchangeable anvil micrometers



Tony
03-28-2012, 11:39 AM
So are they any good?

I've been slowly building my micrometer collection.. up to 8" is my plan..
as "deals" come up on ebay.

Every now and again I see interchangeable anvil micrometer sets come
up for what seems like reasonable money..there is a 6-12" starrett on
craigslist now with all standards in good condition for $300.

So I see these mics and wonder if I didn't make the wrong move going
with individual regular mics (most of which I have to find a standard for
and make a box).

Then I wonder how awkward it might be to take measurements on a 6"
workpiece using a mic with a 12" frame (on a lathe with a 13" swing).

Anyone have / use / like these?

Dr Stan
03-28-2012, 12:16 PM
Every now and again I see interchangeable anvil micrometer sets come up for what seems like reasonable money..there is a 6-12" starrett on
craigslist now with all standards in good condition for $300.

Then I wonder how awkward it might be to take measurements on a 6"
workpiece using a mic with a 12" frame (on a lathe with a 13" swing).

Anyone have / use / like these?

I have used interchangeable anvil mics when I was in the Navy. We had one that was 18" to 24" I believe when I was on the Coral Sea. As you can imagine a mic of this size was awkward to use even in its 23 to 24 setting.

Since you are using a 13" lathe I would seriously doubt if you would ever have need of anything above 8", so I think your original plan of individual mics up to 8" is your better choice.

Toolguy
03-28-2012, 01:01 PM
I have bought a lot of shop stuff on eBay. Like over 500 purchases. The best way to go is separate mics for each inch range. You can get the quality name brands for $20 - $50 a lot of times by being watchful over a period of time. We are talking about Starrett, Brown & Sharpe, Mitutoyo, etc. not cheap Chinese. I like B&S and Mit. the best. The same goes for the calipers and indicators and a host of other quality tools.
In general, the prices now are higher than they used to be so you have to cherry pick a little more to get the good bargains.

willmac
03-28-2012, 01:17 PM
I have a set of these and I don't like using them. To be more specific, if you use them with a long interchangeable anvil they are clumsy and I don't find that the feel is good. When you use them with the shorter anvils (i.e. bigger dimensions) they are OK, but ideally I would like a full set of micrometers instead. The ones I have are Mitutoyo.

Tony
03-28-2012, 01:48 PM
I've been keeping my eyes peeled for the Starrett 216's (digital mechanical)..
just so easy on the eyes. I notice some of them have a scale on them, some don't.. haven't been able to figure that one out yet. Most times you (I) can't even contact the seller. I only get the graduated ones (0.0001").

Used they seem to average me about $60+shipping.

Last week got a B&S 7-8 and 8-9 (not digital mechanical though) in great
shape for $73 shipped.

I've got a hole at 4-5, 5-6 and 6-7.

Anyway thanks for confirming my suspicions on the interchangeables.

Tony

Timleech
03-28-2012, 04:11 PM
Individual ones are certainly better, easier especially in awkward spaces, but the interchangeable ones can do the job with a bit more care. For a long time all I had apart from a 0-1" was a Mitutoyo 1" - 4", then later a Moore & Wright 2" -6". I've gradually collected individual mics up to 6", but have a couple of big ones with interchangeable anvils. They don't come out very often but they are invaluable now & then, I certainly couldn't justify having an equivalent stack of big individual micrometers.

Tim

Carld
03-28-2012, 06:17 PM
Tony, it all depends on how careful you are in calibrating the mic when you change anvils. I bought a set of 0 to 12" Chinese mic's in the middle '90's and they are very accurate and not expensive. I gave my mic that had 0 to 12" changeable anvils to a friend.

J Tiers
03-28-2012, 09:52 PM
Timleech has it...........

Don't count on them for anything you use fairly often, unless you leave it set up for the one size you don't have.

They are basically a pain to use. Always set up for what you needed last time, never what you need now.... so you either use calipers or you fuss around changing anvils and calibrating. Bleeeaaaahhhh. ONLY if you HAVE to.

I have a Tumico 0-6" that I don't like at all.... bad feel, hassle to change anvils, and now it is redundant because I have individual ones through its range...... I'll probably get rid of it one way or another.

They resemble milling on the lathe....... can be done, not something you likely WANT to do, but good to have the capability if you have to do it.

oldtiffie
03-28-2012, 10:06 PM
Odd that.

While I agree that interchangable anvils are not the best option, they may be the only option.

Not all "interchangable anvil" micrometer as "external" as many are "internal" and its very rarely anyone seems to complain - they just adapt to it - same as many bore guages and depth micrometers.

As I said - odd that.

https://www.machineryhouse.com.au/Tube-Type-Inside-Micrometers

https://www.machineryhouse.com.au/Rod-Type-Inside-MIcrometers

https://www.machineryhouse.com.au/Depth-Outside-MIcrometers

Timleech
03-29-2012, 03:46 AM
Odd that.

While I agree that interchangable anvils are not the best option, they may be the only option.

Not all "interchangable anvil" micrometer as "external" as many are "internal" and its very rarely anyone seems to complain - they just adapt to it - same as many bore guages and depth micrometers.

As I said - odd that.



An inside mic is never bigger than it needs to be for the job, whereas an external interchangeable one is bigger than it needs to be most of the time!

Tim

oldtiffie
03-29-2012, 04:20 AM
Maybe so Tim, but the topic is interchangeable anvils per se and inside and depth micrometers are firmly in that category with those of outside micrometers and many bore gauges.

I suspect that many will have more problems with accuracy when using interchangeable anvils or any kind - and it more a problem with the user than the micrometer.

It is not at all unlike the problems some have with telescopic bore gauges - and traditional (not digital or vernier) calipers.

Getting the right "feel" and technique is almost an art form and is an acquired skill that can only be learned and maintained by practice.

J Tiers
03-29-2012, 08:54 AM
Maybe so Tim, but the topic is interchangeable anvils per se and inside and depth micrometers are firmly in that category with those of outside micrometers and many bore gauges.

I suspect that many will have more problems with accuracy when using interchangeable anvils or any kind - and it more a problem with the user than the micrometer.



Politely insulting as is quite usual for the "bin-meister"....... what did we *expect*?

In the real world, it isn't so much a matter of some special technique that needs to be learned.....

No, in the REAL world, several inconvenient bits of reality intrude on the perfect world of "Tiffieon"....

1) If you have one mic, and it is an interchangeable type, there are quite good odds that you may need to change anvils and re-cal before you make the measurement you need..... Perfectly do-able, but hardly convenient if you can avoid it. Particularly as compared with picking up a second mic and making the measurement.

2) If, to your disgust, you need to measure TWO diameters on the work, which happen to span more than one range of anvil, you will "enjoy" certain "advantages" by using an interchangeable mic..... You will get lots of that "practice" that Tiffie advocates..... Whether you like it or not.

3) There are GOOD designs of interchangeable anvil mics and there are BAD designs. The good designs make adjustment easy, the bad ones are quite a bit more fussy. Even then, most will need a re-cal for any anvil change.

4) Some types of mic have inherent issues. The Tumico mic I have is lightweight, yet reasonably rigid... but the thin tubular design of the frame tends to heat and expand rapidly. In only a few seconds it can expand 0.001". You need to grip it in a cloth, at least. (the low mass can be good in adapting to local temp, though). This is obviously not specific to an interchangeable type, but this one IS that type.

5) I'm not sure inside mics are a good example..... since it is a given that you WILL be swapping sections virtually EVERY time you use the mic, most make that simple and fairly fool-proof. And, since inside mics are not highly regarded as primary standards, it is generally expected that they will be set to a standard close to the intended size before use for any especially critical measurement.
Multi-anvil mics typically are much more of a hassle to swap....

6) inside mics, given their use, separate the rod calibration from the rod installation. With the multi-anvil, these are "nominally separate" but the mounting means for teh anvils often is somewhat interactive with the anvil calibration.... inadvertantly.

Inside mics come in two flavors.... short range units where you select one of a range of extenders, and long range units where multiple sections may be screwed together.

The short range type often have a clamp means that is ideal... many use a "chuck" arrangement, with force at right angles to the length... thereby not applying force to the length setting means. One might, if a reasonably trusting soul, swap pre-set rods and get a *pretty close* reading without calibrating... making sure the mating surfaces are clean first before assembly.

Most multi-anvil mics have a backer nut that holds the anvil.... that tends to introduce an added variable...since the force applied to that nut needs to be standardized to avoid possiblyaffecting the overall distance.... although that should come out in the calibration., it negates the quick changing of anvils. (everything is made of rubber, remember). The clamp force of teh nut acts directly on teh "calibrating nuts" for that anvil, as opposed to the calibration being separated by a fixed collar as with many inside mics

With the tubular multi-section inside mics, there are so many potential variables in the joints that it is accepted that a calibration is needed at some size close to that measured. This is closer to the multi-anvil mic situation, but even there, the calibration isn't so much affected, the assembly tend to have a "positive stop" with stretch issue outside the size. Errors tend to be more from crud on the mating faces..

Tiffie's idea that "it's all quite easy when you know how" fails entirely to cover the hassle factor involved with multiple measurements requiring anvil changes. And the "telescopic gage" reference is simply irrelevant here.