Another Would You Bother Thread

[Anorak Bob]

This time, hopefully nothing inciteful.

This time Japanese versus Swiss, both used, both sometimes available relatively inexpensively. The former more so than the latter.

Last weekend I had been fooling around with my .0001" Mitutoyo and experienced a minor variation of reading when running the stylus up a couple of thou onto a gauge block. As a result of this observation, Michael G very generously posted to me his Interapid and his Brown and Sharpe Bestest (TESA) dial test indicators for my humble appraisal. Both tenth indicators, used and in excellent nick.

Surprisingly both Swiss suffered the same tiny variation in repeatability as the Mitutoyo did. Maybe .00002" - .00003". This is just my uneducated observation, others may have an explanation for the occurrence.

Comparison of the physical attributes of the indicators is interesting. The Interapid ( reputedly the best DTI money can buy ) shares the same screw on dovetails as Mitutoyo use on their tenth DTI . My half thou Mitutoyos have integral dovetails machined into the indicator's body casting as does the Bestest. Compac, in their catalogue, make a point of informing the reader that their indicators all have integral dovetails. Different strokes.

The winning feature in my mind is the hinged rear mounting on the Interapid. This allows the indicator to be both swiveled and very conveniently, rotated 360 degrees. A flexibility not found with any other DTIs I've handled.

Interapid also offer an articulated mounting arm facilitating the most convoluted set ups. In defence of Mitutoyo, their universal DTI with its rotatable nose is a handy bit of kit, Stu and RC might agree.

So, would I bother going Swiss? If I hadn't bought a 30 year old .002mm Mitutoyo test indicator two weeks ago, probably and probably an Interapid.

BT

[Michael G]

As I said to Bob at the time "Would I dare to send anything but Swiss to him to test?".

Interesting that other tenth DTIs share the same characteristic. Thinking about the size of the numbers I'm now wondering whether it might be a mechanical play issue. A perfect fit should mean no play but there have to be mechanical clearances and tolerances so that may be how they are manifest.

(And now that you have extolled their virtues I might have to use them more often and take better care of them)

Michael

[Brobdingnagian]

This time, hopefully nothing inciteful.

This time Japanese versus Swiss, both used, both sometimes available relatively inexpensively. The former more so than the latter.

Last weekend I had been fooling around with my .0001" Mitutoyo and experienced a minor variation of reading when running the stylus up a couple of thou onto a gauge block. As a result of this observation, Michael G very generously posted to me his Interapid and his Brown and Sharpe Bestest (TESA) dial test indicators for my humble appraisal. Both tenth indicators, used and in excellent nick.

Surprisingly both Swiss suffered the same tiny variation in repeatability as the Mitutoyo did. Maybe .00002" - .00003". This is just my uneducated observation, others may have an explanation for the occurrence.

Comparison of the physical attributes of the indicators is interesting. The Interapid ( reputedly the best DTI money can buy ) shares the same screw on dovetails as Mitutoyo use on their tenth DTI . My half thou Mitutoyos have integral dovetails machined into the indicator's body casting as does the Bestest. Compac, in their catalogue, make a point of informing the reader that their indicators all have integral dovetails. Different strokes.

The winning feature in my mind is the hinged rear mounting on the Interapid. This allows the indicator to be both swiveled and very conveniently, rotated 360 degrees. A flexibility not found with any other DTIs I've handled.

Interapid also offer an articulated mounting arm facilitating the most convoluted set ups. In defence of Mitutoyo, their universal DTI with its rotatable nose is a handy bit of kit, Stu and RC might agree.

So, would I bother going Swiss? If I hadn't bought a 30 year old .002mm Mitutoyo test indicator two weeks ago, probably and probably an Interapid.

BT

What are the spec on repeatability meant to be? In my experience repeatability, hysteresis and measuring force is a real tricky thing to get right especially at the finer resolution eg 50 millionths and 0.5 um, everything gets in your way to making good measurements with low variability, body heat being the most persistent annoyance. I have only seen (never used) digital probes with good level of repeatability eg ± < 1 resolution division (eg Mahr Federal Millimar 1318).

Hysteresis is also an important one to point out as this is "normally" a couple of divisions.

-Josh

[Brobdingnagian]

Oh the other thing that I seem to recall is that the intrepid is only true at 12 degrees?

[Clubman7]

"Maybe .00002" - .00003". This is just my uneducated observation, others may have an explanation for the occurrence. "
Your worried you need this sort of accuracy for what reason.
Unless your using the equipment in a temperature controlled environment you won't be able to control variations like this anyway.

[RayG]

"Maybe .00002" - .00003". This is just my uneducated observation, others may have an explanation for the occurrence. "
Your worried you need this sort of accuracy for what reason.
Unless your using the equipment in a temperature controlled environment you won't be able to control variations like this anyway.

Yes absolutely correct.. just to put it in perspective, steel expands/contracts at 13 microns per meter per degree C, so for a 50mm part a one degree C change will change the size of the part by 0.65 microns, ( 0.050 * 13 )

So to see a 0.00002" change ( that's 20 microinches, which is 0.5 microns ) would only require less than 1 degree C change in temperature of the part.

Keeping heat sources like hands away and shielding from draughts and air currents, is not always easy..

Regards
Ray

[Anorak Bob]

"Maybe .00002" - .00003". This is just my uneducated observation, others may have an explanation for the occurrence. "
Your worried you need this sort of accuracy for what reason.
Unless your using the equipment in a temperature controlled environment you won't be able to control variations like this anyway.

It was an observation. I did not state that I had need for accuracy of that sort. You might, I certainly don't.

[Michael G]

Bob, have you slipped an extra zero in there? I've just realised that we are talking hundreds of thous.

Michael

[.RC.]

I am just not a big fan of old Mitutoyo gear... The modern stuff is good... The older stuff I think less good.. or probably more to do with just the bad luck I have had with older mit indicators...

[Clubman7]

It was an observation. I did not state that I had need for accuracy of that sort. You might, I certainly don't.

"This is just my uneducated observation, others may have an explanation for the occurrence. "

You asked for an explanation.

[Anorak Bob]

Bob, have you slipped an extra zero in there? I've just realised that we are talking hundreds of thous.

Michael

OK, I was looking at the dials with a 12X loupe screwed up against my eyeball. At that magnification the space between a one tenth graduation is pretty large, large enough to have a stab at the needle position varying .00002'' to .00003'' and I wondered why the variation was occurring. In the case of my Japanese indicator, wear would probably a influencing factor, possibly the same with your Swiss indicators.

I have no illusions about the irrelevance of measurement at this level to me. My shed shares more in common with a tent than it ever would a toolroom.

Mention a micron and the ears prick up. It's a bit like "who does he think he is using the talk of the toolroom."

[Clubman7]

Bob, your talking 0.0005 to 0.0007 of a mm variation.
You might find the manufacturing tolerances of the indicators you tested wouldn't
be this fine when manufactured.

[Brobdingnagian]

OK, I was looking at the dials with a 12X loupe screwed up against my eyeball. At that magnification the space between a one tenth graduation is pretty large, large enough to have a stab at the needle position varying .00002'' to .00003'' and I wondered why the variation was occurring. In the case of my Japanese indicator, wear would probably a influencing factor, possibly the same with your Swiss indicators.

I have no illusions about the irrelevance of measurement at this level to me. My shed shares more in common with a tent than it ever would a toolroom.

Mention a micron and the ears prick up. It's a bit like "who does he think he is using the talk of the toolroom."

You may also be looking at surface deformation of the gauge block and the tip. This always happens to me using a 0.0005mm probe on steel/CI, but also is probably because it has quite a high measuring force; I think it is about 0.1-0.05N.

Also I note in the photo you still have some trace of blue on the rock.

Try gloves, breath/body shield, "super clean"/pristine gauge blocks, "super clean" surface plate, and repeat. To be honest, I'm impressed they hold up as well as they do, as I have said hysteresis is normally at least a division if not 2.