DTI vs DI

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GlennW
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Re: DTI vs DI

Post by GlennW »

The deal with the Interapid DTI popularity is that they are very well made, durable, reliable, and have far more travel than most DTI's.

I wanted an Interapid and ended up with a SPI clone of an Interapid as it was some kind of an Enco deal where after all of the discounts and free shipping it was only $37.00 when normally it was a hundred and something dollars.

It is the vertical style with an integral stem for holding in a chuck or collet and is a very nice DTI, but the bi-directional needle movement keeps me reaching for the BesTest 75% of the time.

The integral stem does make it very nice for indicating small bores though!

I have a Mitutoyo as well, but it also runs backwards, which really isn't a big issue, but just takes some getting used to...
Glenn

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John Hasler
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Re: DTI vs DI

Post by John Hasler »

I've never used either the Gem or the Last Word for anything other than detecting runout or taper. "I can tolerate .002 here. Is the DTI showing less than .001? If so I'm ok." I'd be reluctant to use it to actually measure anything to any closer than about +-30%. Both need to be kept clean and the pivot for the lever lubricated (I never oil the works). Also, if the needle is absolutely still on a running part something is wrong.

The only indicator I've come into possession of that I haven't been able to get working satisfactorily is a B&S that won't repeat better than +- a division. It also has a plastic body.
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Harold_V
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Re: DTI vs DI

Post by Harold_V »

John Hasler wrote: Sun Apr 01, 2018 11:06 am The only indicator I've come into possession of that I haven't been able to get working satisfactorily is a B&S that won't repeat better than +- a division. It also has a plastic body.
Hmmm. I'm not an authority on B&S indicators, but the very idea that the one in question has a plastic body leads me to wonder----is it really a B&S, or is it some kind of knock-off?

I'd like to know.

H
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Harold_V
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Re: DTI vs DI

Post by Harold_V »

Mr Ron wrote: Sun Apr 01, 2018 9:43 am Based on comments made about "last word" DTI's (the only DTI I have is a Gems), I must conclude I will have to use my DI for centering until I can afford a B&S, BesTest.
You never know when you'll find a deal on a B&S. I was perusing ebay a few years back, when I came across a BesTest that was offered for a low price. One of mine has a loose crystal, and I had not made the decision to send it in for replacement. I gambled on the one offered, which I purchased for something like $35 (for sure, less than $40)! It has worked to perfection thus far, so the one with the loose crystal sits unused now.

The difference in how the B&S indicators work as compared to the Last Word is remarkable. Granted, they're not quite as easy to set up, but that's a small price to pay for improved performance. I give Starrett good marks for their multitude of attaching components.

H
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John Hasler
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Re: DTI vs DI

Post by John Hasler »

Harold_V wrote: Sun Apr 01, 2018 3:25 pm
John Hasler wrote: Sun Apr 01, 2018 11:06 am The only indicator I've come into possession of that I haven't been able to get working satisfactorily is a B&S that won't repeat better than +- a division. It also has a plastic body.
Hmmm. I'm not an authority on B&S indicators, but the very idea that the one in question has a plastic body leads me to wonder----is it really a B&S, or is it some kind of knock-off?

I'd like to know.

H
Light green plastic crystal. Marked on the face:

.001"
SHOCKPROOF
JEWELED
Brown & Sharp
8241-612 .250 RANGE
MADE IN USA

It was stuck solid when I got it and the crystal was so dirty as to be opaque. I thought it was badly scratched and would need to be replaced but it cleaned up fine. There was no corrosion visible inside and just cleaning got it moving freely, but it doesn't repeat. Next step will be to tighten the mainspring, something I try to avoid.
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BadDog
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Re: DTI vs DI

Post by BadDog »

Like this?
https://www.ebay.com/itm/Brown-and-Shar ... 2764964448
That's the only thing I found with that number. But that's not like any I have had or own. Most of my DIs are Mits or Starretts.
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John Hasler
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Re: DTI vs DI

Post by John Hasler »

BadDog wrote: Sun Apr 01, 2018 9:12 pm Like this?
https://www.ebay.com/itm/Brown-and-Shar ... 2764964448
That's the only thing I found with that number. But that's not like any I have had or own. Most of my DIs are Mits or Starretts.
That's it.
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Harold_V
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Re: DTI vs DI

Post by Harold_V »

For some reason, I thought the indicator in question was a DTI. I am not even vaguely familiar with the B&S long travel types, as all of mine are Starrett, which I trust without question.

Not repeating may be a matter of dirt, especially judging from the description you provided when it was acquired. If you've opened the back, I suspect you'd see a rack and mating gear (Starrett builds them that way). I'd clean it and the bushings in the ends, then lubricate lightly with a non-hardening oil (clock oil). That's all I've ever had to do with mine. I don't know how repair stations treat them. Could be I'm all wet!

H
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SteveM
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Re: DTI vs DI

Post by SteveM »

When I pick up an indicator and it sticks, I rinse it out with lighter fluid. It will dissolve hardened oil and flush out dirt.

Then lube with Starrett oil.

I'll pick up something off ebay and it's billed as not workink. I'll clean it out and leave feedback like "Thanks, it works great", which should leave them scratching their heads.

Steve
John Hasler
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Re: DTI vs DI

Post by John Hasler »

Harold_V wrote: Mon Apr 02, 2018 2:00 am For some reason, I thought the indicator in question was a DTI. I am not even vaguely familiar with the B&S long travel types, as all of mine are Starrett, which I trust without question.

Not repeating may be a matter of dirt, especially judging from the description you provided when it was acquired. If you've opened the back, I suspect you'd see a rack and mating gear (Starrett builds them that way). I'd clean it and the bushings in the ends, then lubricate lightly with a non-hardening oil (clock oil). That's all I've ever had to do with mine. I don't know how repair stations treat them. Could be I'm all wet!

H
The rack is clean, operates freely, and stops consistently. The problem is deeper inside. Either there is dirt that did not come out with flushing or the mainspring is too weak to consistently take up all the backlash. It's not a high priority project: it's just frustrating to get the thing so close to working so easily.

I was also startled to see the plastic case. I can move the needle most of a division by squeezing hard on the sides with my hands.
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ctwo
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Re: DTI vs DI

Post by ctwo »

Well, it's a nice looking DI anyway - seems more pompous!
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pete
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Re: DTI vs DI

Post by pete »

Years ago I think I got very lucky and ran across a post mentioning something about Long Island Dial Indicator Repair and am a bit surprised no one's mentioned it here. They've changed there website a lot, but at one time sure didn't have much good to say about the Starrett Last Word Indicators. There is some repair tips scattered throughout the website and they usually list the good and not so good about any piece of metrology gear most of us would be looking at buying. It's my first stop when researching anything metrology related. From what I've seen over the years there pretty much unbiased in what they think are the good and bad points. Any metrology repair company should know the equipment more than well and should be capable of providing maybe a bit more honest opinion than any of the manufacturers would be willing to do since they see what needs the same type of repair all the time. I can't think of anything I bought prior to finding there website or after that didn't perform and react about as good as what they had to say about it so I tend to trust what they have on the website.

I'm not even close to being highly knowledgeable about repair of any of this equipment. But anything I've ever found on the net almost always mentions that most tend to use far too much oil. Some have mentioned less than a single drop of oil applied with a needle or tooth pick on gear racks and teeth, micrometer threads etc. is all most of this equipment needs after a good cleaning with solvent. Myself I tend to use an electrical contact cleaner, but that Ronson lighter fluid is supposed to leave behind just a touch of lubricant after it evaporates. True or not I can't say. Any working loads on most of this equipment would be very light. So after reading what I have possibly too much oil left for years to dry out likely does more harm than no oil at all as far as getting results you can trust.

I've yet to even try a B & S Best Test or Interapid DTI, but fwiw my 10ths reading Mit. 513 - 403T and 453 have done everything I've ever asked of them. They repeat really well and are very sensitive. I think I'd trust them as much as I'd trust any DTI. But I also can't recall ever using them for a linear measurement, Checking runout, flat, parallel, machine tool alignment is all there used for.
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