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Interapid 312b Question

1 Jaw Chuck (Chuck Evans)

1 Jaw Chuck (Chuck Evans)

Cast Iron
Joined
Jun 9, 2008
Location
Burbank, CA
Hi group!

Just bought a new Interapid 312b indicator. 2 questions.

1) What is the function of the 3 screws on the body adjacent to the probe?

2) The indicator came in the box with the pointer at a 90 degree angle to the face, how do I change that angle to make it parallel to the face.

Sorry for the dumb questions, I'm totally new at this.

Chuck
 
The tip will swing in an arc, push it with your finger. I'm not near an interrapid at the moment and I can't remember 3 screws. If they are spread out equally around the pivot they could have something to do with adjusting bearing preload. If it aint broke... don't mess with them. -Mike
 
Thanks for all the input.

From the Long Island Indicator website which 2nd's Mike's advice:

"Unless you know what you're doing, you should under no circumstances attempt to disassemble or adjust any of the screws or bearings on the indicator. "

I've already messed with the little screws on the side and now the probe reads erratically.

Anyone know of a method to return the settings to factory or do I have to send this to a pro?

Chuck
 
Define "erratically". is the needle shakey (shouldn't)? Does it return to the same number each time the pressure is released from the point (should)? Is there side-to-side play in the contact point (shouldn't) ? Is the tip still tight (should)?

More than likely you have released tension on the pivot bearings. If the indicator is no longer set to factory specs you have nothing to loose trying to adjust them back. Once you get it "acting right " again, you'll need a good set of gage blocks to verify accuracy. -Mike
 
Holescreek said:
Does it return to the same number each time the pressure is released from the point (should)?
Click to expand...
I question this point. No indicator is read in space. They're made to do comparative measurements which means they must have a load on them to be read. Where it zero's with no load should be irrelevant unless it's very broken.
 
Holescreek said:
Once you get it "acting right " again, you'll need a good set of gage blocks to verify accuracy.
Click to expand...
DTIs are not measuring devices, they're comparators.

While you can get reasonably accurate readings using careful measurement techniques and correction tables, that's not what the instruments are designed to do. And the effort required certainly is not justified in most situations.

The dial scale calibrations are meant as a general indication of the magnitude of error. More commonly, they just present convenient reference points so you don't have to set the needle on "zero" every time.

When you remove pressure from the stem, the needle should return to exactly the same scale position every time. I have two 312b DTIs and they both perform as described. No deviation is detectable with a magnifying glass.

- Leigh
 
What you guys seem to have missed in Chuck's follow up post is that he has loosened the screws that maintain preset pressure on the pivot bearings. Regardless of you indicator religion you have to recognize that correct function must be restored. I repair somewhere between 1 and 10 indicators a week (depending on fate) and much of diagnosing a problem has to do with answering some simple questions. I have indicators come in that "don't repeat" on or off of a part when putting pressure on the tip and releasing or against a part. The result is the equivalent of what you might see from a loose needle but it is never that easy. I have several Interrapids and B&S and Mitutoyos ... at home too, but that is not relevant to Chuck's question. Even a photo won't help. -Mike

Oh yeah, did you see my follow-up post in the "indicator won't repeat" (or somthing like that) thread?
 
The big question is, why in the world would someone take a screwdriver to a new, beautifully crafted piece of the watch-makers art? ;)
Doesn't he know ze Swiss are anal when it comes to precision, workmanship and quality?

So, if an indicator doesn't return exactly to zero each time pressure is relieved it needs service?
 
So, if an indicator doesn't return exactly to zero each time pressure is relieved it needs service?
Click to expand...

A dancing needle as I call it is one that will not return to any single spot when pressure is released. Sometimes it will go plus, sometimes minus, erratically. My experience is that it can be caused by loose pivot bearings (indicated by needle movement when the probe is tapped lightly from the sides), lost preload on the main spring (typical), bent needle dragging on the lens (rare), loose tip (on a lucky day).

But to answer your question, if my indicators don't return to exactly the same spot (not necessarily actual zero) but are close, it is time to have them cleaned professionally. The same amount of "close" is about the same amount of accuracy you can expect from it.

The big question is, why in the world would someone take a screwdriver to a new, beautifully crafted piece of the watch-makers art?
Click to expand...
Inexperience, lack of a mentor, who knows? Maybe he's destined for a life as an indicator repairman.:D:cheers: -Mike
 
Thanks to everyone for their input.

Peddler wrote "The big question is, why in the world would someone take a screwdriver to a new, beautifully crafted piece of the watch-makers art?"

I've done dumb things in the past, but I always tried to learn from my mistakes. Gotta admit, this was pretty dumb.

Mike wrote: "Inexperience, lack of a mentor, who knows? Maybe he's destined for a life as an indicator repairman."

Don't forget curiosity, plus a fairly high FQ (frustration quotient).

Got the indicator close to where it was originally.

Learned a lot, thanks again.

Chuck
 
Chuck,
Don't let it bum you out. I was a paid machinist for 25 years and never had a co-worker that wasn't scared to work on his own gages. They paid through the nose to have some indicator witch doctor clean and adjust their stuff. Taking it apart and cleaning is usually free. Putting it back together correctly is where the money is made. Curiosity is a good thing! -Mike
 
Chuck Evans said:
Hi group!

Just bought a new Interapid 312b indicator. 2 questions.

1) What is the function of the 3 screws on the body adjacent to the probe?

2) The indicator came in the box with the pointer at a 90 degree angle to the face, how do I change that angle to make it parallel to the face.

Sorry for the dumb questions, I'm totally new at this.

Chuck
Click to expand...

Check out also further down the page "best coaxial indicator"
 
Followup on Interapid 312b

Sent the indicator to Long Island Repair rather than trying to adjust the indicator myself.

Works perfectly and turnaround was about a week.

$92.00 making it a very expensive Interapid but 2 lessons learned. One, don't mess with the little screws on the side, and 2) Long Island Indicator is a great resource.

Thanks to all on this forum for their help.

Chuck
Burbank, CA
 
best laugh all day

Chuck, I have to admitt that was the best laugh I had all day. This is in no way because I have never been so curious as to destroy or upset something in the process of messing with it, but because you were more than willing to face up to what it was you did without trying to hide it. We all make poore judgement calls every now and then but when we learn from them and share that with others is when we truly grow. I normaly work all day without seeing anybody much here in my tool room so when I mess up there normaly is no crowd to bear witness to my ooopps s*%^t what was I thinking moments. But you can bet that after the smoke settles or I finaly finish cleaning up the mess I will find someone to tell, if for no other reason than a bood laugh and the ability to show some one else what not to do. And yes I have also wondered about those little guys on the side but not to the point of doing something about it. Thank you and God bless.;):eek:
MFT.
 
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