Test indicator contact point

Can you guys tell me if this (http://www.mscdirect.com/product/details/06445340) will work with a Mitutoyo 513? Thanks! If it will not work, do you guys know of a 2" or so contact point I can use with a Mitutoyo 513?

I see they sell 3 different length stems for 513 indicators on some sites. I would think the longer the stem it would make I more sensitive because of the multiplication of error. I would suggest you contact Mitutoyo or these guys on Monday and ask them.
6 : Questions & Answers

Richard King said:

I see they sell 3 different length stems for 513 indicators on some sites. I would think the longer the stem it would make I more sensitive because of the multiplication of error. I would suggest you contact Mitutoyo or these guys on Monday and ask them.
6 : Questions & Answers

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Hi Rich,
The longer contact point actually makes the indicator less sensitive, as the distance traveled at the tip results in less rotation at the pivot, so less displacement of the display needle. I have to remind myself of that each time I use one for deep bores.

OP, that tip is sized for Interapid indicators, and going by LII those may take a different thread than Mitutoyo indicators. Check these two pages for info (good stuff to read if you don't have much experience with these tools):

�21 : Test Indicator Contact Points (Interapid)
186: Mitutoyo test indicator contact points

Check the catalog these guys have online. Carbide Probes inc: Manufacturer Of Test Indicator Tips | Styli | Carbide Probes

skeeks said:

Can you guys tell me if this (.8 Inch Ball Diameter, Carbide, Ball Test 644534 - MSC) will work with a Mitutoyo 513? Thanks! If it will not work, do you guys know of a 2" or so contact point I can use with a Mitutoyo 513?

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I believe Mitutoyos use the same thread as a Brown&Sharpe: M1.4. They make a 1-7/16 stylus for the B&S DTI's, but they are hard to find and expensive. I grabbed an Interapid 2.75 stylus for cheap from ebay along with an M1.4 die. Interapid's use a M1.7, I believe, and there's plenty of meat to cut down and thread to an M1.4.

Thanks gents. I've got the 513 dti. I'm trying to find a way to measure the throat area of the grooves/lands with a long stylus and without preboring. Ideas?

Which 513 series indicator? The square body or the round body 'pocket' style?

If the chamber is bigger than a .223 chamber, drill it out first and stick the round body indicator up inside. If you have the square one, pitch it and get one with a round body.

Usually if you switch contact point lengths you will get a false reading. Old Interapids used to come with two of different lengths, but the instructions noted that you would have to double your reading with the longer. I would be wary and double check readings with a Cadillac gage.

Why worryt about it? If you have a pilot on the tool and a floating holder that chamber is going to be right behind that pilot regardless. If you try to make it otherwise I see a broken pilot in your future.

tdmidget said:

Why worryt about it? If you have a pilot on the tool and a floating holder that chamber is going to be right behind that pilot regardless. If you try to make it otherwise I see a broken pilot in your future.

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I do have both, I just would like the chamber to be as close as possible. I'm brand new to all this. Hopefully cutting my first chamber and such next week.

tdmidget said:

Why worryt about it? If you have a pilot on the tool and a floating holder that chamber is going to be right behind that pilot regardless. If you try to make it otherwise I see a broken pilot in your future.

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For chambering, I agree. Chuck it in a 3-jaw! But you want the chamber as concentric as possible with the tenon so you need the bore concentric with the spindle.

Play with the length and the reading will not be what the dial face says.
One can do the same with contact angle.
A couple of gage blocks on the plate can get you the new calibration and this is sometimes done to get higher resolution.
Long arms reduce your resolution. A DTI "sees" angles. .001 over and inch is less angle change than .001 over 3/8.

GenePoole said:

For chambering, I agree. Chuck it in a 3-jaw! But you want the chamber as concentric as possible with the tenon so you need the bore concentric with the spindle.

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Then there is "order of operations". If you want the tenon at some mystical concentricity then you must recognize that you have limited control over the chamber location. Cut the chamber first and put the center in the chamber and cut the tenon.

CarbideBob said:

Play with the length and the reading will not be what the dial face says.
One can do the same with contact angle.
A couple of gage blocks on the plate can get you the new calibration and this is sometimes done to get higher resolution.
Long arms reduce your resolution. A DTI "sees" angles. .001 over and inch is less angle change than .001 over 3/8.

Click to expand...

Just adding to what you said Bob,

* Or did I have this backwards? and it is the log stylus makes the reading more? Thanks Mike.

*You may wish to substitute a long contact point on short point models. If the point is exactly twice the length then the readings on the dial will be doubled. A .0001" indicator will now read .0002" and a .0005" indicator will now read .001".
21 : Test Indicator Contact Points

johnb53405 said:

Usually if you switch contact point lengths you will get a false reading. Old Interapids used to come with two of different lengths, but the instructions noted that you would have to double your reading with the longer. I would be wary and double check readings with a Cadillac gage.

Click to expand...

I can't speak specifically to the Interapid model, but I have an older Federal that is opposite of what you say here. It has a longer? point (about 1" long) than what I think was standard, and it reads double, so if it checks .001" on the indicator, it is actually .0005".

For some reason, it confused the hell out of everyone else, but I kind of liked it. Since it had .0005" graduations, I could check to .00025" pretty easy.

GenePoole said:

I believe Mitutoyos use the same thread as a Brown&Sharpe: M1.4. They make a 1-7/16 stylus for the B&S DTI's, but they are hard to find and expensive. I grabbed an Interapid 2.75 stylus for cheap from ebay along with an M1.4 die. Interapid's use a M1.7, I believe, and there's plenty of meat to cut down and thread to an M1.4.

Click to expand...

In the last few months, as I've picked up machining my own rifle barrels as a hobby in my semi-retirement from biotech, I've found this forum immensely helpful in a variety of aspects. The various methods and reasoning for them are great to see and helpful thinking through the how and why. Thank you to all the contributors.

I know this is an old thread, but it seemed the most appropriate one to post this. In evaluating various DTI's, contact points, deviations from true measurements when using contact points that are not the original length, etc., I struggled to find good information on interchangeability of contact points. In particular, specs on threads. I have been corresponding with John Heeg at carbideprobes.com, and he has been very helpful regarding my early 1980's Mitutoyo 513-212, which I inherited from my father.

Here is a method for determining the thread for contact points that match your model. At carbideprobes.com, input your model number. The results will give options for contact points of the appropriate length to match your OEM contact point. Select a contact point to go to the page for that individual contact point, then select the dimensional drawing. Note the threads.

To see your options for contact points of other lengths, return to the carbideprodes.com homepage, follow the link to “Tips for Dial Test Indicators” and input your thread size, desired length, etc. into the filter on the right. The returned search results give you your options.

For instance, the suggested contact points for a Mitutoyo 513-504 (round barrel, 0.0001 indicator) will be found to be 0.598” from shoulder to center of tip and have M1.7x0.35 threads for 0.059”. Filtering “Tips for Dial Test Indicators” for M1.7x0.35 threaded contact points of 2.75” in length and following to the individual contact points shows that these have M1.7x0.35 threads for 0.145”. So, with brief file or grinder time to shorten the threaded shank, the 2.75” contact points (such as part no. 142-060 for Interapid) can be fitted to the Mitutoyo 513-504 and measurements resulting from its use would be off by a factor of approximately 4.6. Thus, the individual marks that originally representing 0.0001” would now represent ~0.00046”.

I'm told that "The standard thread designations with pitch would be M1.4X0.3 or M1.7X0.35, most everyone shortens this to M1.4 or M1.7 because those are the most common pitches for those metric threads.".

I hope others find this useful.

johnb53405 said:

Usually if you switch contact point lengths you will get a false reading. Old Interapids used to come with two of different lengths, but the instructions noted that you would have to double your reading with the longer. I would be wary and double check readings with a Cadillac gage.

Click to expand...

I use an Interapids with a long-point (2.5"?) to align my barrels with the spindle (through the headstock method) and I don't care about the reading's accuracy. As the point jumps up and down over the lands you are looking for the indicator to return to the same reading, whatever it is, to determine concentricity of the bore with the spindle. As I rotate the spindle by hand I adjust the 4-jaws so that the indicator returns to the same "reading" indicating that the the concentricity of the barrel is within 0.0005", or better, with true center. I do this at two points within the bore to ensure that I have a "cylinder" of the bore to this same accuracy while also adjusting the spider at the other end of the spindle.

My home made solution
It can measure about 3.7 inches down a. 221 bore with similar performance .as using just the indicator
Second photo is upside-down it uses gravity to hold the point up in the bore