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Higher Precision | SPI Hole Mike

Hey everyone it is Nick here at Higher Precision and today we are going to be doing a video demo on the SPI Classic 3-Point Hole-mikes.

With me today I have part number 10-734-2. This is the SPI Hole-mike that cover the range of 1.4-1.6". Graduations on this gage is .0002", accuracy +/- .0001" and can get you down to a measuring depth of 3.15" however extensions are available if you need to get down to a deeper depth. The Classic SPI Hole-mikes are used for high accurate bore measurements and once set to a setting ring, you are all set to go out and start measuring. So what we are looking at here is an individual range SPI Hole-mike. SPI offers the individual ranges however the individual ranges are not supplied with setting rings and must be purchased in addition. On top of the individual ranges, SPI also offers large capacity sets which cover which covers a little larger range. It includes multiple hole-mikes, multiple setting rings and an extension in the case there as well. Just make a note that once setting rings hit 7", SPI actually supplies setting frames because once you hit the 7" mark with rings, they start to get very expensive, very heavy, and very costly to ship around.

So lets take a look at some of the features on the Hole-mike. They do have carbide tipped anvils so they are not going to wear out as quickly if they were not carbide. It is a self-centering and self-aligning bore gage. So once you actually put the holemike in the ring or in your part to start measuring, the gage is going to self-center and self-align on its own so the operator does not have a lot of influence with that. It also has a ratchet stop up here at the top. Now the key is setting a precedent with all the users on the ratchet stop so we are all very consistent and we all get the same readings each time. Whether it is 3 clicks, 4 clicks or 5 clicks, we just have to make sure that all the users of this gage are going to achieve the same number of clicks on the ratchet to make sure we are getting the same exact readings. So that wraps up the features on the hole-mike, lets take a little bit more of a closer look on how to set this gage in a ring.

Now that we have a detailed view on the SPI Holemike, lets check out how easy this gage is to set in a ring. As previously mentioned, the range on this gage goes from 1.4-1.6" and as you will see here down on the sleeve you have a 1.4", 1.45", 1.5", 1.55" and the 1.6" mark. Now taking a look here up on the thimble, you will see it counts from 0 all the way around to 25. Now with that, taking a look at the 0-1 range, you will see 5 subdivisions. Each of those sub-divisions is the .0002" (graduation). So from 0-1 up here is 5 increments of .0002" = .001". So for every time there is a full rotation on the thimble, it actually counts up .025" or 25 thou and it has a total of 8 revolutions to get you the whole total travel of .200".

So lets check out how this gage is to set. All I am going to do, the gage is in the ring, I have a 1.6" ring and I am going to turn the thimble until the ratchet kicks in and I am going to do 3 clicks. 1, 2, 3. Now what I am going to do is come over here to see where the zero is pointing down. It should be pointing down to that line. If it is off quite a bit, what we can actually do is adjust the hole-mike and that is very easy as well. So I am going to rotate the tool just a little bit here so you can see this set screw on the sleeve. Also included with the Hole-mike you get this beautiful top-quality screwdriver as well. Now to adjust it if it does need to be done, you can actually back off on that set screw, you can rotate the sleeve just a little bit so that line is pointing to the zero and then you can tighten that set screw again. From there, your gage is calibrated and ready for use.

That wraps up our video demo today on the Classic 3-Point SPI Holemikes. I hope you enjoyed the video demo. If you have any other specific questions you would like to ask, you can feel free to reach out to us at Higher Precision.com.

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