Height Gauges...

[Ray C]

Here are two height gauges and a little explanation of each -to the best of my current understanding.

The first and most simple is dual column electronic height gauge which is as easy to use as a digital caliper. In the example, I'll measure the width of the machinist block which I'm pointing to. This is a simple example and I'm not using a stylus. The anvil of the gauge is placed directly on another machinist block and the electronic unit is zeroed. This is just establishing a zero reference point.



Next, the other block is placed on the reference block and with a crank on the back of the unit (which you can't see in the picture), the anvil is lowered into contact then, a measurement is taken. Simple as that... It's reading 0.500".



This was a very simple case and most often a stylus is used. They can take any shape or be home made and they're clamped to the anvil. I could very well attach a TDI to the anvil and that way, I could see exactly when contact is being made when the TDI starts to show a reading. I purchased this unit used at less than half the new cost but, it did not come with any anvil clamps -not a hard problem to overcome. A simple unit like this will cover all my basic needs.



Although I don't have an immediate need for such precision, I saw this Mitutoyo Height Master gauge and at $200 decided that good deals like this don't come often. This unit has a little dust and light film of grime but appears to be in perfect condition otherwise. I will need to check it with reference blocks but, the PO said it was dead on. These units are very precise -and very heavy to the tune of 50-60lbs. They work on a very similar principal as the other unit but, it does not have an electronic means of zeroing. Also, it has a total travel of one inch but, there are 12 anvils so, the stylus would be placed on the nearest anvil as needed.



Each inch on the face scale is subdivided in 0.1" increments and there are three marks (0.025") subdividing each tenth of an inch.



Once again, different stylus types could be attached to the anvils.



Readings are taken by first zeroing the stylus on some reference point which is done by turning the top (knurled rings) until the reference is touched. Next, the bottom ring (by my thumb) is rotated to the zero mark on the top ring. Note: There are two knurled knobs which are connected and fixed and spin with the top ring. The two knurls are just for convenience and there's also a little crank lever but it got cropped out of the picture.

Next, the part would be positioned and the stylus touched off on the part by turning the top ring until contact is made. The top ring is numbered 0 thru 250 and each line represents 0.0001" (ten-thousandth inch) thus, one complete revolution is 0.025" -which is the amount corresponding to the fine lines on the face scale. On the bottom ring, note the numbers and lines with 0, 5 and 10. Those are hundred-thousandths (0.00001") and just like a micrometer which reads ten-thousandths, you line-up those marks in the event that the 0 on the top ring does not line-up exactly with the 0 on the bottom ring and it gives hundred-thousandths.



So there you have it... Two types of height gauges...


Ray

 

[8ntsane]

Thanks for sharing Ray
Nice tools too :thumbzup:

 

[Cheeseking]

Very nice Ray. What are some typical uses for height gauges? (gage?)
I picked up a B&S 18" vernier version for $50 at a local auction last week. Total impulse buy not sure why I bid but I won it so now what. Ha! Thats what I get going to auctions with no plan.
I do have a steel surface plate I guess it can set on.

 

[Ray C]

Well, I wiped the new/old Mity height gauge with some alcohol and it cleaned-up well. Sorry for not taking pictures with it in better shape but, it just arrived -and of course no instructions and nothing of use on the Internet so... I had to stare at for 10 minutes and figure it out. Writing an explanation of how it (appeared to) work is the best way to test understanding. Of course, I measured a few things to make sure the explanation was on track before pressing the "Submit" button.

BTW: That block that reads 0.500 with the dual column reads 0.49822 with the Mity and it varies about 0.00007 at different corners. The readings are about dead-on consistent with an electronic mic that's good down to 0.00005 but shows a couple digits past it's defined precision.

Admittedly, it takes a few moments thought to read that thing and get all the decimal places right in your mind before writing the number down. -A little practice will be needed.

Anyhow, in some of the work I'm doing, purely as an exercise, I'm shooting for half thou precision (even when not called for) and I've been able to see tenths with my existing mics but this is the first clear picture I've ever seen of hundredths. They're pretty small little fellows indeed and make half thou seem like a half mile...

Ray

 

[Ray C]

For something like the Height Master, you could check gauge blocks for accuracy because you can directly derive heights in absolute numbers.

Eg. If you had a granite plate and some surface ground plate of metal, you could put a TDI on a holder, slide it on the granite with the stylus touching the part's surface and you could see that maybe the surface was uneven by say +/- 0.0002". With this type of unit, you could also measure in uncertain terms, the thickness of the plate along with it's variance.

As for what types of parts need such precise measuring, the sky is the limit. Control parts inside of physics lab equipment for nuclear accelerator apparatus comes to mind. Internal components of guided missile systems... Telescope triangulation equipment for measuring distances of distant galaxies... I'm sure the mechanical bomb dropping aiming devices in the WWII planes were high end stuff with precision in that realm... The list goes on.

BTW: Admittedly, I don't have immediate need for this but, used ones are going for nearly a grand they still make these and they're a couple grand. 200 bucks was too cheap to pass up.


For the dual post unit, Ive already used it to check concentricity of the holes I bored for my taper blocks. I want them under a half thou with a 6" projection.

Ray

Very nice Ray. What are some typical uses for height gauges? (gage?)
I picked up a B&S 18" vernier version for $50 at a local auction last week. Total impulse buy not sure why I bid but I won it so now what. Ha! Thats what I get going to auctions with no plan.
I do have a steel surface plate I guess it can set on.

 

[Tony Wells]

Ray, Ray, Ray.......grasshopper, you have much to learn. When I get time, I'll write up some stuff on the Height Master.

 

[Ray C]

My new name is Kwai Chang Caine!

Ray, Ray, Ray.......grasshopper, you have much to learn. When I get time, I'll write up some stuff on the Height Master.

 

[Ray C]

Here's a quick additional explanation of how to read the dial on the Height Master.

Inches and tenths of inches are read off the face. Each tenth inch is subdivided with 3 lines corresponding to 25, 50 and 75 thou. That part is pretty straightforward and easy to read.

The dial on top has 250 divisions (each 0.0001") numbered 0 through 249... The best way is to show by example but for now, lets skip the face part (because it's nothing more than a ruler) and focus on the fractions.


This first one reads I.TH513 where "I" is inches, T is tenths and H is hundredths read off the front face (ruler). This is read by looking at the bottom 0 and seing that 51 is before the zero tick mark. Next, look at the lines on 0, 5, 10 scale and see which one lines up most closely with another line on the major scale. In this case, I judge it is 3 but one could argue it's closer to 4. -Depends on the angle you look at and I took the picture to purposely add this little complexity. One could argue it should be read as n.nn5135 but that's probably taking liberties that will get you nowhere.






Next is a simpler case and it reads n.nn510.




Reading the dial is pretty straightforward but where I could use a few suggestions (hint, hint, Tony) are postitioning techniqes and how to check against the anvil. In the case of the dual beam, it's pretty darn easy. This seems a little more awkward -and again, I don't profess to have all the answsers on this device as, I wasn't initially in the market for it but, it called-out to me and wanted a caring owner.

Ray