How to correctly use a height gauge

Yes, but why didn't they just change the numbers on the scale so that they correspond with reality, i.e. the 10 becomes 20 (to be extra helpful, with the tick mark at 5 labelled as 10, etc.), since you have to do that multiplication anyway?

I must admit, a digital one would also save having to look for the appropriate reading glasses (I have recently bought a cheapo digital micrometer for that very reason).

To answer Dave's question, you'll need to know that the 1-2-3 block is a metric 20-40-80...

I have a 600mm mitutoyo digital height gauge here with corroded electronics. If anyone fancies that they stand a good chance of repairing it, they are welcome to come and take it for free.

The encoder WAS working, though the plug had been removed and the wires soldered direct to the PCB due to the corrosion mentioned. The battery box is intact but heavily corroded from a past leaked cell which is what I think caused the rest of the corrosion prior to my owning it. The LCD display was hit and miss when I got it, it would come on and then fade out within seconds, or sometimes come on and stay on. It had suffered a couple of repair attempts and now does not come on at all though that is a recent development. It seems the electronics are actually functioning to an extent as the led comes on when the power switch is set to the middle position which I think signifies output to remote display.

Anyway, it's here, it's scrap from my perspective. I'd love to make it work but my electronics knowledge is weak, so if no-one wants to pop along and collect it, it's going in the bin.

It's the same as the one in the link below, except it's in bits and has no scribe or clamp. All of the parts are there for it to be potentially repaired however.

**LINK**

Hi Andy, as I've said, the resolution is 0.02mm, that means each of the Vernier marks represent 0.02mm, so if you made the 10 into 20 =, that would be 20 X 0.02, which would make it read 0.4mm instead of 0.2mm, so then you would have to divide the 0.4 by two to get the correct answer.

Regards Nick.

Thank you for your reply Jason. I am still trying to understand it but I am working on it! it has become clear to me that I could do with some fundamental instruction on how to measure with a height gauge. Is there a web article on it? What I am trying to do is measure hole centre positions on a plate in order that I draw up the item. In my wisdom I thought that by using a 'finger' DTI would give me a more better 'feel' for the bottom of the hole edge and the 'top'? Which would also give the hole dia.. I thought about making dowels to fit the holes then measure the bottom and add half the 'plug' size but that seems a awful long winded method. Any help appreciated.

Gary

Pete. I had a mitutoyo like that with corrosion in the battery box. Some bloke picked it up from an ebay sale and I got 65 quid for it.

That's how I would do it. Hard to measure holes directly.

I don't know of a guide to using height gauges. The principle is straightforward, but as with other precision measuring, technique is vital when accuracy matters, including taking the same measurement several times.

I practised with objects of known size until I got my height gauge to agree repeatedly with reality. As it's hard to judge by feel, I often shine a light behind the pointer to highlight the gap, and/or eyeball it with a loupe.

Digital Readouts are easier - the display is unambiguous, with zero reset and absolute reading, in inches and millimetres. Verniers make my head hurt.

Dave

Firstly, it's probably easier to search for videos than web articles on how to use your height gauge.

If I'm reading your requirement correctly;

How about the following; bear in mind that lever indicators give the best readings when the lever is parallel to the surface being measured.
I'm assuming you have one of the more conventional DTIs, where there is a lever to change the direction of measurement, rather than a central "both way" indicator needle position.
To maintain any consistency, you need to use the clock in the same direction each time.

You seem to have a metric height gauge, so find or make something, which is an exact sensible measurement, say 1 or 2 cm; lets call it 2cm
Ensure that your workpiece is vertical on your surface plate/flat surface
Set your height gauge to the thickness/height of your test block i.e. 2cm
Add the DTI and zero it on your test block height, without adjusting the height gauge.
Move the workpiece to the height gauge/DTI assembly and adjust the height gauge only for a zero reading for the DTI on the bottom of the hole; you're obviously looking for the lowest point.
Read and record the height gauge reading; add 2cm and that's the distance to the bottom of the hole from the lower edge of the plate.
Find a length of round ground bar which fits in the hole, and clamp/wedge it in place at the very top of the hole.
Now use height gauge/DTI again to measure to the top of the ground bar, this time, you're looking for a maximum reading; read and record the height add 2cm and you have the distance from the top of the hole to the surface plate.

Subtract the two readings and you have the hole diameter, and can easily calculate its centre.

It would help to know what other measuring kit you have, e.g. internal micrometers, slip gauges etc. as well as the accuracy you're trying to achieve; also what size roughly is the workpiece.

Ideally now check your calculations using a different method.

This is quite a good video on why DTI's are often best used as indicators, rather than for direct measurements (unlike plunger clocks), and why I've described taking all actual measurements off the height gauge.

Several good points also made in this one, particularly if your surface plate isn't perfect.



Bill

Edited By peak4 on 08/05/2023 16:33:21

Pete,

I managed to repair exactly the same Mitutoyo height gauge, which had a fair bit of corrosion. It is time consuming and needs a good magnifier, rather than being difficult. Pity to throw it!

Andrew.

Hi Nick, perhaps I'm being obtuse here, but if the vernier scale didn't have the "Ver 1/50mm" label, and the numbers ran from 0 to 100, you would simply read it directly, so that in the photo you would get 40mm + the number which lines up on the vernier which would now be 80 rather than 40*, giving the reading of 40.80, no need for mental arithmetic to double the vernier reading (and it would be obvious that each minor graduation was 0.02 since there are five to each 0.1 graduation).

Its not a huge deal, and I don't use the height gauge often enough to be bothered by it, but it always strikes me as a curious design which unnecessarily increases the risk of error (especially for people like me who are rubbish at mental arithmetic).

Hi Andy, I understand what you are saying, however the numbers 10 to 50 are not directly depicting the measurement, but are showing the number of divisions of every fifth of the Vernier scale, and you will see the Vernier scale covers 49mm, therefore each division is 0.98mm apart, which gives you the 0.02mm resolution.

The one I have was at one time, owned by Vickers Eng. South Marston, and was last calibrated in their calibration department on the 1 / 2 / 84 with its next one due on 1 / 2 / 87. If it was good enough for Vickers, I'm sure it meets my needs. I have checked the calibration in the best way I can, and it looks very good to be correct.

Regards Nick.

Thank you Bill and Dave for your inputs. Things are now beginning to dawn on me that I have perhaps asked too much from my measuring techniques and the instruments I use. After using a vernier height gauge I bought myself a digital one in order to get away from all the arithmetic (and mistakes!) but I still seam to have a lot to learn.

Using the height gauge and a 'finger' Mercer Type 301 DTI I thought the measurements would be a doddle by touching the bottom and top of the hole with the stylus and reading the height gauge. Ni eve! Following the input received from yourselves I have adopted the following method:

1) with DTI attached to height gauge zero Mercer clock with about 0.005" (0.127 mm) deflection of the stylus on a gauge block of a known dimension. The height gauge is also zeroed and ABS zeroed. Raise the height gauge and adjust the height gauge to zero the Mercer clock on the lower edge of the hole. Note height gauge reading and zero the height gauge. Now place a piece of round bar in the hole and wedge it to touch the top of the hole with a piece of Plasticine. Then bye again adjusting the height gauge to zero the Mercer clock on the top of the round bar I have got a hole size. Magic! Also using the ABS button on the height gauge I have also an ABS dimension to the hole top edge as a check for the hole size. I am now more confident of my measurements. Don't forget to add the gauge block dimension to the ABS dimension!!!!

Thinking about it, the way the Mercer DTI reads has perhaps led me astray, the needle only rotates clockwise whether the 'finger' is raised or lowered. Pesky thing!!

Regards Gary

Gareth,

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