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Mitutoyo 14" QM-Height (518-221)

dksoba

Hot Rolled
Joined
Apr 8, 2011
Location
San Diego
I'm about to buy one of these from Penn Tool Co. (they seem to have the lowest price). I've been recommended by other shop owners that a good height gage is one of the first inspection tools I should purchase (with a surface plate to go along with it). I've used a Trimos before, and I liked what it could do. I think the Mitutoyo can do basically the same thing as the Trimos my friend has.

Can anyone think of a reason not to buy the QM-Height? I think it's a good inspection tool that can be used to inspect dimensions down to +/- 0.001".

Anyone have any experience buying from Penn Tool Co? Are they reliable?

Thanks,
Matt
 
Did you forget a "0"? If ±0.001" is good enough for you you can settle for less than what you're looking at. That model can do ±0.0001"

Having said that then you won't go wrong with Mitutoyo.

Have you read this? http://www.greatgages.com/QMHeight.pdf

Gordon

Actually I haven't calculated what the error budget really is. But the link you sent me says +/- .00011". I can't inspect a +/- 0.0001" dimension with that accuracy if I use the "general rule of thumb" that the accuracy should be 1/10th of the tolerance. Eventually I hope to get AS9100 certs. That goal is a long time in the future, but I figured I should start now trying to understand the requirements and implement them as best I can. I'm a one man shop. I hope to organize my business such that it can operate completely independent of me.

One thing I have trouble measuring is hole positions. I would like to measure the true position of holes accurately, because they are called out on my drawings. The other thing is that I would like to eventually get into 100% inspection. The only other way of measuring holes that I know of is using gage pins and calipers. It's pretty time consuming if you had to do that on every part.

Do I have the right idea behind only being able to use this probe to measure +/- 0.001" dimensions? And I suppose with calipers that means (my mitutoyo are +/- 0.001 accuracy) I can only measure +/- 0.010" dimensions accurately. Or is it that the resolution of my measuring instrument should be 1/10th the tolerance, in which case I could measure +/- 0.005"?
 
First - height gages are very useful, and that's a good one. But of course it only measuring 1 dimension - up. So getting the true position of holes when there isn't some kind of reference that can be held against a surface plate will require a fixture. Also, while surface plates are Very Flat, they are not Infinitely Flat.

Second - the rule of 10 or rule of 5 are just rules of thumb. There are some fields (astronomy, say) where the measurement is so difficult the error bar will always be larger than the variation of the quantity under study, and advanced statistical techniques are required to prize out the answer. For metrology, it's not just the accuracy/precision, but also the variability. (Hence R&R reports and so on.)

All that said, I think you'll find that to be a good height gage.
 
List of my current measuring tools (in no particular order):

8" Mitutoyo calipers
12" Nikken caliper (chinese calipers... I avoid using them at all cost)
Starrett .0005/foot level
Centering indicator
Mitutoyo 0-1" absolute coolant proof digimatic ... OD micrometer
SPI 1-2" micrometer with vernier scale for .0001 readings
Telescoping gages
SPI 1.2-1.6" 3-point bore micrometer (it's in the mail, anyways)
.061-.250 gage pins, both plus and minus
A few 1-2-3 blocks
.0001" DTI
.001" DTI
.001" dial indicator
Misc. gage pins that I ordered

My "buy it soon list" (in order of priority, not including the height gage):
Depth micrometer (I got my eye on a digital mitutoyo)
Inside micrometers for small stuff (but I can probably get away with just using the height gage I'm going to buy)
81 piece gage block set (but what grade is good enough to calibrate my tools with?)
Possibly the other (less than .061 and greater than .250) gage pins, maybe even the +0.0005" sets too... That's so many pins!
Bigger micrometers, but probably buy as needed
Sine block

Longer term purchases:
Toolmakers microscope
Optical comparator (maybe? They seem quite useful)
CMM (wouldn't even know where to start looking or how much money to save up for one of these bad boys)
3-point anvil micrometer for measuring tool diameter for 3-flute tools (maybe I can do this with a v-block and a height gage)


I've been dieing to get this height gage and saving up for a while now. I know it's probably one of the most essential items for my inspection equipment. But after that, I'm not sure what I'll need next. Probably the depth micrometer since that's something I've needed but I didn't have. It would be especially useful for measuring depth on the machine.
 
That's a really nice height gage. I assume that's the type that makes the little beep noise when you've touched down on the widget you're measuring? This may be ignorance, but can you use those with a dial indicator? I really like to be able to put an indicator on a height gage to sweep tooling holes, etc. If not, a dual beam mitutoyo and a nice indicator might be the first height gage I'd buy, and something like what you posted would sit in the calibration lab.
 
I assume that's the type that makes the little beep noise when you've touched down on the widget you're measuring?
The beep thingy is really just a sales gimmick, of no practical value.

You can't use 'point of contact' as 'point of measurement'.
Proof of contact always requires some deflection of the instrument, thereby introducing a potential variable or inaccuracy in the measurement.

The 'proper' (if I may) way to make a measurement is to set the DI such that it deflects a specified amount at the nominal dimension.
The magnitude of the deflection might be .001" or .005" or whatever is appropriate to the range of the DI and the measurement accuracy required.

I normally try to set things up so the nominal dimension has the DI needle at the 12 o'clock position.
This is the reason that DIs have the hand at 9 o'clock when the stem is released, so it won't be confused with a measurement.

- Leigh
 
The beep thingy is really just a sales gimmick, of no practical value.

You can't use 'point of contact' as 'point of measurement'.
Proof of contact always requires some deflection of the instrument, thereby introducing a potential variable or inaccuracy in the measurement.

The 'proper' (if I may) way to make a measurement is to set the DI such that it deflects a specified amount at the nominal dimension.
The magnitude of the deflection might be .001" or .005" or whatever is appropriate to the range of the DI and the measurement accuracy required.

- Leigh

Leigh,

I appreciate you commenting and helping me understand the tools. The beep I'm referring to is from a very nice B&S height gage that has a floating head. Something similar to this:

All : Brown & Sharpe MICRO-HITE Electronic Height Gage

The gage doesn't register until the head has moved a certain amount (reminds me of a CMM). Are you able to use a dial indicator with this type of height gage? I assumed this was the type that was posted in the OP.

Again I appreciate your input.
 
The Micro-Hite is actually a DRO in a fixed package, so there's no DI to be used with it. It's a different category of machine.

It reads out dimensions in absolute terms, just like the DRO on a mill.

- Leigh
 
The Micro-Hite is actually a DRO in a fixed package, so there's no DI to be used with it. It's a different category of machine.

It reads out dimensions in absolute terms, just like the DRO on a mill.

- Leigh

Thanks Leigh. That helps a bunch. I thought this was the type of machine being posted by the OP. IMO this type of machine is great for a calibration lab but not much use in the tool room. I need to be able to put an indicator on a height gage to sweep holes for a good portion of my height gage use.
 
Anyone have any experience buying from Penn Tool Co? Are they reliable?

Thanks,
Matt

I ordered from them once: One of the items that I ordered didn't seem to be available and they didn't seem interested in trying to get it. Though they may normaly be great, I found myself wondering off to spend my money elsewhere.
 
dksdoba,

You're getting me very confused. Your OP states ±0.001" and then in post #3 you write "I can't inspect a ±0.0001" dimension with that accuracy ......." What tolerance do you want to be able to measure with the Mitutyo height gauge? What's the finest tolerance you're hoping to be able to measure without looking too far ahead?

You list the measuring equipment you have and what you want but what are you making (own product or supplier?) and with what (manual, CNC?)? There's a huge difference between wanting and needing.

Gordon
I want to measure +/- 0.001" with a tool that can measure 1/10th of that. If I had a tool (like calipers) that measures +/- 0.001", I cannot measure +/- 0.001" dimension. If the caliper reads dead on, that could arguably qualify for being in tolerance. However, if the caliper reads off by 0.0005", you don't know if it's in tolerance or not.

I'm making parts per print (job shop style) using a Fadal 4020. I get parts with sometimes ridiculous tolerances or dimensioning. Usually a phone call can resolve this issue, but not always. I've had parts returned to me because I didn't have a way to verify that they were in tolerance, and they weren't. I had to drive 30 miles away to a friends shop who has a trimos to verify that my parts were out of tolerance, and then go back to my shop, remake a first article, drive all the way back, check it, etc.

My local tool supplier quoted me $2420 (+ tax) so I think I'm going to buy it from him. I'll end up spending a bit more but I'll keep my tool supplier happy and he's someone I want to keep happy because he's helped me out in the past. Those guys will come deliver a single $2 drill bit to my shop with no delivery charge.
 
Thanks Leigh. That helps a bunch. I thought this was the type of machine being posted by the OP. IMO this type of machine is great for a calibration lab but not much use in the tool room. I need to be able to put an indicator on a height gage to sweep holes for a good portion of my height gage use.

You can put an indicator on this. It also has the ability to sweep holes. I'm assuming it uses a strain gauge to detect the deflection of the probe.
 
Let's get something out of the way first :) Yes, if you are measuring something with a ±0.001" tolerance then something with a ±0.0001" accuracy is the correct way to go. The "10 times" rule of thumb is a sensible rule.

Then you write "I've had parts returned to me because I didn't have a way to verify that they were in tolerance, and they weren't.".
You are telling me that you delivered parts with a fine tolerance not knowing if they were within tolerance or not? Either you are a very nice guy or very inexpensive (perhaps both? :)) because I don't know many customers that would find that acceptable.

Buying the Mitutyo height gauge is certainly a (big) step in the right direction so "Good luck" ;)

Gordon

I let the customer know that they might be out of tolerance before accepting the job. I asked how they were going to measure it, they said they weren't. If it doesn't fit, they said they would have it measured by an inspection service, which is what happened. If it wasn't a quick turn-around job, I would have taken the pieces somewhere to get them inspected. I still made money on the parts though. I'd like to be able to do my own inspections since it would be a pain to take my parts somewhere else every time I need a certain measurement inspected.
 
I've owned this height gage for about 1.5 years and I use it at least once per day on most days. Overall it's repeatable and accurate, well built. It was worth way more than what I paid for it (something around $2500 after shipping/tax, iirc). There are a few differences from the Trimos gages that I would like to point out, since they were a surprise to me (although it's in the datasheet, I must have glossed over it). The measuring force is kind of high (roughly 1.6 newtons or 0.36lbs), which can make small parts difficult to inspect. The second gripe is the distance traveled between the stylus touching the surface to be measured, and the when the measurement actually registers (about 5-6mm). Of course, this is all for good reason, but I seam to remember the trimos having a much shorter "after-contact travel before measurement is taken".

Anyways, thought I'd post this up here before asking my next question so that anyone interested in buying a QM-Height 350 has this info (and feel free to PM me if you want more details).

Cheers,
Matt
 
How is that Mitutoyo QM height gage going.

How is your Mitutoyo QM height gage going? Went to see one at the local dealer and it looks good.

I'm looking to purchase a height gage. Had a Mahs CX-1 but that stopped working. Was old. Now looking at the Mitutoyo QM, the Tesa Hite, the Tesa Magna and the Sylvac Hi-Cal. Only need about 350mm travel. From what I have researched so far, the QM has air cushion but no motorised carriage, the Sylvac is opposite this, the Tesa Hite is like the QM and the Magna doesn't have either. Magna is less accurate but more robust due to magnetic strip rather than encoder. QM and Tesa Hite are about the same accuracy levels. QM takes AA batteries which is nice.

Have read threads but not many on these gages.

Thank you.
 
How is your Mitutoyo QM height gage going? Went to see one at the local dealer and it looks good.

I'm looking to purchase a height gage. Had a Mahs CX-1 but that stopped working. Was old. Now looking at the Mitutoyo QM, the Tesa Hite, the Tesa Magna and the Sylvac Hi-Cal. Only need about 350mm travel. From what I have researched so far, the QM has air cushion but no motorised carriage, the Sylvac is opposite this, the Tesa Hite is like the QM and the Magna doesn't have either. Magna is less accurate but more robust due to magnetic strip rather than encoder. QM and Tesa Hite are about the same accuracy levels. QM takes AA batteries which is nice.

Have read threads but not many on these gages.

Thank you.


Actually I meant to say I had a Mahr, not a Mahs. One other point is that, while not the most accurate way of doing things, I would like the option to put a dial/test indicator on the electronic height gauge carriage to measure the squareness of a part. The QM's perpendicularity spec is better than the others, and on the Sylvac you can't put a test indicator from what I can tell. As I said, not the main game, but when you're spending this sort of money on a measuring instrument you want to have as much versatility as you can. So I was leaning towards the Mitutoyo QM. The one thing that I did notice which was a bit annoying on the QM was that when sweeping circles, you have to press enter when the low and high points are reached, then enter again I think to get the diameter. The Tesa units don't require this much button pressing for circle diameters, and the Sylvac is even less again from the Fowler/Sylvac videos. Price wise, the Magna is the lowest cost with the other three similar. Also the Sylvac is about 6kg with the other three mid twenty kg's. I can see why the Sylvac doesn't need air cushion.
 
The QM Height gage I have doesn't have the air cushion mode. It also uses batteries quickly, but I wired up a wall wart power supply and that solved that problem. The tool is well made and gets the job done. I learned a lot about machining by being able to measure my parts so accurately with it. Also... there are settings you can change, like whether or not you have to press enter when sweeping in circles. I have it set to just register the bottom when I change directions. Works wonderfully.

I don't have much experience w/other height gages. My QM Height is awesome though.
 
Thanks for the info. Much appreciated. Also great to know you can avoid the constant ENTER button pushing. The batteries will last even less with air cushion being operated but somehow, the AA battery feature seems still nice to have. With my previous height gage (Mahr CX-1) I would have to have it constantly on charge mode and the QM's battery reserve is like 300 hours without air cushion, that's 5 times most others. In theory anyway.

Thanks again.
 
Bought the QM 14:. Impressed so far. Maybe only thing concerning me is that the LCD is not backlit an in certain light (workshop) it is hard to read..
 








 
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