Measuring a ring gauge ?

Milling man · Feb 19, 2022

jccaclimber said:
I’ve used a lot of air gauges, but never tried to DIY one, that’s an interesting idea. One word of caution, you can make the read value on an air gauge change a tenth with changes in surface roughness, so consistency is key as always.

If you make this device yourself, it makes sense to measure not pressure, but air flow. The flow meter is easy to make yourself - it is a transparent tube with a conical bore. The taper is selected empirically, but it should be very small, about 1:50-1:100. The tube is vertical, the smaller diameter of the cone is from below, the air supply is also from below. There is a ball in the cone, the material of the ball is also selected experimentally. Obviously, with a very small taper, even a small change in flow rate will lead to a very large change in the position of the ball.
This is exactly what our old turner described to me. He worked a lot with lapping operations, and the holes had to be measured with an accuracy of about 0.5 microns. Such a thing quite allowed to do this, but there was one rule - the gap between the pin and the measured ring should always be approximately the same. That is, it is impossible to measure rings with a diameter of 20-21 with one pin with a diameter of 20.

Velisendderr · Nov 26, 2022

Milling man said:
If you make this device yourself, it makes sense to measure not pressure, but air flow. The flow meter is easy to make yourself - it is a transparent tube with a conical bore. The taper is selected empirically, but it should be very small, about 1:50-1:100. The tube is vertical, the smaller diameter of the cone is from below, the air supply is also from below. There is a ball in the cone, the material of the ball is also selected experimentally. Obviously, with a very small taper, even a small change in flow rate will lead to a very large change in the position of the ball.
This is exactly what our old turner described to me. He worked a lot with lapping operations, and the holes had to be measured with an accuracy of about 0.5 microns. Such a thing quite allowed to do this, but there was one rule - the gap between the pin and the measured ring should always be approximately the same with air flow meter. That is, it is impossible to measure rings with a diameter of 20-21 with one pin with a diameter of 20.

Hi, how can I make air flow meter by myself? You've explained very well but I'm unable to understand it. I've to use gas flow meter for measuring gas flow in natural gas pipelines, compressed air lines, and other gases like compressed air, oxygen, nitrogen, CO2, Ar and inactive gases.

jccaclimber · Nov 26, 2022

Velisendderr said:
Hi, how can I make air flow meter by myself? You've explained very well but I'm unable to understand it. I've to use gas flow meter for measuring gas flow in natural gas pipelines, compressed air lines, and other gases like compressed air, oxygen, nitrogen, CO2, Ar and inactive gases.

Pressure drop across a know orifice will give you flow rate. Not quite the same thing as measuring pressure vs. atmosphere.

Milling man · Nov 26, 2022

Velisendderr said:
Hi, how can I make air flow meter by myself?

A few questions:
1. Approximately what gas flow rate do you need to measure?
2. What is the gas pressure?
3. What is the measurement accuracy?

The method that I described above (a homemade rotameter) is suitable for a small change in the flow range.

guythatbrews · Dec 2, 2022

Hbjj said:
My old spi bore guage reads .0006 large on a ring vs a stack...? and my homemade around the boring bar guage reads the same!

I made a note on my spi box on how to set the guage so it reads accurately its not ideal but I'm unsure as to how to fix it.

Your contact points may be worn. Sunnen provides a tool to pop the ball out so it may be moved to a fresh position.

To measure with gage blocks, make a stack with blocks on top and bottom sticking out enough to get an indicator ball on them. Level the bottom of the ring with the inside bottom stuck out block, maybe by tapping the ring around on an angle plate. Then check the difference from the top of the ring to the inside top stuck out block.

Hbjj · Dec 11, 2022

I'm confident the error is from the lack of spring pressure on the centering feet when using a block stack vs a ring where the feet are under pressure.

Ps the motor I was line boring turned out nice!

michiganbuck · Dec 11, 2022

.0002 or closer?
Guess one could measure the wall over a measured dowel in a few places to be sure of concentricity, theh go OD minus the wall thickness.

Fill the ID with JoBlocks along with a couple of measured dowels.

Make a Go/No gauge out of a piece of bar stock using a wherlly on the surface grinder...likely get one tenth doing this.. X but I don't have a 3" indicator micrometer so I would have difficulty making such a gauge in my shop

CarbideBob · Dec 11, 2022

michiganbuck said:
Make a Go/No gauge out of a piece of bar stock using a wherlly on the surface grinder...likely get one tenth doing this.. X but I don't have a 3" indicator micrometer so I would have difficulty making such a gauge in my shop

Will a wirley of the best make a standard under 1 tenth or down to 20 millionths accurately round?
Air or running bearing?
Kiss 98 percent of Cmms godbye. Not gonna happen.

michiganbuck · Dec 12, 2022

My wherlly can run to .0001 (perhaps 50 millionths?) with making about +.001 or .0005 on the spin, and then butterfly on only on side/end to finish.

With a bar only the arc of perhaps 1/4 or 1/8" need be this gauge. I have surface grinder beveled such a gauge to use only .02 or so of the gauge size/diameter.

mottrhed · Dec 12, 2022

We measure bores daily to the micron with setups like this. If you need to get to the micron level or tighter there are a lot of considerations for environmental factors but thats another conversation and certainly beyond the scope of this simple engine project.

This wont do much for concentricity, other than obvious eggs and tapers, but to check this correctly you need higher end machinery.

PS there are different quality (tolerance) gauge blocks, you need very good ones, and the more you stack up the further your tolerance stretches.

IMO you are trying to reinvent the wheel on something that doesnt require it. Engines are pretty crude, loose tolerance and forgiving.

mottrhed · Dec 12, 2022

Help if I put the attachments...

dcsipo · Dec 12, 2022

Hbjj said:
View attachment 335213
So simple so obvious (duh)

Now I'm going to (calibrate) my touch with the blocks by making a stack inside a stack so to speak View attachment 335224

Does your setup account for any taper or out-of-round? Would be a bitch to get the ring stuck on the stack

Mabe a go, no go stack? Other than that the half-rounds are just awesome

CarbideBob · Dec 12, 2022

mottrhed said:
Help if I put the attachments...

What is this?

mottrhed · Dec 12, 2022

CarbideBob said:
What is this?

I feel like I'm being set up here, but Ill step in the trap..
Not sure if there is a technical term but I've always called it a gauge block stand...

CarbideBob · Dec 12, 2022

No trap set here.
Never seen this. It is good to micron levels?
Maker and part number? Not sure how it works.
Bob

jccaclimber · Dec 12, 2022

It’s just a fixture to hold your have block stack. I don’t know how perpendicular to the table that one is, but the distance between planes is whatever your gage blocks are rated to.

dcsipo · Dec 12, 2022

CarbideBob said:
No trap set here.
Never seen this. It is good to micron levels?
Maker and part number? Not sure how it works.
Bob

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Hbjj · Dec 13, 2022

The point of measuring this homemade ring gauge to the limit my tools/abilities was to check that my homemade around the boring bar dial bore gauge would be able to do accurate work in the motor.

Did I hit +-.0002 on all the saddles ... no but at least I could measure how bad things were.

The factory tolerance for this engine is .0006 total

If/next time I do this I will want to figure out other some way to adjust the tool inside the engine block to .0001...!

mottrhed · Dec 13, 2022

CarbideBob said:
No trap set here.
Never seen this. It is good to micron levels?
Maker and part number? Not sure how it works.
Bob

Looks like someone beat me to it, but unfortunately this box has no data on it and has been here since before my time. I would think that anyone who makes blocks would make or use a setup like this. Google says its called a gauge block holder, if you search that youll get a bunch of good results.

This is a pretty accurate way to do it, limitations are basically environmental and naturally the quality of your blocks and bore gauge. With any micron measurements everything becomes a factor towards repeatability. We have a "master" set of ceramic gauge blocks we use to check and requalify our "in use" steel sets, with the better thermal stability of ceramic they are certainly better, but for most the steel is fine.

jccaclimber · Dec 13, 2022

They are quite useful, but I've never actually had need to use one for bore gage setting. Any place I've been that uses a lot of bore gages either has high enough volume that they buy dedicated ring gages per size, or enough variation that it's worth getting one of the Sunnen setting tools (not quite as accurate, but very close) to avoid the time spent handling gage blocks.

For occasional and greatly varying bore gage setting it's perfect though, assuming you have the blocks on hand.

As for engine tolerances, the tolerance may be 6 tenths wide, but you might not want to be at the wide end. Narrow end is fine so long as your form (when assembled) is good.

Measuring a ring gauge ?

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