Looking for a Round Taper Gage with Graduations

[Magnus_CA]

My company supplies non-rigid plastic tubing that comes in an array of inside diameters (ID). Sizes range from 1/32" to 5".

ID is ALWAYS stated as a minimum value so we've historically used pin gauges with a go/no-go approach but I've grown tired of buying new pin gauges every time we add a new size to our catalog of parts. I recently came across ASTM D876 that refers to the use of taper gauges to determine the ID of PVC tubing. Specifically it states:

"Tapered-Steel Gages—Use chromium-plated gages suitable for covering the range of tubing sizes shown in Table 1. The gages shall have a uniform taper of 0.010 in./1 in. (0.010 mm/mm) of length, and shall be graduated with circular lathe-cut rings every 0.5 in. (13 mm) of length. The graduations
shall then represent a uniform increase in diameter of 0.005 in./0.5 in. (0.010 mm/mm) of length."

We typically test tubing with an ID between 1/32" to 2". It'd be great if I could find a single gage to cover that range. I'd gladly accept having to buy another gage or two to cover sizes over 2".

I found a flat taper gage from Starrett (google search 'Starrett 270 Taper Gauge') but the part about 'graduated with circular lathe-cut rings' leads me to believe they're referring to a cone-shaped gauge rather than a flat one. Unfortunately I've had no luck locating a round equivalent.

Does anyone know where I may be able to find such a gage?

Thanks in advance for the replies!

PS - So glad to see the forum back!

 

[howste]

They seem to be hard to find. Is this what you're looking for? I don't know if they have graduated lines on them or not.

 

[Magnus_CA]

Thanks for the reply. Those don't have graduations, unfortunately. I found a metric set but only overseas. I'd post a link but can't yet.

 

[normzone]

Since you do this on a regular basis you are already aware of the issues of measuring cylinder ID vs measuring ID at the cylinder lip. Have fun ...

 

[Magnus_CA]

Since you do this on a regular basis you are already aware of the issues of measuring cylinder ID vs measuring ID at the cylinder lip. Have fun ...

Not a terribly helpful post normzone. The spec that describes how to determine ID indicates the apparatus I described as an acceptable measurement device. If you want to argue the validity of the test method you can take it up with ASTM...it's O/T otherwise.

If you question the accuracy of using a graduated taper gage for measuring ID and know of a better approach that doesn't involve pin gauges or an expensive optical comparator I'd love to hear it.

 

[Ninja]

A bit out of the box...but have you looked for folks who make Ring mandrels for sizing finger rings?
Never looked there myself, but I wonder if other gradations are available other than just ring size....

Just thinking....

 

[howste]

I have seen stepped gages used at several o-ring manufacturers. They are likely a more accurate way to measure the ID of tubing than a tapered gage. The ones I've seen have been custom made. I don't know if you can buy something like that off-the-shelf.

 

[Ninja]

Sounds like a business opportunity for someone.....

 

[normzone]

Since you do this on a regular basis you are already aware of the issues of measuring cylinder ID vs measuring ID at the cylinder lip. Have fun ...

Ah, the power of the internet. Alright, I'll parse this out as though it were a detailed drawing with notes.

" Since you do this on a regular basis [COMPLIMENT ON YOUR EXPERIENCE IN THE FIELD] you are already aware of [ACKNOWLEDGEMENT OF YOUR EXPERIENCE] the issues of measuring cylinder ID vs measuring ID at the cylinder lip. [BRIEF SUMMARY OF TECHNICAL CHALLENGE SUFFICIENT TO DESCRIBE THE MEASUREMENT ERRORS INVOLVED WHEN COMMUNICATED FROM ONE EXPERIENCED PROFESSIONAL TO ANOTHER]" Have fun ... [JOVIAL INDICATION OF GOOD INTENTIONS]

" Not a terribly helpful post normzone. The spec that describes how to determine ID indicates the apparatus I described as an acceptable measurement device. If you want to argue the validity of the test method you can take it up with ASTM...it's O/T otherwise.

If you question the accuracy of using a graduated taper gage for measuring ID and know of a better approach that doesn't involve pin gauges or an expensive optical comparator I'd love to hear it. "

[Magnus_CA], I've been in your measurement shoes before, and I sympathize.

If you are anticipating solely on-topic dry technical advice from me you will be sorely disappointed. If you'd like me to avoid your posting threads I will. Or you could (echoing amplified voice) put down the cup and step away from the coffee pot.

Have a better one ...

 

[Project Man]

I recommend contacting some of the gage pin manufacturers (Meyer, Vermont, Shars, Starrett.)