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djm77

Aluminum
Joined
Nov 27, 2011
Location
UK
Hi All,

I am in the process of quoting a job and I am having difficulty in working out how I am going to measure a feature.

I personally haven't come across anything in over 20 years of machining that will allow me to measure an internal groove diameter to the accuracy that I need. However, I am a long way from knowing every piece of equipment out there and so was hoping someone might be able to suggest something I haven't thought of.

I have sketched up the part we are looking at with the relevant features. I am looking for something that will measure the 18.5mm dia internal groove to an accuracy of 0.013mm

I should say, this will be for a quantity of parts, so I am not looking for a quick fix as I know I could have used something like ball bearings and a home made plug gauge for a 1off. I need a proper solution, something like a 3 point bore mic but for grooves.

Any help will be greatly appreciated.View attachment Sketch.pdf
 
Would a custom nose on an expansion style bore-gauge work? (The kind where a plunger moves an indicator?) Seems that various parties make custom tooling like that.
 
To me it looks like a very precise groove gauge is about your only hope. Going into a 16mm hole to a depth of 26mm is going to be a challenge both with regard to machining and measurement.

I strongly advise the use of a setting ring of as close to 18.4285mm no matter what you choose.

I've got to ask as I simply don't have the imagination to figure out the purpose of a dimension diameter of 18.5 d6 will be used for.

BTW, and this is important, small d means that it is an external dimension and not an internal one.
Whoever did the drawing made a mistake and the tolerance might not be the only one.

Limits, Fits and Tolerances Calculator (ISO system)

A tolerance of 18.5 d9 (-0.065 / -0.117) looks much more sensible but should still be written with a capital letter given that it is an internal dimension. It won't then be D any more either

iso tolerance for d - Google-sogning
 
Last edited:
Cheers for the feedback guys. Gordon, yea I know about the small d, I have already gone back to the engineer to double check that is what they actually want, I've also questioned whether the tolerance needs to be as tight as it is. The groove is actually just for an O-ring so I would suggest that they could open it up considerably, given the amount of squeeze you get on an O-ring. We'll wait to see what they come back with.

If they do change it and open it up some of the equipment suggested will be likely to be suitable. As it is nothing will get me the tolerance I need, manufacturing it is relatively easy, inspecting it, not so. I have contacted bowers and they are looking at quoting me for a special tool, I'm guessing a 3 point bore mic with feet for my specific sizes.


Sent from my iPad using Tapatalk
 
djm77 said:
Cheers for the feedback guys. Gordon, yea I know about the small d, I have already gone back to the engineer to double check that is what they actually want, I've also questioned whether the tolerance needs to be as tight as it is. The groove is actually just for an O-ring so I would suggest that they could open it up considerably, given the amount of squeeze you get on an O-ring. We'll wait to see what they come back with.

If they do change it and open it up some of the equipment suggested will be likely to be suitable. As it is nothing will get me the tolerance I need, manufacturing it is relatively easy, inspecting it, not so. I have contacted bowers and they are looking at quoting me for a special tool, I'm guessing a 3 point bore mic with feet for my specific sizes.

Sent from my iPad using Tapatalk
Click to expand...

I guessed O-ring but the tolerance had me puzzled and that's an understatement. With an O-ring that size I'd expect the tolerance to be at least 0.1 mm

http://www.applerubber.com/src/pdf/iso-3601-metric-size-o-rings.pdf

Let's hope your customer comes to his senses :cheers:
 
Was just looking through my drawings as I have an Ø8-h8 diameter alu bushing (mass produced) that has a Ø6mm 1mm thick O-ring mounted on an external groove. The groove diameter tolerance I put on the drawing many years ago was Ø6.05 ± 0.05mm. Has always worked just fine.

The use is to stop the alu bushing from falling out of an Ø8-H8 hole.
 
djm77 said:
Cheers for the feedback guys. Gordon, yea I know about the small d, I have already gone back to the engineer to double check that is what they actually want, I've also questioned whether the tolerance needs to be as tight as it is. The groove is actually just for an O-ring so I would suggest that they could open it up considerably, given the amount of squeeze you get on an O-ring. We'll wait to see what they come back with.

If they do change it and open it up some of the equipment suggested will be likely to be suitable. As it is nothing will get me the tolerance I need, manufacturing it is relatively easy, inspecting it, not so. I have contacted bowers and they are looking at quoting me for a special tool, I'm guessing a 3 point bore mic with feet for my specific sizes.


Sent from my iPad using Tapatalk
Click to expand...

I feel like a broken record today as I just posted about this gage on another thread, but have you checked with Dorsey? I recently purchased a groove gage from them to measure the ID of a bottle and they were able to make me special arms for their groove gage...link is DYN Groove Gages. Whether this gage will work for you or not it may be worth looking into them. I've had great luck with them so far and trying to do my part in spreading the good word of another US manufacturer. Best of luck.
 
Gage_Guru said:
I feel like a broken record today as I just posted about this gage on another thread, but have you checked with Dorsey? I recently purchased a groove gage from them to measure the ID of a bottle and they were able to make me special arms for their groove gage...link is DYN Groove Gages. Whether this gage will work for you or not it may be worth looking into them. I've had great luck with them so far and trying to do my part in spreading the good word of another US manufacturer. Best of luck.
Click to expand...

Must admit I like the look of that gage. Does the company also supply setting rings?

Just looked closer at the website and seems as if they do.
 
Gordon B. Clarke said:
Must admit I like the look of that gage. Does the company also supply setting rings?

Just looked closer at the website and seems as if they do.
Click to expand...

Hi Gordon, yes they do I ordered one with my gage as well. Long story short I stopped by their booth at IMTS on my way to the restroom (great booth placement by the way, as I probably wouldn't have made it all the way down to them otherwise) and ended up having a great experience. Instead of having a team of salesman working their booth pushing the "latest and greatest", they had their engineer who designed a lot of the products, helping people select the right tool for their application and explaining the best way to get the measurement they needed. That's how I even found out that this gage existed, and better yet they were able to modify the contacts to fit my application. On a side note, I'd recommend downloading the catalog it's a bit more user friendly then the site. Hope this helps. Best of luck!
 
Gage_Guru said:
Hi Gordon, yes they do I ordered one with my gage as well. Long story short I stopped by their booth at IMTS on my way to the restroom (great booth placement by the way, as I probably wouldn't have made it all the way down to them otherwise) and ended up having a great experience. Instead of having a team of salesman working their booth pushing the "latest and greatest", they had their engineer who designed a lot of the products, helping people select the right tool for their application and explaining the best way to get the measurement they needed. That's how I even found out that this gage existed, and better yet they were able to modify the contacts to fit my application. On a side note, I'd recommend downloading the catalog it's a bit more user friendly then the site. Hope this helps. Best of luck!
Click to expand...

Probably taking this thread off track but you bring up an interesting point and one that is important IMO.

You saw the gauge at an exhibition. It never ceases to surprise me at how much "new stuff" I see at exhibitions. Don't know about the USA but many companies here send employees to exhibitions (all expenses paid) to get them updated on what's new and come "home" with suggestions. Germany (our next door neighbour) is probably the country that has the most exhibitions within metrology and machining in Europe.

Any company that doesn't keep its employees updated and motivated will sag behind. I stopped being surprised long ago at how many Asians there are in Germany at exhibitions. Cameras clicking incessantly :)
 
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