How would you check this internal groove diameter?

[guythatbrews]

This part is naval brass c46400. The corner radius shown in the bottom of the groove is R.005 +- .005. I will be using a sharp cornered tool so that won't narrow the diameter available to check. I can't think of a readily available measuring tool to check the .330+-.001 internal groove diameter? I'm not interested in cutting a part to check this.

Any ideas? I'm at the quote stage so I can still turn this down.

 

[Booze Daily]

Back up the groove tool by .02. Run it, check it. When good, put it back, face .05 off the part and make a good one.

 

[guythatbrews]

Back up the groove tool by .02. Run it, check it. When good, put it back, face .05 off the part and make a good one.

I could do this but I need a method to inspect a complete finished part. Inspection report and COC required. This customer don't play.

Maybe something similar to this Interapid id gauge, but this one wont go small enough and the tips are too big to fit in the groove. And I've never used one I'd trust for +-.001 anyway.

 

[just Dave]

A spring caliper would do it. You will need to grind the points narrow enough to fit the groove and possibly the diameter . My approach to a measuring tool of that nature is to try to prove it wrong if I can’t, it must be right . Custom points for calipers litter the drawers of my old toolbox’s. Good luck!

 

[michiganbuck]

Having a surface grinder one might grind the jaws of a 1/2 thow digital caliper.
Still a little would be risky, and the jaw width of .010 or so a challenge to feel the bore size.

Amazon.com

 

[just Dave]

A spring caliper would do it. You will need to grind the points narrow enough to fit the groove and possibly the diameter . My approach to a measuring tool of that nature is to try to prove it wrong if I can’t, it must be right . Custom points for calipers litter the drawers of my old toolbox’s. Good luck!

I’m talking about the ones with a dial indicator integrated

 

[FredC]

"Indical " came to mind, My boss had one almost 50 years ago, bragged about it while showing it off. I bought one evidently in '97 and it has never been used. Plus or minus .001 maybe a little tight for it. If you think it might work and they are not available anymore I will sell you this one.

INDICAL Bore and Groove Gage - 30-518-5

Find the best deals on the web here at Light Tool Supply for all your precision measuring and metalworking tools & machinery.

www.lighttoolsupply.com

Looks like you can still get them, I would sell this one for $200.00.

 

[Ox]

+/- 1 in an ID groove?

A) What could possibly be going in there that requires that kind'a tolerance?
B) How is the customer going to check it?

The draftsman is just drawing pics and doesn't know much.
The bore may need to be tight, but for Petey's sakes !!! the capture on the end he has at .001 as well.
Are snap rings or O rings held to that tol? (O-ring in this case)

I would talk to the customer and ask how much they want to pay for a bogus tol.
(or just make the part to the best of your ability and drive on ....)


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Think Snow Eh!
Ox

 

[Ox]

I would agree with a post above about using the same tool to turn the "capture" bore, but that won't have quite the same tool pressure on it as you will have in the groove, so set it to go "+1" and leave some dwell time on it, and it should be pretty close.


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Think Snow Eh!
Ox

 

[guythatbrews]

+/- 1 in an ID groove?

A) What could possibly be going in there that requires that kind'a tolerance?
B) How is the customer going to check it?

The draftsman is just drawing pics and doesn't know much.
The bore may need to be tight, but for Petey's sakes !!! the capture on the end he has at .001 as well.
Are snap rings or O rings held to that tol? (O-ring in this case)

I would talk to the customer and ask how much they want to pay for a bogus tol.
(or just make the part to the best of your ability and drive on ....)


-------------------------

Think Snow Eh!
Ox

Well to me this isn't really the issue with this part. It's not that close just tough to check. And this is a new customer. I'm about a third tier customer on this so pretty tough to get back to the design folks anyway.

When I'm quoting something like this and decide I can't create the feature or adequately measure the feature, I just decline, stating my reasons and leave it up to the customer. I pretty much make it a policy not to question stuff like this. That way no hard feelings are created by me, and it is up to the customer to revisit the design if they desire.

A Mueller gauge will do it, and I trust them to +- .0002 without too much trouble. I'll have to make custom contact points.

High Quality Precision Dimensional Inspection Gages

 

[Mud]

Maybe something similar to this Interapid id gauge, but this one wont go small enough and the tips are too big to fit in the groove. And I've never used one I'd trust for +-.001 anyway.

The Interapid gage is good for .001 or less in my experience, and they come with a large selection of points, might be a pair for that small of a groove. They are mondo expensive though.

 

[guythatbrews]

The Interapid gage is good for .001 or less in my experience, and they come with a large selection of points, might be a pair for that small of a groove. They are mondo expensive though.

They don't make one that is smaller than 10mm. And I don't have one to check but the contact points are about .030 in diameter. They could maybe be modified to fit the groove but it would be tough. They are hardened and very tiny. And not sure how to get that thing in a hole under 10mm anyway.

 

[Skubeesnak]

Go with the indicol. they work great. especially if you can make a ring gage to the finished diameter to set size with. then just use a tenth test indicator on it. I have used hundreds of times and would put up against the interrapid gage. Ironically I would use an interrapid indicator on it though.

 

[guythatbrews]

"Indical " came to mind, My boss had one almost 50 years ago, bragged about it while showing it off. I bought one evidently in '97 and it has never been used. Plus or minus .001 maybe a little tight for it. If you think it might work and they are not available anymore I will sell you this one.

INDICAL Bore and Groove Gage - 30-518-5

Find the best deals on the web here at Light Tool Supply for all your precision measuring and metalworking tools & machinery.

www.lighttoolsupply.com

Looks like you can still get them, I would sell this one for $200.00.

What is the minimum size? The ome I found was .625, way too big.

 

[EmGo]

Pick up a cheap set of dial or digital calipers. Make a set of crosswise jaws thinner than the groove that you solder or braze on. Set them in a ring gage that you make. Viola, cheap near-groove gage diameter measurer.

 

[RJT]

Digital height gage with a probe like this. Easy and accurate. We measure these type grooves all the time this way. Sweep the top edge, sweep the bottom edge, done.

 

[guythatbrews]

Digital height gage with a probe like this. Easy and accurate. We measure these type grooves all the time this way. Sweep the top edge, sweep the bottom edge, done.

Wish I had one!

 

[Skubeesnak]

What is the minimum size? The ome I found was .625, way too big.

use the 06-03-008 points. will go that small easily.

 

[EmGo]

Wish I had one!

You could do a similar trick with a regular height gage, just make a special stylus / jaw / probe, whatever the heck you want to call it. Touch the bore then touch the bottom of the groove, add the diff then multiply by two ...
You best have a surface plate and a height gage or we're gonna run you out of the guild

 

[guythatbrews]

You could do a similar trick with a regular height gage, just make a special stylus / jaw / probe, whatever the heck you want to call it. Touch the bore then touch the bottom of the groove, add the diff then multiply by two ...
You best have a surface plate and a height gage or we're gonna run you out of the guild

Hah. You got me. I do have a surface plates and a heightmaster. Can i still be in the club?

I might do sometimg like this. Put a .015 bent tip on a tenths indicator. It'd be so small I'm not sure I could see it!