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Inspecting 4” shallow bore

kineticmx

Aluminum
Joined
Mar 10, 2014
Location
United States, CT
I have a new production part, made from 6061 with a 4” through hole .1875” thick part. Need to hold 4” +.002 -0 and considering a go no go gauge. What would be a good material to make this gauge out of? Or, is there a better tool to measure these quickly in production? I was going to use a telescoping gauge but the shallow depth has been proving difficult to use the gauge. Cant reach the feature with calipers otherwise I would just do that considering the tolerance.


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I have a new production part, made from 6061 with a 4” through hole .1875” thick part. Need to hold 4” +.002 -0 and considering a go no go gauge. What would be a good material to make this gauge out of? Or, is there a better tool to measure these quickly in production? I was going to use a telescoping gauge but the shallow depth has been proving difficult to use the gauge. Cant reach the feature with calipers otherwise I would just do that considering the tolerance.


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Mueller gage all day, but they are pricey, especially considering .002" tolerance. Or one of the groove type gages with an indicator attached, but I find them not that trustworthy, unless you set it directly with a go type gage bored to the middles of your tolerance...?

shallow bore gage - Google Search
 
Both of those are excellent solutions unfortunately they are just out if my price range. Not seeing either of those available for any less than $500.

Let me further constrain my question. For sub $150 is there a tool available for measuring this? I cant afford to throw $500 at this project right now.

I also was considering a dial bore gauge, but back to the 3/16 bore depth. Rocking it becomes difficult. Also, needing to zero it becomes just another opportunity for error.

That was what pointed me to a go-nogo gauge with my limited budget.

Thank you for the suggestions


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Or if you're really cheap (like me!) you could make one. A bar with a dowel inserted that bridges the hole with clearance for the indicator point isn't too hard to do. Root around in the indicator accessories drawer for an adjustable solution for mounting the ti, or just duplicate the catalog item.

You'll need a master, too.
 
Or if you're really cheap (like me!) you could make one. A bar with a dowel inserted that bridges the hole with clearance for the indicator point isn't too hard to do. Root around in the indicator accessories drawer for an adjustable solution for mounting the ti, or just duplicate the catalog item.

You'll need a master, too.
The problem with using a dowel pin is if you have taper and the pin is not exactly square youll get a bad reading.
use a tooling ball instead. some have threads you can screw into a rod or your makeshift bar.
McMaster-Carr
 
For low cost/low skill production the best bet is go, no go made with stable material and size confirmed with good equipment.

No moving parts and alignment not critical.

If it fits or not fit depending on gauge it is done.

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I have a new production part, made from 6061 with a 4” through hole .1875” thick part. Need to hold 4” +.002 -0 and considering a go no go gauge. What would be a good material to make this gauge out of? Or, is there a better tool to measure these quickly in production? I was going to use a telescoping gauge but the shallow depth has been proving difficult to use the gauge. Cant reach the feature with calipers otherwise I would just do that considering the tolerance.

Make a gauge like this. I've exaggerated the leadin angle. It doesn't have to be as severe. Mount the gauge upright and lower the part onto it. Hold the part with gloves so as not to induce temperature change. Reverse the part to check for excessive taper.

Eugene

Eugene4GONOGO.jpg
 
Assuming an optical comparator with reflection isn't an option I'd turn a chunk of something. That's easy enough to validate with a gauge block and micrometer if you have one that size, gauge block and surface gauge if you don't have the mic.

I'm assuming it's not a through hole, although if it is a stepped shaft does nicely for go and no-go (although you should diamond the no-go part).

Material depends on how long you need it to last. One part you might as well make it out of aluminum. Pile of parts and even chromoly or 1045 will hold up for a bit. Real use get it hardened.

Bar of the right length with rounded ends that you can set in it and rotate through may be easier, also easy to validate with a mic. One for go and one for no-go, or get fancy and make a no-go, then cut in a step so you can flip it and have the go.

If this is blind and the end condition is critical you'd better have an agreement with the customer as to how you're going to do it.
 
...Cant reach the feature with calipers otherwise I would just do that considering the tolerance.
More than enough said here.

I do have to ask how one controls a production process at a .002 total spread with go nogo.
How are size adjustments made? Do things like Cpk and Ppk enter the this world?
Love taper gauges as above but not at this level for what should be obvious reasons on edge condition.
Can we start with the old rule of ten?
The flexi nice, Davis well known and better, both sort of picky about face quality outside the bore.
Rotate either on the part and the number may change which leads to "not so sure good/bad or when to make a move in the machine".
Bob
 
What sort of rate and total volume are we talking here? Several of us have made conflicting assumptions.
Do you have a different method of comping your process or is attribute sufficient?
“Production” and “Under $150” are somewhat mutually exclusive in the world I’m used to living in as are +/- 0.001” tolerances and calipers. That led me to believe that close enough might be close enough rather than actually needing to be fully in spec, but that’s an assumption as well.
Understanding the nature of the obstruction would help as well.
 








 
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