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What's the best way to measure the conical features of this part?

Mikel Levy

Aluminum
Joined
Oct 19, 2009
Location
Seattle
I need to make a few of these valve stems, and I'm not sure how to measure the face diameter of the truncated cone and the short length of cylindrical section that abuts the cone base (circled in red on the attached drawing), while the part is still chucked in the lathe. Thanks for any suggestions.

Mike

Valve stem.jpg
 
Are you doing these in a CNC or manual lathe? And what metrology equipment do you have?

You might have to accept making some dummy parts ahead of the "real things" that are just qualification parts. That would be just the head section, part it off, check off machine, when acceptable lock your process and make the real parts.
 
For the cone nose you might make a quick template with prehaps a .015 to .030 deep mill slot in a small peice of material.. ..1/16" flat stock or what.
trig it to know the correct slot width to make a .200 slot to a right angle ..or with having a 1/4" wheel dress a 30* at each wheel edge and just grind tha slot .015 or .030 deep. easy to hold .001 with template gauge. Decent grinder or mil hand should make the in about 20 minuets or less.

likely the .030 could be milled or ground on the same gauge with eyeball or with looking through a loupe +-.003 shoild be easy.
 
Laser cut a go-nogo gauge in a thin sheet of something for the .200 size, and a .030 step in any old piece of material should work to measure the flat on the other face. If you are really ambitious, you can go every .005 up to a size you feel comfortable hitting before the finish pass to help you get there.

If your eyeballs need some help with the flat thickness, you can use a marker or blue dye and rotate your shim around to scrape the color off the material and try to get a look at how close you are.
 
Try using a fish tail and a no. 32 drill (make sure the drill measures close to size):

170861406
170861406.jpg


170861406
 
All of the answers to your question, are ridiculously wrong. I don't want to type a bunch of text at this moment, but if you do not have the true answer to your problem by tomorrow morning, I will help you. Hint; toolmakers conduct this type of inspection in their sleep, and it can be measured to sub tenths.
 
.... and it can be measured to sub tenths.
I will be interested to hear that and your six-sigma R&R behind this claim.
This part like falling off a log, sub tenths way fancy.
Part size to under tenths you are measuring features under the wavelength of light.
Assume you have deep UV or probes down in that range?
You may have sub tenths numbers, not sure you have sub tenths real readings.
But I will guess that you have the 6 R&Rs to back it up so I could be way out in left field so in that case I bow down and you can do the :dopeslap:
Bob
 
Do you have a scale loupe? That's how I would measure it in the machine.

Yes, I do have a scale loupe and that seems like a very practical suggestion I can implement immediately. I'll just have to take the cutter out of the tool post and slide the carriage out of the way so I can get my fat head in line with the spindle axis.

--Mike
 
I just can't wait to hear THE answer.

And how much the instruments cost.



All of the answers to your question, are ridiculously wrong. I don't want to type a bunch of text at this moment, but if you do not have the true answer to your problem by tomorrow morning, I will help you. Hint; toolmakers conduct this type of inspection in their sleep, and it can be measured to sub tenths.
 
All of the answers to your question, are ridiculously wrong. I don't want to type a bunch of text at this moment, but if you do not have the true answer to your problem by tomorrow morning, I will help you. Hint; toolmakers conduct this type of inspection in their sleep, and it can be measured to sub tenths.

What a dickbag :rolleyes5:

:bowdown: Please, oh please tell us THE answer oh mighty lord
 
... Might get you close... Assuming you have a digital readout (or on a cnc), you could try using an indicator with something like a .030" tip and dial over until it falls off on the left side, set zero, then move to the right until it starts to fall off again and see what it reads...?
 
I need to make a few of these valve stems, and I'm not sure how to measure the face diameter of the truncated cone and the short length of cylindrical section that abuts the cone base (circled in red on the attached drawing), while the part is still chucked in the lathe. Thanks for any suggestions.

Mike

View attachment 293696

The diameter, can't you just measure with a micrometer?
As for the length, there are many ways, but how much time do you want to spend making a fixture or gage?
 
Somebody needs to go to a GD&T class.

My guess is that given that the dimensions leave you tons of room, a fishtail gauge and wire will be MORE than accurate enough. If it's a part for a life critical application, please no quote it, as you don't have nearly enough information, and the engineer doesn't have a clue.
 








 
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