Measuring Internal Angles

SamI

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Hi Guys,

As some of you may know from other threads I am in the process of refurbishing a collet closer and modifying to fit my lathe. To do this I need to reverse engineer a part. What I've got stuck with is the measurement of this angle:

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Now the angle isn't critical so in practice I could probably just guess however I would like to know how to measure it properly for future reference. As it is I currently have some modelling clay setting in it figuring that I can use an angle gauge to determine the angle however I would prefer a direct method of measurement for convenience. Another thought I had would be to chuck it up, offset the compound and run an indicator on the angle but again I would be interested in other methods.

So, how would you measure this?
 
With the dimensions you have provided on your drawing there is no way to calculate the angle. If you can get measurements of the base and height of the desired angle a trig table can be used to determine the angle.

trianglw.JPG
 
I have the physical part that i am trying to measure rather than to find the dimension from the drawing. On the existing part there is a radius at the bottom so it is difficult to measure the base length so I was hoping for a way, if possible, to measure the angle directly.
 
Do as you said. Set up on machine and dial in your angle directly. Will be as accurate as you dialing in.
 
Thanks all for the suggestions. Looks like the dial indicator is the way to go!
 
If the part is taken off the machine it is tricky to measure. When I used to work in inspection we would melt a stiff green metrology wax stick and press it into the inside features. Once removed it would carry the shape of the internal feature. We would usually then set the wax up on a optical comparator and measure the angle that way. Not stuff your average homeshop would have, but still an interesting solution.
 
If you are drawing the part on a cad program. The program should tell you the angle.
 
If the part is taken off the machine it is tricky to measure. When I used to work in inspection we would melt a stiff green metrology wax stick and press it into the inside features. Once removed it would carry the shape of the internal feature. We would usually then set the wax up on a optical comparator and measure the angle that way. Not stuff your average homeshop would have, but still an interesting solution.

Sounds like a high tech version of my modelling clay method! The plan is to take the clay and use an angle gauge to determine the angle. Luckily for this part the angle is not critical and as long as I'm within a degree or two I should be alright.

If you are drawing the part on a cad program. The program should tell you the angle.

The problem is I don't have enough information to determine the angle. I only have one leg of the triangle and have no means of measuring any of the others so while Inventor can give me an angle it is meaningless until I can determine at least one other feature.
 
You could come real close to checking size by using some kids clay ,you can get at Walmart.
 
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