Measuring small angles

Sendit · May 7, 2018

What’s other ways to measure a small angles beside optical comparator and pins?

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Larry Dickman · May 7, 2018

a small protractor?

Care to elaborate?

DMF_TomB · May 7, 2018

Sendit said:
What’s other ways to measure a small angles beside optical comparator and pins?

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part on rotary table zero one edge, rotate til 2nd edge is aligned. read rotary table digital readout ?? horizontal cnc the rotary table often reads .001 degrees

Milland · May 7, 2018

Sine bar set to the nominal angle, flip part around and adjust gage blocks so part top reads zero with a test indicator. Check the block stack height, calculate angle. About as accurate as you're going to get.

AARONT · May 7, 2018

CMM (more words)

Sendit · May 7, 2018

AARONT said:
CMM (more words)

If I had one. I’m just starting out and buying tooling as I need it.

The serrations I’m trying to duplicate.

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Illinoyance · May 7, 2018

Lay the slide on a surface plate. Lay a heavy parallel against it so when you slide it it moves in a straight lie. Set up a dial indicator with a needle point against the serration. Move the slide a known distance and note the change in indicator reading. The change in indicator reading divided by the distance the slide is moved is the tangent of the angle.

michiganbuck · May 7, 2018

A hand held protractor can easily get 1/2 degree with a light behind the object.
A depth micrometer can often get .001 and sometimes better from one side of an object..and check a depth.
A caliper can check an Id, Od and size but sometimes is not so good checking off one side because it is /can be difficult to hole it exactly square to a part..

There are standard serrations. Some times one can look them up..
Some times on can make a feeler to fit in a part and then have a longer angle to check from..If it is straight on one side that can help..perhaps grinding a feeler and angle gauge to fit. bench grinder with attaching a bar to the table..then knock, knock the bar to change the angle by tiny moves...to get a no light fit and then check with a protractor..or like said above trig out the angle by measuring.

crazygoat · May 7, 2018

That that small of a detail, I would find someone with a comparator to check it.

litlerob1 · May 7, 2018

Use a small Drill, measure the diameter of the Drill, set the Drill in the serration resting on the 2 lobes (straight line). Now measure with Micrometer or Height gage the zero point of the non serrated surface, then measure the height of the Drill, do some Trig. Same as measuring Threads over wires.

R

michiganbuck · May 7, 2018

Guess you could suspend a 10x loop over it and mark a sheet of paper the angle then check with a protractor.

michiganbuck · May 7, 2018

Used to be a hand held pocket telescope for measuring and angles. I had one but don't know where it is now..

michiganbuck · May 7, 2018

Milland said:
Sine bar set to the nominal angle, flip part around and adjust gage blocks so part top reads zero with a test indicator. Check the block stack height, calculate angle. About as accurate as you're going to get.

Or if too small to indicate then on the sine look at with a loop when it is at vertical or horizontal eyeball view.
should get you very close..

StinkyDan · May 8, 2018

For the little serrated area u could try making a small mold of it and trimming off the excess molding material and measuring the angle on that.

guest · May 8, 2018

michiganbuck said:
Used to be a hand held pocket telescope for measuring and angles. I had one but don't know where it is now..

I have a pocket comparator from Fowler, I think that's what you are referring to. It's a essentially lighted loupe with a set of interchangeable lenses.

I still haven't figured out what all the lenses are for- damn thing came without a shred of instructions and nothing to reference online. I called Fowler, they didn't have a clue. Go figure.

Technical Ted · May 8, 2018

My suggestion won't help you measure it, but might help just as well. Can you find out the dovetail type? For example, is it a standard 11mm dovetail mount? If so, you can probably do some searching on line and find a drawing or more information on it. Here's an example of an 11mm dovetail.

Ted

DMF_TomB · May 8, 2018

it aint cheap but there are digital scopes that take a picture and you draw on screen, lines on edges you see magnified on screen and you can dimension off of what you see on the screen.
.
better than hand held magnifier with a scale screen. those hand held magnifiers you put right on part and can see part and a ruler angle scale at 10x, 20x or higher magnification. hand held magnifier good ones can be $100 or more

Scottl · May 8, 2018

After you think you have the correct angle mount a faced off rod in the collet in place of an end mill and smear just the tiniest film of lipstick (shhh, we won't tell her) on the end of the rod and adjust your Z until the rod just touches. If it leaves a complete circle of lipstick on the slide serration the angle is correct.

CoraAsher · May 8, 2018

Great to see all the nice suggestion here to do this...

eKretz · May 8, 2018

To do this the easiest and cheapest for a guy that has few tools - here's a method that can be used as long as you have a board, an indicator mounted on a magnetic base or surface gage, a clamp or two and a calculator. Sort of a poor man's sine plate: take a flat board of any given length (say 12") and set the gun on it so that it lies flat against the slide. Put some spacers under the slide if necessary to avoid any levers or buttons sticking out past the plane formed by the slide. Clamp the gun down over the spacers in some manner if necessary. Kick one end of the board up by adding some spacers of some sort under one end of the board (the end that will make the angles lie more flatly). Use the indicator and traverse a serrated flat to check if it's zeroed. Keep tweaking the spacers until you achieve that. Next measure the height of the high side of the board (preferably with a machinist rule). Use trig to figure the angle formed: sine of the angle you're looking for = opposite side ÷ hypotenuse where the opposite side equals your height on the high side of the board and the hypotenuse equals the length of the board.

Measuring small angles

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