Bevel gear pitch cone

[[Ra...]]

I am facing an issue, how to find bevel gear pitch cone intersection. I'm not experienced enough to find out correct/easy way to measure this. For first time I encountered bevel gear. In addition bevel gear surface will stay unmachined. As you can see this intersection is used for height measuring (87.70±0.03). This tolerance leaves no room for a reckless solution. Usually for turning operation measurement we use RT with magnetic stand and part is in the middle (a commonly used solution). I can get all other required dimensions with usual part location, but bevel gear side is placed down... Maybe I should change part orientation and measure it in -Y/+Y direction, but still I don't know how to get this reference intersection (maybe with GearPro?). From customer we get fixture (1st picture left side), but we can't use it for final measurement plan, only for tests. Measuring height with this fixture didn't give us any satisfactory results too. Maybe someone has come across with something like this and can give advice 🙂

unnamed.jpgBevel_Gear.PNG

[[Ri...]]

I'm not a Bevel guy, but I didn't think you could measure the mounting distance? I thought that was nominal geometry input?

[[Ch...]]

Howdy, Gear guy here :

The 87.70 ± 0.03 distance you are after is referred to as the mounting distance. This is typically a BASIC dimension. During assembly there is typically some movement / shim that can be done while still keeping contact pattern.

This being said : pitch diameters are theoretical. With a cylindrical gear we can sort of construct a pitch circle or cylinder with a gage ball. With bevel gear : not so easy, in fact I don't think I've ever attempted measuring pitch cone of a bevel, I've thought about it.

I believe this tolerance is more for allowing them a tolerance to stay within for shimming purposes, but I understand if it has a tolerance on the drawing you may need to report actuals. You could put down the mounting distance it was inspected at (contact pattern - roll test, etc) and try to make an argument for that, which is what I would probably do.

Other than you can calculate the ball size that would contact around the P.D., at heel and toe ( large end and small end of cones) and self center a gage ball to construct a cone geometry - and intersect from there. Due to flank form errors though I would not expect very accurate results - but I suppose it is possible.

There may be an option in Gear Pro - if you already have a master file mapped in with a known M.D. (mounting distance) - you can measure a subsequent gear and it can 'axial best fit' the mounting distance and this will give you a value you're looking for.

BTW : this is for the blank produced and not the die shown below correct ?

Good luck and God speed. 😉

[[Ma...]]

As previously stated this is the Mounting Distance.

My interpretation is that the part must have acceptable bearing contact and backlash when rolled in a test machine with a sample mating member within the range of this tolerance.

[[Ra...]]

We will produce this part from begin to the end except bevel part... so we tried to measure in -Y/+Y direction and get satisfactory results.

Thanks for your time and advice. 😉