Involute Knurling, No base diameter supplied???
Involute Knurling, No base diameter supplied???
(OP)
I am trying to make an exact model of the knurling below. The problem I'm having is that the Base diameter required to define the involute curve is not supplied. Is there a standard will supply the base diameter from the data below?
Tooth Profile = Involute
Module = .44
Number of teeth = 34
Pressure angle = 45°
Major Dia = 15.400mm
Minor Dia = 14.520mm
Pitch Dia = 14.960mm
Over pin Dia = 16.751mm
Pin Dia = 1.000mm
Any help on this would be greatly appreciated.
Tooth Profile = Involute
Module = .44
Number of teeth = 34
Pressure angle = 45°
Major Dia = 15.400mm
Minor Dia = 14.520mm
Pitch Dia = 14.960mm
Over pin Dia = 16.751mm
Pin Dia = 1.000mm
Any help on this would be greatly appreciated.





RE: Involute Knurling, No base diameter supplied???
RE: Involute Knurling, No base diameter supplied???
Thank you. I don't think it is, strictly speeking, essential in this particular case. But, there are more splines defined in the same fasion that have a larger tooth height. These are the reason that I needed the formula.
Aside from that, I was informed the other day that the CAD models containing involute spline shapes could not be trusted. mainly because the method for making the involute was pure math and had no geometry to show as proof. It left the engineers aprehensive. unfortunatly, in my work i found that they were right. the models did not take the pressure angle in to account properly. I am fixing this problem.
RE: Involute Knurling, No base diameter supplied???
RE: Involute Knurling, No base diameter supplied???
RE: Involute Knurling, No base diameter supplied???
A CAD surface or solid representation of a spline tooth flank can be extremely precise or it can be a rough approximation. It all depends on how the person creating it chose to model it. Often it is not necessary to have super high-fidelity surface definition on features like spline teeth since the CAD model is not typically used to produce the spline teeth. In order to simplify the digital model, the spline tooth flank profiles might be approximated by a series of arcs.
With modern CAD softwares and specialized design applications for modelling things like splines or gears, it is very easy to produce a CAD model of a spline or gear tooth flank that is extremely precise. If you are not being supplied a CAD model that meets your standards for accuracy, it's the modeller's fault and not the software.
RE: Involute Knurling, No base diameter supplied???
Is this a knurl, intended to create a rough, grippable face, or is it a gear that must act on another gear? When I want a knurl, I call up a "MEDIUM DIAMOND KNURL", and I get what I want. I could specify pitch and depth, but I do not care enough, I do not want to call up anything that requires the fabricator to do anything other than select his favourite knurling tool.
If this thing is a gear, how are you going to fabricate it? Machinists select an off the self cutting tool to cut the gears. Your model has no effect on this. I model most gear teeth with straight sides, which are close enough to reality. For small numbers of teeth, my 1941 copy of French's Engineering Drawing has instructions on how to use a radius to fake the involute face. Is your rapid prototyping process accurate enough to do functional teeth?
How large and complex will the final assembly be? I have two assemblies up on my SolidWorks right now. One of them has 2390 components. The other has 2797. If you had modelled my knurled components, I would hate you with a passion.
All of this will affect how I model everything.
--
JHG
RE: Involute Knurling, No base diameter supplied???
RE: Involute Knurling, No base diameter supplied???
To accurately model/draw an involute is not that hard and it can be done in any CAD. Just some trigonometry is necessary.
Long time ago we discussed it in these forums. Try to search, it should be still available.
RE: Involute Knurling, No base diameter supplied???