involute spline (internal) 3

[rosie2277]

can anyone help me please, im having trouble using this site as ive seen this question answered on here but cant comment on it! - im wondering if anyone can translate my info into a dxf file please?

INVOLUTE SPLINE DATA, FLAT ROOT, SIDE FIT, INTERNAL.
NO OF TEETH - 24
PITCH - 16/32
PRESSURE ANGLE - 30
BASE DIAMETER - 1.2990 IN
PITCH DIAMETER - 1.5000 IN
MAJOR DIAMETER - 1.5625 IN
FORM DIAMETER - 1.5500 IN
MINOR DIAMETER - 1.4375 IN
CIRCULAR TOOTH THICKNESS
MAX ACTUAL 0.1011 IN
MIN EFFECTIVE 0.0982 IN

 

[Occupant]

"everything on your drawing is correct except the circluar tooth thickness?"

I don't know how you come to that conclusion. The handbook says: "Cicular tooth thickness for 16/32 = 0.0918" Measured from my drawing, I get 0.098175". I believe my drawing is exactly on the money.

 

[gearguru]

To calculate the angle if we know the arc length and the radius of that arc can not be simpler: arc_length/radius = angle (in radians)
And because
2*PI [radians] = 360 [degrees]
one can easily convert to degrees if it is necessary...
I also should be more specific earlier:
"Be sure that the circular tooth thickness is measured AS A LENGTH OF AN ARC (on the pitch diameter)".

 

[rosie2277]

converted the circular tooth thickness to radians then into degrees and it makes sense doing it this way, ive just finished an internal and external of the same size, i ran the wire with a standard offset of 0.175 (0.3 wire plus spark gap) the od and id measure bang on size and im gonna keep the od on external splines tied up to top size minus 0.02mm and internal splines tied upto top size plus 0.02mm this should make sure they can never interfere, the parts fit perfect! - so im now waiting for a the parts to arrive from a different manufacturer to check these fit mine and gonna measure these to mine see how they compare "fingers crossed"
gauges are outa the question so ill be checking with ball bearings and mics but the sizes are coming off my drawings so another reason why ive gotta draw up in middle tol!

 

[rosie2277]

thanks for the help people got this cracked now, parts from another manufacturer arrived and fit perfect, just had them inspected and there within 0.01mm of my 1st off!

 

[dinjin]

Rosie,
Do not offset an involute as it then is no longer an involute.
Rather rotate it to get the clearance that you need. For slow
speeds, offsetting may work, but for higher speeds, you may run
into problems.