Calculate Helix Angle from Sample?
Calculate Helix Angle from Sample?
(OP)
On a large Helix angle and wide face, we measure the axial pitch and then calculate the Helix angle. With a small Helix angle and narrow gear it is not possible to measure the axial pitch. Does anyone know a way of measuring or calculating the Helix angle?





RE: Calculate Helix Angle from Sample?
RE: Calculate Helix Angle from Sample?
RE: Calculate Helix Angle from Sample?
RE: Calculate Helix Angle from Sample?
If thats the case we smear Prussia Blue paste on top of the gear teeth, then the gear is rolled aligned sideways by some kind of straight edge over a sheet of paper, from there with a simple protactor the aproximate angle can be read.
With that angle we set up the gear hobber and load the OLD gear then we fix a dial indicator with a magnetic base to the hob head, set up all parameters as if we are going to hob the new gear, possibly a very high speed for the cutting arbor which is not installed and put the work in motion you will find that if your angle was correct the dial indicator will only move from the starting point to both sides because of the roughness of the old gear. If you are of limits to just one side then you can use a little trigonometry to find the error and adjust the gearing of your helical advance, a new recheck and if you have been careful in your corrections you should be right on the requiered angle. We have found that even when the customer submits machinig plans its better to get hold of the used piece and recheck by this method because many times plan given are not original but drafted with mesurements taken from the piece in order that you can quote, and afterwards when the gears do not mesh well you are the only culprit.
Regards
SACEM1
RE: Calculate Helix Angle from Sample?
RE: Calculate Helix Angle from Sample?
I can see in this instance why it helps to know a member's profile. Our business is a "Jobbing" shop in a small town (Pop 1000) four hours from a "Gear Shop". We have two Maag gear shapers (SH75 and SH150) and our work is replacing existing parts for Agricultural and Earthmoving industries. The Maag has an internal head and rack cutting attachment to auto feed and index that allows machining of internal splines with formed tools. The single tool feature enables all tooth forms to be machined. From previous experiences, I realize I need the mating gear and housing for center distance. It I can't measure axial pitch, I make both mating gears to suit housing supplied.
Regards - Riverina
RE: Calculate Helix Angle from Sample?
You are right really he stated he wanted to know the exact angle not how to make a new one but you can also use this method as detailed before and from the resulting gear train that gave you your acceptable tolerance limits you can with simple math determine the angle, as I said if you don't have the special gear mesuaring devices, its a way out.
Have a Very Good 2004 to all of you
SACEM1