How do you measure the flute helix angle on an endmill

How do you measure the flute helix angle on an endmill. Also how is the angle defined . I see endmills in catalogs described as having a 37 degree helix angle . Is degrees per inch of flute lenght.

A trick I know you can do is blue up or even marker up the cutting flutes of your endmill then roll it across a piece of paper leaving a series of lines then I use a square to join the ends and make a perpendicular line. Using a protractor you can measure the angle of the lines.

Hope this works

Matt

Also Helix Angle is described as the angle formed by the teeth in relation to the centerline of the cutter I think this answers your second question

Matthew Kinsman said:

Also Helix Angle is described as the angle formed by the teeth in relation to the centerline of the cutter I think this answers your second question

Click to expand...

Thanks .It does answer the question. I was going in the wrong direction thinking of degres of rotation and I should have been thinking of degrees of incline

To measure helix angle, layout a triangle where the base is the circumference of the shaft. The height is the lenght to get one complete revolution. Helix angle is the angle on this triangle, or the tangent of height/circumference

Karl

If you can measure diameter (not trivial if you have a 3 or 5 flute mill and don't have the corresponding mike, but you can do it by laying it on a surface plate and squashing it (figuratively) between two square pieces of metal and measuring the inside dimension) and you can measure the pitch (follow one flute all the way around and measure the axial distance along centerline from one point on the helix to another) you can calculate it pretty easily.
If you label cells as Pitch and Diam in Excel, the formula I came up with is

=360*atan(Pitch/(pi()*Diam))/(2*pi())

If you have a 1 inch diameter, and a pitch of about 2.4, you get a helix angle of 37.4º. If I've left out a factor of 2 or something, I'm sure I will be corrected.

Having said all this, Mr. Kinsman's method is clever, practical, and probably gives you a better idea of what "helix angle" actually means.

Good luck,

Jim