Single Position Hob Design
Single Position Hob Design
(OP)
Hello All,
Firstly what does a 8/10 DP Cutter mean, is it a 9.97458 mm Diametrical Pitch, (8*pi*25.40) and wat does the 10 stand for.
Have a sample cutter and when i view it I get a pitch of ony 9.312 over all 12 teeth (it has only 11 teeth), the lead angle is 12.25Deg.
Is there some correction to be given!!!
Firstly what does a 8/10 DP Cutter mean, is it a 9.97458 mm Diametrical Pitch, (8*pi*25.40) and wat does the 10 stand for.
Have a sample cutter and when i view it I get a pitch of ony 9.312 over all 12 teeth (it has only 11 teeth), the lead angle is 12.25Deg.
Is there some correction to be given!!!





RE: Single Position Hob Design
RE: Single Position Hob Design
shouldn it be 9.975mm (8*25.4*pi)..??
RE: Single Position Hob Design
RE: Single Position Hob Design
is it a correction?
RE: Single Position Hob Design
(Pi x 25.4)/Dp
Are you measuring chordal
pitch instead of circular
pitch?
RE: Single Position Hob Design
it shows less, is it cos of the 12.25 deg lead angle??
RE: Single Position Hob Design
imitate the cutting action, ignore the lead
angle.
The 4/5 and the 8/10 Fellows Stubs are the same
as the 4 and 8Dp Stub System for calculation
purposes. The hob is the reverse of the tooth.
So the Tooth Addendum is .80/8 = .1000
Tooth Dedendum is 1.0000/8 = .1250
Circular Tooth Thickness = (Pi/2)/8 = .1963495
So the hob or rack detail is
Addendum .1250
Dedendum .1000
Width at pitchline .1963495
Another way to look at the Fellows Stub is to use the
smallest number to determine the circular tooth thickness
as above and use the ratio as follows:
8/10 times 1.0000 for the Addendum = .1000
8/10 times 1.2500 for the Dedendum = .1250