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View Full Version : Gear cutting, sums check please...



Davek0974
01-12-2010, 02:10 PM
Hi all,
I'm getting close to cutting my first set of gears, nice and small - 4DP :)

Machinery and clamping is all good to go, A&S 2E horizontal mill.

Can someone check my figures please?

Cast iron,
55 tooth gear,
blank is 14.25" dia,
using 4DP No2 cutter of 3-5/8" dia with 10 teeth,
82RPM (nearest suitable speed on mill)
90:1 ratio rotary table,
33 hole dividing plate, using 1 turn & 21 spaces per tooth index,
cutting full depth of 0.539" in one pass after gashing with a 3/16" side/face cutter almost to full depth.
something like .003" chip load?

Thanks in advance
Dave

Errol Groff
01-12-2010, 02:41 PM
Cast iron,
55 tooth gear,

blank is 14.25" dia,

CORRECT

using 4DP No2 cutter of 3-5/8" dia with 10 teeth,

CORRECT

82RPM (nearest suitable speed on mill)

OK, might be a trifle fast.

90:1 ratio rotary table,
33 hole dividing plate, using 1 turn & 21 spaces per tooth index,

That is correct. Don't forget that when setting your sector arms for the 21 spaces DO NOT count the hole that the pin is in.

cutting full depth of 0.539" in one pass after gashing with a 3/16" side/face cutter almost to full depth.


something like .003" chip load?

Feed = RPM x No. of teeth x chip load so 2.5 ipm feed

Davek0974
01-12-2010, 03:02 PM
Thanks, i have the question on another group and one reply has also said the speed is a tad generous, i''ll knock it back a bit.

I'll count the spaces between the hole the pinis in and the hole the pin will be in. I had to mak a new dividing plate of 38 holes for a 76 tooth gear and it all worked well so i'mon the right track.

Dave

Davek0974
01-13-2010, 02:48 PM
Update,

Ok, thanks for the advice, i've got it setup as in the pics below, seems to make sense and appears nice and firm. Just though i'd get a second oppinion before i pull the loud knob:)

Setup with gashing cutter in place...

http://xa.yimg.com/kq/groups/17605961/sn/85335625/name/DSCN1349.jpg

http://xa.yimg.com/kq/groups/17605961/sn/90490285/name/DSCN1350.jpg

http://xa.yimg.com/kq/groups/17605961/sn/1647992084/name/DSCN1351.jpg

The long stud with the washer on has a centering mark on it so i can change cutters easily.

Dave