RobCox
Member
- Messages
- 391
- Location
- Cambridge, UK
A while ago I posted a thread on a gear cutting attachment I'd made for my shaper. The limitation this had was that it would only do spur gears, albeit any size (DP/MOD or teeth) within reason. I was sure that I could adapt this somehow to be able to cut helical gears using the same technique.
The jig uses a universal dividing head. As the shaper table traverses from right to left a chain of gears picks up the rotation of the table leadscrew and uses this to rotate the gear blank at exactly the right speed so a finished gear in the same position as the bank would roll against a stationary rack. The rack is reduced to one tooth and this tooth is attached to the shaper ram and is used to cut the teeth.
Fast forward to the end of the whole construction, this is the whole Wallace and Gromit contraption cutting teeth on a delrin blank (it'll work for steel, but delrin is quicker for a first try):
So with the excitement out of the way, a few of the bits I had to make to get this to work.
First, in order to set the helix angle, the dividing head needs to be rotated. I repurposed the base of a swivel vice that came with the shaper and fitted a piece of 6" x 15" x 3/4" plate on it to act as a rotatable table to hold the dividing head and a footstock. This needed a recess milling to fit the swivel base which tested the capacity of my mill:
This was the only way I could mill the circular recess given the little machines I've got. I popped the gap piece out of my lathe to see if that would work but an M300 just isn't big enough. This is the groove:
And the base it fits:
A keyway was milled on top to line up the dividing head:
And the whole lot bolts on the shaper:
I made the footstock to go with it, along with the ER32 chuck on the dividing head. The aim here was to maximize the space for the gear to be cut.
The jig uses a universal dividing head. As the shaper table traverses from right to left a chain of gears picks up the rotation of the table leadscrew and uses this to rotate the gear blank at exactly the right speed so a finished gear in the same position as the bank would roll against a stationary rack. The rack is reduced to one tooth and this tooth is attached to the shaper ram and is used to cut the teeth.
Fast forward to the end of the whole construction, this is the whole Wallace and Gromit contraption cutting teeth on a delrin blank (it'll work for steel, but delrin is quicker for a first try):
So with the excitement out of the way, a few of the bits I had to make to get this to work.
First, in order to set the helix angle, the dividing head needs to be rotated. I repurposed the base of a swivel vice that came with the shaper and fitted a piece of 6" x 15" x 3/4" plate on it to act as a rotatable table to hold the dividing head and a footstock. This needed a recess milling to fit the swivel base which tested the capacity of my mill:
This was the only way I could mill the circular recess given the little machines I've got. I popped the gap piece out of my lathe to see if that would work but an M300 just isn't big enough. This is the groove:
And the base it fits:
A keyway was milled on top to line up the dividing head:
And the whole lot bolts on the shaper:
I made the footstock to go with it, along with the ER32 chuck on the dividing head. The aim here was to maximize the space for the gear to be cut.