Nomemclature sought for type of movement

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Maplehead

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I’m looking to add some extra functionality to my guitar knob making jig. The knobs I make have radial to straight grooves, as seen in the attached pic. On the straight section, I’m looking to twist the grooves. So that would require the knob to not only turn as I cut with my 1/8” round bottom mill, but to advance down the knob as well. I’m thinking a shaft I can turn that has a single twisted groove that I can follow somehow will be how I accomplish this.
Any idea what those grooved shafts are called? I want to read up on them to see if that’s the correct route and also to figure out what size and length of groove for a given shaft size will accomplish my goal. The end result will be the knob looking like a worm gear on the straight portion of the knob.
As always, any and all advice is greatly appreciated.

8FAC14B7-0D80-4697-B1AA-944F4662BA53.jpeg
 
One other thing I will need to figure out is how to regulate the twisting and advancing so that it is exact timing for each groove I cut.
 
Mitch Alsup said:
That shaft/knob is fluted, flutes can be straight or like threads.
Click to expand...
I always get burned by the most obvious. Oy! But that’s right, flutes just like what’s on a drill bit or end mill.
How can I control the two directions to be uniform? Or will the speed not matter as the mechanical takes care of it?
 
The 4th axis is a rotary table set up on the bed in the vertical position, part held in a chuck on the rotary table.
A set of gears connects the rotation of the x-Axis shaft of the bed to the rotation axis of the rotary table to keep the flutes in a spiral.
The gear ratio between the lead screw and the rotary table angle screw determines the pitch of the spiral.
 
Hey @Maplehead, the "fourth axis" is just adding the ability to rotate the work to a standard 3-axis(X, Y, Z) mill.

You don't mention what equipment you currently use to produce the straight flutes.
You need controlled rotation linked to the controlled y-feed of the table....so much rotation for so much feed.

Helical flutes are normally done by tying this rotation of the work to the feed of the mill.
See page 162 (or 168 of 412)
and 285 (291 of 412)
and especially figure 255 on page 303 (309 of 412)
of this document:
http://www.hobby-machinist.com/resources/cincinnati-a-treatise-on-milling-and-milling-machines.2771/
for the general set-up.

In the first example they are producing a milling cutter, but the idea is the same.
In the last you can see the gears connecting the Y-feed to the dividing head that rotates the work.

-brino
 
Commonly known as helical milling in the machine shop business.

If you want to do such work with a manual machine do a web search for helical milling attachments.
 
Are you using a CNC mill to do the fluting now?
 
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