Helical gear cutting

[crueby]

This morning cut a pair of the gears I showed yesterday, this time in brass. You can see some odd holes near the teeth, the brass I used was scrap that had those holes. I used both templates, right and left hand versions of the same angles. Worked great!

[cnr6400]

 

[Jasonb]

I used both templates, right and left hand versions of the same angles. Worked great!

Could it be done with one template?

Looking at your photo if the jig were moved to the front side of the cutter I think the cutter would produce the helix in the opposite direction. To avoid climb milling the cutter could be mounted the other way round and the mill run in reverse.

[crueby]

I used both templates, right and left hand versions of the same angles. Worked great!

Could it be done with one template?

Looking at your photo if the jig were moved to the front side of the cutter I think the cutter would produce the helix in the opposite direction. To avoid climb milling the cutter could be mounted the other way round and the mill run in reverse.

No. Take a screw, note the direction of the thread, and turn the screw end for end. Same direction of the thread. For mating gears on parallel shafts, you need one right hand and one left hand thread. If you put the jig on the front vs back, you get a mess of wide valleys. Trust me, I  tried it once!

[Jasonb]

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[gbritnell]

I have to say that Don's gear spreadsheets are great. When I was building the Ford 9 inch differential I sent him all the calculations laid out by Kozo Hiroka and Don spent a great deal of time translating them into a workable spreadsheet.

[gbritnell]

Chris is correct.  If you cut on the wrong side of the gear blank all you get is a kerf with a radius equal to the radius of your involute cutter

[Zephyrin]

Care needs to be taken when making the return rotation of the spindle arbor so that the follower stays against the helical template. Chuck had used a spring whereas I just kept pressure against the follower bearing.  Chris took it a step further by making the helical slot in the printed template a close fit to the guide post thereby practically eliminating an unexpected gouge in the gear blank.

exactly, I wouldn't say I got my gears right the first time...
and yes, the 2 sided guide on the template of the Chris setup is a very good improvement !