Hob for Free Hobbing of Worm Gears

[LMMasterMariner]

Made hob from hexagonal bar of 304 stainless steel diameter 24 mm.
I know it's not tool steel but it will do the job in phosphorous bronze.
First turned one part of the bar to 24.0 mm and then turned to 20.5 mm at 3 spots.
Threaded with TR3 insert and made trapezoidal thread 24mm x TR3.
One part of it will be used as worm and another part is a hob.
Good thing is that this bar is hexagonal, so I could easily place it
in 4 way toll post and turn it for 60 degrees each time for milling.
12 mm cobalt end mill used for milling.
No milling machine, nor rotary table on board.

Very simple job which was completed in 3 hours.

Will use this worm and one of worm gears (30, 32, 36, 40 teeth, still have to make them)
and some of the gears from the last picture in one of my next projects = lathe power cross feed.

Regards
LMMasterMariner

[LMMasterMariner]

The drawing

[ragsflh]

like it.thanks for sharing

[DIYer]

Thanks LMMasterMariner! We've added your Worm Gear Hob to our Machining category,
as well as to your builder page: LMMasterMariner's Homemade Tools. Your receipt:

Worm Gear Hob by LMMasterMariner

tags: worm gear

[H.L]

Made hob from hexagonal bar of 304 stainless steel diameter 24 mm.
I know it's not tool steel but it will do the job in phosphorous bronze.
First turned one part of the bar to 24.0 mm and then turned to 20.5 mm at 3 spots.
Threaded with TR3 insert and made trapezoidal thread 24mm x TR3.
One part of it will be used as worm and another part is a hob.
Good thing is that this bar is hexagonal, so I could easily place it
in 4 way toll post and turn it for 60 degrees each time for milling.
12 mm cobalt end mill used for milling.
No milling machine, nor rotary table on board.

Very simple job which was completed in 3 hours.

Will use this worm and one of worm gears (30, 32, 36, 40 teeth, still have to make them)
and some of the gears from the last picture in one of my next projects = lathe power cross feed.

Regards
LMMasterMariner

Muito boa ideia...

[old_toolmaker]

LMMasterMariner,

Excellent workmanship and neatly done. Do you have hobbing equipment or do you use the hob to mill gear teeth while indexing the gear blank? Just curious. I also like your method of starting out with hex stock and indexing via the hex. This is one I am going to make a point of remembering.
Thanks for sharing this!

[LMMasterMariner]

Hello old_toolmaker,

I did it from hex stock because I had it on hand and didn't have milling machine on that vessel. Left it there after fabricating several worm gears from phosphorous bronze. Already had too much steel (weight) in my suitcases, so I didn't take it with me. Have gear cutters at home for making gears in metric modules 1 and 1.5. Also have rotary table and milling machine to do that. If I need to make another hob again will do it from better steel and will not do it with trapezoidal (acme) threads as they are too shallow for worm gears.

Best regards
LMMasterMariner

[old_toolmaker]

LMMasterMariner,

Thanks for sharing your project!
Like you I have made cutting tools from what I had on hand. I have even made milling cutters from soft unhardened steel for machining plastics. As long as they stay sharp all is well.