[Newbie] Acme Screw, Worm gear & Dividing Head

[HMF]

Ok...

Someone needed a worm gear for the drive on the table feed of a Van Norman #12 mill. Theirs was all bungled up.

Started me to think. If you had to make one, what would you do? Would you need a dividing head, Acme screw, hobbing cutter?

In other words, has anyone cut a worm gear, and if so, how?

:tiphat:Nelson

 

[Tony Wells]

Here's a quickie writeup of a guy doing one in 60°. If you wanted an acme, sub in an acme tap. Not too bad. In the real world, this works fine. In the Gear World, it is hobbed with a real hob, as Bill said.

http://www.majosoft.com/metalworking/html/how_to_make_a_worm_gear_reduce.html

 

[HMF]

Here's a quickie writeup of a guy doing one in 60°. If you wanted an acme, sub in an acme tap. Not too bad. In the real world, this works fine. In the Gear World, it is hobbed with a real hob, as Bill said.

http://www.majosoft.com/metalworking/html/how_to_make_a_worm_gear_reduce.html

Great article- will print it out for future reference. Thanks!


Nelson

 

[4GSR]

Way back in my younger days when I was 13-14 years old, I remember my dad and I rebuilding a apron off of a older lathe in the 14-18" size. It had a "open apron" typical worm and worm wheel configuration. We had to make a new "worm wheel" for the apron. I don't recall all the details entailed but do remember making a blank from a piece of brass. At that time we had a "home made" dividing head we set the blank up in. Dad set up a fly cutter in the mill, kicked the head to match the helix angle of the thread on the worm. He fly cut the teeth in the blank to a "hit and miss" depth.
Next, we made a "home made hob" from a piece of tool steel he borrowed from work. Took it to work had it heat treated. We took that hob and set it up in the 9" SBL and made a fixture to hold the worm wheel blank on the compound. This fixture allowed the gear blank rotate with the fly cut teeth freely while the hob was feed into the into it. Of course, the hob did not have any "back relief" cut into it, so all it did was "burnished" and or "lap" the teeth and knock the corners off to get the worm to form to the new worm wheel. It worked out great!!! It all went together perfect.
Wish I had pictures, but don't. Just a old memory from many years ago.

 

[ScrapMetal]

Would the worm gear use the 29 degree worm thread (B & S) instead of the regular acme thread?



-Ron

 

[jumps4]

I'd make the cutter it has to be the same diameter as the leadscrew and when cutting the teeth you have to plunge cut the teeth not cross cut because the teeth are concaved
turn a piece of o1 tool steel to the diameter then turn the shape of the valleys in the leadscrew.
divide it into 4 teeth in the mill relieve the teeth with a stone heat treat and sharpen
I make all my gear cutters it's not hard and i cant afford them
I use the gear maker in emachine shop to figure out what gear i'm working with and pitch by entering in diameter and number of teeth playing with my pitch untill it draws my gear then i have a dxf of the cutter profile
steve