Making a worm on a y-axis lathe?

Hi,
I've got a y-axis lathe with no means of tilting the live tool (with what I've got anyways).
I've been asked to make a worm (gear) and immediately I see trouble with making the worm tooth profile by means of an end mill coming in straight from the side. It would require using a very small end mill and prob take forever. Heard about hobbing, but I take that this is done with machines purposely built for making gears. I also presume that turning is out of the question due to need for a ridiculous z axis speed.
Is there such a thing as "tooth shaped end mill"?
Pardon my stupidity, a lot of pressure coming from above today:-)

PS: I suggested getting a stock worm and putting it onto a shaft.

Thanks!

You could get a tool to match the tooth angle of the gear...14 degrees? Even if you were a degree or two off, by doing lots of passes at a very small WOC you'd get a decent finish.

Harvey Tool - Miniature End Mills – Ball Tapered Rib Cutters

It would be slow going but it would get it done.

Schjell said:

I also presume that turning is out of the question due to need for a ridiculous z axis speed.

Click to expand...

No, regular turning is not out of the question, a lot of worms are made that way. If you do it that way, pretend it's a thread.

Is there such a thing as "tooth shaped end mill"?

Click to expand...

I s'pose you could try that way -- don't know of anyone who has but ... is this a one-off or a ten-off or are we talking 1,000 parts ? Worm teeth are normally straight sides, at least, so you wouldn't have to worry about curved end mills. Deckel profiles spiral bevels these days so anything can be done.

Another common way to make worms is in a thread mill - imagine a 4" dia horizontal milling cutter with 20* taper to the sides, tipped to the lead angle of the thread, and you've got the idea. It's the tipping part that would be difficult on a y axis ... it's possible to do in a hobber but would not be the #1 choice.

If the lead is short enough, just turning is good.

Thanks a lot for your input.
It's a one off fortunately so I'm prepared to "waste" some time on this.
The pitch is quite steep, but I'll definitely look into turning. I'll see how low surface speed I can get away with.
Material not decided yet. There's a chance that POM-C would be acceptable, I was guessing that it would be 316 or equivalent.

You can use a Threading toolpath. Unless your machine can't.

Schjell said:

Hi,
I've got a y-axis lathe with no means of tilting the live tool (with what I've got anyways).
I've been asked to make a worm (gear) and immediately I see trouble with making the worm tooth profile by means of an end mill coming in straight from the side. It would require using a very small end mill and prob take forever. Heard about hobbing, but I take that this is done with machines purposely built for making gears. I also presume that turning is out of the question due to need for a ridiculous z axis speed.
Is there such a thing as "tooth shaped end mill"?
Pardon my stupidity, a lot of pressure coming from above today:-)

PS: I suggested getting a stock worm and putting it onto a shaft.

Thanks!

Click to expand...

on a CNC the previous post are correct it can be single pointed as a thread,
there are new CNC lathes with multi axis that can actually hob, but here is the deal,
if the worm is not standard it has to be special ordered from one of gear tool manufactures like Gleason or helious
if it is standard ash gear & supply might have in their stock
a hob has a lead angle
and the work spindle has to be tilted to compensate for the correct helix angle and lead angle,
it is a formula like this helix angle = 90 deg- lead angle of hob.
a worm can be measured over three wires to get the correct circular tooth thickness.
do they specify wire measurement over (3) wires on the print. gear wires have to be exact.
the worm if single thread cut like a thread, 2 start or more it can be cut like a helical gear.(can be measured (2) wires)
let me know if I can be further help, but have a lot of work at the moment so it may be a slow response.
I have programs that calculate the wire size and bs.
FYI~ the worm has to be precise because the worm gear is cut to a special center distance with a worm master.
like a bevel gear it is verify by tooth profile contact. central contact with 80% on center. and has to have the correct back lash.

edit: a worm gear (not the same as a worm) has to be hobbed to nest the worm a mill might get close but it has to match the worm to get the correct tooth contact and backlash
or there will be interference (which is bad) and will have premature failure.

if the worm gear is brass it is more forgiving . for such

Thanks for your extensive input there, much appreciated! For this particular application the gear will not require to be "proper". It's going to be rotated at prob just 60 RPM (by an ROV manipulator subsea) and the gear won't really see any heavy load. The worm gear will be watercut so it's not even going to be meshing properly. After use its probably going to get scrapped at some point I would guess.

Thanks again, I truly appreciate the valuable time you and others on this forum devote to helping others. One day I hope to add some good input to others. Things that I consider myself "professional" in is telling what mechanical contraptions work and doesn't work underwater when being operated by careless overpowered robots (ROVs)

Schjell said:

Thanks for your extensive input there, much appreciated! For this particular application the gear will not require to be "proper". It's going to be rotated at prob just 60 RPM (by an ROV manipulator subsea) and the gear won't really see any heavy load. The worm gear will be watercut so it's not even going to be meshing properly. After use its probably going to get scrapped at some point I would guess.

Thanks again, I truly appreciate the valuable time you and others on this forum devote to helping others. One day I hope to add some good input to others. Things that I consider myself "professional" in is telling what mechanical contraptions work and doesn't work underwater when being operated by careless overpowered robots (ROVs)

Click to expand...

that's cool, I had a project that was an under water vehicle for the navy many moons ago. except back the it was on a tether.