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Hi. Can a CNC Swiss make these gear/round parts--if so, what do I need?

Better yet one of the Barber Colman Type S benchtop hobbers. Tying up a swiss while it single indexed gear teeth would be pretty slow- even for a hi zoot machine. A swiss could probably crank out 10 blanks in the time it would take to cut one gear- guess on my ignorant self / part though.

A modern swiss doesn't hob single teeth, it's indexing the main spindle and a rotating hob in synchronous cutting.... It'd hob a whole one of those gears in brass pretty durn quick.

 
Hi all:
One of the things that seems to be missing in the gear conversation, is that we're trying to make worm wheels, not spur gears.
The motions of the machine and the dimensions of the hob need to be very different to make worm wheels... plunge infeed without the hob traversing the width of the blank.

Now I know nothing about gear cutting machinery other than what I've read, but I was under the impression that a standard spur and helical gear hobber could not make worm wheels without "special stuff" not the least of which is a hob and machine combo that mimics the worm dimensions and also allows plunge infeeding.
Like these:
worm hob.JPG

plunge worm hob.JPG

So EmGo, ZahnradKopf, Dan from Oakland and any other gear gurus...enlighten us on what it would take to make actual worm wheels on a normal hobber and what it would take to get the hobs for something this small.
Also, for those who know, can you make a Swiss with a hobbing attachment do this easily or is this a major nightmare to get to work?

Last. is it commercially possible or ever even done, to drive the hob into the blank by feeding it as if it were a tap, driving along the axis of the hob across the worm wheel blank, and if you could, one would think you can also do it on a VMC with a 4th axis and not need the hobber at all.
You'd have to index the worm wheel for each tooth
So basically you'd just run a tapping cycle over and over...indexing to the next tooth after every tapping cycle.
For a biggish worm wheel you could fake the involute profile pretty well that way.

I know you can also fake it by simply hobbing a helical gear with the correct helix for the pitch of the worm...but that's cheating, isn't it? :D

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
Hi all:
One of the things that seems to be missing in the gear conversation, is that we're trying to make worm wheels, not spur gears.
The motions of the machine and the dimensions of the hob need to be very different to make worm wheels... plunge infeed without the hob traversing the width of the blank.

Now I know nothing about gear cutting machinery other than what I've read, but I was under the impression that a standard spur and helical gear hobber could not make worm wheels without "special stuff" not the least of which is a hob and machine combo that mimics the worm dimensions and also allows plunge infeeding.
Like these:
View attachment 414373

View attachment 414374

So EmGo, ZahnradKopf, Dan from Oakland and any other gear gurus...enlighten us on what it would take to make actual worm wheels on a normal hobber and what it would take to get the hobs for something this small.
Also, for those who know, can you make a Swiss with a hobbing attachment do this easily or is this a major nightmare to get to work?

Last. is it commercially possible or ever even done, to drive the hob into the blank by feeding it as if it were a tap, driving along the axis of the hob across the worm wheel blank, and if you could, one would think you can also do it on a VMC with a 4th axis and not need the hobber at all.
You'd have to index the worm wheel for each tooth
So basically you'd just run a tapping cycle over and over...indexing to the next tooth after every tapping cycle.
For a biggish worm wheel you could fake the involute profile pretty well that way.

I know you can also fake it by simply hobbing a helical gear with the correct helix for the pitch of the worm...but that's cheating, isn't it? :D

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Feeding along the axis of the hob (like tapping) is called hob shift on my hobber. Hobbers that have it have an extra axis on the hob head. It's intended to be used for utilizing the width of the hob during the cut.
 
Now I know nothing about gear cutting machinery other than what I've read, but I was under the impression that a standard spur and helical gear hobber could not make worm wheels
No, ANY hobber (that can swivel the hob head, some spur-only hobbers have a very limited amount of swivel) can cut wormgears by infeeding. Really old ones often don't have power infeed but you can always do it manually. Most anything newer than 1960 will have infeed. On a Barber-Colman maybe not because those are often used more for shaft work but infeed is really common.

Garwood said:
Feeding along the axis of the hob (like tapping) is called hob shift on my hobber. Hobbers that have it have an extra axis on the hob head. It's intended to be used for utilizing the width of the hob during the cut.
Not exactly ... every hobber I've ever seen does have hob shift, in some form or another, even if it's just moving spacers around.

But there is also tangential feed which is a powered, in the cut motion of the hob along its axis. This is another way to cut wormgears. This would be analogous to a rotating tap threading its way through a rotating part - not a stationary one. You can cut wormgears with a single tooth cutter this way, I may have a video that shows this, it's easier to see than describe. You can also use a full hob for this method, it's not uncommon with bigger teeth because the hob can have smaller roughing teeth at the entrance side then graduate to finer finishing teeth later down the cut.

Also, for those who know, can you make a Swiss with a hobbing attachment do this easily or is this a major nightmare to get to work?
Teachme knows more about swisses than me but the attachments for integrexes and the like run over ten grand. A little barber-colman is pretty easy to find for a thousand. And faster, and actually does work better because it's designed for that. But in some cases it probably is nicer to do it all on one machine ... but I'd imagine not when you are making a few thousand guitar tuners a year. Swisses are not normally cheap. He could make these things on a very low-cost lathe and little b-c easily. I forgot about the benchtop ones, that'd be even better than a #3 if he could find one. People don't even advertise them, they are so cheap.

Last. is it commercially possible or ever even done, to drive the hob into the blank by feeding it as if it were a tap,
See above, but not the way you're talking about ...

So basically you'd just run a tapping cycle over and over...indexing to the next tooth after every tapping cycle.
No, part has to rotate in a timed relationship with the cutter. The straight sides of the tool rotate with the part to create the curve of the teeth. It's just like rolling a spur gear with a rack, just wrapped up around the cutter.

It's probably possible with a 4th axis but now we're getting silly, little barber-colman or mikron or koepfer or hamilton will do that for cheap. Or if he wants to spend some money there's some nifty little cnc ones for eighty, ninety grand, probably not in the budget :)
 
Hi Garwood and EmGo:
That's super useful information...I am not experienced with gear cutting... only with faking it for prototypes and Homeshop Harry projects like making fine adjustment mechanisms for grinder accessories and the like.

So thank you for setting me straight...it'll be interesting if the OP chimes back in with the solution he ends up choosing.
Unless he's aiming for world domination in the stringed musical instrument tuner domain, and needs to make a hundred thousand a month, you're right...a manual hobber and a 2 axis CNC lathe can be had together, for less than the hobbing attachment for a Swiss and even if he had all manual equipment he'd be drowning in wormwheels in a week.

So unless he's made of money, my guess is he goes for a manual baby hobber.
Now where to get wormwheel hobs for such a tiny wormwheel?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
No, ANY hobber

This, up there. Emmy 😜 covered it pretty well. In my quest to learn over the years, I've done most all of these in effort to compare the results to properly generated Wheels and Worms. ( as well as Spurs and Helicals ) I've done it on a turning center as well as machining center. I've used all manner of tooling, from COTS to custom, to hand ground. Aside from the obvious economic superiority of the proper, small, dedicated machine, there is a decided loss in achievable quality in using the more common machines. One thing many people forget ( or fail ) to consider is that most times the Worm & Wheel in a real gear machine is not only much larger than the indexing mechanicals in the other, more modern machines. And, they were made to MUCH, MUCH higher quality and accuracy standards.

Getting back to the OP's query - *Can* it be done? Sure. Should it be done? I won't say "No", but unless one is already sitting on all the machinery and tooling and wants to burn up some spare time, I really can't see any reason to avoid just about any other method. OP's needs just don't justify it from my point of view. Who knows? Maybe OP just wants to make the most accurate, smoothest, highest quality, turning/spinning wire stretchers on the planet.
 








 
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