Info on universal dividing head

[zl1byz]

Can anyone explain how a universal dividing head acheives it's helical cutting function? No need for the basics on dividing heads just the extra theory and setting up for helical cutting. I have done some web searches, plenty on the basics and plenty who will do it for you, but it seems a bit of a dark art when it comes to how it's done.

[pgp001]

I put my universal dividing head manual on my webpage earlier, it explains the set up for spiral milling.

http://homepage.ntlworld.com/phil.procter/VICTORIA%20DIVIDING%20HEAD/

Phil

[SGW]

The short answer is, it's geared to the table feed. So as you turn the crank, it both rotates the work and advances the table.

The exact details of this setup I leave to others....

[zl1byz]

Thanks Phil I saw that mentioned in the other dividing thread, but didn't realize it was a universal one. So I'm having a look at it now. I had kind of figured that they were connected to the screw on the table, but still a little fuzzy on how it accomodates advancing the spindle during the cut without screwing up your indexing registration.

[vmil3]

When cutting a helix(drill bit flutes)or helical gear on a Universal Miller using a Universal dividing head the dividing plate lock(some use a pin, or lever)is disengaged allowing the plate, sector arms and crank handle to rotate, thus turning the dividing head spindle.(You don't loose your indexing because the whole assembly is turning together).
The turning of the dividing plate is done through a set of bevel gears, one gear is under the dividing plate,(your plate actually bolts to this gear) the other is usually an attachment that bolts onto the dividing head,(some are built in to the dividing head) it is a bracket with a shaft and the other bevel gear on one end of the shaft,the other end of the shaft is where you mount the change gear, or gear train. This gear is driven by a gear, or gear train mounted on the feed screw at one end of the table. The table of the universal miller is angled to the correct helix angle required.
When you engage the table feed, the table moves, the table feed screw turns, and through the gear train turns the dividing head plate, which turns the dividing head spindle.
NOTE:It's easier to show than to describe here. I hope I haven't confused you.
Doug

[zl1byz]

Ok Doug, yes I'm with you now. Just about lost me when you talked about the table being on an angle, I guess turning the milling head would acheive that.

Thank you for the help so far.

Cheers, John.

[This message has been edited by zl1byz (edited 09-17-2004).]

[sjensen30]

John, What Doug said about rotating the table to match the helix angle is true. Rotating the head of the machine will do nothing for you as far as cutting a helix. That's why they're called Universal milling machines. They have the capability to rotate the table. Hope this clears things up.
Steve

[bbfmetalworking]

Steve,
Actually, you can cut spiral (helical) gears by tilting a vertical milling head on a mill without a universal table.

Think about using a vertical milling head with a
conventional (horizontal style or "plain") cutter on a
stub arbor, and tilt the head left or right to match the helix angle.
Lining the cutter up on center is similar, but "sideways" to setting up the cutter on center for a universal mill. Your cutter will be on the side of the workpiece instead of on top.

This is the equivalent of using a mill with a
universal table. It won't be as rigid since you're not supporting the arbor on both ends, but it does work.


[This message has been edited by bbfmetalworking (edited 09-18-2004).]

[zl1byz]

Hmm well what I do have is a bridgeport, I also have the right angle drive attachment, arbor and support which makes it operate as a horizontal machine. I thought set up like this turning the ram on top of the colum in the horizontal plane(not rotating the head) would acheive pretty much the same as turning the table. Which on a bridgeport you obviously can't do. The biggest broblem I could see is running out of X travel, as when you turn the ram everything moves out to the side. This might not be too bad if everything was kept close to the colum. Have I lost the plot or not?

[bbfmetalworking]

zl1byz
Turning the ram would theoretically work, but as you say, I bet you'll be very limited in how far you can turn the ram, then position your dividing head, and still have table travel. You'll probably be limited in the range of helix angles you could get from such a setup.