4th axis machining of groove on OD of cable drum

[DOOGIEB]

Hello all,
This is my first ever post since I joined back in September. Been reading and getting a ton of good information and tips, thank you all for posting like you do!!!

Now to the problem at hand:
I have to machine a .380 diameter groove onto the OD of a drum of a wire rope assembly. The pitch will be .300" and I am using a 3/8" ball endmill to create the geometry required. I am using a Leadwell VMC with a Fanuc 18i control with a 4th axis rotary table integrated into the machine control. What I need to know is how do I time the drum rotation with the X axis movement to create the .300" pitch required? The drum OD is about 6.5" and the length of travel from start to finish is only around 7.00". I am having a rectal cranial moment on figuring this one out. The start and end point must be timed the same for each part. I am fixturing the part with drive "dogs" on the rotary table to locate the parts for repeatability and will be using a tail stock to keep pressure on the assembly for support. I have a customer supplied file on Solidworks and will be using Edgecam to create the CNC program.

Any thoughts on how to do this would be greatly appreciated!!!!

Thank you in advance for your help!!!

Doogie B

[fizzissist]

"Unwrap" it in your mind if it helps.

If you need to move 4 revolutions, at .3/rev, and assuming your rotary is a C axis....and the table is moving in X... Then the command will be something like:


G0 X0 Y0 C0
G01 Z-.1 F5. (ASSUMING RELATIVE DEPTH FROM OD AND ARBITRARY FEED
G01 X-1.2 C1440. F5. (C 360X4 POSITIVE ROTATION AND ROTARY ON RHT SIDE OF TABLE

This assumes your control will accept C commands greater than 360...some won't, and be careful, sometimes the C axis will take you literally and simply move back to 0.....there's a big difference between 0 and 360..even though they're the same location!! Depends on your control.

All you have to do is put the tool in the starting position, spec the end X and C(in number of rotations, or fraction thereof), and the control will coordinate the motion. It'll rotate the C while feeding in X...and the result will be profitable magic!

[Geof]

[QUOTE=fizzissist;1039905.....assuming your rotary is a C axis....and the table is moving in X..[/QUOTE]

If the rotary axis is parallel to the X axis is it not an A axis??

control will accept C (A) commands greater than 360...

Your full 7 inches will need 8400 degrees of rotation which could be too large for the control to accept as a single command. You may be faced with doing it stepwise and redefining your work zero using G92 after doing a revolution.

[fizzissist]

If the rotary axis is parallel to the X axis is it not an A axis??

control will accept C (A) commands greater than 360...

Your full 7 inches will need 8400 degrees of rotation which could be too large for the control to accept as a single command. You may be faced with doing it stepwise and redefining your work zero using G92 after doing a revolution.

Geoff caught me with my pants down.

I was thinking lathe....not mill!! You're correct, A axis!!! (B for a 5th axis)
(knee jerk response, since lathe was the last thing I was programming!)

[RICHARD ZASTROW]

Fizz, try a 6-axis gear hobber.LOL

Dick Z

[fizzissist]

Fizz, try a 6-axis gear hobber.LOL

Dick Z

Maybe Jay coulda used one for his Duesy??

Jay Leno Article

(hard enough for me to deal with 5...never mind 6 axis!!... and btw, I've been in Jay's garage.... but just before he got his CNC stuff, and the kitchen. Nice digs!)

[DOOGIEB]

Thanks all for the replies, I will try this out and post back how it works.
I am "unwrapping" it in my mind.......
Doogie B

[DareBee]

You should be able to simply string the extended rotary moves together without resetting zero (G92).

I make a screw like this.


G1 G91 X3. A-1080. F260.
X3. A-1080. F260.
X3. A-1080. F260.
X1.9722 A-710. F260.

This code runs me 11 revolutions at 1" pitch. Please note that it is G91 but could just as easily be done in G90 with a few extra X calculations.
My control is limited to 1080 max (3 revs)