How do I program 180* radii?

[hornluv]

I'm looking to turn the part in the picture below, but I'm not entirely sure how to make the machine do the the 180* radius. I've done plenty of 90* ones. Do I need to do it in two lines of code, one for the first 90 and one for the second? Or do I just give it the Z movement and the radius and hope it will fill in the X movement? It's a Haas lathe (Fanuc controls) and the tool uses .250" diameter round inserts. I was thinking I would cut a series of progressively deeper radii until I reach my full depth (OD is 2" and diameter at the bottom of the radius will be 1.5", material is 1018).

http://www.deharohorns.com/pictures/machining_pics/bendingform.jpg

Thanks a lot!
Stuart

[djc]

...I'm not entirely sure how to make the machine do the the 180* radius....

Short answer: have a look at http://www.dakeng.com/man/turbocnc.html#_Toc90515706

As it says, using 'radius specification' (for want of a better term) is not as good as telling it centre (relative to starting point) and end point (absolute). Hope this helps.

[hornluv]

So I would specify the center of the radius using I and/or K, then I'd have to put in the radius and the X depth, right?

Thanks,
Stuart

[hornluv]

In case anyone else is interested in the future, I think I've got it figured out (I'll graph it on Tuesday and turn it in a piece of Aluminum to make sure). Coming from the face of the part, the code would look like this:

G02 Z-.75 K-.25

Coming from the chuck side it would look like:

G03 Z-.25 K.25

The G02/03 tells the control to dip into the part rather than go over it. The Z coordinate is the ending destination and K is the relative distance to the center of the circle in the Z axis. Note the negative distance on the G02 line since the center point is to the left of the start point and the positive distance on G03 since it's to the right. I'll let you guys know how it worked when I get it done and I'll post a pic or two of the finished product.

Thanks,
Stuart

[fswanson]

I would program something like:

T101
G50 S1000
G96 S200 M03
G00 X2.5 Z-.750
G01 G42 X2.0 Z-.5 F.005
G02 X2.0 Z-.1 K-.75 R.250
G1 G40 X2.5 Z-.75
G0X4.0 Z1.0
M30

I'm rather cautious when machining, so on the tool wear page I would add
.500 to the x diameter tool wear. I would then reduce by .050 per pass until to size. Another option is to alter this code and use a G71 with a cut depth of "what ever you feel comfortable with".