[acncguy]

Hello all,

We have a Mazak horizontal machining center with an M-32 controller (or M-plus or Matrix Nexus) using G-code programming. I want to program a mill for spiral interpolation combined with helical interpolation to create a tapered bore.

I have the programming book, but I honestly can't make sense of the explanation, so I am going to take my best guess at most of the format and hope someone can help me with the rest.

Say the bore is a 10" diameter tapered .750" per foot on the diameter that's 1.000" in length. So the bore starts at 10.000" at the top, down to 9.250" at the bottom, using a 2" button cutter for the spiral/helical interpolation. X0Y0 is the C/L of the diameter. Z0 is the top face. So the program would look something like this:

(Start spindle and all that etc)
G17
G0X0.Y0.B0.
G43Z0.H1
G1G41Y-4.0000D1F50.0 (Go to start of arc)
G3.1X0.0000Y-3.6250I?.????J?.????Z-1.0000P.0500 (Arc ending point coordinates (X & Y) ... but I don't know what the I & J should be for this. Z is depth and P is the number of pitches (revolutions)).
G1G40Y0.
( Etc )

For I & J, would it be the distance from the starting point to the center of the arc at the start (Z0) or at the end (Z-1.0000), or neither? Also, would there be a problem using diameter comp for some reason? I don't know why there would be, but just thought I'd ask. I would just mess around with it at the machine to help figure it out but I can't get in there as they are running hot jobs.

Any help is appreciated. Thanks.

[uperez]

Hi. I've been lookin at this thread and saw that no one is giving any input so thought I could try and help.

I'm not familiar with commands G2.1/G3.1 but judging from your example, I'm assuming the Y command in the G3.1 line determines the taper. The taper 0.75 diameter/foot that you want to make is 1.79 degrees taper, so the 9.25 diameter that you've written on a 1" length is wrong. It's 9.25 at the bottom of a 1 ft. long bore. It should be 9.9375 diameter at 1" length.

The address I and J are similar to the ordinary G03 command. It's the distance from the start point of the arc to the center, in your case Z0.

The start point and end point in Y will vary depending on what radius the insert you're using. This is very important to get the correct diameter on the part. (you can also correct this on tool radius compensation but its always better to know what diameter you shoud be at the first cut.) Also the Z depth should be deeper by a little bit more than the radius of the insert to ensure a clean up at the bottom if the hole is thru.

I edited your example program with 0.25" radius insert. The Y, J and even the Z value will vary depending on what insert radius you're using.

(Start spindle and all that etc)
G17
G0X0.Y0.B0.
G43Z0.H1
G1G41Y-4.0078D1F50.0 (Go to start of arc)
G3.1X0.0000 Y-3.9672I0J4.0078Z-1.3P.0500 (Z deeper by 0.3 to clean bottom material due to insert radius. not sure about the P check your manual for it)
G1G40Y0.


Hope this helps.

Uly