How to Radius corners of a box.

[Xterrian]

I'm making some boxes with lids. The lids will have a recess that the box fits into. Of course the corners of the recessed portion of the lid are rounded just like the mill I'm cutting the recess with. My question is, how do I radius the corners of the box so that they fit into the corners of the lid. I'm sure I have to use R in the G-code, but not sure exactly how to make the mill cut in a straight line and then curve around the 90 dgree corner and then continue in a straight line again. Any help would be appreciated.
Thanks,
Randall

[gar]

070319-0858 EST USA

Download the HAAS mill manual and then study the G02 and G03 codes.

Also G90, G91, G40, G41, G52, and G54.

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[Xterrian]

I've spent the evening reading the Hass manual and am learning a lot, but I just can't get a simple 90 degree turn with a curved corner in cnc simulator. I get an error if I ask for a radius less than 5. I'm having a problem figuring out the offset as well. This is what I'm trying:
T4
G21
G00 X0 Y0 Z5
G00 Z-5
G01 X-10 Y0
G02 X-10 Y10 R5

(I changed T4 to a 4mm end mill)

This gives me a curve, but if I try to lessen the curve by decreasing the radius I get an illegal endpoint error.

I enjoy RTFM, but as usual it reads like a FM and I'm just not getting it. Could someone try to explain it to me? I've read pages 78 and 79 five times and played with the code in the simulator for several hours and just can't get it to work.

Thanks again for the help. I'm sure that I'm heading in the right direction.
Randall

[Verfur]

I have never used the "R" I have always used the cord xy I and J. But I will chime in any way If the format is correct Then the end pionts are wrong.

Usealy if you turn a corner both the X and Y end pionts are difrent from the start piont.

started at x-10 y0 turned corner
at g02 x-15 y5 r5


the way I would right it would be long hand
g1X-10y0
g2 x-15 y5 I-10 j5 F100

You will need a feed rate so I stuck in F100


Hope this helps

[ger21]

Originally Posted by Xterrian T4 G21 G00 X0 Y0 Z5 G00 Z-5 G01 X-10 Y0 G02 X-10 Y10 R5 (I changed T4 to a 4mm end mill) This gives me a curve, but if I try to lessen the curve by decreasing the radius I get an illegal endpoint error.

Your traveling 10 units (Y0 to Y10) with a 5 unit radius, which gives you a half circle. If you decrease the radius, you can't reach the specified endpoint, because you'll have a circle with a diameter less than 10 units. Does that make sense?

[Xterrian]

That does make sense to me now why the radius couldn't be less than 5, but I still can't figure out how to make a 90 degree turn with a rounded corner. I've sat for hours putting different numbers for X, Y and R as well as I and J, but no 90 degree arc. I just can't figure it out. I'm all about showing people how to do things so that they understand why it works that way, but I've struggled with this for three days now and it's starting to get to the point where the knowledge isn't worth the effort expended to gain it. Could someone just tell me how to make a 90 degree turn with a rounded corner so the little light can go on over my head and I can get on with my life?
Thanks in advance,
Randall

[ger21]

G1 X0.00 Y0.00 Z-0.20
G1 X0.00 Y2.00 Z-0.20
G2 X1.00 Y3.00 Z-0.20 I1.00 J0.00
G1 X3.00 Y3.00 Z-0.20

or

G1 X0.00 Y0.00 Z-0.20 F10
G1 X0.00 Y2.00 Z-0.20 F20
G2 X1.00 Y3.00 Z-0.20 R1
G1 X3.00 Y3.00 Z-0.20

[gar]

070321-0701 EST USA

Xterrian:

First, some limitations.

The radius of the arc that you want to generate must be larger than the radius of the cutter. Under some conditions the two radii could be equal. Applies mostly to an inside cut. There can be other limitations on outside cuts.

In cutter comp you will get an error if this requirement is not met.

In non-cutter comp you will get the radius of the cutter, and maybe an erroneous cut.

In HAAS to cut a complete circle in one operation you must use the I, J, K method. The R technique will not work.

In the R method you must have a correct endpoint in relation to the starting point and the radius.

In G40 mode (non-cutter comp) you have to do more analysis for cutter path than in cutter comp mode. However, the machine will not give an error message for a cutter too large for the intended finished arc. You will just get a bad cut.


Now consider your 90 deg corner and I and J (assuming we are working in the x-y plane).

You will start with a straight line to a point P1. P1 is the starting point of your arc. The center point P2 of your arc is Xcenter = P1x+I, and Ycenter = P1y+J . The X and Y values on the G02 or 3 line define the endpoint, P3, of the arc.

Assume we use G90 (absolute), G40 (no cutter comp), the I-J method, and climb cut. The outside cut is 4" in X and 2" in Y with corner radii of 0.5". The lower left corner of the rectangle is 0, 0. Then you can use the following code:

G90
G40
F40.0
G00 X-0.25 Y-0.25 Z+0.1 (move to start point at clearance plane)
G01 Z-0.5 (vertical move to cutting plane)
G01 Y+1.50 (move along Y-axis to start of radius)
G02 X+0.50 Y+2.25 I+0.75 J+0.0 (CW arc of radius 0.75" -- 0.5 + 0.25)
(the start point of the tool path for the arc is -0.25, +1.5)
(the end point is +0.50, +2.25, and arc center is +0.50, +1.50)
G01 X+3.5
G02 (see if you can proceed from here)

Note: I and J are incremental from the start point even though we are in absolute mode (G90).

If I made any mistakes please correct me.

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[Xterrian]

Thanks for the quick replies. I can see that this problem is much more complicated than a simple explanantion. I am working hard to understand it and I think you guys have brought me much closer to a final understanding. My problem is a basic lack of math skills. I can figure out just about any problem, it just takes me a while due to not learning basic concepts in high school. I will probably have to sit down with a piece of graph paper and draw the whole thing out to get to a solution that works for me. I guess I was just hoping there was a much simpler solution. Thanks again and I will post back once I get it figured out.
Randall

[gar]

070322-0512 EST USA

Xterrian:

It is much easier using cutter comp, but that also means you need to learn certain aspects of working with cutter comp.

I am leaving town for a few days and do not have time now to do my example in G41-G42 mode.

Maybe someone else will give you such an example.

.

[ger21]

He doesn't know how to use G2 or G3. Adding cutter comp makes it far more complex than he needs, I'd think.

[ger21]

What size is the box, and what is the radius of the corners? And what size tool are you using to cut it? Give me this info, and I'll try to explain how to do it.