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MazatrolMatrix

Aluminum
So I have programmed a Manual unit for thread milling, we start at the bottom of the hole and climb Mill from there with G91. The thread is M18x1.5. It is done with a 90 degree infeed radius into the material. The tool is a carbide thread mill with diameter 7.5. taking full depth in one pass.
I calculated the infeed as follows:

Radius of m18 = X (9 for M18)
Y = 16.5/2 Y is drilled hole for M18
Start point is Y - 0.5 (16.5/2 - 0.5) for a 0.5mm clearence

Then (X-R)^2 + (Y-0.5)^2 = R^2

This will result in R = 7.836

The offset to center of this radius from Center of thread is then X-R = 1.16.

And now for the code,
N1 G1G90G40 Z-13.375
N2 G91G41 X-7.75 Y0
N3 G3 X7.75 Y-9 Z0.375 R7.836
N4 X0 Y0 Z1.5 J9 I0
N5 X7.75 Y9 R7.836 Z0.375

This results in the machine Wanting to go to Y-0.557 and X-4.127 at block N2 instead of written values. What could be the reason for this? Do I need two G3 lines for the infeed radius because it covers more than 90degrees? So it’s within two quadrants.

I want to add that it turns on compensation, but it shows the values for the center of the tool for some reason regardless.. so maybe the values shown is necessary in order to become tangent to the radius or something like that.

Last edited:

MazatrolMatrix

Aluminum
I figured it out.. or somewhat.
The machine wants to go to the center of the infeed radius, that is -1.16 in Y, however for whatever reason, probably parameter related, it shows the position of the cutters center in relation to this position.

And if you calculate the radius - cutter radius and solve the triangle you end up with the values I wrote, or thereabouts.

The question remains though why it wants to go to the radius centerpoint? I want to start off center in the 4th quadrant by a few degrees and it seems like it refuses..

mzbg

Plastic
Using tool data? I too suspect parameter issues. F92 Bit 7, F93 Bit 3, and F94 Bit 7 are the common offenders that get unhappy here.

MazatrolMatrix

Aluminum
Using tool data? I too suspect parameter issues. F92 Bit 7, F93 Bit 3, and F94 Bit 7 are the common offenders that get unhappy here.
Yeah. I'll look into those. But I use a manual unit in Mazatrol, perhaps the manual unit works under different rules than EIA too.. I'll try that next time.

However it didn't really matter much for the application, I calculated the angle from the radius center in relation to the thread diameter in order to get the right amount in Z for the in/out radius. It's just frustrating when the machine does something you didn't tell it to do.

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