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Author Topic: Rotate Mill head  (Read 3177 times)

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Rotate Mill head
« on: October 22, 2014, 11:09:14 PM »
I need to mill a hole on the Z-Y plane, with X being the depth.  Is this normally done in cam or do you switch the axis in Mach?  Trying to wrap my head around this one, any help would be appreciated.
Re: Rotate Mill head
« Reply #1 on: October 24, 2014, 01:45:52 AM »
Hi QA:

You don't say if you can rotate the mill head, to enable the spindle to be parallel to the X axis, however there is a lot to read before you will get something to work. In the terminology of G-code, the three planes are as follows:
G17; X,Y plane, with the Z axis perpendicular to the plane.
G18; X,Z plane, with the Y axis perpendicular to the plane.
G19; Y,Z plane, with the X axis perpendicular to the plane. This is the active plane you are describing.

If you will look in the G-code definitions, starting with the descriptions of G02, G03, they discuss the relative offsets to be used for each of the above planes. For the G19, the offsets are J and K.

You can play with some lines of code, and watch the tool path screen. The G-codes in the Mach3 program have very few examples to go by. I do not have the book, but the best source for G-code description are the books by Peter Smid. His CNC Programming Handbook in up to the 3rd. edition.

Look on Amazon, they have an entire page for the books on CNC by Peter Smid.

Changing the plane of activity from the normal X,Y is pretty obscure for this forum. I had to do a machine job using G18, to enlarge a mold cavity, and it took a lot of playing around to get it working. I ended up doing the job, but there was a bug in the Mach3 display, and instead of showing a half-circle cavity, it showed a full circle. At first I thought I had written the code wrong, but doing a dry run, with no tool, the motion tool path on the screen was actually correct, and did not move into the upper half of the circle shown on the screen. In my case, the path was the center of a ball mill, and milled a perfect half-circle cavity.

Smids books are not cheap, but from all I have read, they are the best.

Re: Rotate Mill head
« Reply #2 on: October 24, 2014, 04:22:13 AM »
If I rotated the head on my mill I'd deal with that by creating a new machine definition in my CAM package with the new head orientation, that way my CAM simulation and collision detection would all work
Another option would be to process the code with your normal machine definition in CAM as if the part was facing up and create a new profile in Mach3, with the axes and directions re-defined relative to your part, making your machine X run as Z and so on.
Re: Rotate Mill head
« Reply #3 on: October 24, 2014, 09:22:41 AM »
I need to do the same thing. I can rotate the head 90 degrees.  I think creating a new profile called Horizontal Mill is the way to go.  No need to think about a ton of potential gotchas, and if you are using a Cam program you won't have to worry about whether that posts properly too.
Re: Rotate Mill head
« Reply #4 on: October 24, 2014, 02:59:30 PM »
Hi QA:

Perhaps I should have gotten more information before posting a reply i.e., G18 and G19 codes.  The two replies by magicniner and garylucas are correct about a new mill profile. To bore a hole parallel to the X axis clearly requires a rotating spindle at 90 degrees to the standard mill configuration.

However, the Z axis can make an arc in combination with either the X axis, or the Y axis. These are two different effects in CNC machining from boring a hole.

Attached are two short files demonstrating G18 and G19. You can see the motion in the tool path window.


Re: Rotate Mill head
« Reply #5 on: October 24, 2014, 03:01:36 PM »
Here is the G18 sample.

Re: Rotate Mill head
« Reply #6 on: October 25, 2014, 12:22:17 PM »
Thanks for the responses.  A horizontal mill profile looks to be the way to proceed.
Cambam had an issue with dxf files in the ZY plane anyway.  (can't handle arcs)

Thanks again,