Multiple offsets for the same tool in RapidTurn

[BanduraMaker]

Using RapidTurn, I'd like to use an end mill as both a drill and a boring bar to make some plastic bushings. First, I should state I'm new to CNC turning, been running CNC routers for years and would consider myself very well versed in milling.

So, as I've gathered so far (and this whole explanation will be "as far as I understand it" and I'm very open to learning where I'm wrong), lathe controls can store multiple offsets for the same tool for exactly the reasons I'm after. The offsets also store the control point orientation. So for example:

T0101 is tool 01 with offset and control point 1
T0102 (or maybe 0201 - not sure) is tool 01 with offset and control point 2

So, one could setup T0101 as a drill using the center control point, and T0102 as the same tool but with a boring bar control point.

If you're using T0101 and call T0102, the controller simply loads the offset and control points for T0102 without going through an M06 in the process.

The idea is to drill using the offsets for T0101, retract, switch offsets to T0102 and then use the same tool as a boring bar to refine the bore diameter.

I know all this is possible as I've seen videos of machines doing this, I've heard it's by setting up multiple offsets on the same tool and it also seems that this is a pretty common practice (which is why it's supported in G-code).
The issue is that when touching off tools in PathPilot, when selecting a tool, there's no option for a second offset and control point. e.g. If I'm touching off tool 01, PathPilot doesn't have an option for tool 01, offset 01, offset 02 etc.

Anyone know if what I'm after is possible and how to do it?

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[ScottDW]

To the best of my knowledge, and if I'm understanding what you are trying to accomplish, you would have to set the end mill up as two different tools with which ever offsets apply for the intended purpose.

I'm having a hard time picturing how you would use an end mill in the mill spindle to bore anything out. I will effectively be in the X axis for the part, correct?

[BanduraMaker]

Yea, I got the advice from a well known YouTube machinist. The idea is to accurately clock the end mill such that one of the face cutting edges is used as a boring bar. The process would be to drill with the end mill (plastic so no biggie plunging it in) and then change offsets after the drill to refine the bore of the bushing.

Setting this job up as two tools is plan "B" for now. The reason I'm avoiding this is to avoid the cycle start after the M6. If this can work like I think it should it would save a bit of time. I'll need these bushings in multiples of 28 so every little bit helps!

[BanduraMaker]

Ok, so I don't have an answer to my exact question but a suggestion that was given to me is to just set up the tool as a boring bar with the single offset that I have and use it like that.

E.g.: Say I'm using a 1/4" end mill - set up the edge as the control point. To drill, I'd do a boring operation at .250 diameter. Once that's done, do another boring operation at .375 and all's good.

I'd still like to find the answer to this as it can be quite useful. I saw a video somewhere on youtube where they drilled a hole and then used the drill point to chamfer the edge of the bore to knock the burr off.

[kstrauss]

I haven't tried it but how about:
Setup tool #1 in PP with the drill offsets
Setup tool #2 in PP with the boring bar offsets
In your gcode reference the drill as T0101 and the boring bar as T0102.

[TurboStep]

T0101 is tool 01 with offset and control point 1
T0102 (or maybe 0201 - not sure) is tool 01 with offset and control point 2

I think you might be mixing Geometry Offsets and Wear Offsets. If you’re coding manually I’d first try just using T01 without wear offsets to drill the hole and then turn on wear offsets on the same tool with T0101 to bore it out. Setting the X wear offset to the tool diameter should give you the correct total offset, but I haven’t tried it, so I’m not sure offhand whether you’ll need to use + or – the tool diameter. This isn’t the intended purpose of wear offsets, but PathPilot doesn’t mind?
Using the offsets from another tool would probably work but doesn’t seem necessary here. From what I’ve seen of the code Tormach uses some tricks to implement wear offsets, which I don’t believe are supported by Linuxcnc out of the box. I’m sure the standard cases work, but I’d be careful about doing anything special without thorough testing. Also, if you avoid using cutter compensation, from what I understand, you won’t have to worry about the tool control point.
Step

[jwatte]

T word sets the tool changer offset, but H word sets the tool geometry offset. So, use T1M06H1 for tool 1 default, and T1M06H2 for tool 1 with another offset? (And D for diameter, btw.)

Note that Mach 3 (and I think Path Pilot) do NOT change the tool offset just with T, you have to include H. (I learned this the hard way, so that lesson sticks!)