Multiax TP like "parting off motion" using End Mill and continuous rotary.

[huskermcdoogle]

Anyone know off hand a way to spiral inwards with a multiax toolpath.  I was thinking Morph, but it won't let me put in 90 for side tilt.

 

I need to start out at say a 40mm and work my way into a 12mm diameter.  Keeping the rotary moving while in-feeding in Z.  Similar to parting off in a lathe.  But instead its a 5ax H/H router with a rotary table axis along X.   I am currently stepping my way down using a curve 5ax with depth cuts.  Don't like the retract and then lead-in transition from linear to rotary, just seems clumsy.  See picture

 

 

Normally I would have figured something like this out on my own, but my head is in other places at the moment and I am in a crunch to get out of here for the evening so I said, WTH I'll post up and ask if someone has a brilliant idea to share for the next time I can get back to this or need similar deal.  

 

I can create a sample file and post up tomorrow if that would help.

 

As usual any help  or comments are much appreciated but not required!

 

 

 

[gcode]

Maybe a 3X blend then make it 5x with the 3x to 5x toolpath

[jlw™]

use the spiral geo tool to create geo. then a 2d contour the convert to 5. I habe done it myself.

 

upload a file if you want and I'll do it.

[huskermcdoogle]

That makes perfect sense.  I was thinking there might have been a simple way, but my brain wasn't recalling the spiral geo tool.  I have never had very good luck with 3 to 5 conversion.  I will play with it tomorrow night.  As for now, time to hit the road for a few hours.

 

Husker

[Colin Gilchrist]

You can also program this using Axis Substitution, depending on how your post is setup.

 

If you are wrapping on X for example, then you could draw a line along the Y axis, using Pi x Diameter as the length of your "constant diameter" line. Using 12 mm (and ssuming you are programming in Metric units), your line would be 37.7511mm long. That is the "final depth", and ensures the diameter you cut at the bottom will be constant.

 

To calculate the Plunge motion, you need to make a "ramp" line. Change to the Right Side plane, and construct an angled line, starting at the end of your 37.7511 line. The total "rise" in Z would be the depth that you want to cut, plus a little extra for "lead in" motion. Since you mentioned starting at 40mm diameter, your rise would be 28mm. The actual cut is "radial", so your total rise would be half that, or 14mm. The length of the line will now control your ramping angle.

 

The total length of the line would depend on your "pitch", or how much depth per revolution you wanted to cut. Rather than figure out the formula, I just cheated and use the Spiral function to create a spiral that started at 6mm radius, and finished at 20mm radius, using an initial and final pitch of 1.0mm. The 3D length of the spiral was 1180.971mm. Add a couple MM of extra length for your lead in move, and I'd be using a 1200mm line, with 14.5mm of rise. That would give you just over 14 total revolutions of cutting motion, as the tool ramps down to depth.

 

Then just program this as a Contour, with Axis Substitution enabled. No need to use a 2nd 5X path...

[huskermcdoogle]

So if I wanted to go this route then I would need to have a lead in and lead out contour path if I wanted a linear lead in and out?

[Colin Gilchrist]

So if I wanted to go this route then I would need to have a lead in and lead out contour path if I wanted a linear lead in and out?

 

Linear lead in/out in which direction?

 

The issue with Axis Substitution is that you won't really be able to program a tangent Lead In line. You could do a perpendicular lead in/out move, but any "y axis" motion simply gets converted into a rotary position. That is why I suggested adding a little extra height to the "Ramp" move, so that you start above the part, (still on centerline of the rotary), and the motion just smoothly ramps into the cut.

 

With the Axis Substitution, you won't be able to "lead in" with a Y-Axis move. In that case, using one of the other Curve 5X options, or a 2D contour, converted to 5X motion would be your best bet...

[mayday]

post a file, I do this a lot. morph cut driving the outer wall to center

[huskermcdoogle]

Wasn't too hard.  Two circles, one surface.  I tried to have it then transition into spiral motion to create a cylinder, but couldn't get a clean transision.  Will need to two tool-paths for that, but no big deal.

 

Parting_Motion_Sample.mcam

 

[MrFish]

Wasn't too hard.  Two circles, one surface.  I tried to have it then transition into spiral motion to create a cylinder, but couldn't get a clean transision.  Will need to two tool-paths for that, but no big deal.

 

Parting_Motion_Sample.mcam

 

Spiral_In.JPG

Well done

[Mick]

I did this on Mazak mill turn a few years back. Effectively machined a groove using an endmill, ramping down. I can't recall the specifics, but it worked perfectly.

[huskermcdoogle]

Yeah it should work very well, the stepping down method is quite effective, just not as good as a spiral path, hence my desire to pull my head out of my rear.  

 

Anyone have any suggestions on how to have it transition into a side cut at the bottom?  Though thinking about it the step over might be too much, so two toolpaths would likely be needed.  However there may be some cases I can think of in the near future when it would be handy to know how to do this using larger tools.  Name of the game is preventing chip outs. (cutting wood)