2.5d Milling Vs 3d Milling

[weaston]

I HAVE BEEN GIVEN CONTRADICTING INFORMATION. PLEASE COULD SOMEONE CLARIFY.

I WAS TOLD THAT 2.5D MILLING WILL ALLOW US TO DO HELICAL INTERPOLATION AS WELL AS RAMPING INTO POCKETS INSTEAD OF PLUNGING IN THE Z DIRECTION. (THIS WOULD INVOLVE ALL 3 AXES MOVING SIMULTANEOUSLY)

I WAS THEN TOLD BY SOMEONE ELSE THAT 2.5D PURELY ALLOWS THE X AND Y AXIS TO MOVE TOGETHER WHILE THE Z AXIS MOVEMENTS WOULD BE INDEPENDANT OF THE X AND Y AXIS.

THIS WOULD MEAN THAT RAMPING AN THE LIKES WOULD NOT BE POSSIBLE.

IS THIS THE CASE WITH SOLIDCAM 2.5D MILLING. WOULD WE HAVE TO BUY FULL 3 AXIS MILLING???

[Piobaire]

Dear Sir!

2,5D milling have ramping and helical movement as well. The limitation is that 2,5D could not mill with a calculated gauge pass a 3D surface or have the strength of different 3D strategies. To mill pass a 3D profile is possible (line, arc, spline in 3D), but not follow a 3D surface with defined overlap.

Hope it helps...
Piobaire

[DareBee]

Most (maybe all?) 2.5D milling packages will do what you are looking for - even though a helical plunge is technically a 3D move. A 2.5D program will usually be programmed from something like a DXF (stick drawing) and will not calculate toolpaths from surfaces.

You should be getting a demo to evaluate from your vender or at the very least a guided "tour" of the software with a Q & A session. These will answer your questions.

[jlwright]

An example of 2-1/2D in one brand of Cam software is that you can cut a tapered walled pocket with radii at the top of the pocket and also radii at the bottom of the pocket with a flat bottom cutter or ball cutter. That is about as close to 3D as you can get. It is very usefull in my type of work. I'm not sure what other software packages can do.
Jim

[mattpatt]

This thread's from a while ago, but there's something mentioned here that I'd like a little more info on.

Referring to Piobaire's comment; "To mill pass a 3D profile is possible (line, arc, spline in 3D),"

How does one do this?

I have a job now that I want to break an edge on a recess. Said recess doesn't fall on a flat plane in X, Y, so I've got around it by putting a small 0.2mm chamfer on it in solidworks, then used 3D milling for the toolpath, but it makes way too many excessive movements, when what I'd like to do is just run the tool around it once, job done. The tool I used is a 6mm ballnose, only because it's the tool I'm using in the previous op. It comes out ok, but it's not what I'm really after as it takes about 15 seconds, instead of about 3 seconds that it would take if I chamfered the same size recess on a flat plane. Not good.

Is it possible to post the 3D model here? Then I could explain clearly what I want to do.

Thanks,

Matt.

[mattpatt]

Seems that I have a result. Not sure if it's the correct way to do it, but it worked!

I used the 3D spiral strategy, path type circular/arcs/CCW, and then fiddled with the Radius start/end/delta offsets until I got what I wanted. I used a 0 delta offset for just one path.

The recess is 21.5mm in diameter so I set the radius start - 21.5mm / 2 - 2.12mm = 8.63. This would give me the radius of the recess minus a number so that the 6mm ballnose is cutting halfway up the rad.

Works lovely in the simulation, so I'll need to try it on the real part.

Next task will be to edit a shaped endmill as a chamfer cutter and give that a try for future reference.

I'm happy now. Well....happier than I was a couple of hours ago :-)

[mattpatt]

It didn't work as good as hoped straight off the bat, but a little number fiddling and it was good.

Down to 3~4 seconds to do break the edge (as hoped)