Mill Question for Experts

[RandyKopf]

Hi I am trying to help a friend cut a part that exceeds some table limit. Since it has a rotary table it is possible to cut the part.

Does anyone know if there is a way to force Fusion to output code on a mill as you might do on a C-Axis Lathe?

IS THERE A WAY TO EFFECTIVELY LOCK AN AXIS TABLE LIKE Y? to force the output to use a combination of Rotary motion and X Movement to machine around the part. In essence as table rotates X slides out and back as needed to profile this part?

In my old UGII Days with ICAM Post you could lock an axis, and the post would see this as an alternate solution.

In the picture below the part is outlined in Blue. There is a rotary table shown in GREEN. There is a limit on the Y Axis Travel Limit shown in RED. So effectively for a part this size on this machine its not possible to profile the outline of the part with standard XY interpolation. I could code it with POLAR math by hand.

I would like to do this with Fusion 360 CAM

Any thoughts on this? All input is appreciated.

[George-Roberts]

Im not one of the Expert Elites, but believe i could do this with a few post mods. It would be very similar to XC milling on a lathe... could you upload the post your using?

[Steinwerks]

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@George-Roberts wrote:
Im not one of the Expert Elites, but believe i could do this with a few post mods. It would be very similar to XC milling on a lathe... could you upload the post your using?

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You probably should be! 

I was thinking a post requirement as well but aside from thinking of pulling things from XYZC posts to work it, I don't actually know how I'd go about it (not as much post experience as I'd wish).

[xander.luciano]

Hey Randy!

Since I only know 1 machine that you and I both have that has a table like that with a Y axis limit like so, I think I know exactly what the issue is here.

And I also think the easier solution would be to machine half the part by using a sketched machining boundary, then changing the tool orientation, and machining the remaining half with another sketched machining boundary. Probably with a little overlap.

If that isn't quite what you are looking for though, this can definitely be done in post so long as you only want to be doing 3 Axis moves. Here's some quick head math:

To do this, you (I, we, someone else haha?) would just have to offset the X and Y positions by the Sin and Cos of the table rotation times the absolute distance from the center of rotation to the original X Y position.

Using something like:

If Yposition < YmachineLimit
    rotate 45 degrees;

    offsetXY(45);

*note you'd had to check if X is either positive or negative so you rotate in the right direction.

Sounds easy on paper, but no idea how well that'll go in practice though. But hey, I'm all for trying out new ideas at the risk of failure!

Let me know your thoughts,

Xander Luciano

Edit: Oh and that would give you a spherical interpolation which means lines would turn into arcs. You would need a linear interpolation method so that would take some more work and I'd have to go dig up the equations for creating linear interpolations. UNLESS you detected the Y would go past so you retract, rotate the table, then plunge back in so that the spherical (well circular I guess since this is 2D) interpolation occurs above the part.

[RandyKopf]

@George-Roberts Autodesk should make you an Expert Elite... hint hint @al.whatmough Just stating the facts man!

I do feel the post solution is the best overall. In my ancient CAM days with both UGII and Pro/NC I used ICAM's post. And we were able to insert a CLAMP Statement on any Axis. That forced the post to look for alternate solutions to machine the part. And ICAM was very intelligent dealing with that as standard processing. I would love the same thing here with Fusion 360 CAM.

This machine is the Pocket NC. and I attached the latest post I got from the Pocket NC folks that work with new updates on Fusion.  @xander.luciano may have a later version and also be able to help  mod as you suggest he has the same machine. And has excellent post knowledge. But lacks what the knowledge of what we are proposing here. So maybe you two can collaborate.

Xander you are correct in that initial setup solution you offered. It would work. But it is not ideal. I don't want to break up the cut as it could leave dwell marks on the sides of the part and more importantly any error in calibration will be multiplied by flipping the part 180 and resuming the cut. The other interpolation is really a rectangular to polar conversion that is common to lathes that do not support direct motion between two positions. It is just like exploding an arc motion to point to point. Or an angled line into many C and X point Motions.

BTW I am asking this on behalf of the problem Merik Karman ran into as he requested help on Pocket Google Groups btw.

https://groups.google.com/forum/#!category-topic/pocket-nc/pAHbiAajhOs

Thank you everyone!!! And especially Al.Whatmough for you upcoming approval of making George Roberts an Expert Elite. Hell your should toss me in the group as well. If we don't ask we don't get! End of Story 🙂

[George-Roberts]

haha!! Don't think i'm at that standard just yet, maybe one day!

I'll have my first crack at this tonight and let you know how I get on 🙂

[Trigg3r]

If there is no problem reaching the back of the part (Y+ if you like), then why bother ? Just cut the first side, index A 90°, cut the next side etc. 😄

If it's that big that he's on the Y+ limit too, I'll just shut up and sit quietly 😉

*Edited to add @xander.luciano beat me too it

#ireallymustreadallthethread