Rotary (4th axis) normal to surface?

[ericschimel]

Curious if anyone could help me wit this: I am trying to machine a curved surface on a rotary axis:

The problem I keep running into is that the end mill stays "normal" to the rotation point of my 4th axis, not normal to the surface:

I should be able to do this with the machine I am using because it can do simultaneous 4 axis.

Said another way, the rotary can spin around a full 360 and the end mill can still move on XYZ, this isn't a machine/post that maps X or Y moves to rotary moves:

Here's the setup if anyone is interested:

https://photos.app.goo.gl/UjB5fUwRPiMHFcjp9

The only way I can get the toolpath to look like what I want is this:

However that requires changing the origin of the toolpath away from where this 2x4 is chucked up. I haven't physically run this path yet but I assume that it will not work.

Does anyone have any suggestions?

[a.laasW8M6T]

As long as the WCS in  you setup is correct, you can move the "rotary" axis like you have shown an the toolpath will work fine.

I have done this before on several parts an it works great.

obviously the "rotary axis" you select must be parallel to the rotary axis in your setup(physical rotary axis of the machine)

[ericschimel]

Aa far as I can tell moving the rotary axis doesn't work...  Check out these examples

I put 4 facing toolpaths on here so you can see where the 2x4 is, check out the rounded corner. it's working in that it's not digging into my part, but it's using the WCS origin for "normal" What ends up happening is the "side" of the bit is being used to create the curved surface. I'd have to a tiny tiny stepeover for that to even begin be effective.

Here's what happens when I change the rotary position in the toolpath setup, but leave the WCS alone:

That, for obvious reasons won't work.

There has to be a way to do this... Maybe I'm not using the right toolpath? I've tried just about everything to get this to work and I have't found anything.

[a.laasW8M6T]

Does this look like what you want?

This is just selecting the edge of the fillet as the coordinate system.

Obviously with a 5 deg stepover you will get quite a faceted result but if you mad it like 0.5 or 1 deg it would probably look pretty good.

see attached file

[ericschimel]

Yup, that's exactly what I am looking for. I see how you did that, you changed the origin of the rotary axis in the setup. I did the same thing on mine:

The problem is when I preview it I get this:

That is in NCviewer. 

I am away from my machine right now so I can't run these paths, but I've always had good luck with NCviewer showing me good previews, although this is my first attempt at using it for rotary. The preview in Fusion looks fine, but what's throwing me off is that I have to move the origin of the rotary axis to get what looks like a working toolpath. In reality I am not moving the workpiece...

[a.laasW8M6T]

Hmm that's odd that it's not working for you.

I didn't move the rotary axis in the setup, just the toolpath, you are moving the axis the toolpath is calculated on(or rotates around). the Physical rotary axis remains the same as it is in the setup.

Maybe there is an issue with your post processor? I have never had an issue with mine, if it looks good in simulation it always runs fine on the machine for me.

[ericschimel]

What post are you using? I wonder what would happen if I try it with that.

[a.laasW8M6T]

You wont be able to use my post, its for Heidenhain itnc530 control, and requires a machine configuration to work correctly.

Maybe share your post here and I can have a look when I get a chance

[ericschimel]

That would be amazing if you could check it out. 

This is the post I’m working with:

https://github.com/swissi2000/Fusion-360-Milling-Post-Processor-for-Centroid

this is deferent than the built in centroid post that fusion offers. 

[a.laasW8M6T]

Hi

I tried it with your post and it seems to work just fine, even run it through the backplotter:

Did you look at how I had my test file setup and toolpath configured?

The key thing is:

Setup, the WCS is located on the center of the block as that is the location of the rotary axis on your machine.

Toolpath:

I am using select coordinate system:

You can also use setup x axis and then use selected point for the origin and this achieves the same output code for me.

Hope that helps

[ericschimel]

As far as I can tell your setup looks like mine, save for the X and Y swapped, but I can't imagine that would matter:

I used "edge" to get the point on that curve.

Weirdly my preview in Fusion looks fine, but when I backplot it (and run it in real life) it doesn't work... 

I must be missing something really obvious...

[a.laasW8M6T]

Yea that is odd

Everything looks fine that I can see.

I do prefer to never use "model orientation" for the orientation.

I find its safer to use "select Z and X axis" or "select Z and Y axis"

but I don't think this will make a difference here.

Can you upload your fusion file here?

File>Export>save as .f3d

There must be some small detail we are missing

[ericschimel]

Sorry for the delay, here's the file I'm working on:

https://a360.co/43V5G38

[a.laasW8M6T · Accepted solution]

Hi

It looks like you may have the rotary axis settings wrong.

If it the post properties to "along -y" it posts good code in the back plotter.

Even though looking at your machine the axis is facing the y+ direction.

It could be configured wrong in the controller?

[ericschimel]

Ahhh! That worked! Both in the backplotter and real life.

Maybe you could enlighten me (and others) as as to why. I had my post set to rotary table axis along Y+ My thinking was that my rotary (A) is pointing towards Y+.

Or to say another way, if you are near the 4 jaw chuck you'd have to move in a Y+ direction to get to the far end of the rotary. Perhaps Y- means that you want the "base" of the rotary near the lower side of Y? 

I really appreciate you help!! This was a hard one to nail down!

[a.laasW8M6T]

I am not sure if there is a definite convention for rotary orientations.

The one I have seen on most machines uses this convention:

Note that B+ is clockwise looking in the +Y direction, but this is from the point of view of the tool not the workpiece.

so in your case if you Jog the rotary in the + direction looking in the y+ direction the rotary should turn counter clockwise

[ericschimel]

Interesting... That would explain why on routers I've seen both A and B used as the rotary axis. I'll have to dig into this a bit more. Thanks again for the advice!