Machining round a-Axis

[andrew.todd1]

Guys

See attached.

I'm trying to machine all the features round this cylinder head. We have it on a Haas with a 4th axis using the generic Haas A Axis post. The setup is exactly how it is on the machine.

Everything is fine as we machine everything on the top of the head at A0.

The problems arise when we move off A0. Its posting the wrong coordinates. Is this because the head (and datum) need to be set on the exact centre of rotation?

Is it possible to post all the operations around this workpiece on one program? What am i doing wrong?

Any help would be appreciated.

Project attached.

Thanks.

[engineguy]

@andrew.todd1 

Yes, you are correct, the centre of rotation must be the centre of the A axis 🙂

Stay Safe

Regards

Rob

[engineguy]

@andrew.todd1 

Try the attached file, small modifications, works here 🙂

Stay Safe

Regards

Rob

[andrew.todd1]

Thanks Rob

Will give it a go.

great help.

[andrew.todd1]

Hi Rob. what did you change?

[engineguy]

@andrew.todd1 

It is working now ????

Setup, used face for the Z axis and used the X in the Origin list for the X, not an edge as that edge is not on the centre of the A axis, once you get into the 4/5 axis stuff you have to make sure that everyhting is referenced to the axis of rotation, for a standard 4 axis Trunnion setup like yours then that`s the golden rule, do it in Fusion exactly as it is on the bed and if it all matches up then usually good to go 🙂 I did it assuming that the 4th axis unit was on the right hand end of the bed looking at it from the front which is the way most folks setup their machine so the X and Y axis need to be set correctly as well, soon get used to it, make life real easy if you have a bunch of those castings to do 🙂 🙂 🙂 Hopefully, the more work the better eh !!!

Open both files and study the diferences carefully and do one small change at a time to see what each change will do 🙂 🙂 🙂

Stay Safe

Regards

Rob

[andrew.todd1]

The NC code posted is exactly the same so it looks like the issue is still there.  what about a 'datum shift' added at each A movement after posting? would this help.

[engineguy · Accepted solution]

@andrew.todd1 

You shouldn`t need to shift anything, if the movements in Fusion are rotating correctly around the A axis then the code will be correct.

What exactly is wrong with the coordinates ?? Are they too far over in the Y, too high in the Z, going the wrong way so the Trunnion is moving away from where you want to machine ???

You may just need to reverse the A axis ??

Stay Safe

Regards

Rob

[andrew.todd1]

yes, the coordinates are wrong when the a axis moves off 0. Wrong in z. see attached.

Screenshot 1 is the actual NC code shown in cimco for the 2 toolpaths highlighted in Screenshot 2. The z heights should be the same. Im guessing its because the actaul part is not centralised with the datum exactly in the center

[iporter6]

I think you have worked it out between you and Rob.  See pic below.  The cirlces are the centre of the 4th. 

Good luck, looks a great project.

[engineguy]

@andrew.todd1 

Yes, you are correct, the centre line of the casting is not on the centre line so the coordinates will be different on either side !!

Stay Safe

Regards

Rob