topic Re: Limiting 4th Axis rotation when using a trunion in HSM Forum

Limiting 4th Axis rotation when using a trunion

Anonymous — Wed, 20 Jul 2016 13:46:35 GMT

I recently upgraded to a VF3ss with an HRT160, with this has brought many challenges for programing with the 4th axis, and the disappointing realization that true synchronous 4th axis milling is not what HSMworks excels at. But with some tricks I picked up on the forum and some trial and error 3+1 3d milling is serving the purpose so far.

Now on to the question!

I have a trunnion table I built and would like to start using, but I am neglecting to do so due to one glaring issue that I haven't found a solution for.

I need to limit the axis rotation when the parts are to tall to make a full 360 degree rotation, and I can't figure out how.

I notice when programing 3+1 operations, under the Tool orientation tab it will tell you the intended movement of the a axis (ex. 45deg, -90deg) but when it outputs it to gcode it only uses the positive rotation, so 90 turns into 270 degrees, and -90 into 90.... this is going to be a deal breaker for me.

I am hoping there is a method to limit the rotation so it forces the PP to output a negative degree value, or possibly change the PP to output it correctly?

Any help will be greatly appreciated.

Re: Limiting 4th Axis rotation when using a trunion

Rob_Lockwood — Wed, 20 Jul 2016 15:15:40 GMT

This configuration is generally in the post processor. Search out the section that will be similar to this..

 if (true) { // UMC-750
    // using 0 instead of -35 to avoid rewind issues
    var bAxis = createAxis({coordinate:1, table:true, axis:[0, 1, 0], range:[0-0.0001,110+0.0001], preference:1});
    var cAxis = createAxis({coordinate:2, table:true, axis:[0, 0, 1], range:[-999.999,999.999], preference:0});
    machineConfiguration = new MachineConfiguration(bAxis, cAxis);

The "range:" section defines the rotary axis limits, and it sounds like you just want to limit travel from -90.000,90.000

You can also set the 'preference' section, which is likely what is directly causing your issue at the moment. If it's set to +1, it will prefer the axis solution that places that axis in positive.

I'd suggest playing with a combo of the two, you should be able to get it to output how you want.

Re: Limiting 4th Axis rotation when using a trunion

Anonymous — Wed, 20 Jul 2016 18:33:35 GMT

Rob,

Thanks very much for the quick and well put together response. I was really hoping for a condition that could be altered in the PP.

I think I have found the line Im looking for, Although I dont see a range value to change..Here is what Im looking at

if (true) {
var aAxis = createAxis({coordinate:0, table:true, axis:[(properties.makeAAxisOtherWay ? -1 : 1) * -1, 0, 0], cyclic:true, preference:1});
machineConfiguration = new MachineConfiguration(aAxis);

Again, thank you for the input

Re: Limiting 4th Axis rotation when using a trunion

Rob_Lockwood — Wed, 20 Jul 2016 18:58:08 GMT

var aAxis = createAxis({coordinate:0, table:true, axis:[(properties.makeAAxisOtherWay ? -1 : 1) * -1, 0, 0], range:[-90.000,90.000], cyclic:false, preference:0});

Re: Limiting 4th Axis rotation when using a trunion

Anonymous — Wed, 20 Jul 2016 20:55:12 GMT

You are the MAN! I will post with it and see how it works.

Re: Limiting 4th Axis rotation when using a trunion

Rob_Lockwood — Wed, 20 Jul 2016 21:03:04 GMT

Ok, but if it goes poorly, that's not on me 🙂

Re: Limiting 4th Axis rotation when using a trunion

Anonymous — Thu, 21 Jul 2016 12:28:41 GMT

Hahaha, I would never fault anyone for trying to help. No worries, I will have some try runs tested first.

Re: Limiting 4th Axis rotation when using a trunion

Laurens-3DTechDraw — Thu, 21 Jul 2016 12:38:29 GMT

It's always on you if something goes wrong Rob. I always blame you.