3+2 axis Retraction Height adds up

[dan3s2020]

Hi! I'm trying to do some 3+2 axis machining,
my stock is 90x60x125mm , i place the origin point at the center of the top face, everything works fine if i do operations on that top face but if i change to another face of the stock it adds up the distance from the origin point to the face i'm trying to machine .

  
So here it does 5mm(retraction height)+60/2= 5+32.5= 37.5mm. As you can see in the video attached, i set z=0 on the center of that top face and when that Z37.5 command comes in , my Z goes up and hits the limit switch because it doesn't have so much room left 
I'm new to CAM and i'm not sure what i'm doing wrong... Any ideas?

[engineguy]

@dan3s2020 

It looks like you don`t have things setup correctly for doing what you want to do, it would be best if you can upload your Fusion f3d file so your settings can be checked.

Your Post Processor seems to be a very old one but looks reasonable, I will test it on a file here before I make an assessment on it.

To upload a Fusion f3d file go to :-

File > Export > Select f3d format > Save to a location on your computer > Then attach to your reply using the "Attachments" facility below your reply box.

[dan3s2020]

If you try the post-processor is something i tried to edit, even if you see there A C axis i changed the output to B A letters.And for some reason i have to invert X axis in mach3 ,so is a really weird post but that's what i have. 

I would only let me export as f360 archive,i hope is fine

[engineguy]

@dan3s2020 

Forgot to ask, what is the configuration of your machine, is it XYZAC, XYZBC, XYZAB  ??

Your file has a multitude of f3d files in it, you must have links to other files which is why it will only export as an f3z file, break the links and just export a single f3d file with the part that is to be machined.

[dan3s2020]

I really don't know what to say...In the chinese manual it says B A,the letters on the cables are B A, but looks like B rotates arround X axis , A rotates arround Z axis, i think..but maybe is xyzac , that's how i setup the postprocessor aAxis,cAxis but i made it to output B,A

[engineguy]

@dan3s2020 

A normal 5 axis trunnion configuration is XYZAC, the A Axis is usually the Trunnion which swings from one side to the other with around +95~-95 swing, the C AXis is the table that revolves around the Z axis and does full 360 degrees.

Your part must be setup in Fusion with the WCS set to the center of the part revolving around either the X or Y axis depending on how you have actually fixed it to your machine table.

The image below shows where the WCS should be located for the B rotation around the X axis.

See attached Test file, modified Post Processor and G Code file for you to test out.

Without your part to check and setup I can`t do any more so please if you want me to help try to setup your part then please upload the correct f3d file 🙂

[dan3s2020]

"Your part must be setup in Fusion with the WCS set to the center of the part revolving around either the X or Y axis depending on how you have actually fixed it to your machine table." 
So in the picture below the wcs is wrong? if i put it in the middle where do i set the tooltip z zero? i don't understand why in the middle of the part..? You can see how i fixed it on the video 😄 thanks

I will try the post-processor-mod to see the results.

[dan3s2020]

i uploaded the f3d file 

[engineguy · Accepted solution]

@dan3s2020 

Apologies for the delay, been busy with other things today 🙂

I have tried to make a representation of your Chinese Trunion setup as there is no Autodesk Machine to use that is anywhere close, image below 😞

Instead of going through a long explanation of the setup I have done a Screencast for you and here is the link, hope it is of some use to you :-

https://autode.sk/3diHUp9

G Code file for Mach3 attached for you to test very carefully at your machine, it is a fraction different to the code in the Screencast, I forgot to change the PP earlier 🙂 🙂 🙂

P.S. Forgot to mention that I redrew everything the "right way up" in the "Z Axis up" configuration, much easier to get things to line up if the model is created in the same Orientation as it will be actually on the CNC Machine 🙂

[dan3s2020]

No need to apologize sir ! Thank you so much for your time and dedication,i wasn't expecting so much help. tomorrow in the morning i will be trying it.
I have just 3 question: 
1. How did you managed to set that origin point exactly where the b & a axis intersect?
2. That g28 g91 z0 ,i really didn't understand where should i zero the z axis,going down as much as i can and set that to 0?

[engineguy]

@dan3s2020 

Answer to your first question, I just measured from the base of the trunnion for the B axis which would be  on the bed of the CNC and is easy to measure to the center of the pivot, the dimensions my even be in the Manual you got with the machine, A axis also easy just a measure from the end of the trunnion to the center of the rotating table 🙂

Two, the G28 line is a safety position and should be set as high as possible, as you have no switches on the machine then you should jog the Z axis up to it`s highest point and maybe come back a few mm and set that position as the highest point of your Z axis soft limit.

What it does is move the Z axis to that highest point to give as much clearance as possible for the rotation of your trunnion and stock.

This is not to be confused with the Part Z0, that you will set differently 🙂

[dan3s2020]

that "G43 Z80. H1" is still too much and hits the limit switch..other than that everything looks fine... but that 80mm retraction height is too much... 

[engineguy]

@dan3s2020 

It may not be the 80 that is the problem, what is the tool length that the H1 is calling up? In other words what do you have programmed in the Tool Library in Mach3 for Tool#1.

You can reduce the 80 but you need to remember that 65 is the top of your stock so you can try maybe 67 instead !!

Just a question, you said before that you don`t have switches on the machine but you have just mentioned a "limit switch" ??

In Mach3 limit switches are used for both Homing the CNC and as Limits so you don`t need to play around with the "Soft Limits" at all, when you "Home" the Machine it should run to the Z axis switch first before running to the X and Y switches 🙂 🙂 🙂

[dan3s2020]

Sorry if i said something about not having limit switches , in the post i tried to say that Z goes up and hits the limit switch,then the program stops.

My tools in tool library tooltable are all set to 0 on all values 😄 .

[engineguy]

@dan3s2020 

Ouch, something seriously wrong, the first operation is really just a simple 3 Axis operation so it sounds like you need to get your Mach3 setup properly! Do you have switches at both ends of all 3 axis ? Have you set your switches in Mach3 with the Automatic setting facility ? What Screenset are you using ??

In the image below it shows where to go to and what to do to set your switches in Mach3, I enabled all options as if you have a switch at each end of all your three X,Y and Z axis, if you only have a switch at one end of each axis travel the just click on the Green tick mark to toggle it off to a Red x mark, you need to do this 🙂 🙂

[dan3s2020 · Accepted solution]

Thank you ! From here i managed to make it work.
1. Setting my origin point to that 4th 5th axis intersection :
    - set origin at the bottom center of the model

    - move the model down by the distance from the A rotary table to the imaginary B axis (in my case ~45mm but i would have to measure it better by measuring the distance from the table on B-90 to B90,divide it by 2 but take in consideration the tool diameter)
2. Setting my limit switches well in mach3 , and homing my z to have machine coordinates 0 for z at the top so i can use G28 G91 Z0 instead of the retraction that was set in fusion
3. Setting Z0 where the tool touches the table ,then lifting it up by that 45mm distance and setting that new position to Z0

I also had to update the post processor to a final version because my B axis was going in the wrong direction, and my mach3 settings are now totally different from the manual.But it works 😄 

For clearence,retraction,feed height i decide to work with them from Origin(absolute)