Fusion 360 post format

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Fusion 360 post format

Postby Ollie78 » Thu Mar 14, 2019 9:11 pm

Hi

I have got to the stage where I want to surface my spoilboard on my cnc router. I have managed to get the calibration, tool height probe and soft limits done.
So now I want to surface the spoil board. I have screwed on a sheet of 18mm to the table just slightly bigger than cutting area and I just want to take 1mm off all over to make it co-planer with the cutter. I have 25mm 3 wing bit for the purpose.

I have 2 methods drawn up in fusion 360, one is where I have done a 1mm pocket in the board which will just leave a small lip at the edge, the second is a facing operation but I am not sure about this as I have no room to fly over the ends of the board.
Anyway, I get to the bit where I am ready to export the Gcode to test in UCCNC and there is the choice of all sorts of machines or processors to choose from. Which post option should I choose?
My machine is a custom made one from 45/90 extrusion (Pictures here http://www.mycncuk.com/threads/11870-Ab ... hole/page2 ) I have a UC300 eth 5lpt, uniport v2 BOB, Kinco stepper drivers, nema 34 motors, 25mm Ballscrews X and Y and 16mm on Z.
Can you build your own post file specifically for your own machine? Not that I really want to get complicated at this point.

Or is there a better\simpler way to do a surfacing toolpath?

Thanks

Ollie
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Re: Fusion 360 post format

Postby spumco » Thu Mar 14, 2019 9:22 pm

Search in the F360 Post Library for UCCNC.

You will find a "generic" and a "Stepcraft" post processor file. They are exactly the same as far as I can tell.

Download the file and save it somewhere on your computer. When you go to post the file in F360, navigate in the post window to the file you downloaded and choose that one. Check the options in the scroll window to the right of the fields where you name the file and make sure you have the various options sorted out (4th axis enabled, use ATC, ect.).

Post the file and open it in UCCNC. Click edit file and start going through it to make sure the post processor isn't doing something really dumb. They've refined this post a number of time at my request over the past year or two (used to break taps during a G33.x command) but it's working for me now. Only thing wrong with it is that I can't seem to turn off the 'move to xxx position during tool change' feature.

As to teh facing operation, you can set negative stock to leave so it doesn't go outside the sheet size. You can also adjust the linking moves (smooth, straight, no contact) which will stop the swoopy half-circles at the end of the cut.

Keep in mind that the cutter will have to overhang slightly - at least - in order to cut everything.
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Re: Fusion 360 post format

Postby zymurgy42 » Sat Mar 16, 2019 12:17 am

If your top is only a tad out of coplanar, taking out a huge 1mm is a waste, save the extra for next time(s) you want to surface it.
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Re: Fusion 360 post format

Postby Ollie78 » Sat Mar 16, 2019 4:06 pm

Hi

Thanks spumco and zymurgy42. I have managed to get the uccnc post to work however this has lead to a bit of confusion once more.

I have done a toolpath in fusion for a couple of versions of spoliboard surfacing, the toolpaths go fine when I simulate them in fusion so then I post them and load them into uccnc. Then when i go to simulate them inside uccnc it has put the toolpath as if it is trying to remove 17.5mm through the 18mm board instead of pocketing 0.5mm off the top.

Also as soon as I start to simulate it it tells me soft limits have been reached though I think this might be because I need to zero the work position?

I am thinking either there is a setting in uccnc that is wrong or needs flipping. I made sure the origin is in the same corner in fusion and uccnc.

Any help is welcomed.


Thanks

Ollie
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Re: Fusion 360 post format

Postby dezsoe » Sat Mar 16, 2019 5:36 pm

The soft limits are given in machine coordinates.

I assume that you have the workpiece origin at the bottom in Fusion, but without the g-code I can just guess.
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Re: Fusion 360 post format

Postby spumco » Sat Mar 16, 2019 8:27 pm

Set the F360 origin at the top of the stock.
Set the F360 axial stock to leave as "-0.5mm"

In the machine, touch your cutter to the top of the stock and zero the Z-axis.

Adjust your softlimits in the axis setting screen to permit moving the cutter as far as you can without running in to the end stops.
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Re: Fusion 360 post format

Postby Ollie78 » Sat Mar 16, 2019 9:51 pm

Hi guys

I think you may have solved the problem but I will continue with this anyway as it may provide clarity.

So I made another toolpath with a smaller area pocket in fusion.

resized cnc pics 002.JPG
fusion toolpath


But when I put it into UCCNC it comes out like this.

resized cnc pics 001.JPG
UCCNC toolpath


So it wants to mill right through.

After getting thoroughly annoyed with it and more with dumb self, I just decided to do a small random pocket to see if the machine would actually mill something, it has taken me ages to even get to this point and I was worried it would never work.

So I did a random pocket in fusion and put a smaller bit in the spindle.

resized cnc pics 009.JPG
Small pocket


I did a 2d adaptive toolpath at 2000mm/min 24000rpm 6mm 2 flute straight bit.

resized cnc pics 006.JPG
toolpath in fusion


resized cnc pics 004.JPG
uccnc toolpath


I screwed the board down ( the wrong way round, I know) and set the X and Y zero to the centre cross I drew on the board, then did a tool height probe which went well. So I turned on the spindle crossed my fingers and pressed the start cycle button.

It worked !! Woohoo.. But the centre was not centred in the cross ??

resized cnc pics 012.JPG
Pocket


Why this worked and the others didn`t is a bit mysterious as I thought I did it the same in fusion and in UCCNC too.

I am very pleased my machine has actually milled something, the bottom of the pocket is dead flat and i can`t measure any deviation in the depth. Size is bang on too.

However I would like to learn a foolproof way to set up the drawings origins/ toolpath origin and machine to get repeatable positioning.

I am thinking perhaps better to set up all work from a centre point as I have no limit switches at present and it seams I always have to re home the machine by jogging each time I turn it on, is this correct or should it remember?

Thanks for helping me get this far.

Ollie
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Re: Fusion 360 post format

Postby ger21 » Sat Mar 16, 2019 10:01 pm

First thing I'd do, is got to General Preferences in Fusion 360. Set "Default Modeling Orientation" to "Z is Up".


Looks like you just need to practice, and learn and understand how to use the CAM in Fusion 360.
Try these:
https://www.youtube.com/watch?v=Bd6-BQUCbVA
https://www.youtube.com/watch?v=6FzbZNhey2w

In UCCNC, you don't need to "Home" the machine. But you do need to set your X, Y, and Z zero positions (origin) exactly where you have them in Fusion 360.
Gerry
UCCNC 2017 Screenset - http://www.thecncwoodworker.com/2017.html
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Re: Fusion 360 post format

Postby Ollie78 » Sun Mar 17, 2019 8:03 pm

Ger 21

Default modeling orientation to Z is up. Brilliant.
So simple but so much better. Its one of those things that is obvious once you know, and you wonder why you didn`t already know.

I have watched those videos too.
I have been watching quite a lot of the Fusion videos with Lars Christensen but had not got onto any of the CAM content. I think he is a great teacher of Fusion, I often have to pause the video, do what he suggests and then play a bit more. The problem is there is almost too much information packed into the lessons and Fusion 360 itself has so much depth. So much to remember, it will take a while to get good I think.
I am starting to think about fusion in a Skandinavian accent !!

Thanks

Ollie
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Re: Fusion 360 post format

Postby ger21 » Sun Mar 17, 2019 8:11 pm

Default modeling orientation to Z is up. Brilliant.


:D

The biggest problem with Fusion 360 CAM is that for your average router users, it's far more complex than it needs to be.
Gerry
UCCNC 2017 Screenset - http://www.thecncwoodworker.com/2017.html
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