Feed Rate Issues With G Code generated in Fusion 360

Hi all, I hope you’re doing well. Has anyone had any issues with inaccurate feed rates when running G code posted from Fusion 360? For context, I just upgraded to a Journeyman X50 and a water cooled spindle from a Shapeoko 3 XXL with the HDZ and Makita router. My main reason for upgrading was reliability, but given that the Onefinity is a much for rigid machine, and my spindle is a quite a bit more powerful than the router, I figured that I would be able to run it little faster as well. I have a part that I machine multiple times per day, I’ve run the tool path hundreds of times and gotten it pretty dialed in. I got out my machining calculator, and came up with a federate of 200in/m (5080mm/m), the fusion machining time estimate was 15 min. I know that the machining time feature in fusion isn’t particularly accurate, so I usually assume that it’ll be off by about 25-50%. On my shapeoko I would run a feed rate of 90in/m (2286mm/m), fusion would estimate that it would take 30 min, carbide motion would say an hour and 10 min, and it would actually finish up in about 45 min. All of that being said, I was expecting the job to take about 30min on the onefinity. When I loaded the G code onto the controller it gave me an estimate of 3 hours and 45 min, I figured that must me a error, so I pressed go, and started a timer, the actual machining time ended up being an hour and 45 min. The machine reports the correct feed rate (5080 mm/m) of course I have no way of measuring the actual speed, but anecdotally it doesn’t look like it’s moving twice as fast as my shapeoko. Just as an experiment, I ran the job again with the speed set to the machine maximum (500in/m) and it took the exact same amount of time. Does anyone have any idea what’s going on here? I’m using the official onefinity post processor, I do my cad and cam In metric (although I think in inches so I have to do conversions), and the machine is set to mm. Any advice would be greatly appreciated. Thanks!

Search the forum for max jerk and max acceleration settings. You need to use your judgment when tuning them as your mileage may vary depending what you do. The machine can run much tighter and faster than it does with default settings but… With great power… Comes great responsibility…

Another thing to keep in mind is that with the free version of Fusion 360 you don’t get full rapids

Yeah your motor settings could the factor here. I use Fusion as well (paid version) and I have no issues with unusually long machining times. On my journeyman I use the stock 1F controller and on my Machinist model I use the Centroid Acorn and run times are good on both. Can you upload a photo of you motor settings for us to see?

I use the free version of Fusion and find it can do funny things. Once it decided to cut in multiple depths and the machine time should have been something like 20 minutes turn into 4 hours. The weird thing was I was just doing a simple pocket and was experimenting with how much material to leave. I had just made the same cut and decided to remove an extra .020" so the cut time should have been the same. I even had Fusion up on my laptop and was just editing and resaving the pocket cut so I didn’t change anything else.

Critical point.

If you open up your gcode, you will see,

(WHEN USING FUSION 360 FOR PERSONAL USE, THE FEEDRATE OF)
(RAPID MOVES IS REDUCED TO MATCH THE FEEDRATE OF CUTTING)
(MOVES, WHICH CAN INCREASE MACHINING TIME. UNRESTRICTED RAPID)
(MOVES ARE AVAILABLE WITH A FUSION 360 SUBSCRIPTION.)

After thinking about this, I think it’s possible to modify the post processor to compensate for this and insert rapid moves depending on Z movements.

But I’m not sure it’s worth the effort since for hobby the speeds are fine, and for anything beyond I’ll probably just pay for a license.

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Curtis - when Autodesk changed the license configuration and removed rapids, they did nothing to change the estimated completion time. The estimate includes rapids, which the free version does not export. Example, I did a series of bore operations recently that was estimated at 25 seconds, and it took 7 mins in reality. I think it is total bunk they don’t get the estimate right, and I also think it is a little marketing “magic” to show what is possible if you pay. It’s still BS though.

-Tom

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