Related to this topic, I was testing out the machine with some hole boring operations using Fusion. This results in a helix tool path for each hole. A helix is a series of circles in XY while Z is moving linearly. At first it worked fine for holes of about 20 mm. When I reduced the size of the hole to about 19.4 mm or lower I started to get missed steps after about 3 or 4 circles in a row in a hole. You hear the machine shutter when this happens. I was using the controller to do the arc calculations with the circular interpolation box checked in post processing and max deviation setting of 0.05 mm.
My assumption is the controller was not keeping up. To resolve this I had success with either lowering the feed rate giving the controller more time to do the calculations or unchecking the circle interpolation box forcing the post processor to do the calculations with a tolerance of .002 mm. The latter option results in bigger g-code files but faster run times.
Bottom line, with the stock controller, if you leave the circle interpolation box checked and are doing small holes always test first to see if you get missed steps and take appropriate action.
Thanks for the info SkyKam, does it sound similar to the video above your post where the motor would lose steps on tight radiuses? Raising the MAX Deviation worked in my case, but I didn’t go back to do more testing to figure out exactly what was causing it. I currently cut vectors at 0.005 and carve 3D models at 0.0005, so far it’s been very reliable without any missed steps.
Yes it sounds the same. I did not experiment with even smaller circles or a smaller max deviation. My hunch is a smaller max deviation would cause the controller to do more computing for arcs in the same amount of time and so make the problem worse. If you don’t have too many high feed rate G2 or G3 moves in your 3D carve files then its not going to be an issue. I had a job where I was boring a lot of holes that was producing arc moves. I switched to turning circle interpolation off for those runs and that eliminates any G2 or G3 moves for the controller to process and gives better precision than the default max deviation provides.
But had I known about this limitation I probably would not have bought this machine and spent the last two years of my life building it. ( I only have an hour or so per weekend with limited funds.)
I am almost finished with my setup and am about ready to start testing. At this point, if what I am reading here is true, I really don’t want to.
This is very distressing to say the least. I know, I know… it is a “hobby level” machine. Sigh.
Not being able to cut a circle or arc without a lines?? Whisky Tango Foxtrot!!!
This old thread talks about ways of fine tuning to get better curves. I’m curious, what is it that you are planning on making such that this matters so much that you’d give up without trying it? I’ve seen amazing work posted here by people using these machines. Depending on what you are making it could also be very easy to sand off these ‘ribs’.
Not ready to give up. Thinking about getting away from Fusion though.
I had originally planned on making guitar necks. I had hoped with CNC I could minimize sanding. I have seen some necks come off the mill and really only need a light touch.
Honestly, I have calmed down a little. When I bought this thing I was taking a chance that the company was going to stay in business. I hope 1F doesn’t fail and are sucessful. But my thinking is that if the company goes belly up then I still have some good hardware. Maybe before spenting too much more capital on this setup I should investigate a controller that isn’t limiting me right out of the box. Wish I had know this before I just spent a barrell of money and a truck load of time building my current setup. Live and learn. More appropriatly, live, spend, spend some more, empty your wallet, find soul crusing limitations and then learn.
All that being said, I guess what pisses me off is that it is just one more limitation of a “hobby grade” machine. “Hobby grade” is the eplanation I got from support when I questioned them about accuracy problems I was having.
To be fair, it is just that. Sigh… I will carry forth and see what it does. I just hate that I have spent so much time and money and thought on something that may just be “hobby grade.”
I did see an explanation from 1F in another thread warning the Fusion has interpolation turned off by default in one of their updates. This is just one more nail in the Fusion coffin. It is a great program for free… but it can’t be trusted to be the same one update to the next.
Sorry… just venting here. Maybe venting over something that may not even be a reality for me. But those pictures are fairly damning.
I make guitar necks, bodies, fret boards etc designed in Fusion 360, no issues with cut quality. If you use very small step over values on your cut paths you don’t need to sand much but you somewhat sacrifice extra time on the machine vs sanding time, it is a tradeoff and you will find a balance that works for your workflow.
Much of the discussion in this thread is specifically related to how a CAM application outputs the g-code program and how that interacts with the Onefinity. Some CAM applications will change an arc or circle into a series of lines using some value of an acceptable tolerance, lower tolerance will mean more line segments are created in the g code file. Some CAM applications will generate G2/G3 commands which tell the CNC to move in arc or circle that are interpreted by the controller and turned into linear moves. Fusion 360 will where possible generate G2/G3 codes for arcs and circles.
@Ziggy don’t confuse what was mentioned in this thread. Simply put, Fusion will output the G2/G3 arc commands, the 1F post processor and controller breaks those back into line commands, interpolation of the arc movement. I also experienced this, most notably in aluminum, and upgraded my controller to the Centroid Acorn. It is a fantastic system and basically industrial grade and featured. It also outputs G2/G3 arcs. Its not Fusion, it’s the 1F post processor and controller. Upgrade your controller and you’ll be impressed Upgrading to something like this will also require motor drivers, power supplies etc. Very very well worth it.
Life is a compromise. In this case the Buildbotics controller only has so much computing power. It also doesn’t get feedback from the motors. That’s the difference between a stepper motor and a servo motor (A servo motor is a stepper motor with an encoder that sends a signal back to the controller to let the controller know that the servo moved the correct amount). 1F made the choice of using a controller with limited abilities (think a slower laptop) so they could spend more money on a robust drive system (direct drive lead screws and linear motion steel tubes) vs belts and wheels riding on angle channels.
The good news is that you can upgrade the controller if you can’t get to where you want to be. Most of the other cnc machines in this price range you are stuck because there’s not much you can do to make them more robust. In some ways it would be nice if 1F offered a more powerful controller as an option but it would probably add at least $1000 to the cost. The buildbotics controller has a built in cpu, most other controllers require a separate computer. That doesn’t include drivers for the stepper motors (which is also built into the 1F controller).
This is spot on, regardless of the CAM software, the controller will convert arcs to lines, no way around that with the stock controller. That said, this usually is not an issue when working with wood. Even with plastics, you can tweak the conversion settings as shown above to obtain very clean results. It is mostly in metals that you’ll notice this. If you do find yourself upgrading the controller one day, you’ll still end up with a fantastic machine at a great price point.
I would not sweat this too much, start cutting, enjoy the machine
Fusion360 is great for creating 3D objects and technical drawings requiring constraints and precise measurements. VCarve is great for everything else and really quick to create drawings using basic layout techniques.
I finally tried to make a semi-nice carve out of some scrap wood.
The CAM had 5 processes and three tool changes. I could have reduced that to 3 processes but I am using the free version of Fusion360 and I didn’t feel like editing the g-code together in a text editor.
I tried to make this as smooth as possible with very small stepovers. For the most part it turned out nice.
Except…
Except I forgot about the circular interpolation. For some reason that option doesn’t seem to show in Fusion 360 like it shows in the other threads. I’ll try updating the post processor and see what happens.
But more importantly I forgot to make the changes to the 1F controller mentioned in this thread.
I forget to set the Max Deviation too some times and end up doing the same… I wonder if there would be a way for the Max Deviation setting to not reset back to default each time? Some settings are retained following a reboot, some not.
Just remember to set the max deviation, THEN upload the file to the controller. Once uploaded, the conversion is done so it won’t change previously imported files.
I actually just encountered this issue as well. I set my max deviation to 0.0005mm (both in the controller and in Fusion 360) and it’s not even for arcs. However, machine would always lose steps at the same spot in the program. Setting it to 0.001mm seems to solve the problem but so does seemingly moving the zero coordinates. I thought maybe there was some binding but that doesn’t seem to be the case at all as the gantry can move fairly easily when the steppers are not powered.
Upgrading to something like this will also require motor drivers, power supplies etc. Very very well worth it.
