New Advanced Controller that supports rotary 4th axis cutting and stall homing

Now that Onefinity has an option to purchase the CNC without the Buildbotics controller, there is an opportunity to offer a 2nd controller option for new purchases, or as a upgrade for existing users, that includes full 4th rotary axis cutting capabilities as well as include the stall homing. Currently, any aftermarket option for the 4th axis appears to require a change to limit switches for homing, which is a great feature of the Onefinity.


Is this a onefinity option or are you buying outside?

We do not offer a different controller. We only have the one, we just give the option to not purchase a controller with a machine now.

Sorry if I caused confusion here, I was offering an idea for a future hardware offering. I was not suggesting or asking about a different controller offering available now. There doesn’t appear to be any way to add the 4th rotary axis with the Buildbotics, and my understanding is that Onefinity no longer plans to work on this, unless you can advise otherwise.

I believe I had read somewhere - from other forum members with experience - that the 1F BB based controller would not be able to run a 4th axis. This CNC user has a solution where he switches out the axes connections, and loads a new profile to run the rotary axis. He is using Mach 3(4?) I believe, and a different controller, but perhaps the 1F controller can support this workaround. I am sure others will correct or add to my suggestion.

I run a rotary on mine by switching out the Y axis for the Axis, and use vectric to wrap my A axis around the Y axis. It’s not true rotary as I have to tell the controller to move 1mm for 1degree but it works for the lasering I’ve been doing on tumblers.

1 Like

Hey Roger,
I did see your post, however I am looking to carve on the rotary so the controller would have to adjust for the constantly changing diameter. Originally Onefinity stated they would use some sort of add on controller/ box to do this, but I believe they have now decided not to add this ability. I think that is a mistake on their part.

1 Like

Ah I understand. Yeah that would be nice. I have been looking at getting another controller to be able to have better ability for the rotary but it’ll be down the road for me on that when money/time to find a good choice.

That is an option, but then you would also loose the stall homing capability. If @OnefinityCNC can advise if they will not offer this capability for sure, I would start looking to go down that path as well.

1 Like

Does the newest controller not support 4th axis?

I read this review that says it does:

“The controller on the Onefinity is based on the buildbotics controller design.
The buildbotics controller is truly a 2021 controller and it is remarkably better than most other controllers out there.
At its core is a raspberry pi which is a min-computer in itself.
This controller supports 4 axis support with built in WiFi and Ethernet support.

1 Like

The onefinity is not a buildbotics controller… It is based on their open source controller and a fork of the code. It is similar but not the same.

People run a rotary in place of the y axis I believe on the onefinity and previously on buildbotics older versions.

1 Like

So first time posting but, I have been looking in to the 4th/5th axis issue as well. Keeping in mind I’m still awaiting my machine to arrive, I have looked through the documentation on buildbotics and onefinity and assuming the information I read is correct from buildbotics the state as long as the combined amperage is below 6A it is possible to run two stepper motors off of one driver. This would then open up the 4th stepper motor connection once the settings have been adjusted for the driver running two steppers to theoretically attach a rotary attachment. I presume this will also require an adjustment to the controller programming too but, I’m thinking this might be the start to making this a reality. Please, tell me your thoughts or if I’m just missing the mark completely but, I ask for constructive thoughts to see if we can work together and over come this challenge. I am also including
the statement from the buildbotics manual.

In addition here is the stepper motor data sheet that Onefinity uses.

I am not sure if you have done this already but a quick search in the forum will bring up a number of members who have done this with various implementations and successes.

When I contacted Buildbotics a few years ago about this (I was building and looking to add a tangential knife to my 1F) one point that was made was the following:

Thank you for your inquiry. Connecting this tangential knife might be difficult for the following reasons:

1. The Buildbotics Controller has exactly 4 motor ports. If you are using two motors on a single axis, then you will probably use two of the four ports for that axis. Assuming you have a 3-axis machine, this does not leave a port available for your tangential knife. Note - In some cases you may be able to wire the two motors onto a single port thereby freeing up the fourth port for your tangential knife. Oftentimes (but not always) wiring two motors to the same port results in resonance problems between the two motors resulting in motor stalls. Unfortunately, you won’t know whether this is a problem until you try it.

1 Like

Thank you and no I hadn’t gotten that far in to the reading as of yet but, their statement is mostly true as mentioned in their guide wiring two motors together and since one of the axis (I believe it is the “Y” axis) is run on two motors, that would be the one to run the two motor configuration on. The other side of the response they sent you is where (I planned to do this anyway once my machine arrives) after discussing issues with some old CNC builders/engineers, is to replace all of the driver cables with shielded drive cables. This was recommended to help reduce/eliminate EMI/resonance bleed over in the system. Granted this will require a minor modification to the control box as well to add an external ground lug to attach the shield wire from the new shielded stepper motors back to the grounding lug and wired to the main ground inside of the control box. I will also go back and check some of the other writeups too and I thank you for this additional information.

1 Like