4-axis upgrade

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BryanH
Posts: 3
Joined: Fri Jan 17, 2020 6:30 am

4-axis upgrade

Post by BryanH » Fri Jan 17, 2020 1:10 pm

I have a 3 axis DIY CNC with an Android with gShieldv5 controller now. I want to update this to a 4axis controller and this controller was suggested. Given the setup I have now, I dont have individual motor drivers so I think I'm looking for a controller that has them built in, so the Buildbotics controller looks it fits the requirements. I have 3 Automation Technology KL23H286-20-8B motors now that I would connect to the controller and of course will need another for the new 4th axis. Would this controller drive these directly or do I need other equipment. So any thoughts on this ?

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Doug
Posts: 259
Joined: Fri Feb 02, 2018 4:56 pm

Re: 4-axis upgrade

Post by Doug » Fri Jan 17, 2020 2:25 pm

The Buildbotics Controller will drive the KL23H286-20-8B motors directly. The motor drivers are built into the controller and the controller comes with the motor cables. You would simply splice the motor cables to the wires from the motors. I recommend wiring your motors as bipolar parallel as described in the motor data sheet.

While the BB Controller has 4 axes, it only has limited support for rotary motion. The ability to turn a specific number of degrees is not implemented. For rotary motion, you would have to configure it to think the angle traveled is actually a linear distance. For instance, for a metric program, you would configure the axis to move 360 degrees in one revolution. That way, when you tell it to move by 45 mm, it would turn by 45 degrees.

This would work until you tried to run a program that runs with imperial units. Then you would have to reconfigure the axis for 360 inches per revolution.

This can work pretty well if you just use your rotary axis to do rapid turns to a new position.

Another thing that is missing is the ability to maintain a constant feed rate as the distance from the center of rotation changes. In other words, the rotational speed needs to be slower as the distance from the center of rotation increases, otherwise the feed rate will increase and possibly mess up your cut.

We do plan to implement full support for rotary motion, but do not have it scheduled. You can track the status of this request on github at https://github.com/buildbotics/bbctrl-f ... /issues/95 .

BryanH
Posts: 3
Joined: Fri Jan 17, 2020 6:30 am

Re: 4-axis upgrade

Post by BryanH » Fri Jan 17, 2020 3:27 pm

Thank you, I appreciate the quick reply, this helps.

BryanH
Posts: 3
Joined: Fri Jan 17, 2020 6:30 am

Re: 4-axis upgrade

Post by BryanH » Sat Jan 18, 2020 1:52 pm

For the rotary controls, what is your timeline ? Where can I get more information on file formats and how to load the controller from the PC where I will produce the project ? Your product looks very interesting to me.

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Doug
Posts: 259
Joined: Fri Feb 02, 2018 4:56 pm

Re: 4-axis upgrade

Post by Doug » Sat Jan 18, 2020 8:35 pm

We do not have implementation of full support for rotary motion scheduled at this time.

The BB Controller accepts GCode files. Our genre of GCode is patterned after LinuxCNC. I have post processors for some of the most popular CAD programs. If you use a CAD program that we do not have a post processor for, you can select LinuxCNC on most CAM systems. If that does not meet all of your needs, I may be able to help create a post processor that works for you. If I do that, then I will publish that post processor on our github repository for others to use.

You can learn about the specific details (including loading files) in our manual which is available at docs.buildbotics.com/manual/ .

In addition, you can test drive the user interface at demo.buildbotics.com . The demo actuallly lets you load a program and run it on one of our servers. To do this, just go to demo.buildbotics.com . You will enter at the "Control" page. Part way down the page, you will find some tabs. The "Auto" tab should already be selected. If not, select it. Then click the folder icon. This will open a file chooser that you can use to select your gcode program. Once loaded, you should get an image of your cut paths on the screen. Just click the play button to run the program on the demo. This interface is exactly like the BB Controller. In fact it uses the exact same software but there is no physical machine behind the demo.

Feel free to give me a call at 707-559-8539 if you want to talk to me directly. I am available most of the time. If I don't answer, leave a message and I will get back to you.

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