Router related questions.

[martyscncgarage]

Clean control cabinet!

Thanks, Marty.

Was hoping I could replace the Cslabs/Mach3 on future builds with Acorn but looks like that's not going to happen for awhile. But I'll hang in there until it does.!

Edit: Actually just realsied I've got an Old Boxford Slant bed Lathe kicking around which could put Acorn on.! . . . Erm as if aint got enough to do. . .Lol

Boy, I know the feeling!
Marty

[mael]

Hey all! Im new to Acorn and just purchased a board for my 3rd CNC build.
After much debate with myself I finally decided to give this board and software a try; moving on from Mach3.
Anyway, this is a 5' x 10' gantry build with a rack and pinion drive for XY axes, ball scew Z and with a 4th "A" axis. I did contact support prior buying a kit and they did say, correct me if i'm wrong, I can "slave" another motor by doing a daisy chain on the signal and direction.
However, it just hit now about squaring and homing the slave axis.

Can anyone provide a guide on how to go about the slave axis homing?
An earlier post mentioned about scripting but i'm guessing that you would be needing to use the 4th motor slot instead of daisy chaining it right, but i do need to have a 4th axis usable.

If you daisy chain both motors(drivers) and hook up individual input home switches on both the X(main) and X(slave) and wire it in a way that when you tell the machine to home it moves both main and slave until 1 will hit the switch first then cut power to the driver while the other motor hits its switch. Problem is that if I cut power then the gantry will just slop back to its unsquared natural state. This might work if I parallel wire the signal wires and put the switch there but I read that it is not recommended because daisy chain is preferable.

Any thoughts?

Apologies for the lengthy post.

[martyscncgarage]

Hey all! Im new to Acorn and just purchased a board for my 3rd CNC build.
After much debate with myself I finally decided to give this board and software a try; moving on from Mach3.
Anyway, this is a 5' x 10' gantry build with a rack and pinion drive for XY axes, ball scew Z and with a 4th "A" axis. I did contact support prior buying a kit and they did say, correct me if i'm wrong, I can "slave" another motor by doing a daisy chain on the signal and direction.
However, it just hit now about squaring and homing the slave axis.

Can anyone provide a guide on how to go about the slave axis homing?
An earlier post mentioned about scripting but i'm guessing that you would be needing to use the 4th motor slot instead of daisy chaining it right, but i do need to have a 4th axis usable.

If you daisy chain both motors(drivers) and hook up individual input home switches on both the X(main) and X(slave) and wire it in a way that when you tell the machine to home it moves both main and slave until 1 will hit the switch first then cut power to the driver while the other motor hits its switch. Problem is that if I cut power then the gantry will just slop back to its unsquared natural state. This might work if I parallel wire the signal wires and put the switch there but I read that it is not recommended because daisy chain is preferable.

Any thoughts?

Apologies for the lengthy post.

I'm going to let the router guys answer your questions.
But yes you can slave an axis and the next release of CNC12 is slated to address router users needs.
I believe they are still looking for router Beta testers. You might PM CNCKeith to express your interest. You can help others by developing the router specific features.
I want to build a 4x4 router. But I am going to likely go with one screw right up the middle for the Y axis in order to avoid the issues you have. Heavy linear guides and trucks on the sides. Maybe this summer...I have too many irons in the fire now!

I think you will enjoy working with Centroid. PLEASE post a build log.

Marty

[jazzcnc]

If you daisy chain both motors(drivers) and hook up individual input home switches on both the X(main) and X(slave) and wire it in a way that when you tell the machine to home it moves both main and slave until 1 will hit the switch first then cut power to the driver while the other motor hits its switch. Problem is that if I cut power then the gantry will just slop back to its unsquared natural state. This might work if I parallel wire the signal wires and put the switch there but I read that it is not recommended because daisy chain is preferable.

Ok if I'm reading this correctly you want to use only 3 axes to control 4 motors. Keeping the 4th axis for other uses ie: Rotary
I use this workaround with Cslabs IP-M controller which doesn't allow gantry squaring but still able to have it home to individual switches like you suggest.

However, it doesn't cut power but instead uses the Enable signal on the drive which disables motors but keeps them energized. Or if drives don't have an enable input use relay which breaks the Signals to that drive.
It would require a change to the homing sequence macro so it turns an output on after homing which controls relay to disable the drive. Then tell it to home again and when finished turn the relay off again.

Think this should work just same with Acorn.

[mikes]

However, it doesn't cut power but instead uses the Enable signal on the drive which disables motors but keeps them energized. Or if drives don't have an enable input use relay which breaks the Signals to that drive.
It would require a change to the homing sequence macro so it turns an output on after homing which controls relay to disable the drive. Then tell it to home again and when finished turn the relay off again.

Using the enable is a really good idea. However, it sounds like it would eat up two inputs (one for each limit) and two outputs (one for each control line for the enable) I wish the Acorn had more than 8/8 I/O for needs like this. I asked about software access (for the macros) to any unused I/O pins on the Beaglebone, but didn't get a direct answer. I understand, not sure I would want to try supporting a product where users are hacking the board to get additional I/O. That said, a spare I/O header for later expansion would have been nice. It was stated that a USB based I/O expansion board is in the works.

[martyscncgarage]

However, it doesn't cut power but instead uses the Enable signal on the drive which disables motors but keeps them energized. Or if drives don't have an enable input use relay which breaks the Signals to that drive.
It would require a change to the homing sequence macro so it turns an output on after homing which controls relay to disable the drive. Then tell it to home again and when finished turn the relay off again.

Using the enable is a really good idea. However, it sounds like it would eat up two inputs (one for each limit) and two outputs (one for each control line for the enable) I wish the Acorn had more than 8/8 I/O for needs like this. I asked about software access (for the macros) to any unused I/O pins on the Beaglebone, but didn't get direct an answer. I understand, not sure I would want to try supporting a product where users are hacking the board to get additional I/O. That said, a spare I/O header for later expansion would have been nice. It was stated that a USB based I/O expansion board is in the works.

Enable is an output on the step/dir/ena terminals. Doesn't use an input.

You could series your primary home switches to one input and use HOME ALL in the Wizard. That gives you back two inputs. If you have limits on the other end you could series them together with Estop. CNC12's soft limits work very well.

Yes, Centroid has heard from users and they are working on options for more I/O.

Marty

[jazzcnc]

Using the enable is a really good idea. However, it sounds like it would eat up two inputs (one for each limit) and two outputs (one for each control line for the enable)

Yes but really only using two extra outputs because even if worked correctly two limit inputs are required.

However, it is possible to do it with just one Output and One input. It would, however, mean having one switch trip slightly before the other and applying an offset to that motor to bring back square.

[mikes]

Using the enable is a really good idea. However, it sounds like it would eat up two inputs (one for each limit) and two outputs (one for each control line for the enable)

Yes but really only using two extra outputs because even if worked correctly two limit inputs are required.

However, it is possible to do it with just one Output and One input. It would, however, mean having one switch trip slightly before the other and applying an offset to that motor to bring back square.

I don't think it is possible to do this with less than two inputs and two outputs. You have to monitor each home switch independently as it will never be known which will hit first. Based on which is first hit, you will have to disable that driver, and then continue with the second. Using the backoff technique realy only works with different axises. OK, I suppose you could use the backoff technique, but then you are purposely raking the gantry to stop hitting the first home switch.

[mael]

If you daisy chain both motors(drivers) and hook up individual input home switches on both the X(main) and X(slave) and wire it in a way that when you tell the machine to home it moves both main and slave until 1 will hit the switch first then cut power to the driver while the other motor hits its switch. Problem is that if I cut power then the gantry will just slop back to its unsquared natural state. This might work if I parallel wire the signal wires and put the switch there but I read that it is not recommended because daisy chain is preferable.

Ok if I'm reading this correctly you want to use only 3 axes to control 4 motors. Keeping the 4th axis for other uses ie: Rotary
I use this workaround with Cslabs IP-M controller which doesn't allow gantry squaring but still able to have it home to individual switches like you suggest.

However, it doesn't cut power but instead uses the Enable signal on the drive which disables motors but keeps them energized. Or if drives don't have an enable input use relay which breaks the Signals to that drive.
It would require a change to the homing sequence macro so it turns an output on after homing which controls relay to disable the drive. Then tell it to home again and when finished turn the relay off again.

Think this should work just same with Acorn.

Thank jazz! Great info everyone.
Didn't think about enable. Unfortunately the stepper driver i got doesnt have an enable. I would go with the relay or transistor to interrupt the signal. Question though, which should I interrupt, the Dir or Step or both?

Just to second what was said earlier for all to benefit. This method will consume 2 inputs and 1 output. 1 input will be for the independent home switch for the Leading motor while the other input is for the Lagging motor of the same axis while being connected in series with the other home switches.

There might a work around to do the same thing using only one input but it would need a bit more electronics.
The idea is to make a NC momentary switch that disconnects the signal on the leading motor when the sensor/switch hits home then when the lagging motor hits the home sensor/switch (which is the main switch connected as the home input) it then closes back the switch on the leading motor. This way the script can back off both motors at the same time. What do you think?

[Gary Campbell]

I think that you could do this with 1 input and one output using a DPDT relay. One side of the relay toggling between 2 home limit switches, the other side toggling either the enable or step signal, if enable is not available

Relay (output#) inactive
Home (Dual motor axis) as per normal routine.
Back off switch ~.125"
Activate output (relay)
Enable to primary drive is turned off (or step signal if no enable)
Signal from primary home swith open, close to secondary motor home switch
Seek home, apply adjustment
Deactivate relay to primary home/limit switch, toggle on enable or step to primary motor