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Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 3:17 pm
by pescadoman
cnckeith wrote: ↑Sat Oct 22, 2022 3:16 pm
slodat wrote: ↑Sat Oct 22, 2022 10:22 am
With the encoder inputs, will AcornSix allow closed loop on servos like the DMM DYN4?
Scales for positioning is supported. There is a planned encoder expansion board that gives another six encoder ports. Scales for positioning does not care what kind of motors it's connected to.
Scales for positioning does not tune the servo drive servo drive tuning is done in the drive. Scales for positioning looks at the scale and sees if the motor
Made it to the commanded position. If it didn't, it adds a little or subtracts a little to the motion to make sure that it does.
Can it be adapted to different resolutions?
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 3:24 pm
by gerald martin
A technical question about AcornSix - I hope this is the place to post it. I was studying the wiring schematics for Six and it appears that the recommendation for Clearpath motors is to use the 5V step/dir headers as opposed to the open collector headers? Could you verify this, and if that's right would you mind elaborating on the reason? I know the current guidance with the regular Acorn board is to use resistors on the open collector headers, and 5V power instead of 24V, correct?
Just interested in the technical details.
Gerald
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 3:26 pm
by tblough
Yes, you can use different resolution scales but you probably don't want resolutions higher than 1 micron. It's just like any other encoder; you tell CNC12 the scale counts per inch (or mm). There is also no requirement that you have to have scales on all axis or even the same scale resolution on all axis.
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 3:31 pm
by cnckeith
gerald martin wrote: ↑Tue Nov 01, 2022 3:24 pm
A technical question about AcornSix - I hope this is the place to post it. I was studying the wiring schematics for Six and it appears that the recommendation for Clearpath motors is to use the 5V step/dir headers as opposed to the open collector headers? Could you verify this, and if that's right would you mind elaborating on the reason? I know the current guidance with the regular Acorn board is to use resistors on the open collector headers, and 5V power instead of 24V, correct?
Just interested in the technical details.
Gerald
Clearpath with AcornSix on the 5 VDC terminal doesn't need pull up resistors and it works great. so, it is just simpler and more reliable way of doing things (less wiring and stuff to go wrong). thats it!.. (if you really want to you can connect to 24 vdc terminals and install resistors but that is not our recommendation.)
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 3:39 pm
by gerald martin
Got it, makes sense. Thanks @cnckeith
By the way congrats to you Keith and all the alpha testers out there. It's so amazing to see the pro grade cnc capabilities brought to hobby shops everywhere. There's nothing remotely close at the price point (my opinion). And you continue to make CNC12 better. Great opportunity to teach my boys too.
Gerald
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 4:41 pm
by pescadoman
tblough wrote: ↑Tue Nov 01, 2022 3:26 pm
Yes, you can use different resolution scales but you probably don't want resolutions higher than 1 micron. It's just like any other encoder; you tell CNC12 the scale counts per inch (or mm). There is also no requirement that you have to have scales on all axis or even the same scale resolution on all axis.
Forgive me here. Just so I understand.. You are saying .000197(5 Microns) wouldn't be fine? Can you explain an application that would be hindered by that resolution?
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 5:10 pm
by tblough
Assume you have a 10,000 pulse/rev motor controller, a 2:1 belt drive, and a 2mm pitch ballscrew. That gives your controller 10,000 pulses per mm of movement, or 0.1micron of movement per pulse.
If the Acorn is already controlling movement with 0.1 micron precision, why would you want to add 4.9 microns of error?
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 5:52 pm
by pescadoman
tblough wrote: ↑Tue Nov 01, 2022 5:10 pm
If the Acorn is already controlling movement with 0.1 micron precision, why would you want to add 4.9 microns of error?
Because I don't work in tenths and 5 micron's are less expensive and easier to source?
I can get tape and 5 micron readers for my 40x60 Router/Mill for about 320 dollars. The best I could find in 1 micron was about double that.
I'm not trying to be difficult, just trying to understand and be practical with my money. Almost all the work I do is with wood and plastic.
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 5:58 pm
by tblough
If you don't work in tenths, and work with wood and plastic, the you don't need scales at all. The point being is the Acorn is a micrometer, and you want to add a tape measure adjust it's position to machine material that grows by fractions of inches when the humidity changes.
Re: The AcornSix CNC controller kit has been released!
Posted: Tue Nov 01, 2022 7:10 pm
by pescadoman
tblough wrote: ↑Tue Nov 01, 2022 5:58 pm
If you don't work in tenths, and work with wood and plastic, the you don't need scales at all. The point being is the Acorn is a micrometer, and you want to add a tape measure adjust it's position to machine material that grows by fractions of inches when the humidity changes.
Except that it would compensate for backlash and machine "slop" when doing intricate inlaying....right?
I would find that useful.
In case anyone is wondering. HAAS linear scales start at 18,895.00