Re: CNC: Spindle speed control

Hello Erie;

Yes I can, the current component count to do all of this is 1, i.e.
the PIC Micro. If i use an external clock pulse the count will be
2 !!!. (Excluding connectors, etc)

The PIC runs off a 5v supply, so that's why the DC control voltage
goes from 0 to 5volts. I can add an output for 0 - 10 volts, it will
add probably 2 components, but that's not a big deal.

basically I am prepared to add anything (within reason) if there's a
need for it. Personally I don't require the programmable ramp up /
down but someone else asked me to add this, he has a chuck that
weighs 1/2 ton and cannot allow the chuck to suddenly decelarate to
zero upon loss of PWM signal.

I may offer this as a pre-built solution, as a kit or just provide
the circuit diagram and sell the micro chip with the software
already installed. Obvioulsy, this circuit will be EXTREMELY easy to
build even for a beginner, since the part count is so small.

Let me know what you need !

Regards

PeterC

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Erie Patsellis"
<signworks@c...> wrote:

> Peter, can you make the control voltage adjustable i.e. 0-XV,
> many of the older spindles use 0-10v for speed control.
>
>
> Erie Patsellis
> Shelbyville Design & signworks
> 217-774-4444
> signworks@c... <mailto:signworks@c...>
>
> <mailto:signworks@cond>
>
> Visit our website at: http://www.shelbyvilledesign.com
>
>
>
> -----Original Message-----
> From: Peter Cruickshank [mailto:crankshaft_sg@y...]
> Sent: Wednesday, March 26, 2003 4:38 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: CNC: Spindle speed control
>
>
> Hello All;
>
> I have spent the last 2 months learning about the PIC Micro and

have

> 90% completed the development and debugging of a PIC-Based PWM to

DC

> Controller designed around MACH1.
>
> The 5hz output from MACH1 is just too slow to allow it to provide a
> stable control voltage, so the only way to do it is to capture the
> PWM signal and control the output via software routines.
>
> The Micro runs at 4mhz and samples the 5mhz pulse from MACH1. As it
> is running much faster than MACH1's PWM Pulse, It can do a LOT of
> stuff in between ulses. Firstly, it has watchdog (charge pump)
> safety compatible with MACH, it also has programmable speed ramp
> up / ramp down (for large spindles).
>
> This ramp also works if communication is broken between the

parallel

> port and the speed controller, so if the PC crashes, hangs or
> someone accidentally disconnects the parallel port cable, the
> controller will not immediatly shut of all control to the motor,

but

> will ramp down at the programmed ramp rate.
>
> During direction change(M4>M3, M3>M4) , it will automatically ramp
> down the motor to zero, change direction (energize a relay) and

then

> ramp up to speed in opposite direction again.
>
> It has a rsolution of 1000 steps, so if your max spindle speed is
> 3000 RPM, it can control to 3 RPM, the accuracy is about 99.4% and
> it outputs a DC Control voltage from 0 to 5v.
>
> It has programmable minimum speed, maximum speed, resolution & ramp
> speed. It has outputs to LEDs and / or relays for M3, M4, Motor On,
> Ramp Up/ Down, Max Speed and 0-5v control voltage. The resolution
> allows small fluctuations in the input PWM not to effect the output
> control voltage, it is defaulted to 5 RPM so if any change is less
> than 5 RPM, then the output voltage will not vary.
>
> I have monitored the control voltage output over many hours, it is
> stable within a couple of millivolts!
>
> It can also be hooked up to a Serial LCD Display to show the

status,

> but other than in debugging, I'm not sure if its necessary !
>
> It does this using 3 inputs, PWM, Charge Pump & Direction and If

you

> can think of any other features, I would welcome any suggestions.
>
> Cheers
>
> PeterC
>
>
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