Hacking a Roland CAMM3 PNC-3000

[Robin Hewitt]

Hacking a Roland CAMM3 PNC-3000 just about sums it up...

I got it for the look and it has passed wife inspection for home office use (provided it doesn't make a mess). Good idea for cold weather if you can get away with it

It's a small 3 axis mill with ball screws resolving 5um, round linear rails and a robust cast aluminium frame of average section about 1cm. It's also a bit of a dinosaur :naughty:

Good thing is you can download all the circuit diagrams, meaning you can copy it's EPROM's and make sense of them with a Zilog disassembler. It's got a Z80

I have a new proto BIOS written so I can upload new code and run it in RAM. Much easier than blowing zillions of EPROMS. All looks pretty straight forwards. Have you discovered Dosbox? It's a freeby that lets you run antique software under XP, Win7 and, amazingly, it all works. Nominate a directory containing all your DOS favourites, mount it as a disk drive under Dosbox and away you go. Google for dosbox if you want it.

Mechanically I need splash guards to comply with wifely edict. I also want to hush it up a bit. The brushed AC motor isn't too bad but DC would be quieter and I could slow it down a lot, it's much to fast. I'm fitting an ER16 spindle at the same time because Roland collets leave a bit to be desired.

Pic 1: Spindle out, motor out, new ER16 spindle waiting to go in.

[blackburn mark]

i do like the look of that machine, i can see why the wife has passed it for indoor use :)
im looking farward to seeing this one develop

[Robin Hewitt]

I replaced the EPROM so it now comes up and wants to communicate, lets me upload programs and run them.

Just did "reading the buttons". I can see the XYZ positioning encoder knobs on the front panel are going to be tricky.

To read the panel buttons and encoders I have to clock the data out serially by reading two dedicated port addresses. No problem except for the encoders which are odd. I get a direction and a brief pulse to say it's moving. Blink and you've missed it. They are not making this easy. Resisting the temptation to rewire it so I read the encoders raw :naughty:

Worry about that later, they've probably fine tuned the pulse to one step in crawl mode so I just read once per interrupt.

Next, lighting the LED's and setting the XYZ co-ordinate displays. Then I'll fire up the interrupts and get her moving again.

Still waiting for bits to do the new spindle. Bought the Ampflow E-150 DC motor and it looks delighful. Slightly concerned about how much heat it can dump into the metalwork without overheating, may need an extra fan. It's rather apart at the moment, you can see the 35mm round rails supporting the head. Feels fairly solid

[Robin Hewitt]

I got in a couple of days on the new firmware. I now have control of the knobs, buttons, motors and displays.

About 25% of that couple of days was persuading the XYZ position displays to behave themselves. Instead of TTL 7 seg display drivers they use some cack-a-mamy processor that needs to be interrupted when the direction line changes. It needs a delay after a direction change before it is prepared to start counting. No delay and it counts the wrong way. Get the delay wrong and it can go truly bananas.

No goto xyz yet, written but not tested. OTOH it does move because the Home button works. For Home I sidle up to the limit switches at 5mm/s until they are all shut. Then I back off at 2.5mm/s until they are all open. Then I wind into them again at 1mm/s. They aren't exactly brilliant, worst case repeatability is 35um out, need to think about that.

All stop now while I invent a command protocol. I want the host computer to do the sums but there is a limit on how fast i can pump information down the serial line. I need a compromise comms platform, a CCP :naughty:

[cooliced]

i like the look of this machine, whats the total working area?

[Robin Hewitt]

i like the look of this machine, whats the total working area?

Not a lot :naughty: X 180, Y 150, Z 150

I just found a blown ball bushing. Nil problemo because I can replace all 4 XY rails and all 8 XY bearings for around £50 from Gary and it will be like new. They are all 20mm

Robin

[cooliced]

Ah nice one, im looking for something like that but a bit bigger, looks uber retro

[Robin Hewitt]

It's been driving me spotty, but I think I am now convinced that it's the X,Y,Z position display that is wrong not the steppers. Time to give up on the displays and do some CNC type moving.

With my harum-scarum step sequence the counter stays 100% in synch with the steppers.

With my everyone moves together routine the displays are out one count per shift.

Makes not a lick of sense to me.

Pic is the encoder output. When you turn the dial one click you get a 1.25mS pulse. If direction changes you see the direction line (yellow) go 1.25mS before the pulse. This is surprisingly convenient when you are sampling at 1KHz to get 5mm/s at 200steps/mm. The motor will happily slam in to reverse at 5mm/s. Another clue that their 500Hz double step was a ghastly bodge to overcome a problem with the display :naughty:

[Robin Hewitt]

New motor and ER-16 chuck fitted. Used cheap bearings which are running noisy and a tadge warm, I'll give them a few hours and if they don't settle down and start behaving I'll have to shell out for something more up-market :whistling:

[cooliced]

I love this machine, just wish it was a little bigger. looks sturdy tho, what materials you gonna be cutting on it?