Joe's 1000x600x200 steel and aluminium router started

[Kitwn]

It's drilling the bloody holes that's always the pain isn't it? I use SMDs as much as possible and bought a vacuum placement thingy off eBay a few years back. I keep the solder paste in the fridge, especially as inside my shed can get up towards 50C around Christmas and new Year.

I hope it works as you want.

Kit

[Doddy]

Drilling?, if only we had a machine that could do all that for us :-)

And solder paste?, I've thrown more out than I've used, with it's damned stupid shelf-life (fridge or not...and a Northern UK climate). Right now 0.4mm rosin cored solder will do me and a decently "Large" iron tip. Oh, and flux... plenty of flux.

But, yeah, DevMonkey - hope it works and please report back. I need inspiration to continue my DRO/Pi controller for my mill.

[Kitwn]

Drilling?, if only we had a machine that could do all that for us :-)

You have. It's called a CNC router. The trick is making the machine and your ability to register a pre-etched circuit board on it accurate enough. Something I haven't even atempted yet.

I do like using the solder paste. That and a gas soldering iron with a hot-air head makes hand-soldering SOIC chips nice sand easy and the 1.27mm (thats 0.05 inch for our 19th century readers) pad spacing is reliably makeable using the toner-transfer method for DIY circuit boards....without holes!!!

Kit

[devmonkey]

You have. It's called a CNC router. The trick is making the machine and your ability to register a pre-etched circuit board on it accurate enough. Something I haven't even atempted yet.

I do like using the solder paste. That and a gas soldering iron with a hot-air head makes hand-soldering SOIC chips nice sand easy and the 1.27mm (thats 0.05 inch for our 19th century readers) pad spacing is reliably makeable using the toner-transfer method for DIY circuit boards....without holes!!!

Kit

For crude through hole boards with thick traces like this one I use the toner transfer method with a £50 Brother laser printer from Argos, good results and takes <15 mins to make a board including etch and drill, I drill by hand on a tiny toy CNC machine. This process works well for double sided boards as well.



For higher resolution boards I use a CNC photo method on the same toy machine. Spray the copper with black paint then use a low power UV laser in the machine to isolation route it. Wash off the ablated paint then etch. If the board requires any drilling and/or is double sided I use a fixture so to re-locate it after etch. This process takes a bit longer but I can achieve 0.2mm features/tracks.

Anything more complicated with >2 layers gets sent to China, even if just a proto. All the SMD stuff gets soldered with hot air, agree very easy if your solder paste isn't like gritty chewing gum.

[devmonkey]

Interested to see how this goes. Glad to hear you're bit-banging, though as the 328 is inline with the axis pulses to the stepper drivers it has to keep up at all time (not just homing) and I'd be curious if you can hold the signalling whilst I2Cing the display - interesting challenge.

I did realise after writing that the optos were for homing switches/reflection into the DDCS, so, yeah, will be fine - I'll withdraw that.

Hi Doddy,

So it turns out if you ditch the standard I2C/TWI wire.h library and display driver, crack open the 328p datasheet, write your own crude framebuffer and I2C non-bocking state machine that operates directly on the TWI registers you can tick the state machine at a 2-3us per tick penalty. Will put it on the scope and see if this is sufficient.

Main loop becomes:
1. Mirror stepper/home signals with squaring logic.
2. Update framebuffer if needed (using a 5x7 font this is 5 memory reads/writes per character)
3. Tick I2C state machine.

I could remove the framebuffer to make it a bit faster if required, this will effectively amortise the font copy part at one byte/I2C tick.

Cheers, Joe

[Doddy]

Hi Doddy,
write your own crude framebuffer and I2C non-bocking state machine

"Crude"?, I prefer to think of this as "fit-for-purpose".

You know as well as I do the 328 is just one of a thousand different micro controllers that pollute the oceans and the Arduinio packaging is just a convenient way of throwing that chip into an accessible form for stupidly low cost - makes them a sensible solution for even the most simple of problems. There's no reason to use the Arduino libraries unless you're concerned about cross-platform compatibility or speed/ease of development (sacrificing code base, efficiency and real-time performance). I think you'd agree programming at the register level (I gave up at the instruction level many decades ago - I prefer to have a compiler at least) adds a level of complexity and care, but if that floats-your-boat (and it does, me) then hack away to your hearts content. At least you can be confident that you know exactly that the uC is behaving exactly as you want it to.