Ok PCB milled now how to drill the holes ?

[HankMcSpank]

How this normally works is you design the pcb in something like eagle...you then run an excellon job in Eagle & it produces a drd file for all the drill holes, you then use that (for example I use Cambam to pull in the Eagle gerber files for the milling aspect, but there's a user plugin that runs excellon files.....the result is a 'point' for the drill at all the correct coords)

I'm wondering why you'd be thinking you should be drilling by eye? (your copper stock was already being milled by you machine...just get it to do the drilling first...simples! As the saying goes...why have a dog & bark yourself)

[John S]

I just do isolation milling with a vee cutter and start off by just dotting all the holes with the cutter, then do the tracks.
Drill the holes after on a little Proxon drill to save doing a cutter change.
Router can be doing the second board whilst I'm drilling the first, actually quicker this way not doing a tool change.

[HankMcSpank]

But it only takes a minute to do a cutter change? (then there was the time it took for the v cutter to 'spot' them all...your CNC machine may as well have drilled them!)...whereas to drill out all those spots manually will take a while? (plus it's not exactly a nice job!)

IMHO far better to have the CNC machine drill them for you ...this frees up more time for hobnob consumption.

[John S]

Not for me Hank.
I do these mounted on a flat piece of alloy with doubled sided tape, that tape lasts for about 8 pieces before I have to replace it.
If I drilled I'd have to clean all the thru drill holes after every piece to make sure the next board was nice and flat.

Engrave one board, swap boards over, 10 seconds and then drill whilst it doing the next, drilling takes no time at all, I'm always waiting for the router, not the other way round.

That same alloy plate is good for any board that fits it, thru drilling means I have to have different plates and setting up for a new job is fraught with danger if the holes don't line up. only takes the drill to hit the side of a hole in the plate to break it.

[HankMcSpank]

Aahh...I see - I use nice flat acrylic as spoiler backing board with double sided tape, the acrylic gets thrown....



(btw the green wire is my auto Z zero sensor wire to my CNC board..the right hand side clamping strip is conductive & makes contact with the FR4 copper surface. The tool is grounded...therefore when the tool touches to copper FR4 surface, the CNC-USB software knows it's exactly Z0)

....but only after I've used both sides! (I don't need totally flat because CNC-USB software probes the Z plane prior to V cutting)

[John S]

....but only after I've used both sides! (I don't need totally flat because CNC-USB software probes the Z plane prior to V cutting)

How long does that take ?

[HankMcSpank]

How long does that take ?

to do the Z probing?

About 1 minute (depends on big the PCB part is & how many probes you select) The amount of Z probes is set by the user ....eg 'probe four times in the X axis & 3 times in the Y axis' ...therefore 12 probes etc)




About 2yrs ago, I was seeking a slicker way to autocompensate for Z irregularities (all methods I'd tried up until that time were either a complete ballsache or sh1t)...at the time Andrej (CNC-USB author), hadn't offered the feature, but I pestered him sufficiently & he implemented it, so I bought it :-) ...best money I think I'll ever spend wrt PCB Milling

Just load up *any* g-code file (it doesn't have to be pcb related g-code) ....CNC-USB then gets the X/Y extremities of the part ...you tell the software how many Z probes to make within these extremities, then click 'Warp'.....& start your cutting.

It works perfectly.