Isolation Routing PCBs

[Neale]

I've been looking at getting some suitable cutters to have a go at this myself - had a project or two in mind that haven't been started because I haven't decided how to make the PCBs. With auto-levelling software available, though, CNC machining looks viable with my machine.

I'm a bit confused about cutter choice, though. I see "PCB drill/mill" listed on eBay (although they look like milling cutters to me), or V-bit engraving cutters. Cropwell mentions using both, and then there's a wide range of diameters. Could someone recommend a good starting point for making, say, a PCB suitable for 0.1 pin spacing DIL packages (no SMD!)?

[Doddy]

Oh, any pcb endmill with a cutter length more than 2mm isn’t going to last longer than a pingfuckit

[Doddy]

I’d also caution to understand how much grief you’re prepared to put up with. I can go from print to board with the usual uv processes within an hour and that includes 10 thoa routing and 0.5mm pitch SSOP devices with 80% success (and likely reworkable failures). The quality surpasses anything I’ve milled myself. You experience may vary, of course

[Doddy]

Last post, I promise!

Of course isolation routing opens the possibility of through hole plating... something else I promised myself to try.

I really need to get back on the horse with this one.

[cropwell]

As far as cutters are concerned, I use a V cutter of 0.2 mm end diameter. I have ordered some 10deg ones from China, but so far they have sent me 30deg ones twice ! The narrower angle ones have better control of track width.

For drills, I buy from circuit2u.co.uk £6.99 for a pack of 10. They are resharpened ones, but good and sharp. For normal components I use 0.8mm, but headers and connectors need a slightly bigger diameter, so 1mm. Actually, if the pads are large enough, I just drill the lot at 1mm.

Doddy, I understand your frustration, I have one of those F-awful machines from Exeter. I have spent a lot of time aligning it, even to the extent of shimming the bed with layers of kitchen foil. It now gives acceptable results, but I am still not sure the spindle is at 90deg to the bed as a cut with a large cutter produces a very 'steppy' result. I think the rails are twisted relative to each other. This is because of the inaccuracy in manufacture.

I used to use 0.2mm endmills, but those little feckers would break if you looked at them funny. Like the 'pingfuckit', I have a box of them with more on the floor.

Happy Days,

Rob