band saw and FR4

[janoc]

That is exactly the kind of contraption that will embed pieces of diamond coated shrapnel in your face if you try to use it with such disc. It works with normal (metal) cutting wheels because those flex but with the abrasive wheel that's asking for a trip to a hospital unless there is a ruler/guide to slide the material along (and thus avoid side loading the disc).

[KL27x]

It works with normal (metal) cutting wheels because those flex but with the abrasive wheel

I'm not sure what you mean by normal metal cutting wheels. I have only used a diamond disc, a few time. It must have been a different kind, because the metal-cutting abrasive discs (like the one in this vid) are way more fragile and don't like to be bent at all.  It looks like there are different types of diamond, though, made for side grinding or edge cutting.

The lapidiary/tile saws have diamond embedded in mild steel and are tough as a truck. The Proxxon diamond saw blade sounds interesting the way you described it.

The camera view of the guy cutting in the vid is something every Dremel user will quickly learn to not do, yeah! This is the reason I can't be comfortable with a table saw. Years of using Dremel tools and cutting discs makes me uneasy looking at a spinning saw blade edge on. I have a blade guard on my micro chop saw jig, even. 

[janoc]

Aah no, I mean this type of cutting wheel:

https://www.gntools.co.uk/6pc-hss-steel-saw-cutting-disc-wheel-set-fits-dremel--mini-drills-cut-off-discs-248-p.asp

That is what the guy in the video has there. That's certainly not diamond coated, just a normal HSS steel.

EDIT: I have rewatched the video and you are right, he is using what looks like a regular carbide abrasive disc. That is really dangerous, that thing can shatter with little provocation if he doesn't guide the material perfectly straight and pinches the wheel.

The Proxxon saw blade won't shatter completely (it is mild steel core, not just ceramics) but the diamond coated abrasive part can break off into pieces. Not looking straight at the blade and using a blade cover/guard along with pair of safety glasses is a very good idea regardless of the saw/blade you are using anyway - even my tiny table saw managed to kick a piece of wood back at me when I wasn't careful already.

[sleemanj]

Unless you are cutting a lot of PCBs, and I mean a lot, I wouldn't bother with any saw, a saw sounds like a cool idea sure, but it's messy, noisy, and troublesome.

Just use a carbide tipped laminate/tile cutting scribe/knife...



available from hardware stores.  Use a pair of rulers clamped down to form a slot-guide over the PCB where you want to cut, scribe it 3 or 4 times, flip the PCB and do the other side, now it will snap just like a DIY v-score.

Here is my cutting jig (hook knife is what I used to use before I had the carbide tipped cutter)...

[janoc]

That works (as does scoring with an utility knife and breaking it). OTOH, if you need to create a cutout and don't have a router, that's difficult with a knife. Saw is easier for that.