Cutting PCBs, please show your method.

[moffy]

I recently had to make 3 small PCBs with cuts/outline accurate to at least 0.5mm or better. I had a battery powered tile cutter left over from a previous job round the house and some scrap board and aluminum. I came up with the following, which is compromised for cutting size by the mounts, but was large enough for the current job and was very precise.

Would like to see what you guys use.

[RoGeorge]

OK, but do it outside and wear a mask against that fiberglass dust generated by power tools.  Not good to the lungs, and the effects are visible only much later, decades later.

If you do PCB cuttings often, better use a guillotine, or big scissors, or some other method that does not use power tools, the power tools usually produce and spray cutting dust, in this case microscopic fiberglass needles dust.

[Gyro]

A tile cutting wheel is a good choice (wear wise) for surprisingly abrasive FR4 PCB.

Personally I use a cheap table type tile cutter - basically the same thing but inverted and with water cooling. The water captures the dust nicely.

Here are a few previous threads on the subject...

https://www.eevblog.com/forum/beginners/is-this-a-good-(or-overkill)-pcb-guillotine/

https://www.eevblog.com/forum/reviews/mini-table-saw-for-pcb-cutting-worth-buying-from-china/

https://www.eevblog.com/forum/eda/clean-way-to-cut-fr4-pcb/

https://www.eevblog.com/forum/manufacture/cutting-fr4-boards/

(I'm sure there are more if you try a few search term variations.)

[Psi]

I've used the drop/mitre saw before.

But one word of warning,
It goes without saying to not hold the PCB with your hand anywhere near the blades in case it kicks the PCB back and pulls your fingers into the blade.  Note that there is often a ~2mm gap at the rear of the cutting area under the back-stop and it can rip the PCB into this gap violently! So, if yours has a gap there, cut on top of some wood or something.

Also your edge quality will depend on the cutting blade you have installed.

But it is easy to get your desired width by cutting oversize and then slowly trimming down a tiny bit at a time until you get what you need.

[kripton2035]

I use a small band saw with a blade designed for metal cutting (small teeths) . works nice for the (very) small qty of pcb I do.
Now I make them at chinese factory, you have to wait 15 days to get them but it's so much better quality than mine !

[2N3055]

OK, but do it outside and wear a mask against that fiberglass dust generated by power tools.  Not good to the lungs, and the effects are visible only much later, decades later.

If you do PCB cuttings often, better use a guillotine, or big scissors, or some other method that does not use power tools, the power tools usually produce and spray cutting dust, in this case microscopic fiberglass needles dust.

This !!

Absolutely guillotine type cutter. Do not saw it, crushed fiberglass fabric is nasty, asbestos kind of nasty...

[Mark]

For long stright edges I use a guillotine.  For any fancy cut-outs or rounded corners I program the CNC machine. 

[HB9EVI]

I use a Proxxon circular bench saw, but the stock circular blade coming with the saw is not intended for PCBs, either you have to use a hard-metal circular blade or diamond

[tooki]

I use a Proxxon circular bench saw, but the stock circular blade coming with the saw is not intended for PCBs, either you have to use a hard-metal circular blade or diamond

FYI, “Hartmetall” translates to “carbide”. (“Hard metal” is not a term used in English, so people won’t know what you mean.)

[Alex Eisenhut]

I use a Proxxon circular bench saw, but the stock circular blade coming with the saw is not intended for PCBs, either you have to use a hard-metal circular blade or diamond

FYI, “Hartmetall” translates to “carbide”. (“Hard metal” is not a term used in English, so people won’t know what you mean.)

[David Hess]

Notching shear - but I have been thinking of making an sliding saw using a Dremel for precise and clean linear cuts using abrasive disks.

[HB9EVI]

sure, thanks Tooki; I should have known it, but obviously the 'mechanical' part of the english language left me for an instant, I'm not much into the mechanical world after all

[richnormand]

@moffy,
similar idea as your setup but upside down.

I modified a low speed diamond wafering saw to cut small pcb with a good precision.
The rotating blade is under the platform and is exposed like a table saw. The through under is filled with water and the bottom of the blade dips in it.
This cools/lubricates the blade and takes care in controlling the sawing debris.

Works extremely well either with x-y micrometer control or freehand with a 90 degrees machinist square edge.

[T3sl4co1l]

If I need it precise?  CNC mill.  You know, the same ones the fabs use?  Yeah, I just let them figure it out.

For protos?  Nothing anyone would really want.  Hand shears or hacksaw to get rough shape, wet sanding to get smooth edges and final shape.  Indeed, the dust isn't the most pleasant thing, definitely use wet cutting or low-dust methods where possible (hacksaws aren't terribly aggressive tools, but the sawdust can be kicked up).  Works fine for sticking together bits into shell housings and stuff, I've made a few neat enclosures over the years this way -- but it's rather tedious, setting up a bunch of slots for things to slide together or pin/locate on.

I still think doing this with copper clad is less work than carving up most (prefab) enclosures, and you can solder to it.  But not much less, and I do use those from time to time as well.

Tim

[David Hess]

If I need it precise?  CNC mill.  You know, the same ones the fabs use?  Yeah, I just let them figure it out.

With a precise saw, strips of copper clad can be cut to make instant controlled impedance microstrips for prototyping over a ground plane.

[moffy]

Thanks so much for all the info and sharing of experience. I do cut the PCBs outside, the smell apart from the dust is atrocious. The vinyl tile cutter sounds like a good idea too.

[SiliconWizard]

For prototyping, snapping the PCB after V-scoring is the least troublesome, if the cuts are straight. Of course it's not 100% failsafe, so better do this before populating the PCB than after.

[t1d]

I DIY'd a tile saw... The cheap, black, plastic one from Harbor Freight. I added a slide table. Cuts are accurate and fast.

[james_s]

If I'm going to cut a few of them I go to my friend's shop and use the large foot operated shear they have. If I just want to cut a quick one at home I clamp it against a scrap of 1/4" aluminum in my bench vice and using the aluminum as a straight edge I cut it with a hacksaw.

[Miyuki]

I order in a quick proto lab near, so have etched and drilled boards next day delivered
And they use a big shear cutter

[m3vuv]

I have a bench grinder with a thin 1mm cutting disk on one end of it,the thin netal cutting disks meant for a 4" angle grinder,its dodgy to use tho but i dont cut many boards but beats a hacksaw.

[Buriedcode]

I really haven't found anything I would consider easy.  But scoring 3-4 times both sides with a craft knife or knife cuttoff blades with a steel rule, and then just snapping.   Then a couple of runs along the edges with either "cheap" needle files (I say cheap because with FR4 they wear quickly) or 600 grit wetdry.  Cheap, but hard on the hands.

Bare in mind, I really haven't done regular DIY PCB's in a few years due to how incredibly cheap it is to get them made - even odd shapes.  So I never reached the point where I would invest any real time/effort/money into finding a more convenient solution to the many problems DIYing PCB's can have - cutting material, drilling, rivets fro TH etc..

edit: typos

[moffy]

Here is a picture of one of the boards cut, populated and interfaced to a DM556T stepper driver. I used a 16 pin IDC cable to carry the power, gnd, step(x-z), dir(x-z) and enable to the boards. You then set 2 or 3 jumpers to select X, Y or Z (all the boards are identical) and or Enable. The drive signals (3.3v CMOS in this case) then drive the appropriate resistor/transistor which then drives the opto input of the DM556T. Keeps wiring to a minimum, especially as my controller board has the same 16 pin connector.
I also added the Schematic for the board as it is a better description than my words.

[Buriedcode]

Nice. I would recommend SMT - purely because it saves drilling so many holes.  It's obviously not always ideal, sometimes parts are much cheaper, but for passives you generally deal with 100-5k at a time, and of course, power parts are easier with TH, for mounting heatsinks (SMT requires good ground plane. vias etc..). I use SMT where-ever possible for DIY boards, often leaving the only holes being pin headers or connectors.

[ajb]

If I need it precise?  CNC mill.  You know, the same ones the fabs use?  Yeah, I just let them figure it out.

Well, they use routers, which are kinda the same thing in the way that a bulldog is the same thing as a greyhound, but yeah, letting the fab figure out is the best way.

That said, I have use a CNC mill to carve up panels full of prototypes before (IIRC it made sense in terms of price/specs/lead times that I could get at the time and just being a fun experiment).  The big problem with using a typical mill in lieu of a purpose-built router is spindle speed.  Cutting tools work best at a particular surface speed, which is the linear speed that the cutting edge moves through the material.  Small tools at 1-2mm like you typically want for PCB routing, where the cutting edge sweeps a very small circumference need high rotational speeds to get the desired surface speed, so it's not uncommon to see things like PCB routers with 60,000rpm spindles, or sometimes even faster.  Cutting tools also have a defined chip load, which is the amount of material removed by each pass of each cutting edge, which sets your feed rate as a function of RPM, so there again small tools with small chip loads need high rotation speeds to cut efficiently. 

I was using a Tormach PCNC 1100 with a ~5,000rpm top speed, so performance on a 1.6mm tool was far from optimal, but it got the job done.  I threw a chunk of thick acrylic from the scrap rack in the machine, drilled tooling holes and made threaded hold-down holes in the acrylic in place, and milled relief channels in the plastic to clear where the tip of the tool would pass while milling the boards.  For the actual milling I used a drill-point carbide burr, which worked pretty well.  The drill point allowed it to pierce very effectively, and the burr left a pretty good edge finish despite the non-ideal cutting parameters, maybe just a bit less nice than what you'd get from the fab. The clearance channels in the fixture weren't strictly necessary, but burrs don't clear swarf as effectively as helical tools so some extra space there was helpful, and drill points aren't meant to cut sideways so it would have been kinda gross.  The cutting was kind of slow due to the limited spindle speed, but the great thing about CNC machines is that you can press Cycle Start and then walk away from them.

Of course dust control is important, as with any time you cut materials like this.  I wouldn't do it on a machine that wasn't fully enclosed or equipped with really good dust collection.  I also wouldn't do it on a machine set up for flood coolant unless it had REALLY good filtration, otherwise the fine abrasive particles produced by cutting FR4 are liable to cause increased wear and tear on the machine and cutting tools down the line.  Well, really, I wouldn't do it at all because it's just a whole lot easier to have the fab that has the fancy routers with high speed spindles and fancy dust shoes do it, like Tim said in the first place!