Cutting protoboards or PCBs to size - Page 1
Forum section: electronics / beginners

author: kalel
author_rank: Frequent Contributor
timestamp: November 13, 2017, 03:51:19 am
content: Any advice on what tool to use to cut protoboards or PCBs to size? I saw a Collin's lab video where he recommended some tin cutters.I'm not talking about any large volumes, just if I need to get a protoboard/PCB down to size of the project. I'm not looking for a costly solution. What do you use for the purpose?

author: Brumby
author_rank: Unknown
timestamp: November 13, 2017, 04:27:41 am
content: Depends on the thickness of the board. I wouldn't use tin snips myself - but if the board was thin enough, then ... maybe.A fine saw is a nice approach, but can be a bit tedious for a long edge. Personally, I use a Stanley knife and a straight edge for a score and snap approach. A nice deep score, preferably on both sides and reasonably even pressure along the score line for a clean snap. The edges can be filed or sanded to a clean finish.

author: boffin
author_rank: Unknown
timestamp: November 13, 2017, 05:09:13 am
content: I use a small hacksaw I made in O-Level Metalworking class in the 70s. Same one I've been using for 40 years.you can buy a 6" hacksaw for just a few dollars at any hardware store.

author: DTJ
author_rank: Super Contributor
timestamp: November 13, 2017, 06:53:28 am
content: What Brumby said - deeply score both sides using a utility knife - then score again!Hold the board on a sharp edged surface and break it at the score line.If you are only doing single sided boards then use the paper phenolic board as it breaks much more easily.A small sheet metal guillotine is the best way but you need to do it a lot to justify the cost.

author: Berni
author_rank: Super Contributor
timestamp: November 13, 2017, 07:11:14 am
content: Any protoboard that has a grid of holes on it is easy to break in straight lines.I tend to score the board with a knife on both sides to encourage it to break along that line. Then i take some wire cutters that i don't care about and just snip the edge and that starts a crack going all the way down the board where you can just then bend it by hand to break it. For longer cuts i usualy use some long electricians pliers to grab the board right next to the scored line and bend it to make it snap more localy and just move along until the whole line snaps.This does leave a very rough and sharp edge so its a good idea to use a file to smooth it over a bit and this can be done above a trash can so that the dust is mostly contained.(If you don't have a file handy you can also rub together the snapped off board edges against each other to grind down the sharp points)If you want a nice cut then you can use a cutting wheel on a dremel or a hacksaw, but i avoid that whenever possible because it creates a lot of very fine dust that gets everywhere. Breathing in the dust is also not good for you as it contains glass fibers.

author: Brumby
author_rank: Unknown
timestamp: November 13, 2017, 07:56:51 am
content: The Dremel/clone approach creates too much dust for my liking - but if necessary (for tight corners or curved cuts for example) then dust management is my prime concern.

author: John B
author_rank: Frequent Contributor
timestamp: November 13, 2017, 08:00:21 am
content: Cutting and abrading (saws, dremel etc) will always be the safer option compared to shearing (tin snips etc), which can just cause the board to crack in unwanted places.

author: sleemanj
author_rank: Super Contributor
timestamp: November 13, 2017, 08:09:48 am
content: Carbide tipped laminate scorer, available from good hardware stores.A 3 or 4 good drags of that on each side and you've essentially DIY'd a vscore, they are great.https://www.eevblog.com/forum/eda/pcb-cutter/msg930847/#msg930847A craft knife, or hook-knife will work, but FR4 will blunt it rapidly.Do not try using snips or guillotine with phenolic ("bakelite" in chinese speak) PCB, it's brittle, it won't cut well (cracks rather than shears), in fact I don't like a (paper) guillotine or snips at all unless you are talking paper thin PCB material (0.8mm and less) as it just bends and warps and generally does a crappy job.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 13, 2017, 09:39:02 am
content: I tend to go for the score-with-a-stanley-knife technique.Safety wise: keep in mind that a lot of board types like FR4 use fiberglass. The dust that this forms when cutting with any form of sawing or grinding tool, or when sanding edges, is very bad for your lungs. Same goes for drilling. I've seen a few people use a submerged setup to avoid problems with this (drilling with the PCB submerged in oil). It might not be a big deal for a few holes, but I prefer to take precautions anyways.

author: nanofrog
author_rank: Super Contributor
timestamp: November 13, 2017, 10:33:22 am
content: Scoring is both inexpensive and easy.Not the best edges, but a belt sander can clean them up in a hurry without spending a bunch of money on consumables. Tin snips work on thin boards, but there's also a metal shear that does an excellent job from what I've seen (example).In my case, I already owned both a scroll saw and diamond bladed rotary saw (i.e. effectively a tile saw, but it was made for rough cutting gemstone which I inherited from my mother who was a jeweler). The latter uses an oil based coolant, so they have to be thoroughly cleaned prior to component placement and soldering. So the scroll saw usually sees more use (blades aren't horribly expensive and a shop vac makes quick work of the dust).

author: Lee Leduc
author_rank: Regular Contributor
timestamp: November 13, 2017, 11:33:46 am
content: I use 0.031 inch instead of the traditional 0.062 inch and trim with a guillotine paper trimmer. It gives me nice clean, square cuts. Also, you can sharpen the blade when needed.

author: nanofrog
author_rank: Super Contributor
timestamp: November 13, 2017, 04:24:41 pm
content: Quote from: Lee Leduc on November 13, 2017, 11:33:46 amFWIW, I've a guillotine paper cutter similar to what's pictured (mine = cast iron arm/lever + replaceable blade), but was under the impression that this wouldn't last all that long for cutting PCB's.As I have such a device, how do I do a proper sharpening of it's blade* (on the presumption that PCB material dulls a blade rather quickly)?* Not trying to be a smart-ass, but am truly interested (I can sharpen knives with ceramic sticks for example, but that's the best I can do AFAIK).

author: janoc
author_rank: Super Contributor
timestamp: November 13, 2017, 04:40:31 pm
content: For where I don't care about it looking nice, scoring and breaking the board off or metal shears work.For when I need a clean cut, I have the tiny Proxxon KS 230 table saw. Put a diamond (NO 28 012) blade in it and it goes through the FR4 like through butter, with perfectly clean and straight cuts. Don't use the NO 28 011 solid carbide blade - its description says it is for fibreglass but it doesn't work for FR4 at all.Dust is a concern but the saw has a vacuum cleaner attachment that keeps the mess (and potentially carcinogenic particles) in check.

author: Cerebus
author_rank: Super Contributor
timestamp: November 13, 2017, 05:06:30 pm
content: Quote from: nanofrog on November 13, 2017, 10:33:22 amGenerally you don't even need to go that far. I usually clean up snapped v-scores by just putting a sheet of 400 grit Silicon Carbide (Wet'n dry) paper flat on the bench/table, hold the board at right angles to it and stroke the edge of the board backwards and forwards a few times. Gives clean, smooth square edges and takes a few seconds.Scoring works well enough for roughing out boards, but if any precision is required (e.g. you've got traces to miss) then the dremel/router with a solid carbide end-mill is the way to go. I score (with an engineers carbide scribe) to cut board to size for processing, I use a router for finished processed boards. If routing, use some scrap board around the edges of the board you're working on to provide a level surface to slide the router over.

author: w2aew
author_rank: Super Contributor
timestamp: November 13, 2017, 05:38:57 pm
content: I did a video showing a few of my favorite methods:

author: KL27x
author_rank: Super Contributor
timestamp: November 13, 2017, 08:50:02 pm
content: For protoboard, I use tin snips almost exclusively. But this is because the largest protoboards I have are very small. I only ever use protoboard to hold 1 or 2 components. So I take small boards and cut off even smaller pieces. Since this is invariably happening at my bench while I'm making something, I usually just file the edges smooth with a regular steel hand file.If you create large circuits on protoboard, score and snap works great.A good way to cut a lot of FR-4 in straight lines is a wet diamond saw (tile cutting saw). But I graduated to using a router table with 45 degree tilt using a carbide end mill. I'm not sure this latter thing exists as a finished commercial product, where the end mill can extend far enough to reach. (If you can buy this lift, it will cost a lot of $$$, not to mention the cost of a table and a router). I have custom made table for small rotary tool, and this is bomb. I am not sure how much FR-4 a carbide end mill can cut like this, but it is a heck of a lot. Been using the same 1/8" endmill for years. A v-cutter bit will wear out in a blink.For cutting weird shapes, using the side of an endmill is superb. But using the corner of the endmill tilted at 45 degrees is extremely fast and smooth for scoring/cutting square panels, and there's no danger or dust (or water spraying at you) as with a circular carbide or diamond table saw.For cleaning up straight edge of FR-4, after cutting it at 45 degrees, I use a disc sander. I might finish by just touching one side on the router because it gives automatically perfect parallel edge on the opposite edge, when you use a fence on the reference edge.

author: Brumby
author_rank: Unknown
timestamp: November 14, 2017, 12:20:44 am
content: A slight diversion - but related:Cameo appearances of Dave2 with off-camera comment by Dave(1).