I wish to have a mini circular saw to cut my pcb, but sometimes it's enough to have a modified cutter and a proper frame to drive cutter into a straight line. I've designed one in this instructable, it's very cheap and it cames from ordinary objects.
Because you can't simply "cut" the pcb with an ordinary blade, you have to modify it to scratch the two surfaces of the pcb, so to snap it.
This method works well if you draw on pcb two lines on the upper and underneath surfaces, and check that they're exactly aligned. Then slide the pcb into the frame and scrath more and more times the surface until you have a rut which runs over all the lenght, then turn upside down the pcb and make the same on the other side. Now take out pcb and make a little force by hand to break it into two pieces. Round off the pieces with some sandpaper.

Step 1: The Cutter

Let's begin with the cutter. You need a strong one, better with some additional blades. I've bought this aluminium one, it came with 10 blades for about 4$. You can extract the blade acting on the little lever, and when blade is in position it's very tough, also if you pull hardly.

Step 2: The Blade

You need to modify the blade so it will form an hook shape, with a spiky point. You can easily make it with a grinding wheel and refine it with a dremel mini drill. Insert back the blade into the cutter and you'll have a perfect tool to scratch the pcb. Maybe you want to make the same modification to other blades to have the ready when this one will be consumed.
[UPDATE: I discovered that you can buy these blades]

Step 3: The Rulers

Now let's make the rails.
This was a 40 cm steel ruler, you can find it at less than 2$, which I've cut at half. I also made three more holes at far ends. The holes' diameter is the right size to keep the bolts with hexagonal head you already have, or you just could easily find, the exact misure is not so relevant. You also could use four short screws which length is less than board thickness.

Step 4: Drill the Board

The board is sold to cut salami as the one I've used for my column drill stand, they sell these boards at groups of six for a few $.
To set up the exact position of the holes in the board you need to put in place the two halves of the ruler, and leave between them about 1mm or less. Then with a pencil mark the center of the holes. This has to be very precise.
You see the bottom size of the board, where I've already inserted the four bolts. I've drilled a larger hole from bottom to about 1/3 of the thickness, to keep the bolts' heads, then I've screwed them, because the rest of the hole is a diameter a little smaller than the bolts' thread (see detail).

Step 5: And Insert Screws

On the top side of the board you've to thread some washers on the bolts. These will make the right thickness to let your pcb slide under the rulers. Probably you'll have to change them or add or remove some, because height varies depending also on the rubber sheet thickness. 

Step 6: Assemble the Rulers

Here you see the rulers in position, but if you don't add something to make grip between wood (or rulers) and your pcb this will slip when you'll try to scratch it with the cutter. So I decided to use a nice transparent rubber sheet of which I've bought some meters to protect the bottom of my tools drawers. Before adding the rubber check that rulers are perfectly parallel and that slit is narrow enough. If something went wrong you can enlarge the holes in the rulers so to shift a little them. 

Step 7: Glue the Pad

Measure the inside lenght between the bolts, and also the width of the board, and cut a piece of rubber sheet about 1 cm shorten in both directions. Then round off the corners. To attach the rubber to the board I suggest to use a transparent double faces tape. I've made it turn all around the border and also, this is important, put two stripes exactly under the steel rules.

Step 8: Test the Tickness

Now test the thickness of the space which remains under the rulers. The pcb should slide with no resistance under them, indeed you'll keep in place the pcb with a little pressure on the rulers when you'll scratch it, then it will be free to exit also if it's smaller than the rulers width.

Step 9: And Try the New Tool!

After adding four rubber feet your cutter frame is ready, you'll need it soon, together with my column drill, to make the circuits I'm planning to explain into next instructables (as the BBB).
<p>عالی بود آفرین.</p>
<p>What difference would it make if it was a hook shaped blade or a normal one?</p>
it's totally different, hard to explain. the hook takes off material, the blade cuts it.
<p>Interesting, I'll be looking for a hooked blade then. Thanks! :)</p>
<p>you can find hooked blades in most hardware stores, look for roofing blades. they are made to cut roofing shingles.</p>
<p>They can also be used for carpet cutting,in some cases they are better than a straight blade depending on the carpet type.</p>
My only suggestion is that instead of modifying the blade of a utility knife perhaps a different blade or knife. Linoleum and carpet knives digest themselves. Good job and thanks
<p>If still required, you could use acrylic cutter. I have been using this for a while now oto cut my PCBs and it works great. Hope this helps.</p><p>http://www.amazon.com/Plastic-Acrylic-Scorer-Cutter-Blades/dp/B007L31M3I</p>
Oh, you're right, looking for those I've also found these <a rel="nofollow">blades</a>, they seem exactly what I need! Thanks
Those blades will probably work, but I would recommend this: <a href="http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100046621&R=100046621" rel="nofollow">http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&amp;langId=-1&amp;catalogId=10053&amp;productId=100046621&amp;R=100046621</a> the carbide tips on this cutter are fairly robust and you will have no worries about breaking them. I have and use this tool, there are only 2 tips, not sure why the description says 3, but I've been using it to scribe and break cement board, lexan, kydex and a whole host of other things for years and see no degradation of the tips. If you &quot;use this up&quot; you are cutting enough PCB's that it is time to invest in better equipment.<br> <br> It is burly enough that you can really put pressure on it and get a good deep scribe. Plus, the metal that the tips are brazed to is thick enough that it wont wander off your line.<br> <br> Nice 'ible.<br> <br> Glen
I like that scriber, but I still think chisel is the way to finish, a cheap set would last for this purpose many times, no risk of snapping a blade. There is a dude (Egyption accent? He pronounces it &quot;cheyezil&quot;) on youtube. He gave me the chisel idea, this is a great jig for that. Perhaps score with something more nimble like the scriber, then final blows with a chisel?
Well I'll be durned. I got my scribe out tonight, and there's a third cutter on the other end of the metal blade, inside the handle. I learned something new about a tool I already own, thank you.
You should wait Christmas night to open your surprises! ;-)
good, they seem the right choice
I have one of these as well and have used it as Glen well describes.For someone who will do crafting with heavy materials I would describe it as indespensible . Thin cement board is a very tough material, abrasion resistant, water resistant, strong when wet, fire proof not very expensive. This tool will give you and friends the ability to make more use of it. ( I do hope you share tools and projects ). So do give it a thought. Good observation Glen
<a href="https://www.google.it/search?q=Utility+Knife+Hook+Blades&hl=it&tbo=u&tbm=isch&source=univ&sa=X&ei=vEHDUNOMLM_RsgabkoHIAw&ved=0CFcQsAQ&biw=1920&bih=1081" rel="nofollow">these blades</a> (link didn't work in other post)
I was looking for a way to engrave a circuit board to cut lands on the top to solder ic's. There isn't any instructables out there on this topic. I have made plenty of etched boards and drilled holes and soldered the IC's on the bottom, but it is confusing and you have a lot of holes to drill. I came across a gun stock diamond pattern video where once you have a straight line they have a tool that rides in that groove and cuts the next straight line next to it, repeat this process until you have the lands cut for each pair of pins like 1&amp;8 2&amp;7 3&amp;6 4&amp;5 then cut a groove perpendicular to these ribbon lands and you have a place to solder your IC on top like the surface mount components. Just thought I would mention it as there are no instructables on how to do that.
Very clever, and much handier than using a Dremel tool <br>for trimming PC boards. Nice!
Right, I heard you don't want to breathe ground up PCB. Dremel flings stuff all over the shop and into the air. I might make mine to fit a chisel tip.
Both downloaded, and made a favorite fo future reference. But I'm still home to find a used heavy duty paper cutter is good shape for a good price. However if this was something would do a lot new paper cutter isn't terribly expensive.
It's easier to use an office rotary paper cutter. That way you have a ruler already there for the measurement and no need to mark either side prior to cutting. <br> <br>Granted, a decent rotary cutter costs quite a bit more than a utility knife, two metal rulers, fasteners and a board.
For me, and I am an odd one, I find the rotary cutters don't always cut a straight line. If the handler wobbles, so does the blade, as mine do because I'm wobbly ;) <br>A blade &amp; a metal straight edge make much more precise cuts, but If you have a lot to cut &amp; precision isn't essential then the rotary ones are muck quicker &amp; less of a (anal retentive) pain!
Yes but I think the blade of a rotary paper cutter isn't so effective with copper layer, maybe one could change it with a different blade... it should be next instructable ;-)
very handy for one-off boards
yes, mine are very often one-off projects ;-)
Very simple and extremely good idea. Can you consider an L-angle instead of one of the half-rulers, it would help in holding down the PCB much more firmly.
I don't know, I need the flexibility of rulers to push pcb against the rubber sheet... your idea should work in case I tight everything with the bolts.
You can buy blades that are already like your modified blade. They're called hook blades and they are made for cutting roof shingles. It would have a better edge than anything you could do with a Dremel.
yes, thanks, I've discovered it, now I've to search them in shops
I see a lot of great projects on this site but to me and my stripboard site <a href="http://www.paulinthelab.com/" rel="nofollow">HERE</a> (sorry for the plug haha)<br> that is the most useful project I have see so far. if you have a actual site where you post this stuff I would love to put a link on mine to it.
I've to be honest, this concept is not all from my mind, because years ago I've seen a video on eBay in which a chinese guy (if I'm not wrong) cutted a board in this way. At that time I've thought it was handy, and I begun to do it myself. Now in Instructables I can share this concept with you all, so... thanks chinese guy! ;-) <br>Anyway Paul, your site is so rich of nice projects! I really think as well stripboards are handy for simple circuits. You can insert a link to this instructable if you wish.
It might be worth trying a carbide tip knife used to cut formica counter top material.
great instructables, very simple and affordable!
You know that you can actually buy these blades. They are used for cutting shingles and covering.
yes I've discovered that, thanks! :-)
Good Idea!!.........
Olfa makes an acrylic cutting blade that closely resembles your mod. I liked this instructable a lot! Nice rig! I've been cutting (one-sided) pcb's with scissors after heating them a little with a hot air gun or just holding them at a distance over the kitchen range fire. Phenolic can be cut this way as easy as paper. FR-4 is a bit more resistant. I've cut irregular forms this way (even circles!) but your rig looks promising for straight cuts. Also heating might warp the substrate so I'll try your idea. Thanks!
that's interesting, I din't knew about heating pcb... I've to try!
Really nice. Thank you. Grande idea. I used an Ikea plastic cutting board.
This is one of those &quot;Why didn't I think of that!&quot; ideas. Well done.
Love the pictures and illustrations :D
Great idea!!...I really have to make that!!....
I really need one of these. Thanks for sharing :D
you're welcome :-)

About This Instructable




Bio: I'm an Italian freelance structural engineer, graphic designer and photographer. I'm also investigating electronics, robotics and science in general. I enjoy hacking and ... More »
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