Author Topic: Cutting FR4 boards  (Read 28232 times)

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Offline OndraSter

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Cutting FR4 boards
« on: July 30, 2012, 07:48:20 pm »
Hello :)

I am making really small and cheap (almost Chinese-like priced!) gadget. The board itself is 23x34mm big. The cheapest option is (how else than) iTeadStudio with their $15 5x5cm colour boards.

I can fit two of these designs onto one board and save actually a lot of money (parts are less than $2.5 and I'd like the board to be sub-$1). I am wondering what is the easiest and most convenient way to cut the board in half (since they do not allow you to make v-grooving)? I tried exacto knife with not much of a success. My idea is that one could use glass cutter since it is FR4? Basically "V-groove" it manually and then just snap it.

Thanks for any hints :)


PS: PCBCart asks much more $$, just as any local PCB fab house.
« Last Edit: July 30, 2012, 07:51:49 pm by OndraSter »
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Offline Short Circuit

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Re: Cutting FR4 boards
« Reply #1 on: July 30, 2012, 07:54:48 pm »
Ordinary hacksaw will do fine.
 

Offline Chet T16

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Re: Cutting FR4 boards
« Reply #2 on: July 30, 2012, 07:55:12 pm »
I think I seen someone mention here that they had used a tile cutter. Dust would be nasty though!
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Offline mazza85

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R: Cutting FR4 boards
« Reply #3 on: July 30, 2012, 07:57:16 pm »
Usually I score the board several times with a piece of hacksaw blade sharpened at the end, then I bend the board until it snaps in two.

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Offline hlavac

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Re: Cutting FR4 boards
« Reply #4 on: July 30, 2012, 08:07:59 pm »
Idea 1: Use a small PCB mill. In my case, I just mount a small mill bit into my pcb drill/mill stand and lower it all the way down.
Attach a some bar exactly the width of your pcb away from the mill tip.
Slide your double pcb along the bar, cutting right in the middle between the two pcbs.

Idea 2: Make the V grove yourself, using some sharp v shaped tool and a steel ruler. Score and snap off.

Idea 3: I had some success cutting pcbs with massive scissors used for cutting sheet metal. You need the type that allows cuts longer than the blade. I took a piece of pcb to hardware store and tried all the scissors they had, walked out with acceptable ones. Probably not ideal for your situation as one of the two sides gets bent. Good for cutting excess rims. Great for cutting perfboard.
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Offline OndraSter

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Re: Cutting FR4 boards
« Reply #5 on: July 30, 2012, 08:19:38 pm »
Thanks for all the tips guys :)

I tried searching actually on the forums and on the internet of course, but there were 1000 opinions and every odd one said "the even one is wrong!" :D

Hacksaw seems quite thick for my use (since I will go for 1mm thick silkscreen line marking).

@hlavac: that's why I asked about glass cutter - it is glass epoxy laminate. V-score from the top and bottom and just snap them.
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Offline Short Circuit

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Re: Cutting FR4 boards
« Reply #6 on: July 30, 2012, 09:13:24 pm »
A glasscutter only creates a scratch in the surface of the glass doesn't it? Then it will not work because you need to score fairly
deep to snap the boards nicely. I guess the cuts need to be about 25% of PCB thickness, and on both sides.

Big difference with normal glass is that the layers of woven glass are isolated by the epoxy filler material, somewhat like
multilayered safety glass. And a glasscutter does not work very well on such safety glass either, I think...

Also, be carefull when snapping the boards regardless of the scoring method, especially after they have been assembled.
Too much warping can easily result in fractures inside components, or in SMT solderjoints.
 

Offline dbinokc

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Re: Cutting FR4 boards
« Reply #7 on: July 30, 2012, 09:25:54 pm »
I think I seen someone mention here that they had used a tile cutter. Dust would be nasty though!

If you use a wet tile saw,  there will be no dust. This is my preferred way to cut blank PCBs.
However I am have not done this with populated boards. before. The kerf for a tile saw
is rather wide, so be sure there is enough clearance.
 

Offline Christopher

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Re: Cutting FR4 boards
« Reply #8 on: July 30, 2012, 09:41:41 pm »
Hacksaw is too messy, takes ages to cut and nasty dust...

Best is a pair of tin snips or I've found an old pair of LARGE kitchen scissors work good, even if the FR4 makes them blunt.
 

Offline OndraSter

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Re: Cutting FR4 boards
« Reply #9 on: July 30, 2012, 10:48:12 pm »
The boards are not necessarily assembled before cutting them apart!

Okay, glass cutter is off the list then.

The thing is - there is about 2 or so mm thick "line" which I have to make perfect cut (or nasty cut and then sandpaper it).

I will try talking to iTead if they could make new offer... something like $17 for 20x 25x50 boards :).
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Offline digsys

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Re: Cutting FR4 boards
« Reply #10 on: July 30, 2012, 11:01:17 pm »
I've cut up literally 1000's of PCBs using a band-saw. The cut is about 40thou using a thin metal blade,
which will last 100M of cut or so.
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Offline OndraSter

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Re: Cutting FR4 boards
« Reply #11 on: July 30, 2012, 11:10:18 pm »
I shall buy one then. The one I found in the basement does fairly thick line and is... rusty!

Thanks a lot! :)
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Offline elCap

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Re: Cutting FR4 boards
« Reply #12 on: July 30, 2012, 11:49:18 pm »
If you plan to do many, a pcb guillotine is a good tool to have. It's quick and precise.
 

Offline krenzo

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Re: Cutting FR4 boards
« Reply #13 on: July 31, 2012, 12:52:03 am »
I use a dremel.  It takes about 5-10 seconds depending on length.
 

Offline Short Circuit

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Re: Cutting FR4 boards
« Reply #14 on: July 31, 2012, 01:13:35 am »
I've cut up literally 1000's of PCBs using a band-saw. The cut is about 40thou using a thin metal blade,
which will last 100M of cut or so.
This probably depends a lot on the material of the blade.
I have one of these Proxxon bench saws, and tried to use it for cutting a piece of prototyping FR4.
The stock blade was completely blunted after ~3cm of cutting  >:(

http://www.proxxon.com/eng/html/27006.php

 

Offline nanofrog

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Re: Cutting FR4 boards
« Reply #15 on: July 31, 2012, 01:22:50 am »
If you plan to do many, a pcb guillotine is a good tool to have. It's quick and precise.
+1

They can be expensive though (seen them near $1000 USD, though it was rather large; ~400 x 600mm or so, and rated for 1.6mm board thickness).

A small sheet metal shear would be an acceptable alternative for the PCB size the OP listed, and found at a much lower cost.
 

Offline OndraSter

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Re: Cutting FR4 boards
« Reply #16 on: July 31, 2012, 01:25:58 am »
If you plan to do many, a pcb guillotine is a good tool to have. It's quick and precise.

We have (had) guillotine at school but it was creating really messy edges for more than those few milimetres. Not sure if some other (newer) guillotine works better now. Also those were USSR guillotines and PCBs. They remember even Stalin! That could be part of the cause.

I am not planning (yet) to do a lot of them - probably start with 10 or 20 boards (aka 20 or 40 pieces), will see what will be the demand for it :).
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Offline Barryg41

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Re: Cutting FR4 boards
« Reply #17 on: July 31, 2012, 03:52:46 am »
My wife has a glass cutting bandsaw, she does stained glass art. It has a diamond coated blade that does quite well. It is a hobby version, don't really know the price off hand.
 

Offline notsob

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Re: Cutting FR4 boards
« Reply #18 on: July 31, 2012, 04:40:03 am »
Options for at home
1. Proxxon mini bench unit - with a diamond blade for tiny cuts
2. A mini shear http://www.carbatec.com.au/three-in-one-press-brake-bender44-guillotine-roller_c20955
                        http://www.carbatec.com.au/miniature-bending-cutting-shear_c20103
 

Offline digsys

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Re: Cutting FR4 boards
« Reply #19 on: July 31, 2012, 05:17:37 am »
This probably depends a lot on the material of the blade.
I have one of these Proxxon bench saws, and tried to use it for cutting a piece of prototyping FR4.
The stock blade was completely blunted after ~3cm of cutting  >:(   
I'm talking about this type of band saw -  www.diylife.com/2010/07/13/in-the-workshop-bandsaws/
(not this one, just a sample pic). Even a cheap metal blade does several dozen PCBs for me.
Now days I have the metal blades made up (prefer 8mm depth).
The unit I use at home for the last 25 yrs cost app $220 and has done a few 1000 PCB cuts.
The metal blades are NOT technically suited for FR4, but hey, they're damn cheap (~$20-25)
and they work FINE ! Beautiful cut, a quick linish after and viola. I can save a couple 100$ PER
prototype PCB by making an array of smaller PCBs, then cutting them up.
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Offline metalphreak

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Re: Cutting FR4 boards
« Reply #20 on: August 06, 2012, 09:01:48 am »
If you are just doing straight cuts, a wet tile cutter isn't a bad choice. The water flow also helps stop that nasty fibreglass dust getting everywhere in the air.

Offline jeremy

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Re: Cutting FR4 boards
« Reply #21 on: August 06, 2012, 09:42:16 am »
Have you emailed itead with the gerbers for a specific quote? They have done odd sizes for cheap in the past for me.
 

Offline OndraSter

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Re: Cutting FR4 boards
« Reply #22 on: August 06, 2012, 02:19:49 pm »
I have only sent them email asking whether they could offer 25x50 and 25x100 boards (another project). Without reply though :(.

That was without gerbers.
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Offline ampdoctor

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Re: Cutting FR4 boards
« Reply #23 on: August 27, 2012, 11:59:50 pm »
I may be a bit late on this thread but reading though it, I can't believe all the flaming hoops people are going through to cut FR4.  Here's how I do it.  Take a straight edge and secure it along the cut line.  Then take your garden variety chisel and run one of the corners along the straight edge.  First pass go lightly to just get a bit of a groove dug in for the tool to follow so it wont jump out on subsequent passes.  Next pass or two press HARD, and dig in for a deep groove.  Now just snap the board material off.  If you want a really finished look on the edge make a pass or two along it with a fine file to knock the fuzz off.  This whole process takes less than a minute, creates virtually no mess, and uses hand tools that most people have laying around the house.
 

Offline PA4TIM

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Re: Cutting FR4 boards
« Reply #24 on: August 28, 2012, 12:10:27 am »

No dust, nice clean edges, can cut a mm of a board without a problem. Use one for years
Link wont work,
http://www.worldoftools.nl/product_info.php?manufacturers_id=26&products_id=4710 maybe like so
« Last Edit: August 28, 2012, 12:13:22 am by PA4TIM »
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