Cutting PC Board

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Mike6158
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Cutting PC Board

Post by Mike6158 » Sat Jan 22, 2005 1:28 pm

<insert string of expletives here>
<now scream loudly>
<pull on hair>
<gnash teeth together><p>Ok... you are now matched to the poster's mood.<p>How in the h e double toothpicks do you cut these damn boards? I just went through 3 scroll saw blades and I cut one cheesey little 2 x 3 board out. I've got at least 10 more to do. I tried to find carbide scroll saw blades and I had no luck. So... the scroll saw is out. How are you cutting them? One of my boards is in the shape of a 2.375" diameter circle so I need to at least be able to get close enough that I can fit the board into it's "home" with a file but I would rather be able to just cut it out. Which is why I used a scroll saw. That and I already had it.
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

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philba
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Re: Cutting PC Board

Post by philba » Sat Jan 22, 2005 1:50 pm

fiberglass eats HSS cutters - you will dull the cr*p out of anything you use.<p>many ways to do it. some better than others:<p>get a knife (box cutter, exacto, ...) and a metal straight edge. Lay the straight edge where you want to cut and run the knife over it A LOT. When you get a fairly deep score, you can snap it off. YOu might want to score both sides. sand the edge. Think advil when done. <p>drill a lot of holes on the score line. snap. leaves an ugly edge so sand it down.<p>nibble it off with a nibbler. ugly, slow. double the advil dosage.<p>get a carbide blade for what ever saw you have. It will work better. be sure to clamp it really well.<p>my favorite - use a shear. I have a 30" job that has a built in clamp and works great. You put the board in, align it and, snap!, its done. Fairly clean edge. I've seen benchtop units for fairly cheap from harbor freight and grizzley.<p>I've heard of people using tile saws.<p>[ January 22, 2005: Message edited by: philba ]</p>

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philba
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Re: Cutting PC Board

Post by philba » Sat Jan 22, 2005 1:56 pm

here's the harbor freight one I was thinking of. not a bad price but I can't say much to the quality.<p>http://www.harborfreight.com/cpi/ctaf/D ... mber=90757

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Chris Smith
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Re: Cutting PC Board

Post by Chris Smith » Sat Jan 22, 2005 1:59 pm

A Steel straight edge and razor knife, score several passes on both sides, and break.<p> I prefer a jewelers file [flat type] and sharpen the end keeping it cool during this process on a grinder, til it is 90 degrees or more acute at the end, and crisp and sharp, and then grind both sides down until its half as thick or less, so that you create a hardened and sharp scoring tool.<p>Lean the file slightly side ways to get one point touching at a time, and rotate this lean back aaaand forth with each pass so that you cut a small channel with two or three passes. <p> The more drag you can feel with each pass, a little deeper your cut becomes and then clamp to a straight edge on the bottom and top along the score line, and snap.

Mike6158
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Re: Cutting PC Board

Post by Mike6158 » Sat Jan 22, 2005 3:18 pm

Good ideas but they won't work on a round board (51mm diameter) and the board has to be round or I have to come up with an entirely new way to do this deal. Packaging has by far been the biggest hill to climb so I'm not real interested in going there.<p>How do board houses cut their boards out? Will they even make a round board?
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

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dr_when
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Re: Cutting PC Board

Post by dr_when » Sat Jan 22, 2005 3:37 pm

A shear is the best and the straight edge method is great when at home. For odd shapes I use a band saw with a blade I use only for cutting PCB stock. It will have a limited life but long enough to make it worth while.<p>Bob
"Who is John Galt?"

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dr_when
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Re: Cutting PC Board

Post by dr_when » Sat Jan 22, 2005 3:41 pm

Oh... board houses route their boards to odd shapes. Most board houses will do it...you just have to pay more for weird shapes. CNC mills can do all that.<p>Bob
"Who is John Galt?"

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Chris Smith
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Re: Cutting PC Board

Post by Chris Smith » Sat Jan 22, 2005 3:44 pm

A drill press, hole saw, and alcohol. Slow, easy, and it wont even phase the saw.

k7elp60
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Re: Cutting PC Board

Post by k7elp60 » Sat Jan 22, 2005 3:46 pm

I have another hobby, that is woodworking so I have a table saw. I have been able to cut square or rectangle boards, both fiberglass and phonelic with a carbide tipped blade. I push the board thru slow and have excellent results.
One board house that I know of locally uses a router with a carbide blade to cut boards to the finished size boards.

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Re: Cutting PC Board

Post by wolfcreek » Sat Jan 22, 2005 3:59 pm

On the round board if you could drill a small hole in the center of the circle it would be quite easy. I would cut a square the same size as the circle you need. Then drill a hole at the center. <p>Using a table saw with appropriate blade or a tile saw I would make a jig that would hold a pin the correct distance from the blade. The pin would go through the hole in the PCB and allow it to rotate. This will allow you to cut a perfect circle. <p>I have done this many times in wood and other materials and it works quite well. You should be able to make a suitable jig in an hour or so. This could aslo be done with a drill press, router, bandsaw, etc. I would think you could incorporate the center hole in your PCB layout.

Mike6158
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Re: Cutting PC Board

Post by Mike6158 » Sat Jan 22, 2005 4:34 pm

Using a hole saw is a good idea if I can find one that has an id that's at least close. Making a jig for the table saw is another good idea. Even if the current layout has something in the center I can move it easily enough... Good stuff... TNX<p>[ January 22, 2005: Message edited by: NE5U ]</p>
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

Mike
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Re: Cutting PC Board

Post by Mike » Sat Jan 22, 2005 5:10 pm

What I do is use a cutting disc on a dremel tool. The problem is its easy to break the disk. So, wear safety glasses and cover easily breakable (I put a piece of wood in front of my LCD monitor so if it goes flying it wont crack the monitor). Other than the dust, it works pretty well. What I have just started doing is just scoring it and then snapping the board. They are easy to snap.

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Chris Smith
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Re: Cutting PC Board

Post by Chris Smith » Sat Jan 22, 2005 5:39 pm

I think the 2 inch hole saw is close and a little under, [? 50.8mm ?] and the 2-1/8..... 2-1/4 and I know the hole saw for drilling door handles and locks is really close also.

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Re: Cutting PC Board

Post by dyarker » Sat Jan 22, 2005 10:17 pm

A 2-1/2" O.D. hole saw should be close to 2.375" I.D. With a drill press (not hand-held drill), and FIRMLY clamped PCB, you might be able to do it without the drill bit in the center. If you can cut it before etching, you can avoid tearing off traces near the cut.<p>For manufacturing hundreds/thousands of units, I'd bet they use press punch and die.<p>C U L -
Dale Y

rshayes
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Re: Cutting PC Board

Post by rshayes » Sat Jan 22, 2005 10:35 pm

As mentioned several times, board houses use a router with a small carbide bit (possibly 1/16 to 1/10 inch). This is done with a CNC X-Y setup. They also stack up several boards for drilling and cutting. Not very practical for home use unless you have a CNC setup. Freehand cutting with a Dremel tool will probably break the carbide bit very frequently.<p>Sometimes hardware stores have hole saws with carbide teeth. Those might work for your circular boards, but may be expensive. Or they may be cheap, depending on the dollar value you place on your sore hands and frustration.<p>For straight cuts, I usually use a hacksaw, and plan on throwing the blade away. At least here the wear is distributed over about 8 inches.<p>There is also a carbide based blade for a hacksaw frame. It is a rod with carbide grains bonded onto it. I have cut through ferrite rods with these, so glass-epoxy should be no problem. The cut is over 1/8 inch wide, so you get a lot of dust with this approach.

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