++++++++++++++++++ Date: Wed, 14 Nov 2001 18:32:14 -0600 From: Lee Buller Subject: [Elecraft] Cutting Traces I wonder if this has been discussed on the list....but .... What is the best way to cut traces on a PCB? Razor Blade? Exacto Knife? Dremmel Tool? Scissors? Coping Saw? Butter Knife? Skill Saw? Band Saw? Chain Saw? Buzz Saw? HMMMM Dumb questions, but I think I am gonna have to cut some traces to put in the new PIC controller. Lee Buller - K0WA +++++++++++++++++++ Date: Wed, 14 Nov 2001 18:57:22 -0600 From: "Stuart Rohre" Subject: Re: [Elecraft] Cutting Traces Lee, Easy, easy. No need for heavy duty tools. I just score the trace either side of a short piece to remove with xacto knife multiple times. "Tease" up the corner of the foil you want to remove, and apply a soldering iron to the foil to heat the adhesive under it. Grip the corner of the foil you have started up with needle nose pliers,and gently ease it off the board. 73, Stuart K5KVH +++++++++++++++++++ Date: Wed, 14 Nov 2001 19:27:18 -0600 From: "George, W5YR" Subject: Re: [Elecraft] Cutting Traces You left out the one I would use if there was room: razor saw from a hobby shop. 72/73, George W5YR +++++++++++++++++++ Date: Wed, 14 Nov 2001 21:00:22 -0500 From: "Don Wilhelm" Subject: Re: [Elecraft] Cutting Traces Lee and all, Several years ago, I was doing some circuit board rework as part of my job as a test engineer, and we routinely used dental drills to cut circuit traces - worked real slick. Now that I don't have those nice lightweight dental drills, I have used a dremel tool with a dental burr in its chuck - it works FB. If I don't have the dremel handy and have only one or two cuts to make, I use a sharp blade of a utility knife or an exacto knife or even my pocket knife and cut across the land twice so I will end up with a 1/32 inch or greater width gap in the trace - put the point of the knife under the copper and pull it up. (Use a knife blade suitably sized for the circuit trace to be cut - small knife for small tight spaces, etc.) In all cases - check the cut with an ohmmeter before and after - there are occasions when it looks like a clean cut has been made, but there is still a whisker of copper left that will cause trouble. 73, Don W3FPR +++++++++++++++++++ Date: Wed, 14 Nov 2001 21:26:28 -0500 From: w8ur at flatsurface.com (Mike S) Subject: Re: [Elecraft] Cutting Traces I've always used an Exacto knife. Cut the trace twice, very slightly apart, then "gouge" out the trace in between the cuts. Be very careful it doesn't get away from you and damage any neighboring traces. At 06:32 PM 11/14/2001 -0600, Lee Buller wrote... ++++++++++++++++++++ Date: Wed, 14 Nov 2001 20:27:49 -0600 From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] Cutting Traces -- snip -- I used to use a DremelTool, but it's often not 'specific' enough... well, it MIGHT be if I were to use something other than the CUTOFF wheel...! A dental burr might work very well. Anyway, I also tried using a single-edged razor blade, but I had trouble getting enough pressure on it and I'd often 'slip' and cut other things... this comes under the heading of "bad things will happen". I now use a fresh Xacto blade, cut (press) straight down on the land at two points, just barely separated from each other. Then, once cut thru, I gently lift out the 'chad' which has been created by the two cuts. This leaves me with a narrow 'empty' spot and two ends of the land which are still covered by solder mask. If I need to solder to one of the cut lands, I use the Xacto blade (flat) to carefully scrape away a tiny bit of the mask, tin the bare copper, and tack-solder a lead to the tinned portion of the land. YMMV Tom N0SS ++++++++++++++ Date: Wed, 14 Nov 2001 19:57:42 -0800 From: "Ron D' Eau Claire" Subject: RE: [Elecraft] Cutting Traces Lee asked: > What is the best way to cut traces on a PCB? I use just a sharp X-acto knife, making several passes with moderate pressure over the same place. I've never found it necessary to remove any excess trace material if a good, clean cut is made with the knife and any traces of copper are removed from the slot. To do that I usually turn the knife over after making the cut and then draw it through the gap several times with the tip against the board so the backside of the knife blade passes through the gap in the trace. That way the cut ends up as wide as the back of the knife blade... at least half a millimeter. Using an ohmmeter to verify that the cut is clean is a good idea as well. Always check before and after making the cut, so you can tell if you changed the resistance of the circuit. Many times there will be some indication of resistance after the cut is made. There is one such circuit on the audio gain mod, where cutting a trace places the pot itself across the 'gap'. Knowing the resistance before making the cut eliminates any questions about whether the cut was successful. The resistance you should expect is not always as obvious as it is with the audio pot mod. Finally, be sure you don't flow any solder over the gap when adding jumpers, etc. (Of course, I've NEVER done that!). . I've had occasion to want to put a circuit back the way it was too, and it is easy to clean the trace near the break and flow a tiny solder bridge across the gap restoring the original connection. No wire jumpers required. Ron AC7AC K2 # 1289 +++++++++++++++++ Date: Wed, 14 Nov 2001 21:33:15 -0700 From: "Rod N0RC" Subject: Re: [Elecraft] Cutting traces - Warning! Tom, et. al. - ----- Original Message ----- From: "Tom Hammond NØSS" To: Sent: Wednesday, November 14, 2001 7:40 PM Subject: [Elecraft] Cutting traces - Warning! ... > If you have a DremelTool, go visit your friendly family dentist and get him > to give you a few dental burrs, esp. those he used on YOU (less concern > about passing on a disease), and use them... they're great for making PC > board cuts, and you can generally control them a bit better than an errant > knife blade. I'll back that up with my experience. I gave up on Xacto blades after the first time I cut a trace. My Dremel tool came with a tiny burr bit like Tom is talking about. It is the only way to go! Like anything though, it's a good thing to practice on a piece of scrap first. 73, Rod N0RC Ft Collins, CO +++++++++++++++ Date: Thu, 15 Nov 2001 09:26:23 -0600 From: fkamp at home.com Subject: Re: [Elecraft] Cutting traces - Warning! Like Rod, I also prefer the Dremel tool. It is more controllable and a small burr opens the trace enough to positively disconnect the circuit. However, be very careful not to go too deep into the board if you suspect it might be multilayer. All you want to do is to remove a section of top layer foil. Frank Kamp +++++++++++++++++