Dremel accessory for routing PCBs?

[MrSlack]

I've been using FR4 and an X-Acto for cutting PCBs for about 6 months now I am doing one off SMD stuff. It's getting laborious manually slicing and peeling copper now, so Dremel time! I'm not doing proper PCBs for this stuff or dealing with etching - it's usually one shots.

Can anyone suggest an accessory tip that will actually groove FR4 easily freehand?

[DimitriP]

I've used this, but you have to have an "engraver's hand" if you are going to do  a whole board.
I don't

http://www.amazon.com/Dremel-107-Engraving-Cutter-Shank/dp/B00008Z9ZV

[MrSlack]

Thanks will try one of them.

[rob77]

"V" shaped or spear shaped bits are the best for cutting isolation routing in FR4. not sure if dremel makes them but proxxon does them in various sizes (0.8mm smallest dia but you can use the very tip of the V shaped bit only to make really narrow isolation grooves) they make them with a 2.35mm shank. other option is a small diamod ball engraver bit, i use them both.

[MrSlack]

Was looking at an engraver bit for the large traces and a milling bit held at an angle for narrower ones. Will see how it goes. Have just ordered 5 different bits.

My wife doesn't know I'm going to steal her Dremel yet

[KL27x]

For what you are doing, I have found the engraving ball is what will work best. But the diamond dust coated ball will last longer than the high speed steel ones the first responder linked. The larger the ball, the easier to use. But the best you're going to get is like 30/50 or so. Trace/isolation in mils. A very cheap battery powered engraving tool will work just as well as a high powered dremel, IME.

"V" shaped or spear shaped bits are the best for cutting isolation routing in FR4.

Certainly don't bother with pointed V-groove cutters. They will only work with a very rigid platform, not by hand. And even then, they wear out super fast. A regular end mill turned 45 degrees will cut circles around this kind of bit. So unless for a CNC machine, I wouldn't waste any time/money on V-groove cuttters. Even when I tried using them in a router table setup, the cutting is super herky jerky and needs a lot of force (special holder) to move the board in a controlled fashion.

[joeqsmith]

For PCB mods, I use a very small V cutter you can see in the attached video.  I also use some small saw blades that are maybe 0.1" diameter.  If I need to remove a lot of material, I use the X-acto knife, soldering iron and needle nose pliers.   One thing that would really help me when I do this sort of work is a better tool than the Dremel. 

https://youtu.be/QNRFTMk8MVI?t=1752

[KL27x]

A steel ruler and a carbide tile cutter might be helpful, too.
A small hole saw to cut out insulated copper clad discs that you can glue or solder down onto a ground plane may also come in handy.

one off SMD stuff

You're still going to need to buy/make breakout boards. There's no way you're going to easily manually score pcb down to 0.065" pitch. Point-to-point wire jumpers will be easier than that.

[Raj]

This tool (you'll need something equally thick as your pcb to surround it while using it)
its model 230 router attachment...and its older than me, so might me difficult to find

[MrSlack]

A steel ruler and a carbide tile cutter might be helpful, too.
A small hole saw to cut out insulated copper clad discs that you can glue or solder down onto a ground plane may also come in handy.

one off SMD stuff

You're still going to need to buy/make breakout boards. There's no way you're going to easily manually score pcb down to 0.065" pitch. Point-to-point wire jumpers will be easier than that.

I'm only doing sot23, 0805 and ~8 pin soic. Don't need anything too small.

[tautech]

Nobody's mentioned dust masks ! 

[MrSlack]

Already have one of them, and safety glasses, don't worry

[rob77]

For what you are doing, I have found the engraving ball is what will work best. But the diamond dust coated ball will last longer than the high speed steel ones the first responder linked. The larger the ball, the easier to use. But the best you're going to get is like 30/50 or so. Trace/isolation in mils. A very cheap battery powered engraving tool will work just as well as a high powered dremel, IME.

"V" shaped or spear shaped bits are the best for cutting isolation routing in FR4.

Certainly don't bother with pointed V-groove cutters. They will only work with a very rigid platform, not by hand. And even then, they wear out super fast. A regular end mill turned 45 degrees will cut circles around this kind of bit. So unless for a CNC machine, I wouldn't waste any time/money on V-groove cuttters. Even when I tried using them in a router table setup, the cutting is super herky jerky and needs a lot of force (special holder) to move the board in a controlled fashion.

actually works perfectly for cutting straight long isolation lines - i'm using V bits at 20k rpm with my proxxon FBS240 mounted in a MB140 drill stand. and even moving the board under the V bit without a guide is pretty easy. diamond ball engraver bits are great for small areas but not for long lines, that's why i'm using both. and of course for anything more complex than 10 components your best friends are riston & dynamask

[KL27x]

^ +1.

I stand corrected.

Previously, I used the 60 degree v cutter in a proxxon rotary tool at 20K. In a router table. With the height carefully adjusted. But I was using it with the bit directly perpendicular to the board, and also I was cutting deep enough to snap the board.

So I just tried it by hand, and I jumped to the wrong conclusion. It works a lot smoother by hand when the bit is tilted and you are just scoring through the copper. Indeed good enough to be better than an engraving ball - faster, finer, and still easy to control without much jumping. At least in a proxxon, and yeah, I see that the higher the rpm the smoother it works. We'll see how long they last, but I have about a dozen, anyway.

It looks like even 0.05" pitch is doable with this bit!

[joeqsmith]

Welcome to the dark side of PCB cutting with a pointed tip.   Really, I think you just need to use what you are comfortable with.  I had a friend who had a cutter that was more like a dental office tool.  The hand tool would very small and it used good bearings, not like my cheapo Dremel.  The Dremel is just too bulky for me. 

I thought I would post some pictures of a few of my cutters.  Note the size of the smaller tips I use...

   

^ +1.

I stand corrected.

Previously, I used the 60 degree v cutter in a proxxon rotary tool at 20K. In a router table. With the height carefully adjusted. But I was using it with the bit directly perpendicular to the board, and also I was cutting deep enough to snap the board.

So I just tried it by hand, and I jumped to the wrong conclusion. It works a lot smoother by hand when the bit is tilted and you are just scoring through the copper. Indeed good enough to be better than an engraving ball - faster, finer, and still easy to control without much jumping. At least in a proxxon, and yeah, I see that the higher the rpm the smoother it works. We'll see how long they last, but I have about a dozen, anyway.

It looks like even 0.05" pitch is doable with this bit!

[joeqsmith]

In the first picture, there are two very small ball cutters towards the bottom.   let's compare those with the cutters I use for PCBs.

Oops...

Top left is the spear tip you see me with in some of the videos.
2nd down is a ball cutter
3rd down is an inverted cone
4th down is a saw blade

[joeqsmith]

It's a little hard to see, so here are the four cutters next to the smallest under the microscope.  Note the chips.  Tip is broken off the V cutter.  Lots of abuse....

[Ian.M]

Has anyone tried the guide from the Dremel 566 Wall Tile Cutting Kit, to provide router-like depth control for cutting isolation gaps in bare copper PCBs without digging into the underlying laminate excessively?

[KL27x]

Interesting collection joeqsmith.

The V groove cutters I bought are carbide. They look like this. Just one cutting edge on the bit. You can see some of the hand-carved lines I made in the corner of the pcb. I don't remember what the isolation gap settings I used on this pcb; it is pretty generous, seeing as no soldermask. Anyhow, I could easily match it by hand, under good lighting, say under a microscope. (You can't really tell in the pic, but those lines all have a very clear isolation, visually.) The small ball cutters with the multiple facets work great, too, but I find they dull very quickly. This bit was still sharp enough to poke a hole through my finger when I put it away.

Has anyone tried the guide from the Dremel 566 Wall Tile Cutting Kit, to provide router-like depth control for cutting isolation gaps in bare copper PCBs without digging into the underlying laminate excessively?

For the sake of science, I just free-handed this on my router table. Obviously I couldn't see what I was doing, but as you can see it was pretty smooth. I guess these bits are somewhat limited to depth of cut. Going even halfway through the FR-4, things get really dicey. Or maybe it's the material, copper being easy to machine. I think most of the time you rework a pcb, it's going to be populated, though. So I wonder how often you are going to get to use a router guide.

I had a friend who had a cutter that was more like a dental office tool.

Well, I have yet to use a Dremel tool with as little runout as my proxxons. I have indeed used a proxxon tool to grind on a tooth, before. Smooth! I have a couple Dremels and a couple proxxons. With my Dremels, I can manage an endmill on plastic by hand, but not wood. With the proxxons, I can manage wood, no problem.

Welcome to the dark side of PCB cutting with a pointed tip.

If I had known it was this easy, I would have used it the other day. I broke out the sharpie to make a quick and dirty board for wiring up a multi cell battery... and it turned out pretty horrible. I guess I have the wrong kind of pens. This would have done a much neater job.

[joeqsmith]

That's an interesting looking tip.  Post a mfg and pn and I'll pick up a few to try.  Drew a couple of guide lines with a marker and made two cuts free hand.   Left is from the saw blade, right from my pointed tip.  Scale is 0.01"/mark.   Razor blade along with a straightedge would have been the tools to use but gives some idea how they cut.   

 

[KL27x]

I bought them on amazon, no longer available. The lot description says "30 degree carbide PCB cutter bit."

They look the same as this, except these cost twice as much as what I paid per unit. 
http://www.amazon.com/EnPoint-High-precision-Engraving-Diameter-Aluminum/dp/B00QNIXAOQ/ref=sr_1_7?s=hi&ie=UTF8&qid=1464909715&sr=1-7&keywords=carbide+pcb+cutter

I bought them specifically with the intent to score/cut the FR-4, so I figured the thinner the kerf the better. I don't know if the 30, 45, or 60 degree is best for removing copper?  I'm no machinist. But for me the steel bits don't last too long vs FR-4. 

FWIW, thanks to this thread, I get to junk my little Proxxon ball-end engraving tool. The carbide "pointy bit" in a regular proxxon definitely works better and faster. Almost 4 years, I had these bits without trying them for this. 

[joeqsmith]

Thanks!  I checked and saw they have many similar ones.  I'll pick up a few different ones to try out.   

I tried to find out what my old friends tool was.  Sorry, no luck.  He used it for cutting wood and was pretty good with it.   He let me try it out and I have not liked the Dremel since.    I was better off not knowing.....

I have a few different guides for my Dremel.  Picture showing how much straighter I can cut a line with one of them.   Shown with the broken point cutter.  Right to left was 1st through 3rd attempt.  Was getting fair results once I got the depth sorted out.  All plastic. 

[joeqsmith]

These came in.  Looks like they may work alright.   Also got some cheaper ones below.   I'll give them a try over the weekend.   

https://www.amazon.com/Autek-Titanium-Carbide-Engraving-J3-3001Tix10/dp/B00HC98K2C/ref=pd_sim_469_3?ie=UTF8&dpID=41PXkOwZ3dL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=V0F05BGVC0CA37VVZT68

https://www.amazon.com/Generic-Degree-Carbide-Engraving-Router/dp/B00EQ1XMSQ/ref=pd_sim_469_8?ie=UTF8&dpID=41--jeqWaTL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=Q80PN3A1KBVN3HZ5ZH25

[KL27x]

Coincidentally, I wired up another battery pack the other day. So I tried using this cutter, and the line is TOO small (for this). Under the microscope, I can also see a lot of tiny copper particles that don't wipe out, easily.

I ended up using the old diamond dust ball engraver bit. The kerf is relatively huge in comparison, but still a bit too fine for this particular job. The larger radius also lets you wipe away the copper cleaner, without digging and leaving little embedded particles or chewing up the surface of the FR-4 as much. 

Certainly for finer pitch and rework of a factory board, these V grooves will be the cat's meow.

[joeqsmith]

I finally received the second set of cutters and tried them both out.   The last set are not coated, carbide about $8.00 for a box.  They do make a bit of a mess as you suggest.  I am not sure it's any worse than some of my other cutters. Working free hand, I can control the cutting fairly well with them.   They are not made to remove a lot of material fast but seem to do a good job with fine cutting. 

I give them the thumbs up.     

I have used the find grinders (green colored stones) for removing large areas.  Really large, I am back to the knife and heat gun....

Under the microscope, I can also see a lot of tiny copper particles that don't wipe out, easily.