PCB drilling with a dremel

[Krisfr]

Any tips on common sizes and sources of drill bits to drill with using a dremel tool? Also best techniques TOO.

[wakibaki]

I have ordered tungsten PCB drill bits from Farnell in the UK. 0.5, 0.8 and 1mm are the most commonly useful. The tungsten bits have a shank that fits the standard Dremel collet.

I don't have a Dremel, I used to use one at work. I have an imported 'KINZO' tool here at home, but I don't have a drill press for it. I was pleased to discover that I could use the massive (comparatively) bench-top machine shop drill press I do have. It's best with HSS bits, but I've also learned to use it without breaking the tungsten bits, by moving in a slow and deliberate manner.

An easy way to break a tungsten bit is to start to move the board before you have fully withdrawn the bit from the hole. This is quite easy to do if you get into a rhythm and are trying to work quickly.

If you have a lot of holes in a row you can set up a 'fence', an immovable straight-edge that you can slide the board up and down against, then you only have to worry about the positioning in one dimension. I have a vice that works for this, the drill-press table has slots for securing this with bolts and wingnuts. I butt-up a piece of thin wood against this with the board on top so I have something for the drill tip to enter before it strikes the table.

w

[MJL21193]

IMO, the Dremel needs a chuck - best accessory to buy for it. It will hold the smallest bits.
I use mine hand held and use HSS bits. Learn to sharpen them with the side of the tiny cutting disks for the Dremel. You'll get thousands of holes from a single $2 bit.
Etch and tin the board before drilling. The etched out holes will guide the bit.
I think the smallest I use is 1/64". 3/64" and 1/16" are my next 2 sizes.

NPX_01034.JPG

[jackinnj]

0.033,0.040, 0.052, 0.125

ditto on the tungsten bits. I found that using them on the Grizzly Mill saved me a lot of money. But I now buy a bunch of HSS bits in the sizes I use and just pitch them when they get tired. Dremel and Ryobi have a little press which works nicely. I put the board on a square chunk of balsa and use a bright light to illuminate the work surface.

I do have a CNC machine, but haven't gotten up the nerve to use it, relying instead on my board shop out in Colorado for protos.

[wakibaki]

Originally Posted by jackinnj

I do have a CNC machine, but haven't gotten up the nerve to use it, relying instead on my board shop out in Colorado for protos.

Well worth the effort to try the CNC, I wish I had one. I use UV resist board, the uncoated board is 30% cheaper. I made some big boards on the CNC mill at work, 15*24in, 32*9in. I imported the Gerbers into Eagle using a tool from a guy called Falk Stricker, then created the isolation toolpath with PCBGcode. I had to manually tweak the text files to get all the features on the same layer, but it was all possible with free software, even doublesided. Marvellous. They gave me a £5 book voucher for a Christmas bonus. F*cking marvellous.

32" PCB

pcb.jpg

w

[MJL21193]

Give my left nut, I would for a decent CNC machine.

[bob123]

I used to use a maxicraft PCB drill with its stand and found that it works ok. I have used a dremel and the stand with it which seems slightly better.

Carbide drill bits snap quite often when manually drilling especially the ones less than 0.6mm. HSS drill bits wear out in seconds, I found only one board could be done before the drill bit was completely worn.

Luckily I got given a Bungard CCD/2 CNC without having to exchange any body parts or even cash! :-)

I always use the CNC to drill the holes first and then use wet etching for the tracks. It gives a much better result and is more economical.

[bear]

My experience with tungsten carbide bits for PCB drilling is that they don't like any runout in the drill or chuck. A "precision drill" is likely ideal, but expensive. I have gotten away with a lot of slop (relatively a lot) by putting the shank of the PCB drill (which is typically 0.125" here in the USA) inside a bit of "spaghetti" tubing or heatshrink, then chucking that. This provides a degree of flex that the carbide itself does not. It won't keep the drill from shattering if too much down pressure is applied, but it does extend the life.

Myself, I have given up on the possibility of drilling my own PCBs. The only way I could see doing it is with either a mechanical downfeed of some sort (at the right rate) or else a CNC rig. I'd love to go with a CNC rig. These days they are not that pricey, but I'm unclear on how you can get the XY points into the code unless you do the layout with Gerber or "G code" in the first place?? Maybe someone can comment on that... but as the poster up a few said, there is software that can be set up to do precisely this.

Also I've seen some CNCs set up to actually cut the PCB and not etch it at all!

I'm skeptical on the Dremel, but maybe there are some models that do a good job in the stand... John I'm impressed and amazed that you have drilled holes hand held, even with HSS bits... not a job I want to do (having tried and experimented with that!).

_-_-bear

[db!]

I've been (freehand)drilling homemade PCBs with a dremel for years and I have yet to encounter any problems. From my experiences, bits usually break because of poor technique (pressing too hard) and/or improper "drilling backstop".

When drilling, let the speed do the work, put as little pressure as possible on the bit; this may take longer but will greatly prolong the life of the bit.

Also, do not use plywood or scrap wood as a drilling backstop, the change in density (after you've drilled through the PCB) likes to snap the bit; I recommend using a piece of MDF as a backstop.

[MJL21193]

Originally Posted by bear

John I'm impressed and amazed that you have drilled holes hand held, even with HSS bits...

I've drilled literally thousands:

NPX_01120.JPG

Hundreds at a sitting. It doesn't take long either.

My bits:

NPX_01143.JPG

The 1/64" has been sharpened dozens of times. Done by hand, with the Dremel as well. Being able to sharpen the bits is key to using HSS.