replacement for 0.8mm drill bits

[Mugshot]

i am currently into DIY stuff making PCBs but my friend (who is a tech and promised to help) told me that the 0.8mm drill bit we were to use was already broken.

im thinking of any temporary replacements that we can use which will work just as fine. any suggestions? thanks!

[R.G.]

You can use any drill bit up to 1.0mm on most PCBs.

I suggest you see if there is a local machine tool supplier who can sell you solid carbide drill bits in 0.8 to 1.0mm diameters. But only do this if you have a drill press. Carbide bits will invariably break if you try to use them in a hand held drill.

If all you can use is a hand-held drill, get high speed steel (HSS) drill bits in the same diameter. These will wear out after about 100 holes, but are more tolerant of the bending that hand held drills always cause.

Get two drill bits at least, because if you only have one and break it, you are stopped entirely - as you are now.

[Mugshot]

wow thanks! gotta check that tougher bit you suggested. and yes i dont have a drill press, only hand-held units.

"bless me lord with a steady hand and a watchfull eye,
so no drill bit shall break as i drill by.'' yikes!

[hday]

There's a trick I've used for wood working to drill perfect holes for finishing nails. You get two of the same small nail and cut the head off of one of them with some angle cutters. Put the nail in the drill and use the new flat, sharp end of the nail to drill a pilot for the finishing nail. It's not a super clean method, but it works really well for short depths. Just make sure that you drill a little bit, pull the nail out and clean the hole, then drill some more, then clean out the debris, etc.

But a carbide bit is probably the best choice. They make some awesome bits designed for a dremel. They have a weird diameter that makes them more prone to snapping, IMO. I like standard "tubular" bits. If you use a bit thats tubular, if you choke the chuck up on the bit so it's just deep enough to break through your board, you'll have less room for the bit to bend and snap. If it does break, it'll break at the end, and you can sometimes slide the bit out some more and reuse it.

[fixr1984]

I picked These up at Harbor Freight.
They fit in a rotary tool and drill fast and clean. You do have to be careful that you drill fairly straight as they will snap.

[R.G.]

I picked These up at Harbor Freight.
They fit in a rotary tool and drill fast and clean. You do have to be careful that you drill fairly straight as they will snap.

Those are great! However, they're only great if you have a drill press of some kind, even if it's a mini-press for a Dremel-style rotary tool. Otherwise, they'll just make you cry.

They all have 0.125"/3.175mm shanks, and are resharpened bits from a CNC drilling setup. CNC setups are so accurate when they spin that they actually dull carbide bits after several thousand holes. It's rare for a CNC spindle to break a carbide bit. My first batch of those, back in about 1996, I put into my hand-held dremel and promptly snapped every single one of a size for PCBs. I got maybe two-three holes each before breaking. You also have to spin them fast. 10,000 rpm is about the minimum speed to run carbide in the 1mm and smaller range. Running that fast, they cut such a fine chip that it's almost like drilling into air other than the load on the spindle to turn them. The big CNC setups run them at 30K to 50K rpm.

[German]

I remember one day, I extremelly needed to finish one project, but my PCB was not drilled.. And no..
I had nomore drill bits.. 

A little beer.. and..
My ideas - firstly I used a stain nails. Thay were about 1mm, dontt remember correct value..
Damn!! That was traumatic to my fingers and PCB.
I did some holes.. And get to another tricky thing.
I made a "burner" tool.
Same nail was connected to the power. So it get very-very hot and I just burned out those holes.
I made that one in about 1 hour.
And I made that project.

You can take a laser lense from an DVD-writer and make a new generation burner tool. 

[Andi]

It's rare for a CNC spindle to break a carbide bit.

On the other hand, it's far too far from rare for me to break them putting them into the machine, or putting the depth collars on, or forgetting to remove the float screw...

[R.G.]

On the other hand, it's far too far from rare for me to break them putting them into the machine, or putting the depth collars on, or forgetting to remove the float screw...

You do things like I do. 

[Mugshot]

what about using shorter drill bits to minimize breaking?

[R.G.]

Bad idea.

Think of what happens when you try to hold a drill still and drill into a board. Your hand has a fixed amount of wobble. Could be smaller, could be larger, depending on how relaxed you are, how skilled you are, how much coffee you had, but some amount of wobble. Think of this as a random side to side motion of the drill you're trying to hold still. The further away from the PCB your hand is (i.e. the longer the drill bit), the smaller the angle that your hand motions bend the drill bit. The closer you get to the PCB with the drill, the sharper the angle. When you get right to the PCB, even a tiny sideways motion is a 90 degree bend on a drill bit. So with a fixed sideways error, the longer the drill bit, the less flex angle it endures.

But of course, the harder it is to hit the pad center in the first place.   

I've actually seen steel drill bits work when they're noticeably bent as they drill. Carbide never bends. It simply snaps.

[Mugshot]

ah, so i see  gotta have enough patience and practice in this aspect. and the concrete illustration made me realize the bad thing, and helped me avoid any unpleasant circumstances that can happen. thanks.

[hday]

The only reason I suggested that is because I've used that technique when I've had several boards to drill and only one bit left. It's really terrible practice. I've got a steady hand but I snap so many bits by bumping the chuck on the vice, dropping my drill, and tons of other stupid reasons. I really shouldn't handle power tools. 

It works best when using a drill press, but if you're using a drill press you probably don't need to use this technique. Actually, there's probably no time you should ever try this. Just buy a bunch of bits. 

[Andi]

I had some 1mm Wolfcraft bits that seemed to keep on going and going through PCBs. Dunno what was special about them but they wouldn't snap and didn't seem to blunt. Probably made of magic.

[Mick Bailey]

0.8mm HSS drills can be resharpened and will cut cleanly on Glass-fibre PCBs. I use a magnifying glass on a stand and a cheap Dremel clone with a fine abrasive disk. This method works very well - you only need to grind flats on the drill bit for PCB work, the correct relief profile is too difficult to achieve by hand. Study a factory-fresh bit first to give an idea of the correct angles.

[JKowalski]

I've actually been using a sowing needle to drill my PCB holes!

It actually works well. I took a U channeled sowing needle (for a machine) that was around the house, broke off the tip and filed it to a slant. It cuts pretty well, and hasn't broken after 4-5 PCB's worth of drilling. I use a drill press, the sowing "bit" fits snugly and runs smooth, but I would not recommend using it with a hand drill XD

Obviously, id prefer a REAL bit, but im satisifed for now.

[Sody54]

I picked These up at Harbor Freight.
They fit in a rotary tool and drill fast and clean. You do have to be careful that you drill fairly straight as they will snap.

Those are great! However, they're only great if you have a drill press of some kind, even if it's a mini-press for a Dremel-style rotary tool. Otherwise, they'll just make you cry.

They all have 0.125"/3.175mm shanks, and are resharpened bits from a CNC drilling setup. CNC setups are so accurate when they spin that they actually dull carbide bits after several thousand holes. It's rare for a CNC spindle to break a carbide bit. My first batch of those, back in about 1996, I put into my hand-held dremel and promptly snapped every single one of a size for PCBs. I got maybe two-three holes each before breaking. You also have to spin them fast. 10,000 rpm is about the minimum speed to run carbide in the 1mm and smaller range. Running that fast, they cut such a fine chip that it's almost like drilling into air other than the load on the spindle to turn them. The big CNC setups run them at 30K to 50K rpm.

R.G....CNC's not breaking drills (or any tooling for that matter) depends a LOT on what caliber of monkey your company insists on hiring!  Speaking form 20yrs experience dealing with the various simian species.    I've got a couple now that I'm pretty sure can't spell their name the same twice in a row.  "But all all they have to do is load parts and push the start button.  I can pull anyone off the street and teach them to run a CNC" <---Upper management mentality.

Brian

[tranceracer]

A technique I use that minimizes broken drill bits is to keep the expose only about 1/8" of the bit, just enough to penetrate the PC board.  This will give it a little more strength and if it breaks, it only breaks of in small increments.  I just extend the unbroken part of the bit in 1/8" increments or so until all the bit is gone and change to another bit.

The sewing needle technique sounds interesting, I'll have to try that one on my next project!