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Drilling cases and PCBs

post #1 of 25
Thread Starter 
=================
This thread is split off from a runaway thread that hsnam started over here:
http://www.head-fi.org/forums/showth...&threadid=3313

-Apheared
=================


hsnam,

buying a Dremel will change your opinion on drilling PCBs. From a horrible 4-hour chore, it became 10-minute fun. And no, I'm not exaggerating either number...
post #2 of 25
oh no, i had used a dremel to drill all the holes, i took about 10-15 min to drill that board, as you point out.

the only problem was that drilling ruined all my drill bits ($$$) (pcb was fiberglass or somethng and the drill was steel something from digikey).

what drill bit do you recommend for drilling pcbs (that will last for more than 30 holes)?
post #3 of 25
Drilling holes in a PCB will not hurt a bit much. Drilling a steel case is another story. Steel cases ruin your DIY fun. There must be a better way. My tube amp is sitting there waiting for some cabinet work but luckily a guitar amp building friend did use his punches to make the tube holes. I'd try to find some easier to work steel cases myself. Some are hardened to stop flexibility, and are a nightmare to drill.
Dan
post #4 of 25
Quote:
Originally posted by hsnam
oh no, i had used a dremel to drill all the holes, i took about 10-15 min to drill that board, as you point out.

the only problem was that drilling ruined all my drill bits ($$$) (pcb was fiberglass or somethng and the drill was steel something from digikey).

what drill bit do you recommend for drilling pcbs (that will last for more than 30 holes)?
I find that a full size bench drill is much easier to use than a Dremel type tool. I use mine for everything from pcb drilling to making holes in steel chassis. They're cheap too - cheaper to buy a whole new bench drill than a bench stand for my Dremel!

Fibreglass boards do wear bits out quite quickly, but I expect to get a few hundreds of holes from a HSS bit. Tungsten carbide bits last longer, but break more easily, so are best used in a stand.

Does the speed affect the wear rate? I find 2200 rpm is about right for a 0.8mm bit. Dremels can go much faster than this, so perhaps you need to turn the speed down a bit?

Also, look out for reground tungsten carbide bits, which are slightly cheaper than new ones. They can't reuse sharpened bits in CNC drilling machines because they're too short, so they sell them for use in manual drills where they work perfectly well.

Steve.
post #5 of 25
Thread Starter 
I use Dremel with verticall press stand, which makes the job much easier, and probably less likely to break as well. As SMorphet pointed out, you can drill holes just fine at slow speeds and that would probably prolong life of your drillbits. Not to mention reduce the noise by a large factor.

I don't know if a full size bench drill can accomodate tiny drillbits we use. I have a normal drill as well and I had to wrap drillbits in something to get them big enough for drill fasteners to hold on to. If you can find one that can accepts small ones, it'd be a good choice. Dremels are very expensive .
post #6 of 25
SMorphet, how fast do your HSS Dremel bits wear out when working with steel? I've worn down one of my completely new bits only trying to enlarge one hole in a steel case to be large enough for a 1/4" headphones jack. How easily, or not easily, to the tungsten carbides work on steel cases?
post #7 of 25
Quote:
Originally posted by aos
I don't know if a full size bench drill can accomodate tiny drillbits we use. I have a normal drill as well and I had to wrap drillbits in something to get them big enough for drill fasteners to hold on to. If you can find one that can accepts small ones, it'd be a good choice. Dremels are very expensive .
My bench drill uses an ordinary three jaw chuck with a 13mm capacity. It will hold a 1mm straight shank bit perfectly well, although you do have to be quite careful to make sure that it's lined up straight. That's easy to do - just run the drill slowly and watch for 'wobble'. You can also buy 'thick shank' bits, where the bit is 3-4mm diameter where it goes in the chuck and tapers to the appropriate diameter at the tip. These are less flexible than straight bits, so they break more easily, but they're easier to mount straight in a big chuck and I prefer them for 1mm and smaller sizes.

Quote:
Originally posted by Possum
SMorphet, how fast do your HSS Dremel bits wear out when working with steel? I've worn down one of my completely new bits only trying to enlarge one hole in a steel case to be large enough for a 1/4" headphones jack. How easily, or not easily, to the tungsten carbides work on steel cases?
I don't know. I prefer to use the bench drill whenever I can. The bits I use for steel (and aluminium) cases are just ordinary HSS. It seems to be worth spending a little extra for 'premium' quality ones, but I don't think there would be any advantage to using tungsten carbide. Tungsten carbide is great at withstanding wear from an abrasive workpiece, like fibreglass PCB boards, or masonry, but I don't think it's necessary for metals.

I've been using an 11mm bit for the jack sockets that I use. It's a Black & Decker 'Bullet' bit, which is designed for metal and doesn't need a pilot hole (just a punch mark). The trick is to go slow - about 450 rpm for this diameter in steel, and feed slowly - don't try to force the bit through the workpiece. I've done about 300 holes with this one bit, building patchbays, 1mm steel on the backs, 3mm aluminium on the front, and it's only just beginning to feel a bit old. It can help to use a cutting lubricant, messy, but it cools the bit and prolongs its life. It's particularly helpful for aluminium which is soft and doesn't have much lubrication of its own, and so tends to squeal.

If you're enlarging an existing hole then a drill may not even be the right tool. Enlarging from, say, 10mm to 12mm with a drill would be really difficult unless you have the appropriate vices and jigs to keep everything aligned. I'd prefer to use a file, or a hand-held reamer.

I'm sure you can't fit bits of this sort of size into a Dremel, so I wonder what you're trying to do? Are you drilling lots of little holes around the circumference? If so, then you're making life very difficult for yourself, but I wouldn't expect a good quality bit to wear out particularly fast. For, say, 2mm holes in steel, use about 1800 rpm, and make sure you drill straight down. If the bit starts sliding into adjacent holes, or if you push it sideways and try to use it as a router, then you'll break or wear the bits very quickly.

Of course, at jack socket sizes and above you should also be considering punches. You can get clean holes in really large sizes, and you can even do non-round holes - great for BNC connectors, etc. The disadvantage of punches is that you still have to drill a smaller hole, and screw all the fiddly bits together, so it can be quite slow.

Steve.
post #8 of 25
Hmm, maybe I should just get a circular file, one that increases very gradually in diameter (shaped like what jewelers use to measure ring size). After that, the only odd shaped hole I'll have to make is for an IEC power jack. That was my original intention for the hole in my Szekeres' steel case that ended up being the headphone jack hole
post #9 of 25
Well, that and the fact that punches are ludicrously expensive... Some of those manual greenlee punches are $150 EACH... how many drill bits is that? (plus a drill press or even a dremel and vertical stand cause yes, they ARE more expensive than a normal drill press)

Watch those pilot bits. they walk more than a normal bit if you don't have a punch guide or some indent... and sometimes, when you're widening a hole already there, they won't sit centered because of that stupid pilot tip... I love em for wood, but steel? Normal taper bits.

Also depends on you and your drilling volume. If you're just looking to drill out ONE of those KGilmore boards... doing it by holding the bit in your fingers and manually turning it while watching TV or something will work... once.

re: the resharpened PCB bits. Yea buddy! What a concept, right? cheap carbide drillbits in sets for what the CNC guys would pay per bit. Stubby, yea. But for a dremel? Drill away... Check places like alltronics and all electronics (yea, two separate companies) But even resorting to Mouser, things from like #50s thru those human hair #80s are a buck each... go slow!

Dremels are high speed... 10k, 15k, 30k?! for drilling with #72 into FR4 board? hehe. The good side: http://www.dremel.com/productdisplay...ay.asp?SKU=221 The bad side: it's like another $40.
post #10 of 25
I use a Dremel and the tiny little ball shaped bit when I do PC boards. It's about a mm in diameter, easy to start, and the perfect size for leads.

I've gotten about 12 boards out of one bit (drilling into RatShack boards) before it turns into a nub.

Unfortunately, drill bits (and Dremel bits) are consumables - they never last forever.

ok,
erix
post #11 of 25
Re: Irregular holes in cases.
If you already have a Dremel, get a milling-bit for it (preferably tungsten-carbide). that'll cut through aluminum, steel and PCB's like hot butter and it should last reasonably long, provided you don't use it at full speed (a Dremel runs at 25-30 kRpm AFAICR). (BTW - if you want to have ANY fun out of the finished amp, wear ear-protection while working )

I personally wouldn't like to use a standard-sized machine for drilling PCB's, but I suspect that could be matter of some personal preference. IMHO, you don't need to do a lot of DIY-stuff before a Dremel or a similar tool is completely indispensable.
(Note: If you live in Europe, buy Proxxon tools instead of dremel - waaaay better :-)

/Uffe
post #12 of 25
I use a Roper Whitney No. 5 Jr. Hand Punch:












http://www.lowbucktools.com/rw_punch.html










It works well for cases and I would think for pcb's as well since it has a range of hole sizes. Some chassis mounts (large headphone jacks, pots) are larger than 9/32" and I usually just punch one hole and punch around the edges until it fits. You don't really have to drill a smaller hole first. I usually just make an indentation with a screwdriver so I can place the pointed end of the punch correctly.



edit: better link:

http://www.roperwhitney.com/rwecom/num5shapes.asp
post #13 of 25
Thread Starter 
>wear ear-protection while working

No kidding! I use my Ety's as ultra-expensive earplugs when using Dremel...

Mr_happy: that looks like a very cool tool for not too much money!
post #14 of 25
Quote:
No kidding! I use my Ety's as ultra-expensive earplugs when using Dremel...
I guess that could be called an acceptable solution to the problem....


/Uffe
post #15 of 25
I had bought a fixed-speed Dremel, I think 10,000 rpm. Is it safe to use a lamp light taper to slow down the drill? I know Dremel sells speed pedal or whatever, but it's expensive. thanks
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