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Drill Bits for Metal

l008com

l008com

Limp Gawd
Joined
Jun 20, 2002
Messages
374
I'm building a custom 7 bay optical drive tower. I have all the metal I need, and I even bought a rivet gun. It worked great for the first two holes I drilled. After that, the drill bit I was using wasn't going to drill another hole. I assume it was just a wood bit anyway. When I try to drill holes with it, it will barely scratch the surface, but will get so hot from rubbing that it will actually glow bright red. What should I use to put small diameter holes in sheet metal cases? Some special drill bits perhaps, made of some other material?
 
Buy at least high-speed steel bits (HSS). Drill at slower speeds (1000rpm max IMO, preferably slower.) Apply enough pressure. Use cutting fluid/oil too.

There's only so much smoke in a drill bit. If you let it all out at once, the bit's finished. :D
 
I used a 35K one once. I didn't like it, its bad enough when bits crack and explode. At 35K bits will often explode with no warning.
 
I guess i should check my facts before I speak. I just walked over and checked and mine is actually a 35K single speed one. I don't know why i thought it was 15K. But yeah 35K, if 1K is the recommended speed for drilling, I can see why my bits glow :)
 
35k RPMs?? Nah, you don't need to get a different type bit, just reduce your RPMs significantly. No wonder it got hot! You were trying real hard to let all the smoke out at once weren't you? ;)

Since you were drilling pop rivet holes can I assume you were using a 1/8" bit?

Machinist here - just checked my handy dandy "speeds and feeds" tables. The specified RPM for a HSS 1/8" drill bit in mild steel = 3,056 RPMs ... 917 RPM for 1/8" carbon steel bits. Aluminum = 9,170 RPM and 4,585 RPM respectively.

And by the way. You may as well throw out that drill bit now. Once they get that hot they will never hold the same edge again.

Here are a few tips which may help in future :
Always watch the color & shape of your chips coming from the cutter. They are your indication of what is going on. Ideally you want very little discoloration of the chips. Brown means too hot - blue is way too hot - glowing and/or sparks means you are burning metal. This can be remedied by any or all of the following. Back off on the feed pressure, use more cutting oil, slow the RPM's, get a sharper bit/cutter.

Hope that helps.
 
First off DO NOT USE A DREMEL TO DRILL!!!

I can't even remember how many people i have told this to. Dremels are not designed to drill through things and as such have VERY little torque in order to grind through the metal. Make sure you use an actual drill that looks like a gun to drill through metal. It tears bits up far more slowely and actually goes through the metal faster than a dremel would at a higher speed.

As for bits, the best ones i have found are the diamond tipped kind. They are what i use now since I tore apart my last set drilling through 1/8" Cast Iron for a project I was doing :D

But yea, you can use regular Steel bits, just not with a dremel.
 
Well said. Dremels and similar tools rely on high RPMs not torque.

Diamond tipped bit are generally for working with ceramics and tile. Waste of money & tooling to use them on mild steel & aluminum IMO.

You shouldn't be using any drill bits with a Dremel. Not unless you can get the speed down to a usable level.

The fact is most people use RPM much too high for the bit they are using.
As above, the industry standard is 917 RPM for a 1/8" carbon steel bit (which is what many will have) in mild steel. Consider that the RPM required drops as the bit/cutter rises in diameter. For instance, double the bit diameter to 1/4" and you need less then half the speed = 458 RPM. Double the bit diameter again to 1/2" and you need 229 RPM (764 RPM for HSS bit in mild steel).

Given that you can easily see how a Dremel does not have the speed range required for these types of operations = drilling.
 
Also, a good rule of thumb I learned a long time ago, the faster you drill, the less pressure you put on the drill bit.......conversely, the slower you drill, the more pressure you can put on the bit. If you're stuck with only using a 35K rpm dremel to drill (and I really hope you're not, and have at least one friend who will loan you a drill for a couple days), use VERY light pressure, and LOTS of cooling!

Good luck with your project! :)
 
Its too bad dremel doesn't make some sort of cheap disposable drilling sticks, something long the same lines as the cutting wheels. i'll get some new bits and a drill and try again.I'll post pics too. The drives are all in real nice, i'm just trying to mount some fans and all the inside electronics so its not such a mess to use.

Thanks
 
Where did you get your rivet gun and how much did it cost? I have been debating building a custom case for some time now and i always thought it sorta impractical so i was thinking of the P180. But if i can get a rivet gun for relatively cheap, that would make life easier and maybe worth a shot at the case.
 
kill4killin said:
Where did you get your rivet gun and how much did it cost? I have been debating building a custom case for some time now and i always thought it sorta impractical so i was thinking of the P180. But if i can get a rivet gun for relatively cheap, that would make life easier and maybe worth a shot at the case.
Click to expand...

Here is a list of parts that I would suggest :

Rivet gun = $7 ~ http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=7356

1,000 1/8" dia. rivets of 4 different lengths = $10 ~ http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34080

3/8" variable speed reversable drill = $20 ~ http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=3670
~ (cheap but not necessarily the best choice - see next post)

10 pack of 1/8" dia HSS TiN coated drill bits = $3 ~ http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93079
 
please don't use power tools from harborfreight. a corded drill from sears, home depot, lowes isnt going to cost you much, maybe 50 or 60 but they're going to be quality and they're going to last. i've got a dewalt for like 8 years now and its still going strong. and thats with throwing it around and not having it covered in my garage. tried to replace it with 2 cordless drills but nothing will beat its power. just put some money into something that will last.
 
Would have to agree with you on the drill. I'd say the Harbor freight is OK for a few small jobs. Many PC modders will fall into this catagory. But if you want a workhorse definitely get a better drill as sn_85 suggested.

I posted the one above mostly because it was cheap, and available from the same vendor as the other items. That drill has a "keyless" chuck. Some prefer them but I think a keyed chuck is a MUCH better choice. Then again such drills will be a lot more expensive. Depends on your intended use.
 
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