Drilling 0.8mm Brass 1

[var10]

Hello All,

I have to drill a 0.33mm hole through a 0.8mm thick sheet of Brass. Any suggestions on how to do it. I have basically tried it with a 0.4mm 118deg angle high speed steel. Not even a noticeable scratch. Also tried it with 0.5mm and 0.6mm bits. Its a higly tedious process to go through the brass. I am using a dremmel with an attachment to centre it. Any advices on what drill bit material or angle that i should use to drill this size hole? Its a standard so I have to drill a 0.33mm through a 0.81mm sheet. Have already spoken to few suppliers, most don't want to do this and some have quote crazy prices for obvious reason. Leaves me with no option but to do it myself.



Thanks,

V.

 

[MikeHalloran]

These should work:

http://drillbitsunlimited.com/012-83-030mm-Solid-Carbide-Drill-Bits-P2372650.aspx

Call to verify that they are 1/8" shank, which should fit the Dremel tool.

Also buy the Dremel drill press accessory.


Mike Halloran
Pembroke Pines, FL, USA

 

[racookpe1978]

Dremel is an extremely high speed tool: 13,000 rpm+ (depending on the model, some go to 25,000 rpm)

That thin a brass needing very small holes can be easily drilled (almost by hand if only a limited number of holes) at a very slow speed and only modest pressure. Mark your hole location precisely FIRST with a metal ruler and scribe, then use an awl (not even a hammer) to pin-prick it.

A marker pen is not accurate enough. Unless you don't care where the hole will end up at.

 

[var10]

Thanks Mike.

@racookpe1978 so do you suggest using a hand drill instead of a dremmel? Any drill bit material should be fine I guess?

 

[MikeHalloran]

Actually, either way will work.

A spiral drill from a hobby shop will work nicely, and go through in a couple of minutes, probably less.

The carbide drills I referenced are intended for drilling copper at ~30,000 rpm. They should work fine in the Dremel at its maximum speed, even Ludicrous speed. Chips will literally fly out of the hole, so wear safety glasses.




Mike Halloran
Pembroke Pines, FL, USA

 

[var10]

Thank you Mike. I just tried drilling it with a 5mm bit and it was still a little bit hard I would say. May be its my bits or its the composition of copper and zinc? Should I ask for a softer grade Brass sheet or does brass sheets come in only one grade?

 

[MikeHalloran]

Brass 'grabs' any tool with much 'positive rake'.

The PC drills are probably straight fluted, which means zero rake, or a very slow spiral, which means not much rake.

Ordinary twist drills can be 'dubbed' with a small hand stone. It means putting a small or microscopic flat on the cutting edge, effectively taking out all the twist at the edge, so the edge scrapes the brass rather than biting into it. To do it, you stroke the stone parallel to the drill axis, inside the flute. You do not touch the conical surface at the end of the drill where a bit is ordinarily sharpened; you are turning the last 0.00x mm of the spiral flute into a straight flute.




Mike Halloran
Pembroke Pines, FL, USA

 

[dgallup]

What kind of brass are you using? A free machining grade of brass should be ridiculously easy to drill.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[btrueblood]

Take a look at the Guhring catalog, they offer a variety of micro drill bits sizes/shapes/materials, and likely have one with the modifications Mike suggests in stock. Of course, finding a local dealer for them may be difficult, depending on where you are...try mscdirect.com

 

[MintJulep]

Don't drill.

Punch.

 

[MikeHalloran]

Mint, OP is asking for .013" hole through .031" stock.
Punching it might be possible in brass, but it will require good fixturing.
... and I get the impression that the OP wants some kind of 'precision' hole, whatever that means, so the die break might be a problem.



Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

Ah, I didn't catch mm units of diameter.

 

[var10]

Thanks guys. The grade of brass that is available in 0.81mm thickness from our local suppliers is 70cu 30Zinc and its comes in 1/2 hard form. I asked if we could get sheets that are not hardened but the suppliers recon in this thickness we might not get it. I have even tried drilling a 0.5mm hole but it still snaps (with fast and slow speeds). The smallest I could drill so far was a 1mm hole few times without breaking the drill.


Regards,

V.

 

[MikeHalloran]

You don't want softer brass.

Mike Halloran
Pembroke Pines, FL, USA

 

[var10]

But it barely makes a scratch with 1/2 hard one. I was under the impression it should be very easy to cut and drill brass. (I do agree my requirement is a bit crazy but still). All the bits keep breaking. I am going to try your suggestion Mike.

 

[btrueblood]

Micro drilling is an art. IF you are planning to do this on a production basis, I would suggest you contact National Jet in Maryland, they are the experts.

If this is a one time R+D project, then I suggest you invest in a toolmaker's microscope, so you can watch the drill bit as you go. The slightest excess pressure on the drill, or the slightest misalignment of chuck and hole center (spinout) will cause the bit to bow, and then snap. Doing this with a hand drill instead of a drill press is a futile effort, in my opinion, see Mike's first post and the caution on the website link he gave, namely: "Smaller bits are best used in a drill press / CNC Spindle to minimize risk of breakage". Ideally, I would use a milling machine, so that the advance of the drill could be controlled to very fine/slow increments.

And I would still expect to break about 1 bit per dozen holes or so...on a good day...before drinking 3rd cup of coffee...

 

[dgallup]

Can you EDM or laser the hole? We do millions of holes in that size range a year but we don't drill any of them. Usually in thinner stock and never brass. We don't do outside work but we send some low volume stuff to these guys:

http://www.microedm.com/

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[GClegg]

Do you have the material hardness ?

What do the chips come of like

If you can advise i can make some suggestions for the correct type of drill

If you have vibration or a poor set with the Dremel don`t use carbide

 

[var10]

Dgallup - the standard says it has to be Brass. It is very expensive to machine it from someone else. This is just an R&D thing that I need to do myself.

Gclegg - I know its 70cu - 30 zinc. and its half hardened.