Newbie- drilling with small dia drills

[cruiser1]

Need to drill brass with a # 75 drill bit- what speed do you recomend
do i peck at it - should i get cobalt bits - flood coolant?- any tricks to this
before i ruin anything?

 

[Tin Falcon]

run it fast like 30,000 rpm or as fast as your machine will allow.
yes peck, coolant will help. no need for cobalt on brass.
Tin

 

[prof65]

Brass needs very sharp tools, so if piece is "critical" use a new drill bit.

Roberto

 

[Sshire]

Be careful at breakthrough. Brass grabs. I've been working almost exclusively with brass on my Epicyclic engine build and I started using a diamond file to knock the edge of the bit. That helped, although if the piece is held in a vise or clamped correctly, sharp bits haven't given me any problem.

 

[cruiser1]

Thanks - wish me luck - the smallest i have delt with is a #43 - i have 8 hrs
in the part already - already bought some ALUM- and a rope to hang myself
just in case

 

[Aydelott]

ive never seen a machine that can run 30,000 rpms what do you have Tin ? if you have a smart phone there apps you can get to calculate feeds an speeds i machinist, journeyman machinist, if not Google it there are a few formulas for it i would give them to you but there at the shop

 

[Maryak]

3 x drill dia = depth of cut before the flutes must be cleared. The smaller the drill the shallower the depth between cleans.

Best Regards
Bob

 

[Tin Falcon]

I used the data and calculator on the LMS site.
http://littlemachineshop.com/Reference/CuttingSpeeds.php
#75 bit =.021 sfpm 160 those numbers come out to 290102.
I think I plugged in the size of a 76 yesterday . like you said most machines will not go that High . my x-2 with pulleys get up there pretty well have not clocked it.
I would put my dremel tool in the dremel drill press adapter a dremel goes to 35000rpm .
Tin

 

[jtrout13]

How deep is the hole? You might want to use a "sensitive drill attachment" which makes it a lot easier. Check out Little Machine Shop # 3790. There are much cheaper alternatives out there but that's the idea behind it.

 

[Ed T]

As stated above, spin it as fast as you can otherwise the surface speed of the bit is too slow to do much. The most likely cause of a broken bit is that the chips got stuck in the hole so, yes, peck and don't try to cheat; just do it. In my experience Dremel tools don't have wonderful bearings, so if the hole size is real important, I'd not go that way. Buy several drills. In a previous life we found that some of the tiny ones look like drills but don't actually cut. Also it's likely you will break one or two. Since you have a lot of time in the part already, I'd be inclined to learn how to use the tiny drills on a test piece before doing it for real. In fact, I find that learning how to do a new process is almost always worth doing on a trial piece to get down the learning curve a bit before trying it for real. A Dumore high speed, precision drill would be a great tool for this, but a bit spendy for just a few holes.
Good luck!!