Re: drilling steel [TANKS]

["Marc en Wendy" <marcmethorst-at-zonnet.nl>]

Amir wrote:

> Whats the right way to drill steel?  Fast/Slow with/without oil? (if so 
> what kind of oil?)

Slow with oil. There is special oil available for drilling and tapping 
thread, but actually any oil that can act as a lubrication/cooling fluid 
will do.

Generally the right rpm for carbon steel is 10000 / drill diameter in 
millimeters and 5000 / drill Ø for stainless. Since DIY hand drills don't 
show the rpm's you have to guesstimate. So: the bigger the drill size, the 
lower the rpm's.
Roughly you could say that drilling a 10 mm hole you should be able to still 
recognize the cutting sides of the drill while it revolves. That should be 
about the right speed. I hope my Anglo-Dutch grammar makes sense ...

Also make sure you put enough force on the drill. Too little force and the 
drill won't cut into the steel, only producing friction => heat => a molten 
drill tip. Especially when drilling stainless!

> I picked up a set of dewalt bits that list steel as a material they drill, 
> but don't know what its made of.

Since it's DeWalt, it should be OK no matter what material it's made of. If 
it says it drills metal, it will.

> I need to get a 5/8" bit to bore out a sprocket and didn't want to spend 
> $20 for 1 bit in a store.

5/8 " is about 15 mm. I'd drill in steps, drilling a 5 mm hole first, then a 
10 and then the desired diameter (please convert to inches for your 
convenience ;-)
Make sure to punch a small dent in the metal on the spot you want your hole 
to be. If you don't, the drill will wander all over the workpiece surface.

> Would this work: (ebay item 7548244809)
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7548244809
> It claims to drill steel, but I wanted to make sure.

It will drill steel, but the drill has a morse taper shank which is only 
suitable for column drills or whatever you call these huge workshop drill 
machines. Come to think of it, most electric hand drills don't accept drills 
bigger than a 13 mm diameter (again, convert to ''). So you might need to 
look for a professional workshop drill that accepts these taper shanks.

Hope this helps!

Regards,

Marc
Holland