TiggerToo
Well-Known Member
... what are they called?
Drill bit to cut stainless steel
- Thread starter TiggerToo
- Start date
bigwow
Well-Known Member
Cobolt
ctva
Well-Known Member
No idea, I just use HSS at a slow speed with pressure and a cutting fluid. Never been a problem.
pete
Well-Known Member
Cobalt, Hss. I have used both, just Sharp drill go slow and plenty of pressure if it ain't cutting stop immediately and sharpen or replace drill.
sailorman
Well-Known Member
Ditto
sharp n slow with lube does the biz
PS drill a 3mm pilot hole first to remove material from the centre of the larger bit
C08
Well-Known Member
An ordinary 700W drill may struggle to go slow enough to prevent work hardening stainless. Using a 1200W drill at slow speed has lots of torque and in my experience is much better if you have a few holes to drill or drilling thick stainless.
sailorman
Well-Known Member
battery drill on slow spd work well enough
Steve_N
Well-Known Member
If using Cobalt bits then take great care as you break through as they chip very easily.
nemodreams
Well-Known Member
Forget the battery drill -however large and powerful. Cheap pillar drill will eat it and not wreck the drill bit.
There is a special type of bit - its called 'new' - and - 'sharp' - and you need to step up in sizes so you need a set of 'good' bits - either hss or cobalt ( Chronos is your friend for bits ) Use cutting fluid.
There is a special type of bit - its called 'new' - and - 'sharp' - and you need to step up in sizes so you need a set of 'good' bits - either hss or cobalt ( Chronos is your friend for bits ) Use cutting fluid.
sailorman
Well-Known Member
I use both types of drill, a drill press is sometimes a job to get in small spaces.
i have yer to wreck a HSS bit on ss
NormanS
Well-Known Member
Sharp.
DanTribe
Well-Known Member
On a related subject, any tips on removing a broken off tap?
I couldn't remove a grub screw from a stainless steel rudder bearing collar, so I drilled it out and started to retap the thread [5mm]. All seemed OK until I started to retract the tap and it snapped. I've tried cobalt drills to no effect.
Best advice I've had is to grind it all flush, fill with epoxy and start again in a new spot.
I couldn't remove a grub screw from a stainless steel rudder bearing collar, so I drilled it out and started to retap the thread [5mm]. All seemed OK until I started to retract the tap and it snapped. I've tried cobalt drills to no effect.
Best advice I've had is to grind it all flush, fill with epoxy and start again in a new spot.
PaulRainbow
Well-Known Member
If it's possible to use a new spot, that may well be the best bet.
earlybird
Well-Known Member
You won't be able to drill a tap out. Either start again, as suggested or immerse in a strong acid for a while. Nitric won't hurt 300 series stainless steel.
lw395
Well-Known Member
I have seen things like this used:
http://www.sctools.com/master3.asp?classid=2022
Traditional answer is spark erosion. Or weld over it and start again.
http://www.sctools.com/master3.asp?classid=2022
Traditional answer is spark erosion. Or weld over it and start again.
KellysEye
Well-Known Member
>Cobolt
Agree, I tried a HSS drill bit on a half inch thick SS bar than ran around the edge of the top of the hull and it wouln't even dent it.
Agree, I tried a HSS drill bit on a half inch thick SS bar than ran around the edge of the top of the hull and it wouln't even dent it.
PaulRainbow
Well-Known Member
Must have been a blunt bit then. I've drilled a zillion holes in stainless with a decent, sharp, HSS bit. Most stainless fabricators that i know use HSS all day.
PowerSlapper
Well-Known Member
Pilot hole 1/8", sharp drill, lubrication, pressure, HHS or Cobalt, tip angle 135° not the standard 118° on jobber drills or standard hardware store drills. When drilling stainless steel the higher tip angle makes a tremendous difference. With Cobalt bits you can even go as high as 140° (standard on carbide bits)
lw395
Well-Known Member
I have had issues with HSS bits. Probably due to using stainsless that has been work hardened, or some odd flavour of stainless acquired as an 'offcut'.
Cobalt drill are better.
Carbide tile/glass drills also work.
A solid carbide burr or bit in a dremel will work where most things have failed.
Diamond burrs in a dremel are another option.
Sometimes you have to go beyond HSS when previous work has left you with a work-hardened piece of stainless to drill.
Burrs to fit a dremel can be had cheaply.
It's an option when you can't use a pillar drill.
Another tip, SDS drills have lots of power and torque at low RPM. A Chuck adapter is worth having IMHO.
OTOH, you can sharpen a carbide masonry bit to do stainless, using a diamond wheel in a dremel.
For stuff that I really care about, I take it to a man with a Bridgeport.
Cobalt drill are better.
Carbide tile/glass drills also work.
A solid carbide burr or bit in a dremel will work where most things have failed.
Diamond burrs in a dremel are another option.
Sometimes you have to go beyond HSS when previous work has left you with a work-hardened piece of stainless to drill.
Burrs to fit a dremel can be had cheaply.
It's an option when you can't use a pillar drill.
Another tip, SDS drills have lots of power and torque at low RPM. A Chuck adapter is worth having IMHO.
OTOH, you can sharpen a carbide masonry bit to do stainless, using a diamond wheel in a dremel.
For stuff that I really care about, I take it to a man with a Bridgeport.
DinghyMan
Well-Known Member
I work with all sorts of grades of metal including the mystery offcuts of unnown variety and use mainly HSS with lots of pressure and lots of lube, or cobalt because I have them for finish sizes, I do almost all drilling on the mill and if larger sizes are needed easiest way is to put a rotabroach cutter through them.
The "sharpen a masonary drill bit" tip is spot on if its hard stuff, I've got some expensive drills for stainless and I'm sure they are just masonary bits that have been put through a drill sharpener.
If you have a broken tap use Alum to disolve it, but only in non-ferrous: http://www.tap-die.com/contents/en-uk/d296_Tip_Remove_Broken_Tap_Drill_Reamer_Tap_and_Die_Co.html
