Cobalt drills for Hardox 450 3.2mm

[Ianshock]

Anybody recommend with 1st hand experience 6mm cobalt drills off ebay ?
6 good quality HSS drills knack'd (I thought they were good anyway - Axminster tools) 1 large tin WD40 drilling just 12 holes. 8 more to go and run out of drills ! Slowest speed on pillar drill - not over doing it, plenty of coolant and plenty of swearing !
HELP !!! Should I go with a smaller hole 1st ? (tried that with 1 brand new 4mm and didnt last 1 hole)
Cheers, Ian

[calumco]

hey, i'd say just get some propper cobalt drill bits from screwfix or something. i've had no problems drilling hardox with those and they are still fine

i just used plenty of wd40 and took it nice n slow

[typhoon_driver]

Yeah I'm not surprised your HSS drills bit the bullet with hardox. Buy a decent set of cobalt bits, I got the silverline set and i've been using them for a couple years with only a couple of sharpenings.

Also forget using WD40. You'll spend an absolute fortune on it and its not the best thing for removing heat. Buy a litre bottle of coolant from chronos,

http://www.chronos.ltd.uk/acatalog/Chro ... c_124.html

It's water soluable so you put a shot of it in a half litre of water and it mixes to give an oily water mix which is ideal for drilling, lathe work, milling etc etc. Again I bought a litre bottle around 3 years ago, even using it for hour after hour on my lathe and pillar drill, I've still only used 500ml. O and if you throw a tray under where you work, you can catch it and re-use it.

[widow_twanky]

Ian,

For what it's worth you can get some reasonable quality cobalt drills on ebay. I just bought a bunch of 10 6mm drills and used them until they got blunt, that said, dry theyll do about four holes. I don't do that many so i just buy a load and treat them as a bit disposable and they'll last me six months. You can get a set of ten for about ten pounds and it's cheaper than buying a full set of sizes you wont use.

I tend to go straight in with a 6mm and then open it up with a bigger drill if necessary. Never got the smaller drills to work either. Speed setting of 300rpm is good too.

One thing which really kills the drills is breaking through the other side of the hardox. Tried it with wood underneath but it may well be that clamping a bit of hardox underneath would make it smoother to break through as it'd just see a single piece.

Not the best engineering approach and not one for people who like to look after their tools etc etc. It does leave you with loads of 6mm drills which are perfectly good for using on mild steel and ali as well.

[Ianshock]

Cheers guys....gonna try the cobalts from UK Drills off ebay and get some of that coolant Gary recomended.....been after some for a while just didnt want to buy 5litres ! Will take it nice and sloooowwww. First time used hardox and I thought drilling Ti was challenging - knew it wouldnt be easy and was prepared but not quite as hard as this !

Of course my engineering consultant is at Uni now...so nobody to tell me where I am going wrong - heh Will !

Thanks Ian
PS Team Shock and Team Toon had about 1.5 seconds of airtime right at the end on the gadget show...(nice shirts !)

[typhoon_driver]

i find titanium a bigger pain to drill than hardox. Titanium feels soft and wants to stick to the drill bit whereas hardox feels, well, harder, comes off in nice clean sections.

[terry]

Ive had loads of problems drilling hardox and only had wd40 as coolant and cobalt bits, ive found you get about half way through and then it just dont want to go anymore,I have found that if you put a mig weld blob behind where you are trying to drill through untill there is a large orange hot spot mark then continue drilling it seems to go through , well it has helped me ! must make the metal abit softer for a little while or something.

[typhoon_driver]

sharp cobalt drill bits, coolant and a slow speed with a gentle pressure, goes clean through everytime

[Ianshock]

10 x 6mm cobalt from UK drills + 1 bottle of coolant (thanks Gary !), + 1 slow mini mill as pillar drill = 10 holes, 1 drill still sharp as new + 1 happy customer......maybe the pillar drill might be too fast but will try. Only thing that let me down was the oil can from poundland for the coolant - Will got more on his shoes than the drill bit !

cheers Ian.

[typhoon_driver]

I put mine in an old sports drinks bottle (powerade etc). Ideal as you can open it as wide or closed as you require