Drilling hard steel.

[discomark10]

Morning chaps,

I picked a lt230 to refurb, lovely condion.. just needs a few revisions such as a sleaved housing for the center shaft and a drilled input gear.

I like some would rather pay for tools to do it myself that to pay for others to do it for me.

Been looking at drills for hard steel and found that "Tungsten Carbide" seems to be the way to go.
I've seen that the Tungsten carbide tipped masonry drills work but are blunt.
also seen that you can get proper metal tungsten carbide tipped drills, not sure if these are coated or braised on like the masonry type.

Had a go with a diamond drill, it worked well for a bit, untill the coating come off.

If anyone has any input/ ideas feel free to share

Cheers

 

[Trewey]

I use Cobalt bits.
Seem to work well.
Diamond isn't really for steel - gets too hot.

 

[pressbrake]

Tungsten is the way to go with hard stuff. stellite drills work well but need plenty of horsepower and seem hard to find these days.
If you get a green grit stone on a bench grinder you can regrind tungsten masonry drills to cut steel, though if you want to hold tolerance go to your local engineers supplies and buy some proper for steel tungsten drill bits

 

[MrNasty]

I have a friend that just used some tungsten masonry bits to drill out two head bolts from a Porsche 911 head, I believe he said he carefully put an edge on the bits. Never heard of it before, using masonry bits on steel.

 

[boguing]

Had a go with a diamond drill, it worked well for a bit, until the coating come off.Cheers

Were you cooling it with cutting fluid?

 

[discomark10]

Well I've ordered some tungsten carbide tipped drills from the bay of the e.
I'll update with results.

cheers for thr input!

Were you cooling it with cutting fluid?

No, it was only a preliminary test to see if I could get anywhere.
When I drill it properly with the new drills ill use flood collant.

I think some of the issue is there is no way to clear the chips/shavings effectively as its not got a spiral or anything.

 

[discomark10]

Tungsten is the way to go with hard stuff. stellite drills work well but need plenty of horsepower and seem hard to find these days.
If you get a green grit stone on a bench grinder you can regrind tungsten masonry drills to cut steel, though if you want to hold tolerance go to your local engineers supplies and buy some proper for steel tungsten drill bits

To be honest a masonry bit was my next choice.
Stellite is rare stuf. Picked up a piece for the lathe the other day

 

[waldershelf]

Some time ago I bought some DeWalt Extreme drill bits to do a job I was struggling with using normal HSS and Cobalt bits, very impressed.

 

[Brown]

You can do some quite impressive things with masonry bits once they've been re ground to a sharp edge with a green grit wheel. I've drilled holes in files, for example. You have to treat the masonry drill as a sacrificial item though as it is usually not the same again!

 

[easye1]

You can do some quite impressive things with masonry bits once they've been re ground to a sharp edge with a green grit wheel. I've drilled holes in files, for example. You have to treat the masonry drill as a sacrificial item though as it is usually not the same again!

you need a very very fine green grit wheel too.
at work, we either had our drills sharpened in the machine, or just used our wet diamond lap machine.
used to drill all sorts of very hard stuff at work but we used solid carbide or lesser types..
take note of the way you should grind them though as there not ground the way normal drill bits are...google is your friend.
word of caution, use a good cutting coolant in a constant running - like a top water effect,
and the harder the drill bit the easier to snap them..
they wont take any bloody type of sideways movement or "snap" goes your expensive drill bit..


If its only one hole you need drilling - local jobbing engineers always first choice is my advice....

I do still have a few cobalt / carbide/ tungston drill bits left in my snapon box after 40 or so years in the trade, but even I can snap a very hard/tough drill bit unless its all done "profesionaly"
laying on the floor or working with a hand drill on a bench seeks disaster..
WEAR BLOODY EYE PROTECTION TOO......

good luck.

 

[discomark10]

I plan to use flood coolant on the mill, I need to grind a flat/dimple to start as a punch wouldn't touch it!
I want to give it a bash myself if I can, but I know a local machinist which can do it if not.

 

[Thor1950]

I plan to use flood coolant on the mill, I need to grind a flat/dimple to start as a punch wouldn't touch it!
I want to give it a bash myself if I can, but I know a local machinist which can do it if not.

what are you drilling?

 

[discomark10]

I picked a lt230 to refurb, lovely condion.. just needs a few revisions such as a sleaved housing for the center shaft and a drilled input gear.

as per the 1st post

 

[discomark10]

look what mr post man brought me...

 

[Brown]

Drilled any holes with it yet? How does it perform?

 

[easye1]

look what mr post man brought me...

nice..
use coolant and patience but dont let it dwell either...


off subject - dwelling drilling action (peckin) on magnesium on cnc machining centres cause nice fires without coolant...trust me they doo,
as does titainium fine swarf with hard pushed milling cutters using horrid cancer causing neat cutting fluid....yuk stuff - hated it..

 

[discomark10]

Won't get a chance to test it out until the weekend. Might even do a lil vid
By dwelling I assume you mean just letting it sit there and drill without any real pressure?

 

[gemsdad]

Won't get a chance to test it out until the weekend. Might even do a lil vid
By dwelling I assume you mean just letting it sit there and drill without any real pressure?

yes,otherwise you will get heat/friction build up,it will dull the cutting edge.

 

[easye1]

yes,otherwise you will get heat/friction build up,it will dull the cutting edge.

you know eh......
dont do pictures, but some of my drill bits have a cross cut either side of the "flat centre" part of the drill point for use on very hard materials..
think it reduces the friction areas/ allows more coolant/lubricant access to point of cutting areas..

something like this
How to sharpen cobalt drill bits | eHow UK

how to resharpen cobalt drills - Searchya - Search Results Yahoo Search Results

 

[Thor1950]

you know eh......
dont do pictures, but some of my drill bits have a cross cut either side of the "flat centre" part of the drill point for use on very hard materials..
think it reduces the friction areas/ allows more coolant/lubricant access to point of cutting areas..

something like this
How to sharpen cobalt drill bits | eHow UK

how to resharpen cobalt drills - Searchya - Search Results Yahoo Search Results

more like this I would think.......http://g-ecx.images-amazon.com/images/G/01/th/aplus/affinitytools/tormek-DBS-22-3.jpg

And a pilot hole helps. Most drill bits get killed from to fast of speed (RPM's)