Drilling stainless pullpit

[dankilb]

I’ve been impressed with the cheap cobalts (Toolstation). They seem to rip through material inc. SS to my little-trained eye.

I can’t sharpen drill bits so just relegate them to spare/all-purpose use once they’ve had it.

Is there are reason not to use cobalt, or just not worth it vs HSS?

 

[Daverw]

I also tend to use the cobalt from tool station, in drill press no need for pilot hole for 14mm, on boat a few weeks ago did 10mm no issues and also 19mm with tungsten hole saw through 6mm thick, again easier than expecte.

option for OP could be mag drill atached to a section of steel channel stand on the channel to provide weight. They can be hired for not too much

 

[penfold]

No pilot for a 14mm drill is asking a lot of the chisel point, especially through stainless.

 

[Daverw]

The drill bit had the small lead point tip, not sure what it’s called

 

[Poignard]

The drill bit had the small lead point tip, not sure what it’s called

Do you mean a centre-drill?

 

[Daverw]

was one of these
DeWalt Hex Shank Cobalt HSS Drill Bits 12 x 151mm

 

[penfold]

Not sure what most of that is in aid of, other than rendering it impossible to sharpen; the point is a split point which does eliminate some of the friction of a chisel point but is also impossible to sharpen DIY.

 

[Daverw]

It did the 6 holes needed and then it went home to be used on easy stuff, i don’t bother sharpening drills often these days

 

[rotrax]

I am using good quality bits from the 70's.

I bought a couple of boxes from an engineer who was packing up - about 40lbs weight! Mostly imperial. All used, but in useable condition.

Takes but a moment to sharpen on my bid bench grinder, has saved me hundreds over the years.

The mechanics ALWAYS broke the small sizes, I bought those in bulk. Note - I also break small ones - easy to do!

Always HSS, never anything fancy. I have some of these gold coloured titanium coated ones, I use those for threading and boring on the lathe.

I had a failure recently, I needed to modify an old obsolete tool to use for another purpose.

It was hardened steel and even after grinding a patch it just would not cut.

 

[dankilb]

I do both admire and aspire towards the sharpening of decent quality drill bits and indeed anything that involves maintaining, re-purposing, recycling, modifying etc. of existing tools/stocks (rather than buying new/cheap/semi-disposable stuff again and again).

However, for me it’s a function of having to do ‘less with more’. A big part of which is living in a 2 bed flat! I’m lucky to have a small but usable bench in the ‘spare’ room, but grinder/wheel are out, as with anything too potentially messy. With the boat laid up and therefore her contents uninsured, tools are all over the place between a storage unit, various vehicles, and mine/mates’ homes!

That’s why being able to pick up - say - a new, cheap, cobalt bit on the day from the likes of Toolstation (now just up the road from the boat in N Wales, 50 miles from home) whenever you find your other one isn’t to hand, is an absolute godsend. Literally makes it possible for us to do what we’re doing now, refit-wise.

One day I’ll get the proper workshop - then then I’ll move from cheap to cherished tools! I may even dig out and sharpen up all those old cobalt bits I’ve bought (once they get dud in metal they make lovely, clean, holes in ply!).

But that’s major thread drift. As others have said, take it slow, with even pressure and some cutting lube - whether it’s with stepped or regular bits (pilot hole and up size) and whether they’re HSS or cobalt - and should be all good. ??

 

[reeac]

Simple tip from the man who drilled my pushpit in order to fit my own- design mini- davit: make sure that swarf is being produced all the time that you're drilling. If the drill bit skates over the surface you'll get work hardening.