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One for the engineer types...
I've managed to get fed up with my ~25 year old mini set of HSS bits. Always blunt, but always there.
Thinking Cobalt or some such. What is the received wisdom in the world of quality bits please? Mixed materials to be holed but no titanium or fancy rare earth metals...
Ta.
Well if your current ones lasted 25 years then the same ones again would be my advice. Otherwise cobalt.
Does really depend on what you're drilling into. Whatever type, best to steer away from ebay\amazon, My goto is Cutwel, not the cheapest but will last.
https://www.cutwel.co.uk/?gclid=EAIaIQobChMIyf_BwJSL_QIVkbrtCh3_YQQYEAAYASAAEgLKr_D_BwE
Buy a drill sharpener ?.
I was taught yonks ago how to sharpen them freehand on a grinder. Not perfect, but better than blunt.
Ta very muchly. Thunderjobbies on order 👍
I suck at drilling.
If I'm doing anything involving metal, I either snap the bit or blunt it or both.
Masonry, I either explore the wall into dust or whatever brick/stone I hit somehow transfigurates into hardened adamantium.
I can just about do wood.
Presto or Dormer.
As above.
The DeWalt cobalt are very good if they still do them.
Buy the size you need not the multi packs I bulk buy the same 4 sizes mostly
My approach is, buy some inexpensive but not supercheap ones, destroy em, replace em. THing is I'm reasonably sure it's bad drilling practice on my part, stuff like piloting wrong or going too fast or pressing too hard, so probably nice bits would be wasted.
HSS drills sound like they'll fit your need. Cobalt; great if you're drilling tougher metals as they're more resistant to heat & hold an edge for longer but also £££££. A good quality HSS drill bit can be destroyed in seconds but is easy to resharpen. A drill sharpener is a great idea especially for smaller bits as these are difficult to do accurately by hand on a grinder. Sharpening is another subject but getting yourself some cutting lubricant like "Rocol" will prolong the life of your drill bits a lot.
I'm pretty sure the Thunderjobbies are just Milwaulkee branded HSS bits but we'll see at 10:25 to 11:25 (according to DPD). I don't do much drilling (ahem) but (probly like most) occasionally need 'just that size' and it to be sharp so am happy to pay for the convenience. I do sharpen them and the only non original in my existing little setette is the 3mm. So I tend not to break them - so far.
If they're shite, I might just buy a few individual Dormer/Presto Cobalts of my most used sizes. Sadly, the local tool shop closed recently where I could buy individual needle files and individual drill bits. Blaaady Internet...
A lot of cobalt drills have a 135 degree split point design, which are much harder to hand sharpen than the 118degree point on a typical hss drill.
A drill will only cut well if its sharp. If you feel you will have trouble replicating the 135 degree split point design, you would be much better off having ,admittedly inferior, hss drill bits with the 118 point.
You can get very good results by hand sharpening hss drill bits, we used to sharpen the cobalts on specialist machines to get a good result.
You can get very good results by hand sharpening hss drill bits
Do you mean with a file or some sort of grinding stone? I've done it with a little grinding stone in a drill before and although the results are much better that trying to use the blunt drill, getting the point of the drill exactly centre is a little tough
I meant with a bench grinder, not a hand grinder, though i have honed carbide drills with diamond hand "files", but this isnt what i meant. The larger the wheel diameter, the better the results will be.
it takes practise, but you can get decent results by tack welding / gluing two hex nuts together to give you an angle of 120 degrees to act as a gauge. This is close enough to 118 degrees, with time youll be close enough by eye.
when the angle is right, next thing to check is that both lips of the cutting edges ( the sloped bits) should be the same length.
once this is right, the drill still wont cut unless you have the rake ( clearance ) right. Difficult to explain in words, but essentially, when the drill is rotating, you need to ensure the leading edge of the lip is the first and only part of the tip actually touching metal. Any other part is rubbing not cutting and will cause heat by friction, and cause the drill to blunt quicker.
watch from about 3 mins in.
@johnnymarone that's enough of an explanation to indicate home sharpening Cobalt is probly a non starter. The Hss's I just give a little whizz on a stone in the drill press - no bother. Very likely inaccurate but good enough for the odd DIY ole.
In other news, 2 Milwaukee flavoured holes in and the bits are both better than the old HSS ones and still intact 🙃
The Hss’s I just give a little whizz on a stone in the drill press – no bother
Interesting idea. What sort of stone?
The secret to getting your drill to cut properly and last longer is to try and keep the cutting edge cool. I guess you are trying to drill steel. Any sort of lubricant will be better than none. In the trade we use a soluble oil mixed with water which keeps the edge cool. Don't push too hard , just "feel" the drill through the metal. Drill a bit and then relieve it and keep applying the lubricant !!
What sort of stone?
It's just a little (~3"?) circular grinding wheel that I mounted on a ~20mm dia bolt. The bolt's in the chuck and I just gently sharpen the bit end freehand. Very unscientific I'm afraid 🙃
Very unscientific I’m afraid
Methinks you need to up the bodging device. 😉🙃👍
https://wood.tools4.co.za/blog/multi-sharp-the-cost-effective-way-to-sharpen-your-tools/