Drill bits... spend more or less?

i get more response in this bit from fellow tratter drivers than anyother, so...

i need some new bits cos ive been snapping mine and wearing others out. do i buy another cheap set and keep replacing things or splash out and get some quality ones? or just take more care and stop being so violent with a drill just looking for advice from the more experienced of you. ive seen a set of bosch Ti's but they want £50 for it. i need up to 10mm as ive worn my £2.99 one out can anyone recommend sets, or best places to buy? also should i be using oil, as ive been drilling stuff dry! *smirk*

cheers,

G

When I was a apprentice anything less then 10mm was consumable.
So if I were you I would buy a set of drills and then get a couple of boxes of the more common sizes.
Expect to snap them fairly quickly, especially if hand drilling.

Anything less than HSS is crap and I wouldn't bother with the Titanium coated drills (They still snap)

Wot I did was to nick em when I was in engineering.

Any how if you buy a Screwfix box with em all displayed nicely, then as you bust em buy decent replacement ones from a local tool suppliers, your looking for HSS(high speed steel) ones for value for money, I don't reckon much to the coated ones cos you can't sharpen them. Tek it easy with em and keep em cool while your drilling by dipping them in coolant, water, oil, **** or whatever, if your reely keen get some cutting lubricant but if it costs a fortune any old oil is better than nowt.

cheers guys. HSS it is. i did start using WD40 but it kept smelling like it was on fire and then the ends of the bits would go blunt and would drill no more.

my old man gave me a 10mm bit last time i went home. he said "try this, quality bit that". i used it once and now its ruined! i reckon he was palming off cheap ****.

will nip over to screwfix later.

cheers guys.

G

cheers guys. HSS it is. i did start using WD40 but it kept smelling like it was on fire and then the ends of the bits would go blunt and would drill no more.

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Thats cos yer off like fook with it, slow down there's no hurrying steel.

There was a tutor at Tech College when I wuz an apprentice, he reckoned spit was the best cutting lubricant there was. Don't necessarily agree with him but it's better'n nowt.

I buy the common sizes in boxes of 10 from screwfix - just the normal HSS ones and throw them away when blunt. Rarely use oil or lubricant, but do take my time and start off small for bigger holes. So if I want a 12mm hole, I'll drill it 3mm, 6mm, 10mm first before using my more expensive 12mm bit.
If I do need lubricant (e.g. in a thick piece of steel) then I just use 3in1 oil. The key point with using a coolant when machining metal is to use plenty of it, otherwise you can cause just localised cooling and damage the tool.

Optimum cutting speed forr HSS bits in mild steel is 30m/minute removal rate. From maths, RPM = (1000 x S)/ Pi x D. So for a 10mm drill bit, it is 30000/31.4 which is roughly, 1000rpm. If cutting through Ally, it is softer and the optimum removal rate is lower than steel, you should run slower than for steel.

For example 6mm drill speed is 1600 rpm approx for steel, but going through Ally, you qouldn't go over 1000rpm as drill gets clogged up and blunts. If you ain't got any Tellus emulsion, tallow is a good substitue - cover your bit in it and start to drill. Friction will cause the tallow to melt and cool/lubricate at the same time.

I use wd40 as a coolent/lub.
and as Grunt says take it slow on the bigger drills
Ie a 1in drill should be doing no more than 120rpm through steel.

er, yer. ok. cheers take 5. im gonna get dizzy counting the RPM of a small drill bit!

gonna buy a set from screwfix as their cheap and upgrade when nec. gonna take it slower to and spit on me bit so to speak.

G

Griffdowg said:

er, yer. ok. cheers take 5. im gonna get dizzy counting the RPM of a small drill bit!

gonna buy a set from screwfix as their cheap and upgrade when nec. gonna take it slower to and spit on me bit so to speak.

G

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Those are optimum cutting speeds that you can expect to achieve with a CNC machine tool with loads of coolant. For manual drilling, keep the speed down to keep the heat down

Take5 said:

Those are optimum cutting speeds that you can expect to achieve with a CNC machine tool with loads of coolant. For manual drilling, keep the speed down to keep the heat down

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porky uses hss un if they go blunt he sharpens them wiv er drill sharpnin machine e bought on flea bay, he even sharpens masonry bits ,but anyfink smaller then 3mm he just chucks as it wint fit int is machine. . . .

I use an oil stone. Have a nice selection I inherited from the old man, all different shapes, sizes and grades. Really lovely one set in a wooden block is great for doing chisels

Masonary drills generally have a negative rake on em for extra strength. If yoove got a bench grinder and a bit of time it's quite easy to teach yerself to sharpen HSS drills by hand, the trick is, as in drilling, not to let em get to hot or you'll heat treat the end and you'll be wasting yer time. And unless yoo've got good eyesight then little un's are a pain in the arse to sharpen.

FFS guys - anything less than 10mm disposable Ahhhhhhhhhhhhhhhh! I may not not know a whole heap about landies but I do know how to sharpen a drill bit. I work all day with young 'tradesmen' and it shocks me how poor their bench-fitting skills are. If you use a lot of drill bits, or just enjoy engineering, buy a bench grinder and teach yourself to grind a drill bit. I can quite happily go down to 1.5mm and 1mm once I've got my eye in.

And while I'm ranting WD40 is a **** coolant for general use. It's far too thin; tallow is excellent but any thick oil will do - even old engine/GBox oil.

Feck me am going to bed - less then 10mm............ nightmare ensue!!!!!

I use WD40 as a coolant/lubricant and titanium coated bits when it matters. anything under 6mm is just annoying and the bits are too thin for anything other than drilling sheet, unless you have a quality drill and a steady hand or drill stand.

For big holes start small and then use larger drills don't go balls out with the speed.Get your hands on some Rocol RTD metal cutting fluid,it's the dogs bollocks as far as metal lubes go,a small bottle will last a very long time and you use it for drilling and tapping.Try to find your local friendly Toolmaker who I am sure for a reasonable "drink" will resharpen your old drills.
Regards Steve

The general rule for drilling steel is lots of pressure and little speed.
We can all do this by hand and eye, so no need to count the revs!

If you can, use a pillar drill, and once you have it set at its slowest speed you probably won't ever change it. DO use a cutting lube - if all else fails use engine oil from a squirt can. WD40 and the like are mostly kerosene, so they may not do a lot of good, but you will feel better.

Low speed .... high pressure ... way to drill in steel and iron.

Charles