Drill sharpeners

[Alexander Smith 1Participant @alexandersmith1]

Question for JohnP. I also have a Christen drill grinder that I picked up for a song at our local scrapyard. Unfortunately, it only came with one collet- you get very poor service at some scrapyards these days!

the collets are quite strange – split at both ends with a cone also at both ends, presumably to grip the drill shank evenly.

does anyone have any spares lying around or know of a source for these – I have toyed with the idea of using an ER11 collet chuck on an 8mm spindle- dead cheap from China, but the originals would be better.

sandy

[Bo’sunParticipant @bosun58570]

As others have said, practice grinding by hand on some old bits. It can be quite satisfying. Get familiar with the tip geometry and you never know. Equal cutting lip lengths are important, otherwise you can drill oversized holes. A useful tip however, if you want a slightly larger hole than you have a bit for. It needs some experimentation though.

I'm not a big fan of cheap drill bit sharpeners, they rarely produce a good profile, and I really don't like those that use the side of the wheel.

Less than perfect eyesight does make the sharpening of small bits difficult, if not impossible, so with the smaller sizes, I just buy new ones a few at a time.

[SteviegtrParticipant @steviegtr]

I was taught in a tool room at a factory where I worked as a maintenance electrician. The old guy in there Cyril taught me over a period of time & I am so glad he did. Took a while to get the wrist movement correct. But recently have not done too well sharpening large drills. Would be nice to have a good sharpener for the workshop.

Steve.

[Clive IndiaParticipant @cliveindia]

I have always used 118°

When would I need to use 135° please

[clogsParticipant @clogs]

have said before…….

buy 2 cheapo drill sets……. Lidil etc…..keep 1 as a pattern and practice on the other…….

after each attemp at sharpening try it on a peice of angle etc…..

u'll soon learn what works…….

no cheapo drill's when I was a lad tho……horrendus waste of good Brit drill's…….still, gotta learn……

[Brian MorehenParticipant @brianmorehen85290]

Well remeber the 2Ft Grinder that my Dad had used to run this in a wet bath and crank this wile dad sharpen whatever he neded to sharpen Seem to remember being told place 2 hexagon nuts side by side when your drill fits into the V slot this looks good and will cut OK

Brian Morehen

[BazParticipant @baz89810]

Alexander Smith1 I have a Christen 05-10 and uses the collets you describe, they are still available as are all bits for the Christens, the company you need to google is Anglo Swiss tools, they are based in London. Sit down before you ask the prices though,as with all Swiss stuff they are eye watering expensive!

[Mick B1Participant @mickb1]

Posted by Clive India on 18/02/2020 16:33:31:

I have always used 118°

When would I need to use 135° please

When you're drilling thin section material and you want minimum burr on the far side. The drill bit acts a little more like a punch in the last few thou. But 135 is just one of a spectrum of values. The idea is to get the cylindrical land into the material before breakthough.

Also the so-called 'crankshaft point' for deep holes in tough materials – but that name seems to be unfashionable nowadays. The point resembles some variants of the 4-facet, which is very much in fashion.

[Clive IndiaParticipant @cliveindia]

Posted by Mick B1 on 18/02/2020 17:22:41:

Posted by Clive India on 18/02/2020 16:33:31:

I have always used 118°

When would I need to use 135° please

When you're drilling thin section material and you want minimum burr on the far side. The drill bit acts a little more like a punch in the last few thou. But 135 is just one of a spectrum of values. The idea is to get the cylindrical land into the material before breakthrough.

Also the so-called 'crankshaft point' for deep holes in tough materials – but that name seems to be unfashionable nowadays. The point resembles some variants of the 4-facet, which is very much in fashion.

Thanks very much.

[Howard LewisParticipant @howardlewis46836]

Not sure about "four facet" being "in fashion".

Having once experienced drills sharpened in this way, do not want to use any other method.

Mine are sharpened on my Worden cutter grinder, using an ER20 holder of my own design, with a setting jig to ensure that the cutting edge is vertical, (assumes just a minor trim up, not a major recovery from broken )

The last couple of MEW issues contain articles about making up a simple jig to four facet grind drills.

Might be well worth reading and making up the simple sloping table and two wedges.

Howard

[Mick B1Participant @mickb1]

Posted by Howard Lewis on 19/02/2020 14:23:24:

Not sure about "four facet" being "in fashion".

Having once experienced drills sharpened in this way, do not want to use any other method.

…

Howard

Well – fine, each to their own. But there's no doubt in my mind that a 4-facet point requires more time plus more dedicated tooling to achieve. Back when I was machining for pay, nobody I knew ever talked of 4-facet points – the only known variant was the rarely-seen crankshaft point, used as said above for deep holes in difficult material. 4-facet grinds on standard drill seem to have become more available lately – I have some from Lidl that work nicely – and IMO that's what has increased the level of interest, perhaps beyond the real improvement they offer as compared to the extra resource need to produce them.

I agree that the 4-facet design has benefits, but at least some of them can be obtained by careful web-thinning on a standard drill, which requires only a sharp eye and a steady hand plus a few tens of seconds extra at the bench grinder. There's very little work in my usual spectrum of model engineering that needs anything better.

I'd see it chiefly as a matter of how you want to use your time.

[John BaronParticipant @johnbaron31275]

Hi Guys,

Four facet ground drills tend to be self centring and take less force to drill a hole ! In mild steel anyway.

As far as tip angles go, I learnt a long time ago that the so called crankshaft point was good for stainless steels but you still have to keep them cutting to avoid work hardening.

I also use brad point drills for sheet metal, the raised lip cuts the outer just before the centre punches through.

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