of countersinks and centre-punches

[PeterC]

Using (or trying to) various countersinks on chipboard flooring, most didn't do much and one that did work got very hot and took about 30s per hole [1] Without spending a fortune, are there countersinks that will cut various materials without setting fire to them? (I have both fluted and 'snail' type and they're OK on ordinary wood).

Centre punches: could do with something that will handle steel and stay pointy [2]. Also need pin punches that don't bend too easily.

I've looked at SF and TS; they have largely sets, which I don't mind if they're good. Axminster's countersinks seem to start at dearish and go to FO!

[1] Solved it for chipboard by blipping the hole with a slow, 10mm masonry bit then finishing with countersink. Care needed, as masonry bit really chews off the surface. [2] Perhaps a bit unfair using a small punch to unscrew the front plate of a freewheel, especially starting the wrong way 'til I remebered it was LH!

[sm_jamieson]

Whats wrong with using a largish (say 12mm) normal HSS drill ? It doesn't chew up the surface. Just be careful not to drill all the way through ! Simon.

[stuart noble]

Combined drill/countersink bits are useful, where the sink part locks with an allen key to adjust the depth. Alas the ones I have only seem to work with the drill bits they come with, which are some weird in between size. IME nail punches need to be concave to work reliably. You get a slightly bigger hole than required but, as they sit over the head of the nail, they don't slip off

[Mike Clarke]

You must have super armour plated chipboard or a cheapo monkey-metal countersink. I use a CK 2601 snail type countersink and it copes with wood, chipboard and MDF without any sweat. In fact with chipboard I find that screws like goldscrews from Screwfix will pretty well countersink themselves without using a countersink bit.

Depends on your definition of fortune, mine cost me about £4.50 when I bought it about 5 years ago from a local toolshop. Rapid have them for a similar price but delivery will more than double that, though I expect they should be readily available from local shops.

[Dave Liquorice]

The tip angle on a normal drill is 135 deg (*) that of a counter sink is 90 deg.

As to the OPs problem I can't say I've ever had a problem but it is vital that the counter sink is sharp and properly centered into the hole. I use a high speed on the drill, let the bit self centre, and only apply light force. Counter sinks are not designed to remove material quickly.

One tip I saw during a google to check my memory of angles was to drill the counter sink first then the hole but that might be more related to reducing chatter rather than makinga neat job but worth a try?

(*) Ideally it varies with the material you intend to drill, soft stuff pointy, hard stuff flatter. These days "off the shelf" drills tend to be 135 deg. Counter sink tip angles also vary but the common one is 90.

[Spamlet]

You can 'concave' any bit of rod or punch just by tapping it on the side of the tip with a hammer , as you rotate it on the anvil of a vice or similar. If you have had a punch long you will probably need to be doing it by now, as it will already be wider than it was. Large nails do for punches for me most of the time: the genuine efforts generally serving more like drifts for pushing pins out of chain links and the like.

I also like the combo drill countersink, and just for screws in wood I don't think the odd sizes matter very much. The resin in chipboard can be fairly hard but a properly hardened new bit should not have any trouble with it.

S

[Spamlet]

Yes I find these days of powered screwdrivers the problem is usually how not to get far too much 'countersink'!

;-) S

[Nightjar]

I've just laid a 2.4m x 3.6m floor, using a cheapo countersink from Focus without any problems at all.

Colin Bignell

[dave]

The tip angle can be changed to 90 degrees if you can grind a drill.

The problem with using a twist drill as a countersink is the rake angle of the cutting edge.

Called the lip angle in this link.

is ground for a tip angle of 90 degrees and the rake angle is not flattened, the drill will corkscrew itself into the work and leave you with a large hole that the countersunk screw will fall through

HTH

Dave

[David WE Roberts]

I found that high speed, high power and strong pressure tended to get the countersink to spin and burn the wood.

I use a slower speed and lighter pressure - usually with a 12V cordless drill - and that seems to work better for me.

I have some fine and some coarse countersinks but the number of cutting edges doesn't seem to make much difference in chipboard.

HTH

Dave R

[The Medway Handyman]

My thoughts exactly. Why use a countersink? Turbogold from Screwfix countersink themselves.

[NT]

Chip is as hard as peanut butter, its an unusal screw that neeeds a countersinked hole in chip.

Some countersinks simply arent sharp. Ordinary twist drills make effective countersinks, the angle of the hole it makes is anything other than fussy in chipboard.

NT

[The Medway Handyman]

Dunno where you get your chipboard, but most is as hard as nails.

[PeterC]

They look quite good - sharp edges, which some don't have. Thanks.

[PeterC]

The board is much harder on the surface - indeed, for the first 1 - 2mm in

- and is noticeably harder to drill there. I did a couple of holes on an offcut with a wheelbrace and new 5mm bit and it was relatively hard work to get started. (The boards suffered from some rain - after drying out the surface was still flat and smooth and the exposed tongues etc. were still as new!).

[PeterC]

I'm just using Goldscrews (5x60), so no ribs. I'm not sure that Turbos would work on this surface.

[PeterC]

Yup, we used to back off the drills so that they scraped rather than cut, as we used to countersink Perspex etc. and an unbacked-off bit will shatter that.

[PeterC]

Did the board have a hard surface? My csk bits will do chipboard OK, it's just this surface.

[PeterC]

Tried both (started with a 7.2V screwdriver) and only the Makita running fast did anything at all.

[NT]

I've been regrinding twist drills for years, and routinely make both angles much steeper for wood driling. Never had one corkscrew in yet. I expect if someone were to lean hard on one maybe it would, but they cut so fast with almost no pressure, there's no sense leaning on it.

NT