Countersink / counterbore and clearance hole all in one go?

[matt]

Hi,

I'm struggling to find something I can't believe it is not more readily available...

I frequently have cause to drill a clearance hole and countersink / counterbore. Most often for 8 guage screws - my "go to" for fixing most things... I would like a single drill bit to complete both in one go. I can find pilot hole and countersink bits in abundance but nothing capable of drilling a 5mm clearance hole with a 8-9mm countersink.

Am I missing something (other than the aforementioned drill bit...)?

Thanks in advance...

 

[MattRoberts]

Do you mean these? Trend Snap/Cs/Set 5pc Countersink Set https://www.amazon.co.uk/dp/B0001P120G/ ... FybAECH74E

 

[memzey]

I've got a set of trend snappy counter bore, countersink and pilot bits. Came with matching plug cutters. Good quality and if I recall correctly they came from screwfix.

 

[matt]

Thanks for your replies. I have some of those but none produce a hole large enough to act as a clearance hole (vs. a pilot hole). I need the thread to pass through the hole so the parts being screwed together clamp rather than jack apart because the screw is threaded in both parts.

It is possible to use the larger Trend bits to produce a clearance hole for smaller diameter screws but the downside is a disproportionately large countersink.

 

[MikeJhn]

If you can match the disproportionately large countersink hole to a plug cutter you have your solution.

Mike

 

[matt]

For some applications, I agree. That is where the screw size is less than 8 gauge (because the Trend set does not include a drill bit large enough to drill a clearance hole for 8+ plus) and where the material being drilled is large enough for a large countersink and also not profiled (and therefore easier to use wood filler and sand back to profile). Under any circumstances I would prefer to remove less material and not have massive plugs.

I do have the plug cutters too and do use them. I'm simply looking to invest in a 8-9mm countersink fitted to a 5mm bit.

 

[Doingupthehouse]

I use the Stanley Screwsink, don't think they're made anymore, but available on the Bay... here's a link to a number 12 one, but lots about.

http://www.ebay.co.uk/itm/Vintage-Stanl ... SwepJXXsrM

Strange things, but work really well.

Simon

 

[Sheffield Tony]

I got a similar set, #8 and #10 with matching plug cutter, but mine drill three steps, pilot, clearance and counterbore in one go. They are branded Disston, and came from Screwfix but many years ago.

 

[matt]

I do have the three step Disston "screw diggers"; however, a pre-requesite is a clearance hole of the particular length dictated by the bit. Nice idea for some applications but not where the clearance hole needs to be longer. I end up drilling from both sides, having already forced the bit into the wood from the face side further than necessary and ending up with an overly deep countersink to fill.

On close inspection the Stanley ones appear the same concept as the Disston.

I'm sounding fussy but only because I'm after a very specific solution. Grateful for all the suggestions.

 

[matt]

https://www.wealdentool.com/acatalog/Online_Catalogue_Counterbore_Assembly_769.html#aD_2dCB_2f2TC

 

[n0legs]

Trend do a clamp on countersink attachment.
They'll fit from 3 to 6mm drill bits IIRC. You can set it anywhere up the length of the bit to suit your application.

 

[MikeJhn]

http://www.ebay.co.uk/itm/COUNTERSINK-A ... Swal5YKu1k

OR

http://www.ebay.co.uk/itm/Stanley-Screw ... SwepJXaE8O #-o

Mike

 

[paulrockliffe]

I don't recognise jacking as a problem if you drill the right sized pilot hole. So long as you hold the pieces together as the screw goes in it doesn't jack. So long as you use a screw with a non-threaded section longer than the thickness of the board you'r attaching any small amount of jacking is removed once the last of the thread leaves that piece.

 

[squib]

I had some a bit like these......

http://www.diy.com/departments/ptx-mixe ... 7Qod06ADqA

and the clearance bit is a sleeve that is adjustable for length as well as the pilot....
I can't see from the pic here if this clearance is actually adjustable.
However i found that they clog badly and have always found that the stanley fixed ones are good and I ground the end off back to the sizes I used mostly.

 

[Paul200]

Trend do a clamp on countersink attachment.
They'll fit from 3 to 6mm drill bits IIRC. You can set it anywhere up the length of the bit to suit your application.

+1 for the Trend Universal Countersink. https://www.trenddirectuk.com/uni-cs Looks like it can produce a small counterbore :?

 

[LancsRick]

In the past when I've had things like these I've always struggled with the countersink collar not gripping the drill bit for any length of time. Any of the items above particularly good or bad for that aspect?

 

[monkeybiter]

This may or may not be relevant or work for you, just the way I do it; when using a fully threaded woodscrew to join two pieces I allow the the screw to 'jack' and force a gap between the two, then immediately reverse the screw back into the first piece allowing the wood to meet again, then drive the screw fully home and in practise it always tightens up fully.

 

[SteveF]

this sort of thing?

https://www.wonkeedonkeetrend.co.uk/tre ... meter.html

Steve

 

[AndyT]

Interesting question this. I'm wondering what sort of screws you are using, Matt?

Your question makes sense for traditional woodscrews where the shank is wider than the threaded part, but there are plenty of screws around now where the unthreaded part is thinner than the threaded, like this

I realise these are really meant for quick driving into softwood with no pilot hole, but I think a pilot hole of the same diameter as the shank might achieve what you are after, or at least simplify the problem.

 

[MikeJhn]

I think, if I remember correctly that's the difference between a rolled and cut thread, cut obviously cuts the thread from the material therefore reduce's the overall diameter of the shank being cut, whereas a rolled thread moves the material to make the thread, therefore makes the thread a larger diameter than the original shank.

Mike