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Self Centring Drill Bits

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custard

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What's the view on using self centring drill bits for installing butt hinges on small cabinets and boxes?

I can pretty much guarantee the location and depth of the hinge mortice to 0.1mm, but every now and again I'll get a hinge that's fractionally displaced, and I'm pretty sure it's due to an off-centre screw/pilot hole.

Do self centring drill bits guarantee real precision, or are they just a "close enough is good enough" convenience for larger door butt hinges?
 

MattMoore

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I use one regularly for hinges, jigs etc, as long as the drill is plumb it will be very well centred. I would spend a bit of money to get the better quality ones rather than the very chap ones that are out there. my set are trend ones fwiw.

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custard

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Thanks Matt, I'll give the Trend No 6 and No 8 sizes a go.

You make a good point about keeping the drill bit plumb, I remember reading an account of David Charlesworth going to extraordinary lengths to guarantee drill accuracy on a wooden hinge joint he was making, he set up his drill press using a dial test indicator to ensure it was absolutely vertical. I'm not sure I want to go quite that far but you're right, it's pointless being centred if you're not also plumb.
 

bugbear

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custard":2f747l7t said:
What's the view on using self centring drill bits for installing butt hinges on small cabinets and boxes?

I can pretty much guarantee the location and depth of the hinge mortice to 0.1mm, but every now and again I'll get a hinge that's fractionally displaced, and I'm pretty sure it's due to an off-centre screw/pilot hole.

Do self centring drill bits guarantee real precision, or are they just a "close enough is good enough" convenience for larger door butt hinges?
Twist bits will follow grain to some extent. The self-centring bits not only start off in the right place, but are HELD there for the duration of the drilling process.

BugBear
 

custard

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bugbear":12r7oekg said:
custard":12r7oekg said:
What's the view on using self centring drill bits for installing butt hinges on small cabinets and boxes?

I can pretty much guarantee the location and depth of the hinge mortice to 0.1mm, but every now and again I'll get a hinge that's fractionally displaced, and I'm pretty sure it's due to an off-centre screw/pilot hole.

Do self centring drill bits guarantee real precision, or are they just a "close enough is good enough" convenience for larger door butt hinges?
Twist bits will follow grain to some extent. The self-centring bits not only start off in the right place, but are HELD there for the duration of the drilling process.

BugBear
Very good point.

Wish I could find a good quality smaller self centring bit, the smallest Trend self centring bit is 5/64" (2mm) for a No 6 screw in hardwood. I'd like a 1.5mm or 1.6mm pilot hole for a No 3 or 4 screw in hardwood, but so far haven't found anything. Does anyone have any suggestions?
 

Pete Maddex

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Hi,

You can use a bigger one to form a depression on the centre of the hole and use it to locate a smaller drill bit, it’s what I do.

Pete
 

custard

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Pete Maddex":61yc46md said:
Hi,

You can use a bigger one to form a depression on the centre of the hole and use it to locate a smaller drill bit, it’s what I do.

Pete
What a cracking suggestion! Thanks for that.
 

Jacob

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custard":3chptorp said:
Pete Maddex":3chptorp said:
Hi,

You can use a bigger one to form a depression on the centre of the hole and use it to locate a smaller drill bit, it’s what I do.

Pete
What a cracking suggestion! Thanks for that.
Or just use a bradawl, a nail, a centre punch etc just like everybody else! For tiny no2 screws (and for scratching lines/points in general) I use a dart (as in the board game). No feathers - can tap the end with a pin hammer.
 

bugbear

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Pete Maddex":3r5c306p said:
Hi,

You can use a bigger one to form a depression on the centre of the hole and use it to locate a smaller drill bit, it’s what I do.

Pete
It's a good system for marking, but doesn't give the "guide DURING drilling" behaviour that I pointed out.

(BTW, you might be entertained by the female counterpart of these drills, an engineering gadget called a "bell punch")

BugBear
 

custard

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bugbear":18kzg6zc said:
Pete Maddex":18kzg6zc said:
Hi,

You can use a bigger one to form a depression on the centre of the hole and use it to locate a smaller drill bit, it’s what I do.

Pete
It's a good system for marking, but doesn't give the "guide DURING drilling" behaviour that I pointed out.

(BTW, you might be entertained by the female counterpart of these drills, an engineering gadget called a "bell punch")

BugBear
Damn! You're right, although if it's precisely marked then a box at least could go on the drill press.

Nine times out of ten my hinges work out fine, but I can't quite get the process 100% bomb proof.
 

bugbear

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custard":1iyhqlvo said:
Nine times out of ten my hinges work out fine, but I can't quite get the process 100% bomb proof.
Hmm. Do you always use the same (model/size) hinges?

If so you could make a metal drilling guide. A piece of steel at least as big as a hinge (probably bigger for ease of handling and/or clamping) with holes in it with the correct locations and size.

Then "just" drill through the holes. This would locate and maintain the position of the drill.

BugBear
 

Pete Maddex

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Hi, BB

The problem could be with the manifacture of the hinge, an accurate guide might cause more errors.


Pete
 

bugbear

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Pete Maddex":1jz3vyq5 said:
Hi, BB

The problem could be with the manifacture of the hinge, an accurate guide might cause more errors.


Pete
Hadn't thought of that - fair point.

BugBear
 
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