Pilot hole size in chipboard?

[bugbear]

I've got any number of old texts that give detailed recommendations for traditional woodscrews in both hardwoods and softwoods, including pilot hole size and shaft clearance size.

Very nice.

Since I'm now working on a modern(ish) fitted kitchen with chipboard cabinets it's all of no use to me.

The screws used are proper chipboard type, fast thread, and are threaded for their whole length. The thread is 4mm OD.

So - gentles all - what pilot hole should I drill? I'm guessing either 2.5mm or 3.0mm.

BugBear

 

[Myfordman]

If the screw manufacturers don't supply that info, then I would measure the core diameter of the screw first. That would be the absolute minimum pilot size. I'd start off a bit bigger than that to allow space for the waste cut by the screw and experiment with sizes so there is no sign whatsoever of any splitting.

 

[bugbear]

If the screw manufacturers don't supply that info...

They're just the screws originally used to secure the old hinges.

...then I would measure the core diameter of the screw first. That would be the absolute minimum pilot size. I'd start off a bit bigger than that to allow space for the waste cut by the screw and experiment with sizes so there is no sign whatsoever of any splitting.

I'll use my beloved "digital photograph with a scale in shot" technique to get the info you suggest.

I know that piloting in soft wood and hard wood is different, due to the different compressibility (and consequence tension) of soft and hardwood, so I didn't know what appropriate "fit" for chipboard was.

BugBear

 

[dzj]

For a standard butt joint in melamine particleboard, i use 4x50mm screws and drill a 3mm pilot hole, about 10mm in length.
Some people go for smaller diameter screw and no pilot hole.
I imagine the density of the chipboard would be a factor that determines if a pilot hole is needed, also how close you are to the edge of the panel...
Better to use conformat screws if possible.

 

[lurker]

density of the board is the factor
If they do rip out (DAMHIK) dribble cheap superglue in the holes leave overnight then re fix the screw

 

[ED65]

If you're using a pilot hole at all I think with chipboard under-size is the way to go actually, depending somewhat on the quality of the board.

 

[bugbear]

If you're using a pilot hole at all I think with chipboard under-size is the way to go actually, depending somewhat on the quality of the board.

<genuine question>How else do I get the screws to go in the right place?</genuine question>

BugBear

 

[ED65]

You mean if you don't use a pilot hole? Make a decent mark using an awl. Or driving them into the (nadir?) of the countersink.

 

[Racers]

Put the screw on the magnetic bit holder on your impact, stab the chipboard with it and spin it in really fast, stopping just (hopefully) before you strip the hole.

:wink:

Pete

 

[bugbear]

Put the screw on the magnetic bit holder on your impact, stab the chipboard with it and spin it in really fast, stopping just (hopefully) before you strip the hole.

:wink:

Pete

Out of sheer perfectionism/cowardice(*) that's not the sort of thing I'm comfortable with.

And I don't have a rechargeable drill/driver!

Screws go in via either a Britool hex-bit holder, or a brace adapter (if I need speed and/or torque).

If I can find a piece of scrap chipboard, I guess I should do a couple of trials.

BugBear

(*) at least one of the two

 

[RobinBHM]

I would think a 2.5mm hole would be ok for a 4mm screw.

Generally I find a bradawl tapped with a hammer makes a good enough mark on MFC and then drive the screw straight in with a cordless. (I dont think I could survive without a cordless!)

The most important thing is dont over tighten the screw or the screw will start to pull out the chips leaving hardly any purchase on the screw.

 

[bugbear]

OK, I found a piece of coated chipboard, 14mm, and a 15mm x 4mm fast thread screw.

I proceeded to use this single screw to fix a spare hinge plate in place, using different size pilot holes from 1mm to 4mm, in 0.5mm steps.

Each screw was turned until it spun in the hole (this turned out to be always possible).

Conclusion - all the pilot hole sizes from 1mm to 3mm gave the same holding strength. With a 3.5 pilot the grip was reduced and with a 4mm (duh!) grip was near zero. it appears that chipboard (or my sample, at least) really is rather soft and compressible.

My preference (for a 4mm screw) after this experiment would be 2.5mm; the larger pilot holes give marginally easier starting of the screw.

BugBear

 

[lurker]

The saga of your kitchen door hinge replacement has been riveting reading

 

[bugbear]

The saga of your kitchen door hinge replacement has been riveting reading

I'm afraid it is at an end; the new 3mm offset mount plates arrived today, the first door got a plate switch, the second door got the full new-hinge-holes-plates treatment, the adjustment screws got twiddled, and the cabinet has newly re-fitted double doors.

Domestic brownie points for me!

Thanks to all for your guidance and kind words.

BugBear