I have to drill some large holes in a large sapele hardwood board. They need to be clean…so I did some tests. I bought augur bits from screfix and used the hand press drill to drill holes in an offcut.
Inc into end grain just for curiousity sake.
I got tear out on the topside! How can I prevent this?
It didn’t even drill into the end.
The wood was an offcut from the bin. Not sure what type.
Put scrap on the top as well as bottom and clamp into a sandwich
Thanks.
Silly question…but how do you know where to drill (in you main board) if it’s covered by a sacrificial piece?
That also looks like Oak.
Brace and bit …
Remember the induction?
Drill a pilot hole with a 2mm bit in the sacrificial piece. Use a sacrificial piece thin enough that the point engages into the proper piece straight away
: ( sorry boss, don’t remember…Mark ran my induction ; )
What’s brace and bit? Same as the sandwhich Barnaby mentioned?
I thought using hand brace drill would give me a cleaner hole…oh well.
Oh yeah, that’s the one I used…the spaces one anyway…with new augur bit
When you say ‘large’: how big? We have a set of Forstner bits – I always thought they gave clean holes, with little tearout? However I probably just reached the limits of my knowledge here…
Or drill a 2mm hole and countersink it to size before you drill
LYou could also trim the scrap to the same size as your workpiece
What wood are you drilling? Brace and bit usually leaves a really clean hole and inly breaks through in the bottom. Are you applying enough downforce? Is the auger bit sharp out of the box?
You could also drill through the piece until just the tip of the bit is poking through (if you’re using a brad-point, forstner, or similar pointy-end bit), then flip your piece over, and using the tiny hole to centre your drill bit again, drill through to finish up.
This section of video might help you visualise what I mean! (Starts at 19:12, just in case the link doesn’t take you to the right point).
Sharpen it and use a low speed bit
As i understand it his piece is breaking out on both sides, top included.
Ah my bad, must’ve missed that bit of detail.
yes this is what I do for clean holes top and bottom.
If it’s tear out on the top, there’s probably a problem with technique? e.g not putting enough down pressure when using hand drill?
Never had much problem using electric drill and forsner, even on pretty crappy wood
Sharpen the bit
That too
Def seems to be a big part of the problem
A sharp bit should cut a really clean hole from the top
