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Tear out when drilling holes

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alanwetherall

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Im making a clamping jig for picture frames and need to drill a number of 8mm holes every 50mm. Using a proper wood drill how do i eleminate the tear out on the start of the hole. Im just using 2x2 wood from the local large shed.
many thanks
alan
 

TheUnicorn

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normally I find tear out more an issue when the drill punches out to the other side of the wood, which I would overcome with a sacrificial bit of board / wood clamped to the back. By the same logic you could drill a hole in a sacrificial piece and clamp it to the front. A lip on the sacrificial piece could help get it an even distance from the edge, and if the centre of the hole was 50mm from the edge in either direction it would make alignment easy. It would work best if you had some hardwood, as the hole would stay crisp for longer
 

Popey

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I had a similar issue recently when I was using my pillar drill. When the drill speed was low I got tearout but when I upped the speed to about 1400-1900 RPM (can't remember the exact speed), the problem went away.

HTH

Mark
 

robgul

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I'm in the clamp a waste piece either side of the workpiece camp - especially if using Forstner or spade bits (I've pensioned of the latter in favour of Forstners) - clean holes every time. Likewise if using a hole saw then a piece of waste clamped under the workpiece to run the drill into for a clean hole.
 

Trainee neophyte

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Another option is drill halfway and go in from the other side. Getting the two holes to meet in the middle is the fun part.

Edit: I have now read your post, and you say "tear out on the start of the hole". Interesting. The glib answer may be to buy better wood - overly fibrous soft pine could be the problem. A pilot hole might help, or even using a marking knife or similar to sever the fibres before you start drilling. Apologies for not understanding the issue first time around (assuming I have understood it correctly now, that is).
 
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mikej460

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Another option is drill halfway and go in from the other side. Getting the two holes to meet in the middle is the fun part.
maybe more than halfway, you need the point of the forstner to break through to act as a guide
 

Rorschach

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Soft open grained wood is always prone to this. For your size hole a good quality brad point bit is what you need, it severs the fibres around the edge first.
 

alanwetherall

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I was using a Brad point bit and it still tore out the surface. I think clamping from both sides is an excellent idea which I will try tommorow. The wood is a poor quality wood but would you buy expensive wood to just make jigs. Would using a good quality plywood be any better?
 

TheTiddles

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You’re probably...
-Using the wrong drill bit
-Using a blunt drill bit
-Pushing too hard
-Spinning too slow
One or more of them
Aidan
 

FAC

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I have had the same with various Brad points until I bought an Alpen dowel drill bit set, absolutely perfect entry every time no tearing, still good to have a sacrificial piece on the back though.
 

TheUnicorn

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The wood is a poor quality wood but would you buy expensive wood to just make jigs. Would using a good quality plywood be any better?
As you've brought the subject up I was wondering why tearout was an issue on a jig, in my mind tearout just looks a bit ugly, not an problem on a jig?? Ply is generally considered more stable, so I assume would be more accurate and would possibly hold a truer angle. personally any kind of jig I have ever made has been built, used and scrapped within a few hours, and has been made from whatever was sitting in my scrap box at the time
 

Just4Fun

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Others have suggested increasing drill speed, which can work. You can also go the other way: turn the chuck slowly by hand until the drill bit scores the edge of the hole in a full circle. Then use the power as normal.
 

MikeJhn

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JoshD

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Japanese Star-m drill bits have a particularly clean entry. Don't run them too fast, don't force them, and don't drop them, they're quite fragile.
 

alanwetherall

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I have the fabric band clamp but am trying to build a clamp shown on youtube
to see which is a better solution as our charity (www.ourshed.co.uk) intends to make picture framimg an income generator
Many thanks for all your comments iv taken all of them on board
alan
 

profchris

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If you run the drill backwards for a couple of rotations, or even turn it backwards by hand, the bit scores a nice circle. When you run the drill forward, that should give you a clean entry hole.

On soft, splitty pine you have to score much deeper though, otherwise when going forward the bit just separates the wood fibres and levers them out.
 

TheUnicorn

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that looks a nice little jig,however I find it odd that when making the 'pacman' pieces he says they don't need to be perfect, in my mind the whole point of the jig is that the mouth in those pieces is as perfect a 90 degree cut as possible, measured precisely, cut, sanded, remeasured and tweaked till perfect. I would also look to make the mouth a bit bigger, to give more support to the edges and minimise any bowing on flexible frames

plenty of valid ways to minimise tearout mentioned here, however unless you are selling the jig I still do not consider tearout to be an issue
 

Cabinetman

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Funnily enough I was making a pair of Oak picture frames yesterday for the first time in quite a while, I had forgotten just how good that 10 second mitre glue is, quite incredible and no cramping needed. Ian
 

eribaMotters

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If all else fails regarding higher drill speed and a nice sharp lip & spur/brad bit, then use a thicker piece of timber and re-plane the surfaces once holes have been drilled.

Colin
 

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