Drilling 32mm Holes through plywood

[FrenchIan]

If I can ask for some advice...

I have to cut holes into the side of 45mm ply (3 x 15mm pieces, glued together). The holes are to be 32mm diameter, and around 50mm deep. They're blind holes, because I'm cutting into waste which is later cut away on the bandsaw, so there's no problem with breakout., but the sides of the holes have to be reasonably clean. I don't have a drill press, so I'm using a hand-held drill.

So far, I've cut four with an Axminster sawtooth cutter, and it's blunt.

So, what are my options? I can't justify a very expensive sawtooth bit such as Clico (even if they did one in 32mm). I can see a Power Auger Bit from Colt @ £34, an Armeg Wood Beaver Bit @ £11 or a Bosch Spade Bit @ £5. Are there any other methods?

Cheers

 

[mailee]

How about using a router and guide bush with a circular template?

 

[Bradshaw Joinery]

Decent forstner bit?

Will require some forward pressure but ive cut bigger holes by hand with one.

Flat bit will do it also and is probably the easiest option.

 

[Benchwayze]

In the past I used brace & bit (1.25 inch bit = 31.8mm) for fitting Yale-type lock barrels in 2" thick exterior doors. Sharp bit + patience = piece of cake. You might be able to buy metric bits for hand-braces these days.

You can buy augers for use in power drills too, but NOT in a drill press, or drill stand.

HTH

 

[FrenchIan]

Decent forstner bit?

Will require some forward pressure but ive cut bigger holes by hand with one.

I thought a sawtooth bit was more efficient, which was why I tried that first. Would a forstner bit be better?

Flat bit will do it also and is probably the easiest option.

It's cheap and fast, but I'm not sure about the quality of the cut?

Cheers

 

[FrenchIan]

In the past I used brace & bit (1.25 inch bit = 31.8mm) for fitting Yale-type lock barrels in 2" thick exterior doors. Sharp bit + patience = piece of cake. You might be able to buy metric bits for hand-braces these days.

You can buy augers for use in power drills too, but NOT in a drill press, or drill stand.

HTH

That would be a good idea, if I still had my brace, but I gave it away around 20 years ago.

I'm thinking about the four flute wood drill, from the likes of Armeg or Irwin. Has anybody any comments to make about them? I've heard they're "aggressive"....

Cheers

 

[Benchwayze]

Ian,

The augers I have are also aggressive. Hence I don't use them in a drill-stand.
You could file off the thread which makes them less 'pulling'. But with a decent power drill, I find it easier to use free-hand, and drill in small 'bursts' rather than going straight in.

HTH

 

[beech1948]

Ian,

I just had a look at the Axi site to see what you have. Limited choice in your chosen size.

I suggest that the saw tooth bit you have is OK and just blunt. Take a file ( saw file or needle file) and sharpen it. Will take 2 mins and then resume drilling.

Saw tooth drill pictures show quite clear shape and places to file....might be just a touch up needed.

Ply is made up from as much hard glue as wood and this is why your drill bit has blunted plus they may not be the best metal as they are a low cost way to get a hole.

Al

 

[FrenchIan]

How about using a router and guide bush with a circular template?

My earlier reply to this seems to have gone missing.....

Not possible, I think. I'm drilling into the side of a crescent moon shape, cut from a rectangular block - concave side to convex side - so only really possible with some form of drill.

Thanks

 

[FrenchIan]

#beech1948 - sharpening isn't so easy with my eyesight, but I'll have a go, as a fall-back

#Benchwayze - I think I'll invest in an auger (probably Irwin, available here in France) and try that. Probably after filing off the thread, so it's more controllable.


Thanks everybody, for all your help

 

[paulm]

As mentioned, touching up the sawtooth bit periodically should be easy enough, or using a spade bit should be easy enough too and even easier to sharpen (can be kept on line by drilling a small pilot hole first to guide the point), or maybe a holesaw and chisel out the waste ?

Cheers, Paul

 

[beech1948]

Ian,

If your eyes are playing up then you know the solution....I have something of the same problem....its a very bright light and a 10x magnifying lens on a stand.

Al

 

[woodaxed]

I would use a router i know you say that the item is convex one side just match the underside of the template to the convex
clamp then router out or if youve got the waste from them then use that to match the convex
A pic of what your doing would help as to size etc of object