Tip for drilling with large auger bits

[justigator]

I'd never used an auger bit larger than 12mm until recently. Trying a 19mm one, I found it so powerfully pulling itself into the wood that it overwhelmed both my cordless and my corded drills, both grinding to a halt halfway through. Apart from anything else they were very uncontrollable. I have a pillar drill which might have aided control, but chuck to baseplate distance was too short for this drill. I assumed it was the design of the main part of the bit that created the strong pulling force. However I saw someone online recommending a pilot hole so that the screwed tip of the bit has nothing to bite into. Tried it - 6mm in my case - and it worked well and was easily controlled. So, it seems that the short screwed end of the bit is the part that pulls it so strongly into the material. Apologies if everybody knows this but I didn't and thought it might help others to let them know.

 

[foxhole]

They were originally made for hand turn brace drills so in power tool should be used at lowest speed possible .

 

[Deleted member 174758]

Dial the speed right down and it all becomes a lot more controllable. For whatever reason people (OK, apprentices and DIYers) often seem to think that auger bits need to be run at the same speeds as spade bits. This is completely wrong. When you consider that auger bits were originally designed to be used with hand braces, that should inform you of the speed you should be running your drill at, i.e. S-L-O-W (i.e. more like 200 rpm than 2000 rpm). The bigger the auger bit, the slower you should be running it, but also the more powerful the drill you need. If you need to pilot drlil first when you are doing it all wrong

Also bear in mind that the average cheap Chinese auger bit arrives, brand new, very poorly sharpened with both the spurs blunt and the cutting edge just as bad. They are, however, easy to sharpen

 

[justigator]

Neither of my drills can go anything like as slowly as a hand brace, but using a pilot hole worked for me.

 

[foxhole]

Neither of my drills can go anything like as slowly as a hand brace, but using a pilot hole worked for me.

Easier to use forstner bits with power drills .

 

[Deleted member 174758]

Easier to use forstner bits with power drills .

Except for the fact that you can't drill deep holes accurately with Forstner bits be
Cause they tend to run off line

 

[Deleted member 174758]

Neither of my drills can go anything like as slowly as a hand brace, but using a pilot hole worked for me.

You run the risk of the drill bit running off line because the bit it guided by its' pilot. You are also going to have to push a lot harder because the pilot normally draws the bit through the timber, so whilst your technique may work for a couple of holes it isn't accurate and it would be tiring to use on a big project, such as sistering the joists foe a whole house

 

[foxhole]

Except for the fact that you can't drill deep holes accurately with Forstner bits be
Cause they tend to run off line

Not had a problem and OP has not mentioned depth requirement .

 

[Deleted member 174758]

Try drilling through a 3in joist, then! Forstners are designed to be guided by their rims - auger bits are designed to follow their screw point, which also pulls the bit into the work. That is why you use them for drilling deeper holes/through holes - a typical useof Forstners is to produce short blind holes, e.g. kitchen hinge recesses. Quite apart from anything else Forstsners are far more prone to clogging, especially in the smaller sizes. But then, that is just conventional wisdom

 

[justigator]

I used aforesaid 19mm auger bit successfully today with a 6mm pilot hole to drill for the top part of a Euro cylinder lock through a 44mm wooden door which had a void in the centre for the old lock. It's softwood but still took a while as I took it so slowly. I agree with JobAndKnock that the procedure wouldn't work for multiple holes. I addressed the accuracy point by knocking up a sort of wooden jig which I clamped to the door and which held the bit straight and level. Freehand, yes, it would have wandered with a pilot hole.

 

[Deleted member 174758]

You do seem to be going the long wsy round with this