Are those 'steerable' drill bits tough?

[T i m]

Hi All,

Looking ahead to drilling the remains of the 9" sq wooden fence post out of it's concrete shell, I've been looking about for suitable drill bits.

I think someone posted a link here recently to one of those 'steerable' drills and I wondered how 'tough' they were?

What I was thinking of doing is turning a long (stiff, so it won't whip about) 50cm extension and possibly MIG'ing the drill into a hole bored in the end. If I let the weight of my new 'cheapo' SDS drill (and std chuck) do all the work I hoped I could easily drill a 'gap' across the stub to make it collapse and pull the parts out (I want to keep the concrete 'holes' for the new steel posts).

I'm not sure a speed drill would be good as they don't fare well when there is break-through between holes? A brace_and_bit type bit would be no good at speed and take ages by hand.

Any thoughts please folks?

All the best ..

T i m

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[Bob Smith]

Do you mean those drill saws? If so, the one I got seems OK. They are meant for sticking in and levering sideways, so they are probably quite tough.

Not sure what effect they have on drill bearings when you put a sidewards force on them though. Drill bearings are not designed to take a lateral force are they?

I have the same job to do (only 3" square posts though) and would like to know the best way to remove the rotten post stump. A 3" auger would be ideal...

Bob.

[T i m]

Hi Bob and is that what they are called? ;-) I was thinking it needs to be a big enough diameter to move a decent amount of material whilst small enough to not overload the drill etc.

Probably not 'loads' but the combination of the main bearings plus any thrust bearing sorta supports lateral loads? With a 50cm shaft on this thing I'm not actually going to apply side loads but I hope to be able to get to the bottom of the stub without laying on the ground?

My worry wound be what would happen to that sort of bit (saw) if it touched the concrete sides on the way down?

For your posts I would of thought 3 x 25mm dia holes across the middle of the post and then push one side onto the other to make a gap down the side etc ..

All the best ..

T i m

[Dave Plowman]

Do you mean 'Mad-bit'? Cuts in any direction? I've got one, but never really got on with it. Looks good in the demo video, though. Bit like the demos of all those gizmos at Ideal Homes etc.

[T i m]

Could be Dave? I think someone posted a link to a picture / advert of one recently (can't find it now). I think it showed a hole that had been 'drilled' though 90 deg?

I've got one, but never

Wanna sell it Dave?

Looks good in the demo video, though. Bit like the

Oh indeed .. and some of those guys (gals) are good at what they do! I bought one of those drill chuck things that 'hold' a screw and allow depth settings etc. He was putting 3" screws in a lump of wood in the ceiling of the stand with ease. I buy one (free bits and a multi cutter tool and sharpener thrown in etc) onlt to find the head of the first screw I tried to use was too big for the chuck thing ..(doh).

I didn't actually want a / the bit to be 'steerable' as such but something that wouldn't snag on the sides of other holes like a speed-bit would and would work at drill speed rather than brace and bit?

I 'suppose' a 25mm wood / steel conventional twistbit with a suitable sized shank for a stock (long) extension or the threaded stock pipe extension idea (posted before) might do it?

I have some 1m long SHS masonary drills but I don't think they would be any good in wooden post stump?

All the best ..

T i m

[N. Thornton]

exactly

Regards, NT

[T i m]

Cool, so it's just to find a 1m long (so I can stand up and use it)

25mm high speed wood bit that won't jam on breakthrough or mind if it skims the concrete .. ?

All the best ..

T i m

[Paul Mc Cann]

One of those that drills round corners?

Got one of those also but have since realised I have never wanted to drill around corners so it lays rusting in a drawer.

On the question of drilling out rotten fence posts. Why ? Is a new fence post going to be inserted into the old socket ?

Perhaps drilling a few holes into the rotten stump, filling them with diesel and letting it soak in followed by a match would solve the problem.

Blacksmiths used to burn out the stump of a broken spade or fork handle before renewing it.

Paul Mc Cann

[T i m]

I believe so Paul. Only because I was unsure what would do the job the best?

Hmmm .. I might be able to find it a good home *if* you think it would do what I think I want to do?

Thats the idea though there are no firm plans as such. This is the second time (in 26 years) I've had to replace the posts and this time it's going to be steel posts and a sliding gate (loads of reasons).

Possibly .. when I've tried that before it won't burn as it's too deep and starves it's self of oxygen? Also, if it's anything like the last time I did it the rot will only be for a couple of inches down from the surface .. the other two feet will be clean dry wood and fairly easy to drill, given the right tools.

This is right on a pavement and I'm sure the local kids will find something to put in / on the fire .. ;-(

All the best ..

T i m

[Bob Smith]

Thats what I thought.

If you get down to a nice firm bit (mine last week was rotten all the was down) you could put a large screw in eyelet into it and lever it out.

Bob

[Ian Stirling]

You'r not thinking hard enough. Charcoal, and a hoover (on blow, they don't live long on suck) to provide the oxygen down a pipe.

I'd consider taking a SDS 1m drillbit (there's a guy selling a set of

1m SDS drills on ebay for not too much) and resharpening it with a diamond file or wheel in an angle grinder so that it will cut wood better.

[Pete C]

A few eyelets, some fencing wire, a length of RSJ/scaffolding and a hydraulic car jack might do it.

cheers, Pete.

[sylva]

As long as the wood is square without any protuberances I thing a pre drilled hole and then a lug eyed coach bolt might give enough purchase for a high lift jack.

If you do go the burning route then the charcoal is best with a light blow. Diesel just volatises and flames above the hole. You don't want an inferno as the concrete will fail somewhere above 500C. Even when burning I find I need a pilot hole with stumps, though I have not done one this way in the last 20 odd years.

AJH

[T i m]

Thanks for all the replies guys. ;-)

I might try the eyebolt / long lever / car jack route but assume the wooden 9" square by 18-24" deep woden plug would have expanded into it's concrete hole with all the rain we have had of late (maybe the summer would be a better time to do this?) As soon as we have a dry day or two I might try the 'extraction' process and go from there ..

All the best ... and thanks again ..

T i m