cutting a 45mm hole in 3 inches of walnut

[Eric The Viking]

I"m with Jason, and whoever suggested starting the holesaw in a piece of ply first - it'll stop breakout round the edge. It's then easy to chop the waste with a chisel. A key element to this is that the saw is only cutting round the edge, so the drill is doing less work than using any other powered solution. That means it should cut well. You WILL need to clear the cut rig of dust occasionally too, so withdraw the saw often and vacuum the ring.

The traditional approach was to use an expansive bit in a hand brace, such as this:

They do work, but you need to keep the spur nipped up well or it slips, and it'll be bloomin' hard work in oak and probably would need sharpening during the process! And you have to treat the scale as a joke on the part of the manufacturers - test it until you get the right size.

I'd never ever use one in a powered drill though.

E.

 

[Phil Pascoe]

Eric The Viking------they do work........ and then I read the Mark Twain quote underneath!

 

[Eric The Viking]

Eric The Viking------they do work........ and then I read the Mark Twain quote underneath!

I can't believe I struggled with those expansive bit things for donks.

I've two holdfasts in my benchtop, and I'm morally certain I cut the holes with an expansive bit. I spent hours trying to get a razor edge on the spur, etc., but I was never very good at that and anyway the steel was pretty rubbish.

They do cut in a very 'controlled' way though!

E.

 

[Benchwayze]

I'd be inclined towards patience. Use flat-bits. New. Good quality. Buy a set, but make up your own sizes, the biggest being the size you want to finish with.
Start with the smallest and work your way up to the size you need. That way no bit is going to get overloaded, and if you drill that 6mm hole right trough first, you could work from both sides to lighten the load even more. Just be sure the workpiece is upright.
You will have the bits for future use in many more projects! Bonus, yes? :mrgreen:

You have all the time in the world!

HTH

 

[jasonB]

I'd be inclined towards patience. Use flat-bits. New. Good quality. Buy a set, but make up your own sizes, the biggest being the size you want to finish with.
Start with the smallest and work your way up to the size you need. That way no bit is going to get overloaded, and if you drill that 6mm hole right trough first, you could work from both sides to lighten the load even more. Just be sure the workpiece is upright.
You will have the bits for future use in many more projects! Bonus, yes? :mrgreen:

You have all the time in the world!

HTH

How do you propose to keep the flat bit centred, if you try using one in an existing smaller hole they just jump all over the place. Also 38mm is the largest I've seen for sale.

 

[Benchwayze]

I'd be inclined towards patience. Use flat-bits. New. Good quality. Buy a set, but make up your own sizes, the biggest being the size you want to finish with.
Start with the smallest and work your way up to the size you need. That way no bit is going to get overloaded, and if you drill that 6mm hole right trough first, you could work from both sides to lighten the load even more. Just be sure the workpiece is upright.
You will have the bits for future use in many more projects! Bonus, yes? :mrgreen:

You have all the time in the world!

HTH

How do you propose to keep the flat bit centred, if you try using one in an existing smaller hole they just jump all over the place. Also 38mm is the largest I've seen for sale.

Good thinking batman. Intellectual Intermission.........

 

[Cheshirechappie]

I'd be inclined towards patience. Use flat-bits. New. Good quality. Buy a set, but make up your own sizes, the biggest being the size you want to finish with.
Start with the smallest and work your way up to the size you need. That way no bit is going to get overloaded, and if you drill that 6mm hole right trough first, you could work from both sides to lighten the load even more. Just be sure the workpiece is upright.
You will have the bits for future use in many more projects! Bonus, yes? :mrgreen:

You have all the time in the world!

HTH

How do you propose to keep the flat bit centred, if you try using one in an existing smaller hole they just jump all over the place. Also 38mm is the largest I've seen for sale.

Good thinking batman. Intellectual Intermission.........

That would work if each size of flatbit was fitted with a round pilot the that neatly fitted the last size hole drilled. Engineers' counterbores use the same principle.

Mind you, given the amount of time taken to make a set, it wouldn't be worth it for anything less than a production run of several. For just a one-off, or a couple, it would be quicker to chisel and rasp the holes.

 

[Jacob]

...
Start with the smallest and work your way up to the size you need. ....

Won't work. It's a one shot drill. Will only cut into nice clean solid wood - but do it very well.

 

[Benchwayze]

So I have been advised Jacob...
Suitably chastened.
Dyslexic thinking. Mixed up. Starting with a larger drill first there's a guide, but there would be a stepped hole.
Result a co*k-up....

I know I got it wrong, but I need telling only once and Jasonb got there first.

:wink:

ccasion5:

 

[xy mosian]

I have often wondered about grinding my flat bits so that the pointy bit at the front is the same size, smallest, on all the bits.
xy

 

[MusicMan]

I have often wondered about grinding my flat bits so that the pointy bit at the front is the same size, smallest, on all the bits.
xy

What would that achieve?

 

[xy mosian]

I have often wondered about grinding my flat bits so that the pointy bit at the front is the same size, smallest, on all the bits.
xy

What would that achieve?

In any case where a large, counterbored hole is needed, a smaller diameter hole could subsequently be drilled using the same centre, crucially with no rattle. If the smaller hole is bored first, with a flat bit, then unless the centre prong on a larger bit is larger, at its root, than the existing hole again loss of centre induces rattling.
xy

 

[Stanleymonkey]

Your link doesn't show what you re trying to make!