Gentle reminder of some safety in your workshop.

[petercharlesfagg]

Recently I have been posting in a thread concerning Forstner bits, their usage and speeds etc.

Looking around the internet there are many hundreds of different designs of cutter available BUT only some of them are safe from a woodturning point of view.

The central section or point is sometimes shown and advertised as being important but if it is threaded it can be potentially dangerous.

Most lathes do not stop on a sixpence (That dates me!) and if drilling at a fast speed the whole drill will be drawn inexorably into the end of the wood and eventually possibly the jaws of a chuck etc.

If you consider purchasing such a drill bit, as I am, please remember to grind or file off the threads so that you have a clean point that can be withdrawn from any project reasonably quickly.

Regards, Peter.

 

[PeterSk]

Surely you'd need an extremely chunky thread to be able to not only grip the inside of a hole being drilled, but also to then be able to pull the rest of the forstner bit down into the workpiece?

 

[monkeybiter]

Good point, thank you.

 

[tekno.mage]

Good point, but it's usually other types of wood bit that have the point threaded (normally augers for use with a brace & bit - the threaded point in the middle is designed to help pull the drill bit into the wood) - and these should not be used on the lathe unless you grind the threads off first.

On the subject of Forstner type bits, I've actually ground the centre point very much shorter on a number of mine - which does not affect their use in the lathe (or pillar drill) at all, but means it's so much easier to tidy up the nasty little hole left the the middle of the bottom of the hole - and there is far less risk of the point breaking through on thinner work.

 

[Bodrighy]

I have found that with any bits there can be a point where the torque on the drill in the wood can be greater than the holding power of the Jacobs chuck in a morse taper and the chuck suddenly starts spinning. If using a drill on the lathe I keep the speed low and wind the drill in, withdrawing frequently to clear and wood swarfe (is is swarfe with wood) also helps prevent burning. With a forstner bit (don't like them but have used) this possibility is greater and a heavy Jacobs chuck spinning freely is not a nice sight.

Pete

 

[dickm]

With a forstner bit (don't like them but have used) this possibility is greater and a heavy Jacobs chuck spinning freely is not a nice sight.

.... and it also plays h*ll with the morse taper in the tailstock.

 

[tekno.mage]

I cheat and have a set of MT2 collets with drawbar that will hold most drills securely in the tailstock - except for very large forstners, which have shanks too big for my largest collet :-( and drills with hex shaped shanks.

 

[goldeneyedmonkey]

I've heard these Irwin Blue Groove Bits are a bit mental when using any type of drill. You have to turn the torque right down. Can't see the need myself?

Cheers_Dan