mortise bits

larryone

Is there such a thing as mortise bits for hand drills?
Or are these only available for larger bench drills?

...or could a mortise bit be modified for use on a hand drill?
......or am I just asking for trouble there?

dubtom

If your talking about mortice machine bits,square with an auger (sp) bit inside then I don't think you can get them for hand drills. I'm nearly sure I saw an adapter for a bench drill somewhere,most probably axminster. I have a mortice machine,cheap b+Q model, and although the tiny motor will do the job, holding the wood securely is the problem. I'd imagine the same problem would happen on a bench drill. Much faster just to drill and finish with a chisel, for me anyway.

ircoha

the main effort in a Mortising machine is the leverage to drive the 4 chisel faces down through the timber as the hole is bored out. it is no mean feat so it wont work in a hand drill, the bench drill attachments are a bit iffy unless as noted above u can lock the timber v tight: if it moves, game over.

The other critical matter is having the correct clearence between the bit and the chisel faces, too little u risk jamming/breaking the bit, too much, it can easily snap, particularly the smaller dia ones as the shaft at the cutting end is very thin

JoeB-

Yes, it can be difficult to use mortising machines if they are a bit light... I'm sure the heavy duty versions are ok but the very light versions would be more difficult to use sucessfully.

As Ircoha says you do need leverage to drive the bit through the wood so the wood has to be clamped firmly (when withdrawing the bit).

Ideally you have a cross table of some sort... so that the wood is clamped once and it can be moved sideways and forwards or backwards without releasing it (by turning handwheels... for very small runs you could re clamp each time but it makes if hard to get it lined up correctly. (Axminster sell a crossvice which can be retro fitted to some machines to provide this functionality, it is quite good with adjustable 'gibs' so the action is straight with little sloppiness)

The cross vice is pretty essential as well because for through mortises you need a backing piece or you'll get bad breakout, (spelching?)

You would probably be best to drill out the mortise (with a normal drill) and finish it with a sharp chisel, effectively that is what a mortising machine does but it does it in a single step.

Cheers
Joe