Shell bits

[steve355]

Hi

Does anyone have any experience with shell bits for a brace? Pros/cons, tips, etc.

I might get a couple.

Thanks
Steve

 

[mouldy plane]

Hi Steve. I sometimes use them for the fun of it. They are good for drilling at an angle, and cut reasonably fast, and you don't have to worry about them snapping in half if you put too much bending pressure on them.

 

[steve355]

Hi Steve. I sometimes use them for the fun of it. They are good for drilling at an angle, and cut reasonably fast, and you don't have to worry about them snapping in half if you put too much bending pressure on them.

Aha… yes and indeed thats what I would use them for, as you’ve probably guessed!

May as well explain. No point in trying to explain to my wife. Someone may be interested.

I was working on a pair on #18s this afternoon. I have made this new gizmo that sits on my pillar drill and uses a milling bit to rough out mortises. I’ve always been in two minds about it, because the traditional method (using a shell bit) is probably not slower, but requires more elbow grease with the float, and more skill with the brace.

But my new gizmo undercut my first mortise and made it slightly too deep towards the blind side, which in practice is not a disaster, the plane will work fine, but it’s not ideal either. At which point I got fed up and thought about going back to traditional methods.

But then I redid my calculations and realised that the lean angle of a typical moulding plane mortise should be 2.1 degrees, not 1.2 degrees. Minor error, but enough to wreck a plane. So I reset it and it worked nicely for the second one.

I may get a couple of shell bits anyway.

For what it’s worth, a couple of other improvements, a new template (gold plastic thing) to give me a much tighter mouth. Problem Is, one starts off with a 3/16” mouth but by the time the profile is on, it has opened up. So now the mouth is a smidge less than 1/8”, which should still result in a tight mouth one the hollow or round profile is applied.

Also, another improvement is sawing the blank to give a better grain direction.

WIP #18’s, last weeks #14, and new template

Mortise roughing gizmo

Mouth prior to profiling

grain direction….