A Basic Knob Question

[Richard T]

The only wood turning that I am familiar with is green wood/pole lathe turning. Job either spun between centres or bowl sized pieces attached to a face plate.

I have been pondering how to best turn front knobs for planes. Too small to successfully attach to a faceplate? Held with the tail stock and parted off?

Any ideas gratefully appreciated

 

[Bodrighy]

You can do them between centres or alternatively turn a disc on the lathe and then hot glue the wood for the nob to it to turn. Another way would be to use a screw chuck as there will need to be a hole in the base anyway.

Pete

 

[Random Orbital Bob]

For a clean "no mar" finish with no holes in the piece then parting off is the best way. If you don't mind a screw hole you could use either a screw chuck that you make yourself or a chuck with a purpose made woodworm screw. Using that method, you can get finishing access to the knob itself with the screwed end held in the chuck on the headstock. This will give you the quickest access to finish the ball end of the knob. It would also use the least amount of wood, but you end up with a screw hole on the bottom side of course which may affect how you ultimately attach the knob the plane.

With the parting off approach you leave no holes ie its solid but of course it will be joined at both ends and you'll need to sand whatever stub is left by hand once parted since you'll not have tool access as well as above. It also will use more wood as there'll be some waste either side of the parted off finished piece.

The upside is you could do say a 12" spindle length like this and create repeat knobs down its length, perhaps 3 out of a 12" length which makes it faster. Then part them all nearly off and finish with a hacksaw or fine toothed gents saw etc and hand sand the rough.

 

[Random Orbital Bob]

Whoops, mine and Pete's crossed in the ether. I also forgot about the hot glue approach as its not a method I use a lot. Personally, given the huge crater the woodworm screw would leave I would use a screw chuck or do it between centres. I make quite a few patio planters with acorn finials and I do them two at a time between centres because I find it easy to compare their dimensions when there are two in front of me (so they end up the same). I use calipers of course but its so easy on the eye when you're turning two of the same thing on one spindle as you have that instant comparison where they're exactly co-planar

 

[Racers]

Hi Richard

I drill the counter bore and through hole first on a over length piece and then chuck and tail stock center into a length of dowel in the hole.
I have done a spigot in a scrap jammed into the counter bore in the plane end of the knob, works well with the dowel and tail stock.

Pete

 

[Richard T]

Thanks Pete and Bob,

I will have a go between centres and see how it goes.
How big -a- hole would a wood worm screw leave ? Do they vary? The hole to take the fitting pin will be 7mm which will need to be left intact for most of its length to be threaded for 8mm rod. Of course I could leave enough wood to cut off afterward ... :-k

 

[Richard T]

Thanks Pete - that's interesting.

These will be non - through bored though. Although I might have a go with a Stanley type screw head look in future.

 

[chipmunk]

Richard,
If the final knob is to be threaded with 8mm then I'd drill and tap the blank with 8mm and screw onto a length of threaded rod held in a chuck - like bottle stoppers get turned. I turn drawer knobs like that with an M6 threaded insert in the blank screwed onto a headless M6 bolt. It's handy to have a wooden washer between chuck and blank of the right diameter to save your tools from hitting the chuck.

Alternatively if it has a hole all the way through then drill the blank and mount on a bolt of the right diameter held in a chuck with a nut on the end - like a pen mandrel. You will need to mount a couple of spacers this time; one between the chuck and the blank and another between the blank and the nut. If you countersink the end of the bolt you can bring up the tailstock to give some support if the bolt flexes with heavy cuts.

HTH
Jon