Thread: Technique for small turned knobs

You could try a morse taper collet chuck - I bought a set of 5 (6mm and up) for about $50, but I can't remember where I got them - a search on the web should find them. The collet won't crush the wood as long as you cut the tenon the same size as the hole in the collet.

Just make sure you get ones which are threaded on the end so you can insert a threaded rod through the headstock and tighten up the outboard end to prevent the chuck from coming loose.

The following youtube video shows how it works: http://www.youtube.com/watch?v=IqvCrH4dam8

Could you possibly make up a glue block with a countersunk bolt/nut through it to go into the Jacob's chuck, then glue that block to your blank for turning? Turn the tenon etc, shape as much as possible, then part off at the top and hand finish.
(Sounds like it's time to start saving for a scroll chuck. )

By coincidence, I'm wrestling with small knob making myself at the moment, but have a scroll chuck to make things easier. I turn the tenon and a 25mm base for the knob, then wrap masking tape around the base to prevent marks and reverse the base into the scroll chuck to turn the top. No help to you, I'm afraid.

Originally Posted by Starr

Just make sure you get ones which are threaded on the end so you can insert a threaded rod through the headstock and tighten up the outboard end to prevent the chuck from coming loose.

Fuzzie, along these lines, I hope your Jacob's chuck has the same setup. You don't want to get smacked in the head by the chuck if it comes loose from it's moorings.

Thanks Starr. McJing seem to have something like that for about $125 and Carbatec have something for $250 but they look different and I'm not sure I want to spend $$ on a solution here.

I had a thought that maybe I could do something similar and strengthen the tenon with a plumbing olive. The GPW chuck is only 12mm but my drill press has a 16mm chuck which would accept the OD of the olive, so I stuck a thin brass olive on the 1/2" tenon and tightened it up in the drill press chuck as a test, unfortunately the olive just distorted and squashed a cleaner triangular shape to the tenon and still wobbled out with small sideways pressure. Back to the drawing board again.

For small work like this I prefer to use a collet chuck as it doesn't just hold the work in 3 or 4 places but all around.

I use this regularly for my pen work with smaller than what you are talking about and certainly some quite soft material, eg the bark from the Red Ironbark.

See here (collet chuck came from Vermec)

https://www.woodworkforums.com/showth...ghlight=finial

Originally Posted by Hermit

along these lines, I hope your Jacob's chuck has the same setup. You don't want to get smacked in the head by the chuck if it comes loose from it's moorings.

The MT adapter for the GPW chuck has a thread at the end of the MT2 side but not at the JT33 taper end for the chuck. It's going to take a really long screw to get all the way through the drive shaft though. I've had the MT loosen up during my experiments so far but I also hadn't seriously knocked the MT into place yet.

Originally Posted by Fuzzie

The MT adapter for the GPW chuck has a thread at the end of the MT side but not at the BT taper end for the chuck. It's going to take a really long screw to get all the way through the drive shaft though. I've had the MT loosen up during my experiments so far but I also hadn't seriously knocked the MT into place yet.

When I only had an MT2 collet chuck I used a suitable length of all-thread.

Something like this perhaps?

http://www.ebay.com.au/itm/Collet-Chuck-MT2-with-7-collets-/261501612956?pt=LH_DefaultDomain_15&hash=item3ce2b5f39c

http://www.ebay.com.au/itm/1-8-5-8-P...item51bdf0658d

Could you make the blanks longer and turn most of the job between centres? And then just sand the of knob in the drill chuck?!
Or turn tendons then turn a Timber Morse taper and then belt it headstock drill hole in Timber to tight fit tennon then turn rest of knob, and if it comes lose dip tennon in water!

Originally Posted by chuck1

Or turn tenons then turn a Timber Morse taper and then belt it headstock drill hole in Timber to tight fit tenon then turn rest of knob

The chance of me turning anything that accurately to that tolerance is something less than Buckley's......

Just a thought how about a short piece of copper pipe that will fit in your chuck spit it length ways and spigit inside and tighten no crushing .

Cheap & cheerful - cylinder of softwood drilled for knob spigot, saw down length one side and hold in three-jaw chuck. Not super accurate but works OK for small knobs. I've turned dozens with spigots down to 1/4"
Leave spigot a bit longer than required and cut off before fitting as mentioned above.

Mark

Originally Posted by Fuzzie

The chance of me turning anything that accurately to that tolerance is something less than Buckley's......

Now I think you are being too hard on yourself.

It snaps off? Silly question....... Do you have the grain going the right way? Other wise the wood just might be to soft. Or maybe use a gouge rather than a scarper which puts a lot of stress across any holding mechanism.

I turned a stack of nobs in a little home made jam chuck with a little screw coming up from the bottom.

Here is some pics of how I did nobs. Was some softish cedar. But you can see the chuck I hope.

doorknobs 015cs.jpgdoorknobs 001cs.jpgdoorknobs 003cs.jpgdoorknobs 004cs.jpgdoorknobs 006cs.jpgdoorknobs 007s.jpgdoorknobs 008cs.jpgdoorknobs 010cs.jpgdoorknobs 012cs.jpg