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Thread: Technique for small turned knobs
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12th June 2014, 01:32 PM #1
Technique for small turned knobs
I'm attempting my first turned small knobs. I've attempted to follow some descriptions for turning Shaker style pulls. Two FWW articles I've read, one by Philip Lowe and another by Christian Becksvoor, both cut a tenon first on a blank and then mount the tenon in a Jacobs Chuck to turn the rest of the pull. We're talking a 1" pull on a 1/2" or so tenon.
I've had ZERO success with this method. I'm turning some rather soft Maple Silkwood. After I've got as far as cutting the tenon I try mounting it in the drill chuck, but the 3 jaws just squash into the wood and cannot really hold it. If I tighten up the chuck firmly the blank also goes off centre somewhat.
Even if I get a hold onto the tenon in the chuck, the rest of the blank snaps off pretty soon when I try turning.
I'm suspecting the North Americans would be turning pulls from Maple or Cherry which must be a much firmer wood than Silkwood. Not sure what to try next. I bought the Jacobs chuck from Gary Pye and don't have any other style of scroll chuck or anything like that to play with, just a drive spur for turning between centers.
Any suggestions??
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12th June 2014, 01:59 PM #2Member
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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
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12th June 2014, 04:01 PM #3
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 StarrLast edited by Hermit; 12th June 2014 at 04:54 PM. Reason: Got names backwards
... Steve
-- Monkey see, monkey do --
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12th June 2014, 04:16 PM #4
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.
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12th June 2014, 04:18 PM #5
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
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12th June 2014, 04:24 PM #6
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.
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12th June 2014, 04:26 PM #7
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12th June 2014, 04:34 PM #8
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12th June 2014, 06:01 PM #9GOLD MEMBER
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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!
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12th June 2014, 06:10 PM #10
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12th June 2014, 06:14 PM #11Senior Member
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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 .
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12th June 2014, 06:34 PM #12Senior Member
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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.
MarkWhat you say & what people hear are not always the same thing.
http://www.remark.me.uk/
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12th June 2014, 06:45 PM #13
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12th June 2014, 06:49 PM #14
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.anne-maria.
Tea Lady
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Follow my little workshop/gallery on facebook. things of clay and wood.
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12th June 2014, 06:55 PM #15
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.jpganne-maria.
Tea Lady
(White with none)
Follow my little workshop/gallery on facebook. things of clay and wood.
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