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Maximising a rough wood blank

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CHJ

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As always there are many ways to tackle any project but the following is typical of my method of maximising the potential of a bit of rough wood, particularly those with limited depth.

Starting point.

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First task determine if bark is sound enough for a decent Natural Edge piece and make a note of any major deformaties that will influence form and wall thickness.

In this instance majority of bark not sound enough to stay on so it's set up the Cole Jaws with suitable studs to get it spinning.
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As there is going to be some pretty sharp interrupted cuts to start with I bring the tailstock up as a precaution.
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Having knocked off the corners so to speak and tested its chuck grip I then gently dress the centre to provide a sounder centre support pad if needed.
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Then continue with the defining of the outer form.
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CHJ

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When it looks like I have removed enough of the bulk to give a chance of producing a reasonable form I make a decision on fixing for reverse turning.
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And because the blank has limited depth I opt for a Hot Melt Glue spigot, note rough pencil rings to aid quick positioning.
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Adding a little peripheral bead to maximise the hold.
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True it up and form suitable spigot to match chuck.
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CHJ

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Then proceed to finish outer form.
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And finish sand, taking care not to heat the Yew and induce surface cracks.
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A coating of sanding sealer checks for finishing blemishes.
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After a final check that spigot is running true (blank has not moved in chuck) it's time to change jaws, in my case chucks, and turn the piece around.
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CHJ

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With piece firmly mounted in Jaws and the very central area cleaned up for tailstock support it's time to check for any cracks that may be a problem, don't want any tool catches and large splinters flying off, always a risk with Yew.
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Give the peripheral log core star splits a dose of thin CA to firm up.
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Then true up and blend in the outer form.
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Sand outer to finish and coat with sanding sealer to check for blemishes.
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CHJ

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Clean up top face and edge and define wall thickness with a parting gouge, this serves two important functions,
1. it prevents the skidding of the bowl gouge across the top edge if you get initial contact wrong as you have an inner surface for the bevel to locate on.
2. if the wood should start to warp you have a nicely even thickness top edge to your piece regardless of what happens just inside.
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Then proceed to remove the bulk of the inner wood using either bowl gouge or even a parting tool in steps if tailstock prevents access.
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Being very mindful that this piece has quite a deep surface depression, we don't want to break through.
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Proceed to remove the meat of the inner wood.
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And having got to the primary wall thickness and limit of access with the tailstock support, remove the central support, I use a parting tool.
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Strictly speaking there is rarely an essential need for tailstock support with a decent hard wood spigot support, but we can all have a catch and security and peace of mind goes a long way to making the job more pleasurable.
 

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CHJ

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All that remains is to reposition the headstock for better access and take a continuous full swing pass or two with a steep nosed bowl gouge to remove any ridges.
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Check for any visible cracks or splits.
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And treat with thin CA.
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Not very good images but note surplus applied CA has been wiped across surrounding surface, with figured woods this disguises the hard edge of glue penetration along crack.

Finish sand.
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And coat with sealer to check for blemishes.
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CHJ

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All that remains is to sort out the base, parting off the bulk of the mounting spigot to avoid too much reverse turning with light chuck hold.
If I have doubts about security of parting tool and depth of cut required I finish off removal with a thin Japanese pull saw.
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True up spigot face before removal ready for future reuse.
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Then it's change jaws again with suitable buttons, this is where a slight undercut on a bowl inner helps considerably in reverse mounting.
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Once again bring up the tailstock for security and proceed to remove the remains of the spigot block and hot glue.
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With heavy cutting finished remove the support and carefully clean up the central area, if in doubt about chuck grip sand this off.
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Final sand and seal.
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And a quick show of the Buffing Wheels.
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CHJ

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And finished just in time for the mid morning Coffee call.
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According to the EXIF data on the originals,
Started at 8.27
Coffee at 10.39 with only a couple of minor interruptions to the work flow.
 

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Bigbud78

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Stupid question maybe but why do you use the cole jaws instead of a big wood screw ?
 

jurriaan

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Interesting point of view. If I see that the bark won't stay on, I'll often make a natural edge piece anyway, just without bark. The contrast between white and orange/brown is striking enough to make this work out with yew, I think.
 

CHJ

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Bigbud78":359qcss4 said:
Stupid question maybe but why do you use the cole jaws instead of a big wood screw ?
I do sometimes use large wood screw, it's a matter of assessment of the piece and what experience deems more suitable for a particular project.

If an item is heavy and of a form that can take an integral spigot or socket mounting base component for remounting I more than likely will use long spigot jaws reaching 50mm or so into the blank, less likely to move than on a screw chuck.
 

Dalboy

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A very good tutorial Chas many new turners will find this very helpful and open them up to another method of mounting a blank, it may also help some of the more experienced turners as well
 

Random Orbital Bob

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Delightful as always Chas. I was almost there at the coffee break with you appreciating the rural view....I think I could hear a bit of Joni Mitchell in the background :)
 

Stiggy

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You've out done yourself Chas!

What a FANTASTIC walkthrough and instructional thread!

THIS is just the type of thing I (and most others I imagine) find incredibly useful - I will read this another few times at least!

Well done Chas - you're the man!

:D
 

Mal

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A wonderfully instructive post, thanks very much!

Just over 2 hours???

'must practise more, and more...........' :)
 

CHJ

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Random Orbital Bob":27x9hx88 said:
Delightful as always Chas. I was almost there at the coffee break with you appreciating the rural view....I think I could hear a bit of Joni Mitchell in the background :)
Thanks Bob, Derek, Paul, Stiggy et al for the comments.
The walk up and down to the lathe shed through such surroundings is all part of the hobbies enjoyment.
 

Mark Hancock

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Very well explained Chas. Well done.

It's hard to tell from the photos if your spigot is cross or parallel grain but I would question the use of a parting tool on cross grain timber. I know many use this techniques for removing spigots but with it's reduced tang it's a similar situation to using a SRG on cross grain. On another forum a beginner did something similar and the parting tool broke. Just wanted to make people aware of the possible danger.
 

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