Spindle turning question(s)

[JPG]

Seems to me you have the right idea concerning grain orientation. You have designed the largest possible wood movement to be from the center to the outside of your gavel.

First let me say the 1 1/2" diameter should not offer enough space to cause significant wood movement. Also, the largest amount of movement will be radial, from the center outward. next comes a lessor amount in a tangential direction. I really don't know much about the expansion of the African wood, but the other three should be pretty compatible, if all species are arranged with the same (or similar) grain flow. (When one expands they all will expand similarly)

Don't over think it! Just do it!
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BTW - I agree with Titebond for the reason it will allow a little creep if there is a difference in wood movement.

Just thinking the wood movement of red oak (being one of the highest) is 8% tangentially. This is roughly twice the movement radially. (in your piece the tangentially oriented grain will be radially situated and the radial movement of the wood will be around the outside circumference (tangentially)

That 8% movement is it's extreme - between fiber saturation point and bone dry. The finished gavel will probably only be subject to 70% relative humidity to 20% - and the wood only from 6% to 10% moisture content.

So a little very simplified math shows that from fiber saturation to bone dry 8% of 3/4" = .0600" The actual radial movement of your gavel will be only a very small amount of that figure. You can figure the edge movement of you gavel will be only half of that smaller amount. Nothing to worry about!

Thank you for your thoughtful response. However I do not think we are in sync. Please review post #3. The figuring I want to show on the outer surface is on the face with the rings running from center to outside(this causes the expansion to be 90 degrees from the surface). I. E. the pith 'direction' would NOT be toward the center. I want the funky speckling of the red oak and aspen to be on the outside of the handle.

If I have further confused everyone, I will try to sketch something up free hand.

I do have a concern that I be worrying about an unlikely event, but this is my initial attempt to turn multiple species.

[iclark]

I need to pick a glue. I be thinking either titebond II or thin CA. Thin as in 'runny', not this gel crap.

in a recent workshop here (I think that it was David Ellsworth), the guest turner reported that some of their older museum-level pieces had partially fallen apart because some of the CA joints had lost their glue integrity. these were segmented bowls. they were easily repaired but it was a surprise.

it is sounding like the CA glue may have a shelf life after use as well as before use. these were ~10 year old pieces.

titebond is looking better all the time.

[charlese]

The figuring I want to show on the outer surface is on the face with the rings running from center to outside........If I have further confused everyone, I will try to sketch something up free hand.

Yep, When reading post #3 - guess I'm not on the same page. I pictured the annual rings of the wood slices will run from the inside to the outside. This is what I attempted to describe. Here's a part copied from Post #3 --the grain features I want to show seem to be in the area between the rings. With this 'edge facing the outside

Is the fact of the matter you want the annual growth rings to be concentric circles (sort of)?

[JPG]

Yep, When reading post #3 - guess I'm not on the same page. I pictured the annual rings of the wood slices will run from the inside to the outside. This is what I attempted to describe. Here's a part copied from Post #3 --the grain features I want to show seem to be in the area between the rings. With this 'edge facing the outside

Is the fact of the matter you want the annual growth rings to be concentric circles (sort of)?

No, the opposite. If you take a piece of quartersawn oak, the side I want to face out is the face with "Ray Fleck"(thank you Nick/Workshopcompanion).

This is the funky grain I was initially referring to. The fleck is a feature that develops between rings.(spans a couple of years growth) i.e. if you split a tree in half, the ray fleck would be visible on the flat face between the pith and the bark.

Thus in my case the expansion would be 'tangent' to the outer surface after turning.(if I understand expansion direction correctly - greater in the direction from the pith to the bark)

I am finding great difficulty describing the ring orientation unambiguously!

[charlese]

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Thus in my case the expansion would be 'tangent' to the outer surface after turning.(if I understand expansion direction correctly - greater in the direction from the pith to the bark)

I am finding great difficulty describing the ring orientation unambiguously!

Yes it is hard to describe! Now you have confirmed my original assumption. Happy to disagree with your assumption re]http://www.fpl.fs.fed.us/products/publi ... eader_id=p[/URL]

[SDSSmith]

I am finding great difficulty describing the ring orientation unambiguously!

Why don't you post pics of the wood and the way you want to arrange it? Make sure you get lots of other stuffin the background of the pics thatwe can comment on !:D

[JPG]

Why don't you post pics of the wood and the way you want to arrange it? Make sure you get lots of other stuffin the background of the pics thatwe can comment on !:D

That would require proceeding with initial sawing to shape, but at this point I am trying to determine if that grain orientation will be a mistake!

Well! It appears I had it bas ackwards!


"With respect to dimensional stability, wood is an anisotropic material. It shrinks (swells) most in the direction of the annual growth rings (tangentially), about half as much across the rings (radially), and only slightly along the grain (longitudinally). The combined effects of radial and tangential shrinkage can distort the shape of wood pieces because of the difference in shrinkage and the curvature of annual rings." Chapter 4 page 5

Thank You Chuck! Your earlier comments make much more sense now that my head is redirected.

I have reached the conclusion that the orientation I desire(from a cosmetic view) is also the best from a movement view. i.e. Tis better to have them all moving in/out than around. Therefore arrange the grain so the 'lines' formed by the annual rings run radially in the handle!

Have I got it correct Chuck???:)

[skou]

in a recent workshop here (I think that it was David Ellsworth), the guest turner reported that some of their older museum-level pieces had partially fallen apart because some of the CA joints had lost their glue integrity. these were segmented bowls. they were easily repaired but it was a surprise.

it is sounding like the CA glue may have a shelf life after use as well as before use. these were ~10 year old pieces.

titebond is looking better all the time.

As a former RC aircraft enthusiast, let me back this up, and add.

CA glue is great for quick-assembly. Unfortunately, it sucks at most everything else. All the kit instructions I ever saw practically demanded that we do the wing join with epoxy, and the slow-set kind. (Wing join is where you join the left and right main spars together, and is a VERY critical joint on the plane.)

CA is also very prone to shock breakage. I remember gluing a part just a bit wrong, and noticing it the next day. It was a small piece glued to the side of the main spar. Slid a heavy square pointed (I think I used a box-end wrench) piece of metal at the joint, and it popped right off. A little sanding, and you'd never know.

Try that with cured epoxy.

JPG, I know that people say that finishes aren't water tight, but would a couple extra coats of decent varnish help?

steve

[charlese]

Have I got it correct Chuck???:)

Yep! I believe so!

BTW you may enjoy calculating your predicted wood movement figures using the formula 13-2 in chapter 13 (page 15) and coefficient values for radial and tangential found in table on page 16 & 17 of same chapter. Have a ball! I'm sure you won't be disappointed over the small amounts of movement. Here's looking forward to what you find.

Ive done some of these calculations for a table I was building and found predicted movement was a lot less than than I had thought.

The tricky part about that formula is it only predicts true radial and true tangential grain. Rift grain is somewhere between the two. (True tangential movement is used for true quartersawn boards.)

[JPG]

As a former RC aircraft enthusiast, let me back this up, and add.

CA glue is great for quick-assembly. Unfortunately, it sucks at most everything else. All the kit instructions I ever saw practically demanded that we do the wing join with epoxy, and the slow-set kind. (Wing join is where you join the left and right main spars together, and is a VERY critical joint on the plane.)

CA is also very prone to shock breakage. I remember gluing a part just a bit wrong, and noticing it the next day. It was a small piece glued to the side of the main spar. Slid a heavy square pointed (I think I used a box-end wrench) piece of metal at the joint, and it popped right off. A little sanding, and you'd never know.

Try that with cured epoxy.

JPG, I know that people say that finishes aren't water tight, but would a couple extra coats of decent varnish help?

steve

Sorry I have not replied sooner, but Chuck was getting pretty much all my attention! I intend to finish the entire gavel with a tung oil/poly finish that is rubbed off after 10-15 min soak in. Thus not a very good vapor barrier! That finish be a personal preference.

Thanks again Chuck!

I am about to cut/glue up the handle this week.

Thank you ALL for your help and suggestions. You SHALL be seeing the finished gavel by Christmas!