Large Platters from Slabs tips?

[Rick Helmig]

I really enjoy maxing out the 22" swing on my G0766 and making big platters. But is it generally a bad idea to use a single piece of non-quartersawn Slabs as the material?

I typically ensure the wood is dry-dry; however, I still get the occasional slight cupping which I really want to avoid.

Got any tips on things to consider when buying slabs for this purpose? Such as should I only pick the slabs that were cut the closet to the center of the log? How about a cut that includes the pitch? Things to avoid perhaps??

 

[Richard Coers]

Big slabs will move because the blank is usually a combination of quarter and flat sawn grain. The wood near the center of the log really moves and the outer grain doesn't. Absolutely stay away from the pith. If you are buying hardwood, try to find a dealer that sells sequential boards. Then you can book match them and the color of the wood at the seam is identical. I see that some of your glue ups are a bit gappy at the seams. Use a jointer and better clamping to draw them tightly together.

 

[Kent Jaffrey]

If the orientation of the grain varies (from flat to rift to quartesawn) within The board you are likely to get cupping with humidity changes as the wood will likely expand/contract more in one direction than the other. That is why when doing tables you usually glue up many narrow boards with alternating growth ring orientation, so when the cupping occurs it is on smaller boards in different directions and the overall table stays “flat”.

The most stable wood would be quarter sawn slabs, or completely flat sawn wood (with hardly any arch in the grain) but then you need really big trees.

 

[Ron Solfest]

Have you considered gluing up your blanks?

 

[Larry Copas]

I saw lots of big thick slabs on my sawmill.

They get sold green, air dried, and kiln dried. Thick lumber takes a long time to dry properly and in reality their is a moisture gradient between the shell and the core. Take more off one side than the other and guaranteed cupping.

Another tip. Slabs from the biggest logs stay flatter than slabs from small logs.

I normally turn platters out of air dried slabs. To combat cupping, I'll turn close to my finish size than wait a few days for the platter to cup and finish turn. Similar to twice turning bowls but on a much shorter interval. Also most of my big platters are about 1/4" thick through the center but sometimes the rim will be much thicker, depending on the design. Being only 1/4" thick through the center helps prevent cupping.

 

[Dean Center]

I have only limited experience with platters, but have been using walnut plates for about 6 years. They were made out of kiln dried lumber, flat sawn, but stayed flat until about 6 months ago. Not sure why they cupped this late, but my granddaughter has been living with me and she is probably not as careful about avoiding dunking in water. Rats.

 

[Doug Freeman]

I always 2 turn platters. ~14” large as I go. Wrap in kraft paper to dry. Even “dried” slabs will move - usually not completely dry, and stress relief. I cut some on both sides, working the thickness down, to help with stress relief. Using dried lumber to piece together a project works great, just give a few days for the moisture from the glue to evaporate.
The tighter the grain arch (close to the pith) the more it will move.

 

[Russ Braun]

Have you considered gluing up your blanks?
View attachment 44853

Now you’re “cooking with fire” Ron!!

 

[hockenbery]

Now you’re “cooking with fire” Ron!!

Ha!
Every few years a “pure Woodturning” group emerges with simple rules like 50% of the work must be done on the lathe.
Then someone points out that 50% rule eliminates most Natural Edge bowls where blank collecting, blank prep, sanding off the lathe and finishing take much longer than the turning.

And when gluing up remember how much fun :-( it is to turn glue

Room for everything in the woodturning tent.

 

[robo hippy]

Quarter sawn slabs will cup less than the ones more towards the outside of the tree, but wood is never stable.

robo hippy

 

[Richard Coers]

You'd need a 4' diameter tree to get a quartersawn 22" diameter blank. Those are pretty rare!

 

[Rick Helmig]

Thanks all for the feedback.
Best Regards,
Rick

 

[Don Wattenhofer]

You'd need a 4' diameter tree to get a quartersawn 22" diameter blank. Those are pretty rare!

And as you get closer to the pith the annual rings become more circular and the more chance that hidden knots will appear.