Prevent discs from checking?

[Davericher20]

Hey guys, first post and a complete newbie based out of Canada so go easy on me. Not sure if the Mill section or here was better to post in, hope you can help.

The Wife started a business last year (ARicher designs) doing various kinds of art and we always wanted to cut wood discs and do art on those. I personally have always had the desire to make coffee tables and end tables out of slabs as well but thats always only been a sparkle in my eye. Till now.

The discs is where I ran into a problem. Haven't got into the slabs yet.

On a whim one day I went to the local dump and picked up the free firewood stumps they had, loaded them in the car and from there went and bought a chainsaw (measured out the stumps and I needed a 24"). So I bought a Stihl MS362

Talked to the guy about our project and he said I would need an Alaskan Mill and a ripping chain, fine, placed the order for those.

 

 

As any man would do I used my new badass chainsaw just to use it. Sliced a few discs off of the stumps I had and voila! I had just taken initiative to help get on the path of self sustainability and am now in a new class of man!

 

 

Until the discs cracked. (1" thickness)

And warped...

 

 

Well, the alaskan mill came in

 

 

 

And I'm in love with that too.

 

Before I use it I wanted to get professional opinions.

I did some research and found a solution you're supposed to apply immediately after the piece is cut, or have the tree dry out for a year or so....I can't have that.

Our work is custom so the pieces would be cut, and then drawn on and shipped out immediately, we can't have them cracking when they're in the customers possession.

I can appreciate that a special type of care needs to be taken with this, but I'm looking at the least amount of time to ensure these will not crack on us.

 

Would polyurethane work to seal in the moisture?

 

Appreciate any help/advice

Cheers

[biggarlogs]

dry them slowly away from direct heat and repalce moisture with linseed oil ,and it might work.i dont think there is an easy quick method ..it all takes time:thumbup:

[Woodworks]

Stopping rings shrinking and cracking is no easy matter. A few years ago there was lot of talk about polyethylene glycol (PEG). The idea is that you submers the wet wood in PEG and it displaces the water in the wood without it shrinking. I have never used it myself only read about it. A quick google found this http://www.leevalley.com/en/html/05k9805ie.pdf

[Ty Korrigan]

Man, I love your humour!

Great angry baby there:thumbup1:

Ty

[JLA Arborists]

Stopping rings shrinking and cracking is no easy matter. A few years ago there was lot of talk about polyethylene glycol (PEG). The idea is that you submers the wet wood in PEG and it displaces the water in the wood without it shrinking. I have never used it myself only read about it. A quick google found this http://www.leevalley.com/en/html/05k9805ie.pdf

 

Mary rose was treated with PEG so she wouldn't dry out too fast. She was underwater for over 400 years.

[se7enthdevil]

i think your best efforts will be with as timber that has a low radial shrinkage. 4% and lower should be ok so maples and buckeye for a start.

 

once you've cut the disc seal the end grain with something that won't penetrate too far (i use pva) and leave for 6 months or so. write the weight of it on the disc and after 6 months weigh again to see if it's lost enough moisture. you will loose discs but you can still use them to see just how much weight a bit of wood needs to lose from the rest of that same tree.

 

with the operation you are trying to pull off you cant stop discs cracking at will, it's what they do.

 

patients will be needed and as others have said lots of time but if you cant spare it then do the drawing with the splitting in mind.

[daltontrees]

I am having good results painting the ends once with 50:50 turps:varnish mix. If anyhting it takes the wood lonmger to season because it can only dry out through the sides.

 

As seventh devil says, choose species that dont have high shrinkage. Ash for example (and your photo looks like Ash) is ridiculous for shrinkage. You can hear cracking in stems as you ar dismantling them, as radial tension is released.

 

Conifers at the nodes can't crack and the grain effect is fabulous.

[se7enthdevil]

ash has a high shrinkage but can actually be good at not splitting so my earlier statement may not be completely accurate.

 

often it can be down to how the wood behaves as well as it's mechanical statistics.

 

the piece of black walnut pictured is a good example of a wood that will be hard to stop a split as walnuts often have a star shake but others like beech ash and maple can often be without and dry completely with no splits.

[aspenarb]

An old boy that used to buy rings from me for turning used to rub candle wax on both sides so it dried from the outside in if that makes sense.

 

Bob

[morten]

As others have already pointed out, to limit discs cracking, you need to do two things:

 

1. Choose a wood species where the shrinkage is small, and without too much difference between the tangential and radial shrinkage rates.

 

2. Slow down the drying process, to get an even moisture level throughout the log. This avoids the cells of the outermost areas drying out (thereby shrinking) before the centre, causing cracking. Moisture is transported much faster through end grain than across it, so treating/covering the end grain is a good idea. But don't cover it too well, as you might quickly get discoloration from mould. Wax is generally used.

 

Look up some shrinking rate tables and other resources:

 

- Wood Shrinkage Table

- Shrinkage