Request for advice on timber prep for moulding planes.

[Plumberpete]

As has been discussed elsewhere on this thread, steam drying the timber reduces moisture content more-so than airdrying making it marginally lighter in weight and therefore the cell structure more widely spaced (hence spongy).

It's got to be a stretch of imagination to suggest that drying wood, any species, somehow causes the cell structure to become more widely spaced. For the cell structure to become more widely spaced indicates that somehow the links that hold the cells together loosen causing the cells to be move apart somewhat. What happens as wood dries is the cell walls distort, and the drier the wood the more they distort. As the cell walls lose moisture below fibre saturation point they shrink and buckle and this tends to reduce the volume of each cell's lumen. Indeed, the warping that occurs in wood as it dries is because of shrinkage and distortion of all the cell walls, with the greatest shrinkage (in all species) following the same direction as the roughly circular growth rings. Slainte.

You have put it in much better words than I ever could. Thank you!

 

[Corneel]

The antique plane makers used air dried beech, but they sure let it dry for a long time! 4 to 5 years I have read. I guess to get some moisture cycles under the belt of the piece of wood. That helps the hysteresis effect.

 

[Trafalgar]

Kiln-drying is fine as long as it is performed well. The problem is that a lot of times it is not.

 

[graween]

Hi,

Some pointed you to videos about moulding plane making. Just for the record you might as well check Tod Herrli video on hollow and round plane making.
It is well done and worht it.
I also have Larry William video, Whelan and Finck book. They're worth it.
Tod's video is a little more practical and straight to the task. Larry gives some more details on some parts.

Like often been able to watch some one do it helps a lot.

And yes steamed beech is more stable than regular one. Now as you want preferably quarter sawn beech, and since the section is not very wide for those planes, it's ok. You probalbly want to make sure the'yre acclimated to your shop, since you're likely to make and use them in the same place.

Regards.

 

[custard]

Depending on where you store it, 20% moisture content is fairly normal for externally air dried timber in the UK. You need Kiln dried which changes the cell structure for ultimate stability.

Dont get this at all. The great old woodies were air-dried and of course at a stage the wood goes into an internal environment to bring it down to workshop-normalised. How does kilning change cell structure, and if so how for the better. Air-dried is far superior in my own experience, and will behave excellently over decades or centuries, as our old tools testify.

p.s. no to airing cupboard also. Far too fast, aggressive. Get it into a dry workshop, patience pays dividends.

From what i understand once you get timber down below about 8 or 10% MC (which for most practical purposes requires kilning) it partially loses it's ability to take up moisture again because of a change at the cellular level, so if a kilned and an air dried piece are subsequently subject to variations in humidity, then the kilned piece will show a smaller range of MC, and hence move less.

 

[Sgian Dubh]

From what i understand once you get timber down below about 8 or 10% MC (which for most practical purposes requires kilning) it partially loses it's ability to take up moisture again because of a change at the cellular level, so if a kilned and an air dried piece are subsequently subject to variations in humidity, then the kilned piece will show a smaller range of MC, and hence move less.

There's truth in that custard. The cause is a hysteresis loop where wood cells distorted because they've been dried to very low MC levels won't return to their original shape and form when they regain moisture. For example, take a tangentially cut piece of wood dried from green to 15 percent MC whereupon the drying process is paused. Let’s say the width measures exactly 400 mm (15-3/4”) at this MC. Further drying of the wood to 6 percent MC could realistically result in the width finishing at 398 mm (~15-11/16”), a reduction in size of 2 mm (~3/32”). If the wood then returns to conditions that take it back to 15 percent MC it will be found on measuring that it probably hasn’t quite reverted back to 400 mm (15-3/4”). It may actually measure 399.5 mm (~15-23/32”).

In another example of a hysteresis loop occurs where a test sample of wood dries to an EMC at a specific set of temperature and RH conditions followed by further drying of the sample to a very low EMC. Lastly, allowing the sample to regain moisture by returning it to the previous conditions of temperature and RH at which the EMC was determined results in the wood reaching an EMC about 2% lower. Further, wood dried from green at high temperature and with steaming reaches an EMC about 2- 3% less than wood that is air dried.

The consequences of being aware of this information for makers of wooden planes I'll leave for them to decide: I know in broad terms how I might proceed if that was the task I'd set myself, which isn't the case. I just use what I know to help me design and make furniture. Slainte.

 

[condeesteso]

Just wondering Bern, how's that beech doing? Thought it might be getting quite close by now.

I have a bit of beech now also, but doubt I have the patence to make a plane, let alone a set!

 

[Berncarpenter]

Hi Douglas
Well I've got the whelan books on planemaking and the Larry Williams DVD from Alex at Classic Hand Tools . Had a good chat to Phill Edwards at the Yandles show and gained some good advise . I haven't checked the MC latley , but everything looks good with no signs of any drying defects at all. Got plenty of projects on at the moment thats keeping me busy but will keep you posted when i make a start on the planes.

Thats a hell of a lot of beech you got there Douglas , should keep you warm this winter

Cheers Bern