Mini indoor "kiln"

[transatlantic]

I've recieved a lot of green Oak beams offcuts (some 4x4" and some 5x5"). Some of it has some knarly cracks, and some of it is currently crack free. My plan to make the most of it, is to rough turn it into box/vase/hollowform blanks before it cracks any more.

I'm wondering what would be the best way to dry these small pieces?

1. A cardboard box kiln, with foil backed insulation and a heat lamp
2. A cardboard box simply full with shavings that surround all the pieces? (does this still need the foil insulation?)

I plan to keep the box indoors, as my shed is pretty damp.

 

[Lefley]

Do they all have a Center Pith going through them like the pictured one. If so they are bound to crack if you do not rough hollow them to allow them to move while they dry. Then go for a slow dry, the slower the better. Anchor seal on all end grain on outside. Not much heat.,

 

[transatlantic]

Do they all have a Center Pith going through them like the pictured one. If so they are bound to crack if you do not rough hollow them to allow them to move while they dry. Then go for a slow dry, the slower the better. Anchor seal on all end grain on outside. Not much heat.,

Yes, most of them appear to have the pith, or are very close to it.

- Anchor seal even after rough turning?
- Slow dry as in just leaving in a box of shavings? or should I also apply the heat lamp? I'm thinking something like below?

 

[RichardG]

Rough turn and hollow ASAP and then put in your damp shed, leave for 6 months. If you'd rather keep in dryer conditions then put in a paper bag or cardboard box first, (add some shavings to slow the drying even further). Your aim is to dry it slowly over min 6 months, the six months come from the rule of thumb that wood takes 1 year per inch to dry and I assumed the turned piece would be ~15mm ish thick. Avoid any form of heat including the Sun.

I haven't sealed my rough turned bowls but the slower it dries the less likelihood of splitting. so won't do any harm.

 

[Adam W.]

Is that a picture of one of the actual pieces?

If it is, you could cut to the pith on two sides, effectively quartering the log. It won't split, but will dry into a rhomboid shape and you'll also end up with two quater sawn boards to use for something else.

 

[Paul Hannaby]

Most of what is sold as beams is the centre square that was left after all the rest of the wood was milled. They usually have the pith in them which makes them very susceptible to cracks as they dry. On way round the problem wold be to cut the beam to a smaller size to lose the pith but depending where it is, that might not leave much wood!

 

[Lefley]

Is that a picture of one of the actual pieces?

If it is, you could cut to the pith on two sides, effectively quartering the log. It won't split, but will dry into a rhomboid shape and you'll also end up with two quater sawn boards to use for something else.

but they are only 3x3 and 4x4 inches. He would have noting left.

 

[Lefley]

Yes, most of them appear to have the pith, or are very close to it.

- Anchor seal even after rough turning?
- Slow dry as in just leaving in a box of shavings? or should I also apply the heat lamp? I'm thinking something like below?

View attachment 129313

With the pith in, I’d put anchor seal on outside on bottom end grain, or your going to lose a lot of them even though you rough hollowed. A lot of people turn goblets with the pith in those 3x3 blocks. You can finish turn while wet and make sure pith is off Center when making a goblet so stem is s nice strsight grain piece of wood.

 

[Adam W.]

but they are only 3x3 and 4x4 inches. He would have noting left.

4x4 and 5x5.

He'll have nothing left if it degrades from drying either. So I guess if it needs an inch off two sides to stop that, it might be worth it.

It may even be able to get rid of the pith with a slice off one side.

 

[Lefley]

4x4 and 5x5.

He'll have nothing left if it degrades from drying either. So I guess if it needs an inch off two sides to stop that, it might be worth it.

It may even be able to get rid of the pith with a slice off one side.

My apologizes Adam. I misread the sizes. I still believe the lights should not be used, as in my opinion with the pith included or barely just cut out, it needs to be a slow dry. Anything to speed it up is asking for trouble, if you don’t use anchor seal, brush a bit of shellac or water and glue on outside end grain. It will help. The inside makes its own little environment and dries a little slower while the outside will dry faster. You want the piece to dry evenly all together.

 

[Adam W.]

That's OK, it's easily done.

I agree about not trying to force dry it too.

 

[transatlantic]

Thing is though, on these blanks, it's not actually the pith area that has cracked. The pith is fine, it is the outside edges leading to the pith that have cracked.

A bit like this (not my photo)

Or did you mean the pith area will crack once roughed out?

 

[transatlantic]

Oh, and all the pieces have had their ends sealed with Chesnut End Seal. as it's going to take me a while to rough them all.

 

[Lefley]

Oh, and all the pieces have had their ends sealed with Chesnut End Seal. as it's going to take me a while to rough them all.

They will still crack with end sealer on them. Just takes longer if end sealed. And yes the picture you show is exactly what I’m talking about. Lots of turners when they get good wet wood and can’t get to it. Will submerge it in water so it can’t dry out then rough it .

 

[Adam W.]

@transatlantic On a boxed heart section, like the one you have shown, they split on all four sides.

They crack towards the pith because the tangental shrinkage is roughly twice the radial shrinkage, so it pulls the section apart at its weakest point, the medullary ray which originates at the pith

 

[Richard_C]

The bulbs in your picture don't look like heat lamps to me, they are the decorative sort that people use in mock-coal fireplaces. I would think about an ordinary low wattage incandescent bulb. Even then a 40w bulb uses about 6 kwH a week, assuming electricity will be close 25p per unit soon you could end up paying £40 if you leave it there for 6 months.

(Maybe just stand it somewhere warm. In our house the boiler feed/return runs under the floor in the spare bedroom so there is a warm patch.)

The methods suggested above might be better value.

 

[Lazurus]

I think you may struggle to get decent blanks from these beams, maybe better to sell on and get some better quality, and avoid a disappointing 6 month or more wait

 

[Sgian Dubh]

If you're needing or wanting to build a small cabinet type of thing to try and dry wood you're better off looking for an anti condensation cabinet heater rather than using light bulbs. Unlike a bulb cabinet heaters are robust and last for years with continuous use. Farnell is one supplier and their power ranges from about 20W upwards. Slainte.

 

[transatlantic]

I think you may struggle to get decent blanks from these beams, maybe better to sell on and get some better quality, and avoid a disappointing 6 month or more wait

I'm fully expecting a lot of failures. I'll see how it goes.

 

[transatlantic]

If you're needing or wanting to build a small cabinet type of thing to try and dry wood you're better off looking for an anti condensation cabinet heater rather than using light bulbs. Unlike a bulb cabinet heaters are robust and last for years with continuous use. Farnell is one supplier and their power ranges from about 20W upwards. Slainte.

Something like this RS PRO Enclosure Heater, 20W, 230V ac, 70mm x 65mm x 67mm | RS Components ?

So would this just be an empty box with the heater hanging from the top?