Thread: accelerated drying of blanks

Microwave is ideal just never use it for food again. do a search and you should find a few on the matter so I reckon a dehydrator should work

That temperature range is pretty well ideal for drying hardwood once the timber has been brought down to fibre saturation level. Work on fibre saturation level being about 20% moisture content measured as the mass of moisture expressed as a % of the mass of completely dry timber . All moisture meters use that algorithym. You should be able to finish dry your average hardwood in about 3 days from FSP to about 10% to 12% MC

25mm air dried boards reach that MC% in about 6 to 9 months. 25MM squares likely would be there in three months.

You cannot start drying from green with the temperatures available to you. You wouldn't want to exceed 23oC max if you want to start from green and without having close control of humidity I'd suggest you don't try.

A word of caution. Timber drying kilns almost always have a dedicated over temperature sensor that shuts down the process if the set temperature is exceeded. That gives you both fire protection and protection against wrecking the timber. They also have under set point humidity sensors that shuts down the process and floods the kiln stack with sprayed water in the event the set point RH% is exceeded (ie goes lower than the set point in this case).

I wouldn't operate a food drier indoors to dry either food or timber without that level of protection being in place.

To go about this seriously you will have to buy yourself either a good quality MC meter or good quality small scales set that can measure to probably +/- 0.5 gm. It's nearly as bad to over dry the timber as the converse.

You are talking here about acquiring a major chunk of timber technology knowledge if you want to get it right. I wouldn't discourage that in itself but its a steep learning curve. I've been there .


Old Pete

the unit i got is got a small heat element like a fan heater blowing the air outtowards the edge of the base the it goes up the sides with small gaps letting the air pass to each level level a insulated lid on top with a 50mm hole for really hot air to escape and suck in fresh air
will find camera and post a pic or 2

troy

Troy having a heater element below may be a safety issue sap may drip and ignite.
I know when microwaving I use med heat setting and do only a few minutes at a time for a small bowl blank.

If they are pen blanks size they would dry very quick and possibly ignite, once used for wood you wouldn't want to use it for food ever again.

ok i just went and tooks some pics
the base is 390mm diameter and i have about 20 shelves that would bring units total height to about 60 -70 cm high and probably only use 4 or 5 shelves at a time

troy

Originally Posted by wheelinround

Troy having a heater element below may be a safety issue sap may drip and ignite.

thanks for that but the element is in middle of unit and nothing is able to get in the unit also comes with about 4 sheets used for drying liguids like yogurt and stuff i can use as a drip tray or i can always turn something up out of mdf or ply


troy

Originally Posted by wheelinround

If they are pen blanks size they would dry very quick and possibly ignite, once used for wood you wouldn't want to use it for food ever again.

Just wondering why you cant use it for food if it is cleaned out?

The odour off wood permeates and remains behind and then will transpose into food unlike smoking meat etc it can become toxic.

Originally Posted by wheelinround

The odour off wood permeates and remains behind and then will transpose into food unlike smoking meat etc it can become toxic.

Good point Ray. If one wants to use a microwave to dry their timber it might be an idea to buy one of the cheapies on the market today solely for the purpose of drying their wood.
I would imagine blanks for pens would not take much time to dry out ready for turning.

the dehydrater hasnt been used for about 6 years and will not be used for food again so i am prob just gunna give it a go i think

troy

Thanks I didn't know that.

Hey There,

I don't want to hijack this thread, but I just come home from the local woodturners group, one of the guys there was talking about drying timber bowl blanks, he has an old fridge set up with a 100watt real light globe and a dimmer set up, he roughs out a bowl about 350 diameter and about 30-50 wall thickness (Green Jarrah) and in about 6 weeks he can finish it off, he said that you need to have some water in the bottom of the kiln, the humidity should be about 30%, temp about 25-30 degrees. It works for him he's been doing it for about 10 years now.

HazzaB

Originally Posted by HazzaB

Hey There,

he said that you need to have some water in the bottom of the kiln, the humidity should be about 30%, temp about 25-30 degrees. It works for him he's been doing it for about 10 years now.

HazzaB

So I do not need a fridge then just leave it out side more room for the rum

Hi MKY Penturner,,

Have been following this thread with interest. One thing I forgot to mention in my original response is that the vapours from drying Eucalypt hardwood timbers are highly acidic and they will chew any metal other that marine grade aluminium alloy and high chrome stainless steel to bits in a very short interval.

Many folk have attempted to build home made kilns utilising domestic air conditioners or reverse cycle heat pump set ups. The coils in those units last no time at all. You have to have a unit with coils of a metal appropriate to the application.

Why is life so difficult??. Don't ask me!!


Old Pete