Advice sought, slab table top prep.

[NOCO Jim]

I have a couple dozen slabs, about 3 to 4 feet square, more or less and about 2" thick, hard maple.  I have had it up off the ground and stickered outside in northern N.Y. under old tin since last October.   I do quite a bit of artistic blacksmithing and I want to use these slabs as tops for artistic forged bases.  Anyone want to walk me through what you would do to make these stable and ready for use as table tops?

[doc henderson]

you might check MC%.  are they covered for rain but open to air?  are they relatively flat?

[Ianab]

Wood moves as it dries, so the best way to get it stable is to get it dry. If it's now outside it will probably only dry down to 12-14% MC. Problem is if you then make it into a table and bring it inside it's probably going to dry out more, down to 6-8% depending on your house. That's enough to cause noticeable movement. 

So like Doc says, you need to check the moisture content, and if it's down under say 14%, then bring the wood inside (climate controlled space) and let it dry down to the right moisture to match. After that it should be relatively stable, so you can then start planing / sanding / filling holes with epoxy etc (and make some bases) 

[Crusarius]

I can only offer encouragement. but really look forward to what you can come up with. I have some pretty nice 12' long slabs I want to make a big conference room table out of, but really need a buyer before I build it.

[WDH]

The slabs are not dry enough to make flat table tops like Doc said.  Bringing them inside and stickering them in an out of the way place in a climate controlled building will get you there in 3 or 4 months.  Do you have any way to check the moisture content?  It is very difficult to do if you do not have a good moisture meter. 

[NOCO Jim]

So I need to move them into conditioned space and patiently watch the moisture content.  
Would planing them now speed them along any?  
It's possible I could bring a few in to the house where the 24/7 wood stove produces some very dry air during the heating season.  
What is a good method for measuring moisture content?  I have an old prong moisture meter I use for rough estimating my firewood....but how to accurately measure the core of a slab?
I am willing to consider assembling a kiln.  What kiln designs might be suitable?  I could just dive into the forums and mine for info, I suppose but if there is a simple, proven design suggestion I'm happy to hear it.

[Ianab]

Would planing them now speed them along any?

Not significantly, and chances are you will have to plane them again after they finish drying. 

What is a good method for measuring moisture content?  I have an old prong moisture meter I use for rough estimating my firewood....but how to accurately measure the core of a slab?

Best is a good quality meter, with probes that insert into the wood to measure below the surface. But another way is to weigh a piece (with some accurate scales), then put it back to dry for a week, and weigh it again. If it's now lighter, it's still loosing water, so let it dry more. When a couple of weeks go by with no change in weight, it's stopped drying. You won't know exactly what the number is, but it's as dry as it's going to get in that environment, (Equilibrium Moisture)  

am willing to consider assembling a kiln.  What kiln designs might be suitable?

For small amounts you can build a "kiln" out of plastic film, with a box fan and home dehumidifier. Keep the humidity in there low enough and circulate the air, and wood will dry down to match the conditions. Just be aware that you won't have a high heat to kill bugs or set the pitch in pine etc, so there are some downsides. But you can get wood dry this way.  Next step up is a solar kiln which is something you can build yourself fairly cheap, and needs little power to run (a couple of fans). The drying heat comes from the sun.  

[kantuckid]

Gun stock makers have used a drying box to process their stock blanks over the years as most don't like kiln dried stock wood to work with plus it's hard for most stock makers to utilize a kiln. A light bulb does the heat in ones I've seen. 
Microwave oven and my gunpowder scale give me highly accurate moisture but limited by the sample issue. In your case there might be some edges you'll later remove to play with but the core of the wood is the true objective.
In my area you'll never get to 14% outdoors and I doubt NY state has that possible either, even covered up well. 

[Crusarius]

Most of my stuff checks out at about 15%. Seems the only way to get it any dryer is in my dad's basement.

[NOCO Jim]

What about moisture meters?  The one I have is an old analog prong type thing someone gave me.  Looks to be pretty dated.  
What is a good, fairly accurate one for hobby level work?  
I am wanting to monitor +/- 2" hard maple slabs as well as +/- 5/4" sawn various hardwood planks.

[doc henderson]

I have an older and a new Wagner pin less.  gone up in quality and price.