Pondering moisture meter use for wood turner

[Bill Bolen]

I have been wanting a moisture meter for a few years thinking it might be a big help when I think it is safe to finish turn a bowl rough out. The more thought I gave it the less desirable a meter really sounded. The meter really only gives you a moisture reading for the surface of a piece of wood. I did take advantage of the Lowes $10 meter and kind of proved this thought to myself. I tested a few very large Walnut blanks that I harvested in April of this year. The sealed square blanks had a surface reading to 9% but when I cut them to round blanks and exposed the interior of the wood the moisture readings were over 30%. Looks like I will have to depend on the weight of the blanks as a true indicator and use the meter to confirm the moisture content once finish turning is under way. Any thoughts?

[Chris Burgess]

You know I have been finding this out myself as I also picked up the $10 meter. My thinking is the meter would be good on a rough out that is drying but not so much a nice thick chunk. I have been debating a scale for some time and HF has one for for $12 that goes to 1000 grams (2.25lbs) and a $20 one goes to 5000 grams (11lbs) but concerned about quality and more so durability......my shop is a mess and things fall on other things.

[Lee Koepke]

Bill ... I have come to the same conclusion. Read on here once that the pins usually only read 1/8" into the wood, so its less useful to turners. I only spent $12 for a cheap on at HF ...

Chris ... I bougt the 11 lb scale from HF a few months ago, and it seems to be working just fine. I keep it in the box on a shelf when not in use to reduce exposure to the dust and falling things.

[John Keeton]

Bill, I have a Lignomat from my flatwork days, and on rare occasion, I have used it to test a piece that I have cut from a larger burl or chunk of wood. That is about the only way to get any true guidance on the possible movement, etc. Otherwise, you are simply testing the exterior. In flatwork, I would cut a board, and test the middle of the cut. That would tell me the moisture content of the lumber, assuming all of it was cut at the same time and approx. the same thickness.

[Scott Hackler]

Bill, I too bought one of the $10 specials and have found it handy in the sense that I turned a vessel to finish thickness and left it overnight to dry. I checked it (inside and out) to verify it had equalized to "dry". Registrering a 6.5% on both surfaces helped to reassure me that I could start piercing without any issues.

I have also checked a couple rough outs after they had gone though the Dna drying process and I checked 4-5 different spots to see where the bowl was in the drying process. I know that 1/8" into the wood doesn't show the interior, but the rough outs are only 1" thick so by checking both sides I figure that there is only about 3/4" of the thickness that the meter cant really check. That is good enough for my purposes. Before (and I still do it) I relied on the smell test. Still smell the Dna...still wet.

[Cody Colston]

Pin-type moisture meters are good above 6% MC and below 30% MC. As has been noted, though, the wood must be checked on it's interior. I do like John and rip a test piece and then check the newly exposed long grain, also with a Lignomat. You can also drive finish nails into the wood and use alligator clips on a wire to connect the nails to the meter probes. That will give you a better indication of interior MC than just using the pins.

The most accurate way of measuring MC is the oven dry method. With a scale that weighs in grams, weigh a test piece then place it in an oven at 215 - 217 degrees F. Weigh it periodically until it is no longer losing weight. This is the oven-dry weight. The moisture content can then be determined by the following equation:

MC% = (initial weight - oven dry weight) x 100
................... oven dry weight.................

The other way is to pay several hundred dollars for a pinless meter that can be calibrated for temperature and species.

On turnings, I use a highly scientific method...I guess at it. :)

[Bill Bolen]

Chris, I also use a postal scale that came off the "bay". Weighs to 35 pounds and seems just right for rough outs. It was about $20 or so.

[Jeff Nicol]

Bill, You are on he right path, the cheap testers are useful to a point and then in the end it is all about time and weight if you want to keep close tabs on the drying. I turn so many rough outs that I usually have something on the shelf for customers to look through and find a piece that will fit there needs. Or if I get wood from someone and they want me to use that I try to get it turned and dried as soon as I can with my floor dry and other methods incorportated to get it down to a few weeks instead of a few months.

We all need more tools, so we really don't need an excuse to get more!

Jeff

[Michael Mills]

I do about the same thing as Scott. I have a Delmhorst and the pins are 3/8 long. I also try to use the Grumbine method of turning the foot thinner than the rim (a 1” thick rim would have a ¾” thick base). I also typically use a recess rather than a tenon and that probably makes it more accurate.
Not perfect but few things are.

[Kyle Iwamoto]

I have a Lignomat, and find it marginally useful for all the reasons stated before. I find it informative and "fun" to play with, but it really only measures moisture after you're done turning off the exterior wood. Oh, it's not that dry yet.... So, I use Cody's method, and take a guess.

[Alan Zenreich]

It's been said that "a man with a watch always knows what time it is, but a man with two watches is never sure".

So here are three photos comparing the General pin meter (set to wood) with a Ryobi pinless meter (set to hard wood)


Square dry mahogany
Round waxed walnut bowl blank
Roughed out pecan bowl that had been soaked in Turner's Choice for 24 hours and allowed to dry for 72 hours.

Your guess is as good as mine as to what the number mean < vbg >

[Clint Baxter]

I have two Lignomat meters, one pin type and one pinless. The pinless one can be set to measure either 1/4" deep or at 3/4" deep. You need a relatively flat surface for it though so maybe it could be used on the bottom of a bowl, but I don't think it would work on the sides. The nice thing about this meter is that you can even get an idea of the MC of wood that is still wax coated. I've found the two meters are pretty close when you compare the 1/4" deep setting of the pinless to the the pin type meter. And on pieces that I know are drying out, the 3/4" setting will normally come in at a higher MC. The pinless meter is pretty pricey, but does work well for it's intended uses.

Clint

[Steve Kubien]

Bill, I see no value for a moisture meter for 99.9999% of turning applications. A decent, consistent scale is all you need (ok, and a notebook and a pen). This is even more true if you use some method to speed drying (DNA, fridge kiln etc). I use a fridge kiln myself.

[Curt Harms]

You know I have been finding this out myself as I also picked up the $10 meter. My thinking is the meter would be good on a rough out that is drying but not so much a nice thick chunk. I have been debating a scale for some time and HF has one for for $12 that goes to 1000 grams (2.25lbs) and a $20 one goes to 5000 grams (11lbs) but concerned about quality and more so durability......my shop is a mess and things fall on other things.

I have the 11 lb. one. If works pretty well -- if I can get it to turn on. It seems like the on switch has some internal corrosion. If it hasn't been turn on for a while I have to push the button a number of times to get it to come on. Once it comes on it'll work okay until it sits for a while. It does seem pretty accurate weighing things like canned foods or other known weights.

[Josh Bowman]

Bill, I see no value for a moisture meter for 99.9999% of turning applications. A decent, consistent scale is all you need (ok, and a notebook and a pen). This is even more true if you use some method to speed drying (DNA, fridge kiln etc). I use a fridge kiln myself.
Not trying to hi-jack this thread, but what's a fridge kiln?

[Steve Kubien]

Here you go Josh. This is a link to my blog where I describe how I built and use my fridge kiln.
http://greenleafwoodstudio.blogspot.com/2011/03/building-and-using-homemade-wood-kiln.html