Scott M Posted February 24, 2013 Report Share Posted February 24, 2013 I'm going to be doing some steam bending so I bought some air dried walnut and a pinless moisture meter. After an initial pass throught the jointer/planer I was getting readings right around 48%. I stickered them and came back the next morning and the MC had dropped to about 26%. After another pass through the jonter/planer the reading are back up to 48% again. Is this normal? What is the real MC of the wood? The moisture meter indicates it is scanning to a depth of 3/4". Quote Link to comment Share on other sites More sharing options...
wdwerker Posted February 24, 2013 Report Share Posted February 24, 2013 Pinless meters can be off due to some situations. Check the center of a board from side to side and end to end, smack in the middle. Moisture leaves a board faster from the ends and surfaces, when you plane it you expose the wetter center. They recommend a year to the inch of thickness as a starter guideline for air drying lumber. The wood needs to be stickered to space it apart and allow air to move. It also needs to be kept out of the weather, shed, barn, garage, something to keep the rain and snow off. Patience is key, don't get in a hurry when the moisture content is that high. Quote Link to comment Share on other sites More sharing options...
Boatworks Today Posted February 24, 2013 Report Share Posted February 24, 2013 You'll need to make sure your meter is calibrated for the particular species / density of the wood to get accurate readings. How long has the wood been drying? Also, how thick? If it's in the 40% range it was probably freshly cut. If this is your first time working through the steaming process, this may help with a few questions Quote Link to comment Share on other sites More sharing options...
Scott M Posted February 25, 2013 Author Report Share Posted February 25, 2013 The meter has been calibrated for walnut so I think I'm good there. I don't know when the wood was cut but it was 6/4 and I'm looking for a finished thickness of 4/4. The research that I have done suggests a MC of 20-25% is the best time to steam bend. If the 26% readings that I'm getting are correct them I'm almost there but I'm concerned abut the higher reading right after milling. Are readings right after miling acurate or do I need let them aclimate again before I get a good reading? Quote Link to comment Share on other sites More sharing options...
wdwerker Posted February 25, 2013 Report Share Posted February 25, 2013 If I had a piece with a big cracked end on it I would cut it off and test the fresh cut. That will give you a reading on the center moisture content. Or borrow a pin meter and drive the pins in someplace likely to be cut off eventually . At least you don't need to get it very dry to steam bend it. I am not an expert on moisture content but I have had problems from trying to build from wet wood and it cracked and twisted on me as it dried out. Quote Link to comment Share on other sites More sharing options...
Boatworks Today Posted February 25, 2013 Report Share Posted February 25, 2013 When it comes to steam bending, moisture is king . 20-25% is good, but more isn't necessarily a bad thing... It's after it's bent that you'll need to allow it to dry before putting into it's final structure. One other tip that I didn't include in the video is to initially over bend the piece to account for spring back, and as it dries (over the next couple of weeks) the bend may actually increase somewhat as the fibers tighten up. If you keep it in a form there shouldn't be any issues but if you allow it to "sit free" it will move somewhat. For example the toboggan that I built; the initial finished curl that I was going for was 10" (going off of memory) but since then it's actually tightened to a 9" curl on it's own. Come Summer with higher humidity this may actually spring back somewhat, but thought I would mention it... What are you bending the pieces for? Quote Link to comment Share on other sites More sharing options...
Trip Posted February 25, 2013 Report Share Posted February 25, 2013 great video -- after all's said and done, what was the % keepers from your bending... i think i saw 3 fails and about 6 or 7 wins.... Quote Link to comment Share on other sites More sharing options...
Boatworks Today Posted February 25, 2013 Report Share Posted February 25, 2013 great video -- after all's said and dome, what was the % keepers from your bending... i think i saw 3 fails and about 6 or 7 wins.... In total I had 14 bends and 10 were keepers :-) Pretty good for me! I typically try and account for 30% loss.. Sometimes it's better, others it's worse ... But on average 70% success... The MC% when I tried to bend those was 25% BEFORE I put them in the dunk tank overnight. Following morning I would guess 40 or better.. On my meter 35% and higher is pretty much standing water... Quote Link to comment Share on other sites More sharing options...
Scott M Posted February 26, 2013 Author Report Share Posted February 26, 2013 Boatworks I'm building a bow are morris chair, similar to this one. Here are pictures of my first 2 practice runs. I ran across a lot of sites suggesting that is was possible to bend not only fully seasoned air dried lumber but also in some cases kiln dried so this first attempt is with air dried lumber at 7-8% MC, it was a lot more springback than I was expecting. This is my second try with my current batch of lumber at about 26%. Much better results. I hadn't planned on having to let it sit in the form and dry so I guess I'll be building a second one. P.S. - Love the toboggan. I grew up in WI and remember cramming 8-10 people on one and flying down the hill. I'm in TN now and everyone thinks a toboggan is a hat! Quote Link to comment Share on other sites More sharing options...
Boatworks Today Posted February 26, 2013 Report Share Posted February 26, 2013 Boatworks I'm building a bow are morris chair, similar to this one. That's a pretty minor bend, I'd say that your last try is about as close as you need . As it dries it should continue to pull itself in the rest of the way.. Even if it's a little higher MC% when you assemble it, let the entire piece continue to dry you should be fine (meaning it really cant move too much).. Just make sure that the MC is where it should be BEFORE you apply any sealers or finish. If you're able, please post progress pics on the build!! I know that others (myself included) would really enjoy watching it come together .. Good luck! ~Andy Quote Link to comment Share on other sites More sharing options...
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