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Main Boards => The Bowyer's Bench => Topic started by: MaceG on April 05, 2009, 03:18:00 AM

Title: Hot box question
Post by: MaceG on April 05, 2009, 03:18:00 AM

Without a moisture meter, how do you know how long to leave the stave in to bring it down to your target level?

Title: Re: Hot box question
Post by: Pat B on April 05, 2009, 10:17:00 AM

If you have a postal scale you can measure the weight loss over a period of time. When your stave's weight loss stabilizes for a 3 day period, your stave should be fine for bow building. Reducing your stave to almost bow size will allow it to dry quicker and give you a more accurate weight reading.

Title: Re: Hot box question
Post by: Dano on April 05, 2009, 10:41:00 AM

Pat's method is good. I like to use temp and RH (relative humidity)to calculate moisture content. You can get a good temp/RH meter at the hardware store and use this calculator,  http://www.woodbin.com/ref/wood/emc.htm

It takes about the same time to bring down the MC, as Pat said.

Title: Re: Hot box question
Post by: MaceG on April 05, 2009, 12:11:00 PM

Thanks, Pat. Sounds like a good way to go. Is .1 oz accuracy enough?

Dano, the temp/RH meter is used to measure the temp and RH inside the hot box?

Title: Re: Hot box question
Post by: Pat B on April 05, 2009, 12:28:00 PM

Mace, I've never used the method so I don't know what values to use. I go by sound and feel. After many years of building wood bows, that works for me.

Title: Re: Hot box question
Post by: Dano on April 05, 2009, 02:46:00 PM

Yep, you'll be surprised at the difference between inside and out.

Title: Re: Hot box question
Post by: MaceG on April 05, 2009, 10:19:00 PM

Thanks, Dano.
Sounds like the way to go, if the temp/RH meter is not too pricey.
Would something like this work
 http://cgi.****.com/LCD-Thermometer-Hygrometer-Temperature-Humidity-Meter_W0QQitemZ270364588059QQcmdZViewItemQQptZUK_Gadgets?hash=item270364588059&_trksid=p3286.m63.l1177

Title: Re: Hot box question
Post by: Dano on April 06, 2009, 01:11:00 PM

That link didn't work for me, they are pretty cheap as I recall, Here are a couple that Ace sells.
 http://www.acehardware.com/product/index.jsp?productId=1279391&cp=&sr=1&kw=thermometer&origkw=thermometer&pg=6&parentPage=search&searchId=36772411603

 http://www.acehardware.com/product/index.jsp?productId=3203794&cp=&sr=1&kw=thermometer&origkw=thermometer&pg=8&parentPage=search&searchId=36772369013

Title: Re: Hot box question
Post by: dave_570 on April 11, 2009, 09:09:00 AM

Pat B is correct....wood drys from the center out..that's why it splits...by roughing the bow
shape out first removes most of the surface wood and leaving ur TIPs full width...will dry quicker and u have a better chance of no splitting.

Title: Re: Hot box question
Post by: dave_570 on April 11, 2009, 09:11:00 AM

P.S.. Pat B is also right.....wood weight is the
ONLY way to tell how much moisture has been
removed...u must not have less than 9% or 10% moisture...Bowyers Bible Vol 1.....