Problems with wood bowing after resawing
tkerestes
| Posted in Power Tools and Machinery on
I have justed started resawing. In the past, I did most of the resawing on a 12 inch craftsman, but wanted to get serious so I bought the 14 inch Laguna.
For a current project I resawed a 8/4, 10 wide, 48 inch long piece of red oak to use as bookend for the bench seat. I used the 1- 1/4″ laguna resaw blade and everything worked great, but the two pieces bowed out ward from the blade. Why did this happen? Does the grain of the wood impact the resulting resawed pieces? Someone told me it was moisture. I bought the wood from the hardwood shop I use all the time.
Thanks,
Tom Kerestes
Replies
Wood moves. As a result, internal stresses can develop. You may have had an 8/4 board with cup and or twist, that you jointed one face straight and planar, planed the other side parallel, Jointed one edge and ripped the other parallel. Now you have a flat, straight, and square board.
Resaw it down the middle and you can have two boards that need all 4 faces machined again to create usable lumber.
It's the nature of the beast.
Greg
•••••••
Exo 35:30-35
Thanks... I kind of figured that may be the case... Have a great weekend
The moisture difference between the inside of the board and the outside is almost certainly a factor, but also tensions within the board may have been released.
Sometimes too, the kiln drying of the boards results in case hardening which is better explained in this URL
http://www.ces.purdue.edu/extmedia/FNR/FNR-132.pdf
Hope that helps
Eric in Calgary
Yes that is what happens. It is regrettable there has to be so much waste. I try to resaw off some thin stuff from the hight spots to use as decorative veneer if possible rather than take it all off with the jointer/planer/hand planes and just turn it into useless shavings. I still throw out bags and bags of hand plane curls etc.
With a fairly sure expectation of failure I have tried stickering and weighting even thin stuff. It just sprang back to the way it came off the saw. No surprise.
Just the way it is.
roc
Give me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
According to Timberwolf successful re sawing is a combination of blade tension, blade set, gullet, the specific wood wetness and height, and proper speed for the particular wheel size of your band saw.
Right............this is not the answer you want and the right answer requires reading notes by the founder of the company in the spring - summer catalog. I am going through the process to set my 21 inch saw up, and I think you would be interested in the info. For years I was in the dark on this issue but get the catalog and read up there is a definitive, detailed answer.....and an 800 number!
go to http://www.suffockmachinery.com
TT
Cincinatti and Cowtown have en-lightened you to what generally happens on re-saw. I am going to add a few discoveries I have made personally so take them for what they are worth...
Softwood will generally bow or cup more than hard-wood but that doesn't exclude hardwood from doing it by any means.
Flat sawn and rift saw will have more tendency to bow or cup than Quarter-sawn.. More in QS softwood than QS hardwood.
The thinner a piece of stock is re-sawn.. the more likely it will bow or cup and the species.. moisture content.. external stresses comes into play here also.
Within the last month I have re-sawn around 1000 linear feet of QSWO in various thicknesses. 1/4" is straight as an arrow. A few (but not all) of the 1/32" bowed. I also have re-sawn around 300 linear feet of Spanish cedar into 1/32" that was flat sawn and nearly all of that had some bow.
So... bow is the norm. The amount just depends on various circumstances from my own experience and observation.
Sarge..
To the extent that the moisture differential between the original surface and the newly-exposed interior plays the primary roll, does it help to re-moisten the original exterior surface, and then allow them to normalize?
Not sure if you refer to doing it during the re-saw process or after the stock has been re-sawn. If you mean "during".. the thought really never entered my mind as once I start I'm heading for the finish line. But.. if you mean after the stock has been re-sawn... that's a different story.
After re-sawing I always allow stock to acclimate for a day or so. I have tried moistening a badly cupped piece like one does a cupped board before or after a glue up. It seems to help a bit on the occasions I have done it but I would say the result is marginal the times I have done it.
But.. it's a good question and would be nice if someone did some home-work and really pay attention to the results on it if they have the time. I might just do that as soon as I finish this desk-hutch. I usually lay off for several months in the summer as it gets pretty humid here so.....
Regards...
Sarge..
>Cowtown<: )Haven't had any stray cows in the yard. Yet. We have had lots of deer, coyotes, the rare fox, rabbits every day, hawks over head. Queenmasteroftheuniverse said she thought she was watching a pair of eagles yesterday but by the time she got her monocular on them they were too far away.A riffle shot across the highway is a very popular spot for runners, hikers and tourists. Red rock formations jutting up (dikes). I spent many an hour there my self. In the past. Recently they been seeing mountain lions over there. One lady was hiking and looked up to see two mountain lions observing her from a small distance away. Yes she has a picture of them. She put her coat just over her arms and raised it up above her head to do what the Hawaiians call "make big body". Her husband finally came along and they left. I don't run over there much these days. The idea of carrying a fire arm powerful enough to stop an attack by multiple mountain lions is just not what I had in mind for a nice "unencumbered " run.My old machinist partner used to carry a derringer with rat shot when he lived in Arizona because the local whacko's would sick their pit bull on him. Not sure a mountain lion would respect that.Who knows maybe they have always been there and I was just too oblivious to see 'em.A coworker destroyed his brand new car he only had a few days when a big buck decided to take the right of way in the middle of the city crossing a major artery roadway.Had one bear in the driveway a couple of years ago. Not a single cow. Yet.rocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )Edited 5/10/2009 1:59 pm by rocEdited 5/10/2009 2:03 pm by roc
Edited 5/10/2009 2:07 pm by roc
Getting older I get kind of confused but... I really must be more confused than I originally thought as.. I really don't have a clue with the post you addressed to me. ha.. ha... ha..ha..ha..
Regards...
Sarge..
Sarge, that is funny now that I think back to someone getting that post who doesn't know what it refers to. Here is why I sent it I thought you were referring to me living in Wild, Wild, West USA as it says in my profile. You began your post . . . COWTOWN :>Cincinatti and Cowtown have en-lightened you to what generally happens on re-saw. I am going to add a few discoveries I have made personally so take them for what they are worth...<Sorry
PS: now I see Eric in Calgary is Cowtown.Blush ! How immberiskin I am I am
rocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
Edited 5/10/2009 4:09 pm by roc
Will the Real Cowtown.. please stand up! ha.. ha... ha..ha..ha..
Even though confused.. I suspected the post was in reference to someone else as I have accidentally clicked on the wrong persons post I intended the post too which mis-directed it altogether.
And in a confused state.. I did achieve cutting my yard.. weed-eating and bush-whacking. Just because it's Mother's Day doesn't mean Dad has the day off. No shop work today as it's chore day for the less fortunate that can't afford a gardener. hee.......
Have a great day....
Sarge..
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