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jethro Member
Joined: 07 Apr 2007 Posts: 178
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Posted: Fri Dec 01, 2017 1:59 am Post subject: plate joints- |
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Here is what I observed-
Using the longest Lie-Nielsen plane--- I cut the plates perfectly flat.
Air tight joint all the way down end to end. Then I painted on the hot glue to both sides---- put the edges together and rubbed them back and forth.
Durring the next 10 sec. or so---- I watched the ends pull apart leaving
the center 1/2 touching and a big gap at each end. No good.....
The after researching-- discovered that the ends absorb the water in the glue
slower than the center so you get differential swelling. That is what the bow is intended to prevent. Then I tried a very small tapering gap in center. That
worked but it is very hard to calculate how thick it needs to be. Sometime too much- other time not enough.
However-
when I saw the differential swelling - that was on bare naked wood.
I am wondering NOW--- if I sized the edges with diluted glue the day before-
and only planed a small amount off before putting on the glue--- the sizing
might be a barrier to the rapid water absorption and also the differential
swelling. This MIGHT help in possibly having a flat or closer to flat
geometry before gluing.
any thoughts on this idea? anyone tried it ?
Tim |
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SioFong Tong Junior Member
Joined: 20 May 2017 Posts: 10
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Posted: Fri Dec 01, 2017 11:43 am Post subject: |
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My maple can change a lot. I have try plane the maple joint perfect flat and waited for weeks. They can change to concave or convex in different room humidity.
Mine are deep flame maple. They soak things.
If I wet the maple, they will not fit. So when I applied glue, they won't fit too.
So, sized and hollow joint may be a good way.
I use lie nelson no.8 too:) |
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jethro Member
Joined: 07 Apr 2007 Posts: 178
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Posted: Sat Mar 31, 2018 2:11 am Post subject: |
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Sio and Michael-
I wonder if another approach might be to put your plates in a sealed box with warm water or steam for a couple of days before planing. If the wood had a higher than normal water content before glue-- then it seems like a rapid
water absorption out of the glue (and differential absorption) might be slowed
down orders of magnitude. Just like how you cant sweat when its 100 degrees
and 100% humidity.
Im not sure what excess water would do to the wood-- but remember that Strad stored his logs underwater didnt he ? I would think if the grain is straight and regular it might swell some but not warp much overall.
Kind of a radical idea maybe----- just food for thought.... |
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SioFong Tong Junior Member
Joined: 20 May 2017 Posts: 10
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Posted: Mon Apr 02, 2018 2:09 am Post subject: |
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Jethro,
I always keep my room humidity in between 50-60Rh. After resaw if, I wait for at least one week because sometimes the wood will bend after resaw. Here in my city the humidity can go as high as 90%. I don’t want my plates jointed in 80%RH, it may cause open seam in the ends when the violin is on the airplane. The humidity on plane is around 20-30%RH. |
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