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Help with warping

PostPosted: Mon Mar 11, 2019 4:11 pm
by Harleyretired
I am making cribbage boards and finding the lowers are warping. The wood is glued up and kiln dried. This board even warped after the poly was applied.

Re: Help with warping

PostPosted: Mon Mar 11, 2019 4:23 pm
by garylmast
Just because it was kiln dried doesn't mean there's still not too much moisture. If I remember right you need be down about 6% - 8% for carving to prevent warping. If you got it from a lumber yard, it's probably in the 20% - 30% or more. If you clamp the material to a table or something for several days immediately after carving and let it air dry, you should prevent it from warping. Moisture meters are fairly inexpensive and a good additive to you tool crest.

Gary

Re: Help with warping

PostPosted: Mon Mar 11, 2019 4:58 pm
by dah79
I had warping to a recent cribbage board despite a moisture reading of 7-8%. I was told some of it has to do with the amount of material removed in the carving in relation to the thickness of the material.

I tried clamping for a day without any success. I then cut some shallow V grooves in the back side of the board to "relieve" the warping and then clamped flat again for a couple of days. This did help. I then finished the board and attached a thin layer of cork board to the back of the cribbage board. I felt this would hide the V grooves and also provide scratch protection to whatever the board was set on while playing.

Re: Help with warping

PostPosted: Mon Mar 11, 2019 5:55 pm
by Harleyretired
The moisture was around 6% when I carved it. I did clamp it for awhile but still warped after the ploy was applied. I did put grooves in the back after the carve and warping was happening it did improve help out the warp issues.

Re: Help with warping

PostPosted: Mon Mar 11, 2019 6:47 pm
by ger21
Unless you live in the desert, the wood will start gaining moisture back as soon as it gets out of the kiln. It will continue to gain moisture until it reaches equilibrium with it's environmnent.
When you carve it, it absorbs moisture at different rates, in deifferent places, which causes warping.

Finish does not stop moisture from getting in the wood, it just slows down the process. If you don't finish both sides exactly the same, the two sides can gain or lose moisture at different rates, also causing warping.

Re: Help with warping

PostPosted: Mon Mar 11, 2019 8:09 pm
by jay pieper
Harley Retired
From my experiences with wood you will never completely get away from warping.
you can do a few things to help keep it minimal.
you should glue up strips about 3 inches wide.
make sure you flip the pieces to alternate the grain pattern
this will cause the pieces you glue together to pull against each other to help keep it flat.
This along with what others said should help.

Re: Help with warping

PostPosted: Tue Mar 12, 2019 12:01 am
by Wayne Locke
I would glue up the boards if you need to based on grain and color match between the pieces don't worry about flipping small boards. The holes are probably not causing the warping so it is the center pockets. I would cut the pockets and then give it a day. If they warp I would resurface them and, if needs be, repocket the center and then drill the holes. If the exact thickness is important you will need to start with thicker stock and you may need a way to index them. I think that this is about the only way to definitively deal with the warp. Clamping overnight and all is a low probability long term solution. Let it move then deal with it. You could even make the pockets a bit smaller on the initial cut so indexing is not so critical.

Re: Help with warping

PostPosted: Tue Mar 12, 2019 12:47 am
by TReischl
Moisture can be a factor and often is. However, there are other forces at play in wood.

Looking at your pic I see the rings are very pronounced, especially on the center board. Boards like that are born to warp, it is in their DNA. Actually, that board is not "warping" but rather "cupping". The ones on either side of it are also cupping but probably in the opposite direction. There can be lots of stress in wood, especially from the kiln drying process if not done very carefully.

Rift sawn or quarter sawn eliminates quite a bit of the warpage/cuppage when carving. Furniture has the same problem which is why a lot of folks very carefully select their wood avoiding boards that show lots of "cathedral" grain on the faces. Problem is that a person has to sort through a heck of a lot of lumber to find a few boards that are not face grain.

I do quite a bit of my work in that nasty old dreaded construction grade pine. I try to buy 2 X 12's and then rip out the good vertical grain stuff and glue up panels. Works pretty darn well. Pine is notorious for cupping, but what I can tell folks is that even though it is construction grade and still quite moist it is not the moisture that is the main culprit.

Re: Help with warping

PostPosted: Wed Mar 13, 2019 2:55 pm
by Will Williamson
I have had good luck, by taking a shallow pan and fill with water, full sheet cake pan in my case.
place you carving, face down, over the pan, use small stickers, to hold over the pan.
Watch carefully, it does not take long, an hour or two, for the caving, to straighten out
Be careful, it will gain too much moisture.
Once flat, clamp, and hold, til dry, face to face, back to back.
I have used this method, many time, on large carved door panels

Re: Help with warping

PostPosted: Thu Mar 14, 2019 1:45 pm
by rscrawford
Kiln dried wood has tension in the rings. When it is cut, some of that tension is released and you get movement (warping, cupping, bowing, etc).

Cut the top of your piece and sit it for a day. Then run the back over a face jointer to get a flat surface (or if you don't have a wide jointer, surface it on your cnc). The top isn't critical as no one will know if its a little warped.

In my furniture building, I always rip my rough boards slightly oversize before jointing and planing them. The initial rip releases most of the tension. But if you then carve that piece, all bets are off. Important surfaces need to be milled AFTER all carving is done, if you need them perfect.

Re: Help with warping

PostPosted: Thu Mar 14, 2019 7:22 pm
by TReischl
rscrawford wrote:...... Important surfaces need to be milled AFTER all carving is done, if you need them perfect.


Now there is a gem!

I am assuming Randy is advising to cut deeper on the carve leaving some wood for flattening when the carve is finished.

After all these years that had never occurred to me. Brilliant for that fussy type of work.