Maple! Behave yourself!

[Acer Saccharum]

Down, boy,  Down!

I have this piece of drop dead gorgeous maple i want to use for a long rifle. But the forestock has a lot of stress in it.

At the moment, I am sawing slabs off the blank down to get rid of extra wood, hoping it will relieve some of the stress. The slabs curl 3" in 48", and the stock curls in the other direction. I can plane it straight, but as soon as I slab off more wood, it will curve again.

Is there a cure for this stress? Can it be 'annealed', so to speak, with heat or steam?

Advice welcome.

Tom

[tim crowe]

Acer,

What is the moisture content of the wood? If it is above 10% it could be part of the problem?

[Acer Saccharum]

Hi, Tim!

It's around 14%, and I don't think it's going to get any lower around here. It's air dried wood, 2 3/4 thick, been drying for about 5 yrs.

Pretty close to dead quarter sawed.

Tom

[rich pierce]

When making a bow, I can fix most any bend, permanently, with heat.  The rule is to use steam on green wood and dry heat with oil or wax on the surface with dry wood.  Steam actually "over-dries" dry wood, according to bowyers with more experience than I have.  So for dry wood, dry heat with an oil or wax to keep some moisture "in" is the normal practice.  Of course with a bow we are dealing with less mass of wood, and easier to manipulate, so a forestock will be challenging. 

I would rip it to within 1/4" of the desired width or thickness, and make a form to hold it "just past straight".  In this case it could just be a 2x4 with holes for 5/8" dowels.  I use a heat gun for stripping paint and work 8-10" at a time.  Bend it just past straight, put it in the form, let it cool down completely for a couple hours, then work the next section.

[Acer Saccharum]

Cool info, Rich. Thanks, bud.

Tom

[T*O*F]

Set the bowed side face down on a piece of black plastic in the sun and wet the side facing the sun.  It'll straighten out.  Inlet a barrel into it real quick and then slab the forestock down to 1/4" per side.  Make sure you inlet the barrel correctly so that when the remainder bows again it goes to the cast off side.

Like Rick said, the old way is to saturate the stock with HOT linseed oil, then wrap it with rags also soaked in same.  Keep it near the radiator for several days.  Repeat as necessary.

[Rolf]

Rich, how hot do you heat the wood? I tried straitening a couple of flame Birch chair legs by putting them in a jig over night in a sauna at 85⁰c. Did not work. They were 2"x2"x 60".

Acer, if you try it, please keep us posted on the results.

Best regards

Rolfkt

[Long John]

Acer,

Everything I have been able to gleen from the professional wood working operations that I work for tells me that it is a moisture problem.

Water in wood exists in 3 forms: free water, bound water and water of consitution.  The free water is the water that was flowing though the veins of the tree.  It keeps the cells of the wood plump.  When the log is cut this water begins leaving the log.  The surface dries fastest so the cells skinny down on the surface while the cells inside the plank are still fat.  The result is stress and checking.

Bound water is the water that holds the cellulose fibers and the lignin fibers together in a mat.  It is also the water that holds a sheet of paper together.  Kiln drying leaves this water behind as it is a major contributor to the strength of the plank.  Heat causes these water molecules to move around inside the wood matrix.  When you heat a piece of wood the bound water molecules start hopping around inside the wood matrix.  When Rich is heating a piece of wood what he is doing is energizing the you-know-what out of the bound water and the water starts moving about inside the wood.  As the wood cools off the water gets latched onto cellulose and lignin molecules and stays put.  Hence the "permanent" change in the piece of wood.

The water of consitution is the water molecules that hold cellulose molecultes together in a cellulose fiber.  Leave it there!  Without it the wood looses its structural properties.

I think you have too much water inside the plank.  When you kiln dry a plank you raise teh relative humidy of the air to 100% and you raise the temperature to the temp where the bound water is freed up.  You then lower the humidy very slowly.  For hard woods most kiln schedules run 60 days to go from 20% moisture content to 7%.  By keeping the temp real high and the humidity slowly descending the moisture in the plank is essentially uniform from center to skin.  Isuspect the bending methods Rich is familiar with will  only work on relatively thin sections where the application of heat can increase the temp of the whole stick.. tough to achieve with a stock blank.

There is a fair amount of hardwood logging in westerm Mass.  See if you can find a lumber producer with a little spare space in his kiln.

Best Regards,

JMC

[D. Taylor Sapergia]

Tom, I think Rich has the advice that I'd follow, if I were you.  Use dry heat from a good heat gun and straighten the stock a little at a time in a form that holds it just past straight.  It will remember that it wants to bend, and when released will return just enough to make it perfectly straight.
For those with guns that crack them in the cheek, and are worried about damaging their finishes with heat, here's a solution.  One of my friends bought a Centre Mark Tulle Fusil but the stock slapped him silly, with only 65 grains of FFg GOEX.  He asked if I could add some drop to the stock, and after a phone call to Sydney, I decided to use his advice and use hot oil.
I heated Canola vegetable oil in a pan on an electric burner until it was almost smoking.  I secured the gun to the top of my work table with C clamps and soft pine boards so that it could not move.  I wrapped shop towels around the wrist and tied them there with nylon tie straps.  I made a wedge out of a piece of rough western maple and marked it where it would not go any further under the stock for fear of breaking the wrist.  then I poured the hot oil over the wrist catching the run off in a pan underneath, and kept this up for about 30 minutes or so.  When I started pushing the wedge under, I was amazed how easily it went in.  I continued the process until I had pushed the wedge under the comb until I had increased the deflection of the comb from the table by about an inch.  You can see by the before and after photos how much I actually moved the butt.  Now I just removed the towels and let the stock stay there overnight.  Of course in the morning it was cold, and when I removed the wedge I lost about 1/4" of the increased deflection, but I had achieved my goal, and increased the stock's drop at the comb and heel by about 3/4".  Two things happened or rather didn't happen.  First the great finish on the gun was unmarred in any way.  Second, the gun is now very pleasant to shoot and does not crack the shooter in the face any more. 
this will work well on a finished gun, but on raw wood, it likely will interfere with application of stains and finishes.  So dry heat is the ticket.

So, short story...just do it.

[woodsrunner]

Not that it will help much, but I recall from wood tech 101 many years ago, that warping and twisting can be the results of tension and compression within wood cells in trees which leaned 10% or more from verticle during growth.

[rich pierce]

Rich, how hot do you heat the wood? I tried straitening a couple of flame Birch chair legs by putting them in a jig over night in a sauna at 85⁰c. Did not work. They were 2"x2"x 60".

Acer, if you try it, please keep us posted on the results.

Best regards

Rolfkt

Hi, when straightening bowstaves I use a heat gun/paint stripper and try to be real patient, rotating the stave, working it lengthwise, not close enough to scorch.  It gets too hot to handle where the heat is applied.  I probably heat for 10 minutes for each 10" area of the stave I want to straighten.  Osage orange can be awful twisty, with spiral areas as well as the side to side and up and down undulations.  With patience, it is possible to straighten a 20 degree dogleg with a  knot.  Like Taylor said, when the temperature gets right, the bend becomes much easier than we'd think.

[David Rase]

Just bend the barel to match the stock and I will get it inlet for you.    I am sure Joe won't mind.  I couldn't help myself since we were dealing with Tom.  Merry Christmas Tom.  See you in Lewisburg.
DMR

[Licensed to kill]

I don't know about the wetting of one side and leaving in the sun, never tried that, but I think TOF has the right idea. Get it as straight as possible, get a barrel inlet into it and slab it down to 1/4" per side. At the end of the day, the forestock will be so thin that it won't have any affect on the barrel. THEN if you feel compelled to straighten it, you aren't straightening a whole slab of lumber that will be cut off anyway. Remember, the barrel supports the wood not the other way 'round.

[T*O*F]

I don't know about the wetting of one side and leaving in the sun, never tried that, but I think TOF has the right idea.

When I built my shop, everything above the walls was rough sawn lumber.  A small local mill had everything I needed which had been air drying for several years under cover.  It was half the price of commercial lumber.  One scrap board about 6 ft long was laying in the grass, bowed like a barrel stave.  I would flip it over and the next day it would be straight.  I repeated this several days in a row with the same results.  The dew would wet the board and the sun would bend it.

You've got a slab sawn piece of lumber which is always going to bend toward the outside of the tree.  Your problem is that the board probably isn't thick enough to correct and you've probably already hacked off too much wood.  Normally, you would remove wood only from the ends of the inside curve side until you remove enough of the small rings that the warping is minimized.  Then inlet the barrel and slab down on either side of it.

Put periscope sights on it and build a gun that will shoot around corners.

[Robby]

Tom, I have bent a lot of wood using Riche's method for localized bends and crick's in bow wood and it works great. For long sweeps, I use steam, and have done stock wood using steam because of the thickness, and it worked great as well. I even did something similar to what Taylor did, except I was using steam with a tin foil bonnet around the bend area, and putting in a cast off. If the stock is fairly straight and only the slabs being cut off are curling, I think, by steaming the stock, the pent up stress will show itself, and you will have a better idea what you are dealing with, and how much to over bend. Either way, when she's ready to bend, its like linguini el'dante, it doesn't take much force. Good luck!
Robby

[Pete G.]

Odd that someone with the forum name you have chosen would choose such a thread title. You talking to a plank, or is this a self help thing ? (I still remember the Viking helmet).

[Acer Saccharum]

Oh, my gawd. I am trying to stay in my chair, but I'm laughing so hard, I have to put my seatbelt on.

Thanks for the reality check, Pete.

[Woodstock]

Ritch has the method,
I did not see the term "slowly" used but he did mention patients. You must get the heat to the core otherwise you are wasting your time. I have heated and straighten cedar arrow shafts and bow staves from Osage to Cocobolo for years and only had a few that would not cooperate.  I have had real good luck doing that. If you soak it for a few days then heat it, you can make a pretzel out of it. Once heated, be sure it is where you want it before it cools.