Stock Bending

[Bob Smalser]

It’s real simple in theory...to minimize the grain runout that causes fragile toe sections, you mill the stock blank from the natural bend in the crotch of a tree.  But what if the crotch angle doesn’t cooperate, ie too much or too little?  Or what if you can’t find a blank milled from a crotch at all?  How about cast-off?  Is carving your cast into the stock the best method, creating short-grain at the weakest part of the stock at the tang and wrist?  And have you enjoyed the comfort of mounting a gun with a tad of toe-cast as well as cast-off?  A gun tailored exactly to the shape of your shoulder pocket that recoils away from your face rather than into it?

Why not rough shape your existing blank and then bend it to align the grain perfectly with the angle of the wrist?  And then perhaps bend it again when it’s finished to fit it to the user?  Gunsmiths and fitters here and in Europe bend finished, high-end shotgun stocks every day without incident.   It’s easier than advertised, and there’s no reason you can’t use the same techniques on at least a stock blank…and with dryer palms than clamping nine grand worth of a client’s Perazzi in your jig.  Here’s how:

Make yourself a jig designed for your purpose (below).  This one of heavy CDX plywood is for finished guns.  The upper part of the gun is held firmly by blocks and bolts.  The top blocks are carved to match the profile of the barrels, and I have another set made for over-unders.  The base blocks are purposely set a little wider than necessary so the fit can be made perfect using thin, soft cedar shims, which also act as pads.

Construct a couple of stands to hold whatever heat lamp you are using about eight inches from the work piece.  Also note the hole in the bottom of the jig to recover the boiling oil.

On the end you intend to bend, build a sturdy brace with an index.  On this one I’m using simple, padded clamps to make the bends and stringlines as an index, but you can get more elaborate and use threaded rods/pads salvaged from C-clamps and clear plastic with a grid drawn on it as an index.  If all I wanted to do was align the grain of the wrist with the planned stock-forearm angle on longrifle stocks, I’d build an even simpler jig with the stock blank laying on its side, and one pressure point for the heel of the blank.

Remove any trigger guards or hardware that can interfere with bending.  They will be bent separately and reinstalled later.  Cheesecloth is wrapped tightly and thickly around the area that will take the bend.  Insure there are no air pockets that can cause uneven heating and even bubble the varnish on finished stocks.  Add a meat thermometer to your wrap, and heat some peanut oil in a double boiler.  Any high-flash point oil will do.  Linseed and other low-flash point oils will smoke and burn.

Keep the cheesecloth wet with hot oil and let the heat lamps heat the wood to 180-190 degrees F for 30 minutes.  The wood will become plastic when its center reaches around 180 degrees, so heat slowly and as it gets hot test frequently using the clamps or turnscrews as the bending end.  You’ll feel the difference at the right moment.

When the wood is hot, gradually make your bends.  Here I’m using a ruler and dividers to bend toe and heel the preplanned distance from my string line index.  Don’t overbend in an attempt to compensate for springback.  Many pieces don’t spring back at all, and it’s easy enough to put the workpiece back in the jig and bend it again.  The hot oil method doesn’t seem to interfere with future bending like overcooking in a steambox does.

What woods aren’t good candidates for bending?  While even the stiffest wood species can be made to bend the small amounts described, long stocks carved from a straight blank with the grain runout mostly in the wrist are problematic, as are highly-figured blanks where it is difficult to read the grain.  In a roughsawn blank, a light pass through the planer to clean off the sawmarks, a temporary coat of stain, and a scratch awl are all methods to aid reading the grain.  Slow, careful heating and a longer time under the lamps (with greater risk of damaging any finish present) usually works, but there are no guarantees….you’ll have to try it and see.

Will the peanut oil applied to an unfinished blank interfere with staining and finishing?  A thick slurry of whiting (powdered chalk) and mineral spirits applied to the oily spots and allowed to dry will draw it out of the wood by osmosis.  Repeat as necessary.

This isn’t my work, but this old Fox was fitted to a disabled person who required a gun capable of using right-shouldered and left-eyed.  Several bends and trial fittings were made over a period of weeks.  It’s a good example of what gunstock woods are capable of.

[BrentD]

Yup, bending is easy - or has been so far. I have a similar jig.  I use canola oil however and no cheesecloth.  Just wipe it on occasionally. 

I overbend by about 50% to account for spring back. 

Your twist for the toe is exactly what I need to do but haven't.   The next one however.

Brent

PS.  I've bent very old (~150 yr) stocks and they don't seem to be any more brittle than newer wood. 

[Jim Kibler]

That's a pretty impresive set-up.  I can see the feasibility of bending a finished gun to adjust to a shooter, but bending a gun while building to adjust grain direction seems like a lot of work for little gain.  The best stocks are stump cut which naturally has the proper curve to the grain.  They are readily available today.  With just a little care in picking out stock wood drastic problems with grain direction can be avoided.   Its pretty clear that longrifles in this country received very heavy use, perhaps even abuse from todays perspective.  The vast majority of guns built today will never see these service conditions.  In looking at original rifles, one must also consider the effects of wood shrinkage as well.  I would hazzard a guess that the rifle shown has cracked from the wood wanting to shrink and the butplate restraining this movement.

[Bob Smalser]

I would hazzard a guess that the rifle shown has cracked from the wood wanting to shrink and the butplate restraining this movement.

Most likely.  But barring reaction wood or severe impact, which this stock doesn't exhibit, fracture lines almost always run along either growth rings or rays (which run 90 degrees to each other).  I chose that photo because its a perfect example of a short grain fracture.  Had the grain been better aligned with the wrist, the potential fracture lines would have been longer, and the shrinkage of the maple impeded by the butt plate may not have been enough to overcome the wood's natural sheer strength.

Here are some examples of expensive maple blanks that would benefit from bending to preclude serious short grain in the stock toe. 

[Rasch Chronicles]

Fascinating example of something I had wondered about but had litle idea of how it was done. Some woodworking methods require a pressurized vessel and ammonia!

Thanks Bob for the informative post!

Best regards,
Albert A Rasch
http://trochronicles.blogspot.com/

[rich pierce]

should be a tutorial.  I think Taylor has posted how he does it also, with nice results.

[D. Taylor Sapergia]

My experience with changing stock architecture involved increasing the drop in a Tulle musket to facilitate aiming and reduce cheek cracking.

I removed the lock, and clamped the gun to the top of my work table, a solid cherry slab in the middle of the shop.  I cut a wedge of maple to slip under the heel of the upsidedown butt, and marked it's position on the wedge.

I wrapped the wrist, barrel and tang in place, with several clean shop cloths, securing them with nylon tie straps, heated Canola oil almost to the smoking point, and ladled the hot oil onto the wrist, catching the over-run in a vessel beneath the wrist.  When I was satisfied that the wood was as hot as I dared make it, I simply pushed the wedge further under the heel, and the stock moved easily.  I increased the drop at the heel by about 5/8" and let it cool in that position.  When I removed the wedge, and the cloths, the wrist returned by 1/8", leaving me with an increase of 1/2" more drop at the heel. 
The result suited the client perfectly, and the finish on the stock was not injured in any way.  I was simply amazed at the success of this experiment.  At one time I posted images of this process here.

There's another lesson here I'd like to point out.  I did not go online and ask how to do this though I did consult with a friend (Sydney).  I just got to it and did it.  I would like to suggest that many of the processes in gunmaking can be figured out by 'smith using common sense and a little bravado, instead of seeking advice at every turn.  Go out on the limb...give it a go!

[Jeff Durnell]

I agree. I don't want spoon fed. I'm certainly not afraid to do it, or to do it without someone holding my hand. I've bent bow wood with heat hundreds of times,(without oil) creating jigs and methods as needed to suit individual circumstances, and to much greater contortions than I'll ever have to bend a gun stock. The idea came to me while trying to find a gun in a blank, and in the other thread I started, I was more curious if others had done it with gun stocks, or if there was a definitive reason not to.