Home Forums Hunting & Shooting Gunsmithing stock crack

Sure, epoxy will bridge a loose joint/crack and bond with strength. But loose joints and cracks left wide are the work of apprentices, not journeymen. As long as the epoxy penetrates a bit into the opposing surfaces before clamping and before it starts to harden (another reason for using slow cure rather than 5-minute) you're good to go. Tight clamping as such won't expel all the epoxy, a micro layer is still there ready to do its job. I had that explained by a West System rep long ago, who said that an epoxy soaked joint that retains just a few molecules thickness of remaining epoxy after assembly/clamping will bond with strength greater than the surrounding wood- provided surfaces are clean and free of contaminants. Natural oils in wood can work against you in situations like that- for example with teak, which is naturally oily, we always washed the joints with acetone first to provide a dry surface for the epoxy, then clamped the bejesus out of them. Several hundred projects still in use on the local waters are testament to its veracity.

So with epoxy should you clamp or not? Or does it depend? A problem I've seen with stocks on older bolt guns are cracks located between the mortises for the magazine and the trigger. I figure those develop from wood shrinking which means that clamping would likely make a mess of the inletting. What would be the best epoxy or solution for this problem? And my apologies to the OP for pirating his thread.

Clamp it, IMO.

I would use any quality epoxy, short of the 5-minute stuff, and proceed as outlined by one and all above. You will merely be bringing the wood back to original dimensions and shouldn't effect the mortise (inletting) if it wasn't too tight to begin with- which may or may not have contributed to the crack happening to begin with (probably not). In that unlikely event just address the inletting afterwards by spotting in and scraping the high spots.

On another note, epoxy has become a panacea for sloppy inletting in general IMO. A precisely inletted stock mortise, that bears evenly and tightly all around especially at interfaces that bear recoil, is the equal of a sloppily inletted mortise with epoxy bedding slathered in to take up the slack. What we call "glass bedding" an action to improve accuracy is nothing more nor less an act to create a perfect joint, an act that can be avoided if the wood/composite is precisely configured to begin with. If for example a beautifully executed inletting job is present, it's foolish IMO to excise material to make way for magical epoxy bedding.

Good info Gents.

I have a stock with a crack at the butt that basically runs parallel to one of the buttplate screws.

Below is a pic of the dilemma. Crack doesn't go all the way across - only from the left side to the screw hole



I was thinking of drilling a hole close to and parallel to the crack. Fill with slow curing epoxy. Then tapping a dowel into the epoxy-filled hole with the hopes of it driving the liquid through the crack.

Suggestions would be more than welcome. Thanks

Use WEST (Wood Epoxy Saturation Technique) epoxy, but there is no need to vandalize the stock by drilling holes or Dremel-ing it. WEST epoxy is formulated to soak into wood. Mask the area to the edge of the crack and just keep applying epoxy until no more will be absorbed. Remove masking and cleanup before epoxy has cured.

Note: mix precisely as recommended by the formulator. WEST is generally 5:1 resin vs hardener. Use slow or extra slow hardener wherever possible. You must not vary this ratio. A powder scale can be used to mix very small batches precisely. Cold temperatures inhibit the epoxy's ability to soak in. Store at room temperature.

Very good advice.

With the crack shown above you probably won't get good purchase for a clamp, and it may not do much good anyway. After getting the crack mostly lubed with un-thickened epoxy, I would then mix some coloring agent into what remains and slather that in last in an effort to camouflage the crack. That is chancy in the best of circumstances though- it's really easy to overdo it and end up with a dark line anyway. (One trick to making light colored epoxy is to mix some sanding dust into epoxy thickened first with coloidal silica. Starting with thickened stuff, and here's where Brown-give-me-all-your-money-ell's Gel comes into its own, it's easier to get the right tint without going too far. A little sanding dust goes a loooong way.) Thickened epoxy is good for bridging a gap that can't be closed up by clamping too.

You might also try mixing two separate batches of tinted epoxy also, in an effort to match the light and dark areas of the grain shown above. That's cutting it fine though.

Along these same lines: I've not had to deal with cracked stocks coming from the days when folks literally soaked everything in oil. In such instances would some of the residue free, aerosol brake/electrical sprays be suitable for cleansing such cracks before attempting repairs? How about the same approach on fiber glass? Have a cab high shell with a stress crack in the back corner.

Dons1:
In your instance, one could use either suction or pressure to move materials into the deepest recesses of that crack. After application, one might be able to close the void if he had access to a good wood working vise.

I wouldn't use a spray like that if I had any intention of not refinishing the stock afterward. If the wood is well and truly oil soaked and the crack is an old one I would weasel as much flotsam out with a needle or somesuch and flush with acetone as best I could. Excellent instance for running a drill bit in from the end following the crack if you can, in an effort to generate some fresh wood surface for the glue. Nothing says you can't spread the crack open more, even if you extend the length of the crack a bit, in order to give yourself more room to excavate the gunk out of the crack. Try to avoid buggering the outside of the crack up at the wood surface so when clamped back together it'll still close up tight there.

I would feel better about a fiberglass repair if I could lay up a piece of fiberglass cloth behind the break too.

I am fond of composite construction for its strength and stability and light weight (foam composites, epoxy is heavy). So I don't mind vandalizing a stock a little so long as it's inside the inletting or otherwise invisible. The outside, say 1/8th inch of the stock, is for looks, the rest for strength.

Agreed getting the ratio right is important for full strength. For some early industrial epoxies it was absolutely critical. Not so critical today with standard epoxies but more important for some formulations than others. Good to be as precise as practicable.

Now that you've been careful to get the ratio right you need to mix, mix, and mix some more while scraping the side of the cup or whatever substrate you're mixing on to insure that the precise ratio you've been worrying over is the same throughout the batch.

This is the recipe for achieving maximum strength which, unless you're building an aircraft or the like, probably isn't necessary. It's a plan, but don't agonize over it.

Dons1,

It's hard to tell what to do without fondling the stock to see what it wants and contemplating your navel a while. But here's what occurs to me offhand.

Drill a hole through the crack from the butt end. Depth is what feels right, suppose I'd be happy with 2/3rds the length of the crack. Epoxy in a length of small diameter carbon arrow shaft. That will stabilize the crack and is plenty, plenty strong. One advantage of the shaft over a dowel is it's hollow so you're not fighting it in. And it's lighter than brass or all-thread.

Finish the exterior by your preferred method and restore the screw hole the usual way.

Many ways to skin this cat.

Looking at the wood around the crack it looks like it came from directly under a limb, button up. The figure is from a bunch of extra wood cells trying to occupy the same space. The crack is a drying defect, not a result of the screw or abuse. Ain't no vise anywhere that close that gap without crushing a lot of wood.

As several said, a hole bored parallel to the crack, even right in it is a good plan.

Heat will get the wood to suck the epoxy in but realize the issue has nothing to do with strength in your application, just filling and hiding the crack.

For a crack like the one above I have had success by mixing a loose ,runny, batch of epoxy and using air pressure to blow as much as possible into the crack. Do this outside caus it gets all over everything in the shop , about 20lbs of air ,then use a rachet strap to clamp the crack shut.

Thanks folks. I'll give'r a go.

WOW! Just WOW!

Wow indeed!

An old trick for cracks that are hard to clamp is to use a bicycle inner tube. Put blue painters tape on either side of the crack and wax the heck out of it and the wood not covered by the tape. Use Sitka's heat and plastic trick or air hose trick to force slow cure epoxy into the crack, then wrap with the inner tube. Pump up the inner tube to get max clamping force. After the epoxy sets let the air out of the tube, remove, and clean up.

I have wrapped stocks using surgical rubber tubes with success after applying epoxy.
Did a Remington 572 forearm that was in five pieces, after making a insert to fit inside to keep everything in place, so the rubber tubing could be wrapped tight.
Showing a friend the repair after, he couldn't see it.

Realize the forces that cracked the OP's stock will never be bested by bicycle inner tubes, band clamps, nor simple pressure. The wood was pulled in too many directions and focused on just one plane and it opened way up.

Besides, the confined forces if you could clamp the thing shut, and they are strong, will set the stock up for failure at the next weakest spot.

An old boy told me the same thing once repairing an old clock case--no good deed goes unpunished...