Splitting, avoiding of

[Australopithecus scobis]

Greetings,

I just whipped up a triangle loom for SWMBO. I wound up using finishing nails, because chucking and shaping box nails was taking too long. (Had to finish by yesterday.) The wood was 4S 1x3 maple from the borg, ripped and trued to 2" x however thick they turned out after hand planing.

For those who don't recognize this sort of loom, like me a week ago, they comprise an isosceles right triangle with a hundred-odd nails along each of the wide faces. The hypotenuse nails are, of course, 1.41 times as far apart as the side nails.

Driving a row of nails along the grain is going to split the wood. So, I pre-drilled. Too lazy to look up the exact diameter of the #3 finishing nails, I just cut of the head off of one and chucked it in the DP. (Had lots of practice chucking nails recently, you see.) Thus I had holes that should be exactly the same diameter as the nails. Hole depth was a couple of millimeters shy of the final nail penetration depth, and 4 or 5 mm shy of the far edge.

My nail wore out after the first 104 holes. I drilled the two sides with a 1/16" drill. Much faster... Those holes seemed a shade tight.

Drove the nails while holding a stop block against them. The hammer head hit the block, ensuring consistent height. So far so good.

The long edge split. That was the one drilled with a nail. So if the holes were the same size as the nails, and the nails were spaced farther apart than those on the other two sides, which did not split, how the heck can I prevent splitting on the Mark II model? Hole deeper than the nail?

[Guess who]

Better a longer hole if the nails are *snug*. Then tension from the wool is sideways to the nail, and no change of moving them [except time deals with all things]. use slightly longer nails for added strength. Overall you are not wedging with a poitned nail, just driving into a snug-fit hole. The end could actually be blunt. also, it is a functional unit, so holes *could* be drilled through to alleviate tension. Nails could even go all the way through , then file and sand giving a pattern effect.

Also, consider staggering nails slightly they have to be in that

*direction* but not precisely in a line. Distance apart along that line is still important. Compare with harp strings.

[Andy]

Sounds to me like you did a good job of preventing splitting, and it split anyway. Hm. My thought for the next version would be to try using a good-quality birch plywood, like the kind they probably don't have at the borg. Then it seems it couldn't split, but if you get good hardwood plywood, it should still be dense and solid enough to be durable. Of course if looks are important, the asthetics are a matter of opinion, but I think the birch grain can be pretty on the face, and from the edge, the many fine layers of mostly void-free wood look a lot nicer than your average cheap plywood. I got some good baltic birch ply on ebay, but of course selection there would vary. Rockler has

12x30" pieces of 3/4" for $8, but I haven't used that particular kind before. Good luck, Andy

[Gooey TARBALLS]

"The long edge split. That was the one drilled with a nail."

Sounds as if you have the answer, no? Drill holes and add a drop of epoxy?

[Mekon]

IMHO when you 'drilled' with the nail all you did was drive a nail into the wood twice, once with the DP and once with the hammer. Each nail spread the grain in the timber until it reached the breaking (splitting) point. When a drill bit drives into wood it removes some of the wood, so you should have a hole in the timber with no pressure in any direction. Then when you drive the nail down it will exert enough pressure sideways to retain the nail but not enough to split the wood.

To avoid splitting you should pre drill, not pre nail.

Mekon

[Scorp]

Find some metal to inlay, 1/8" or so, then predrill as close as possible without going over. Nice small brass strip would be perfect.

-------------------- Steve Jensen Abbotsford B.C. [e-mail] chopping out the mortise. BBS'ing since 1982 at 300 bps. Surfing along at 19200 bps since 95. WW'ing since 1985 LV Cust #4114

Nothing catchy to say, well maybe..... WAKE UP - There are no GODs you fools!

[Morris Dovey]

| IMHO when you 'drilled' with the nail all you did was drive a nail | into the wood twice, once with the DP and once with the hammer.

This is also my guess. The drilling operation needs to remove some part of the stock to make room for the nail shank - it's not enough to just tear the wood fibers where you plan to drive the nail.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Unquestionably Confused]

While drilling would seem to be the absolute "cure," how come simply dulling the tip of a finishing nail by striking it against a piece of concrete, etc. seem to prevent splitting in a great many cases?

I know it sounds quite counter-intuitive but the explanation given for the the success of this technique is that the dull tip of the nail doesn't cut the fiber of the wood as much as it pushes it aside.

Don't have the answer myself but it's something worth pondering.

[Morris Dovey]

| Morris Dovey wrote: || Mekon (in DGZZf.2585$ [e-mail]) said: || ||| IMHO when you 'drilled' with the nail all you did was drive a nail ||| into the wood twice, once with the DP and once with the hammer. || || This is also my guess. The drilling operation needs to remove some || part of the stock to make room for the nail shank - it's not || enough to just tear the wood fibers where you plan to drive the || nail. | | While drilling would seem to be the absolute "cure," how come simply | dulling the tip of a finishing nail by striking it against a piece | of concrete, etc. seem to prevent splitting in a great many cases?

My really nerdy guess would be that a blunt end tears/cuts/breaks the wood fibers - possibly compressing at least some of them into the bottom of the "hole". If the wood is dry and the fibers are long, dense, and parallel then it may be more inclined to propagate what under other conditions might be just tiny splits local to each nail. I'd guess that this kind of problem would be rare in hardwoods like elm and common with hardwoods like white oak.

| I know it sounds quite counter-intuitive but the explanation given | for the the success of this technique is that the dull tip of the | nail doesn't cut the fiber of the wood as much as it pushes it | aside.

Hmm - I'd think that a pointed nail would do an even better job of pushing the fibers aside if that was what worked.

| Don't have the answer myself but it's something worth pondering.

Agreed. It'd also be interesting to hear from construction folks whether it makes a difference how 16d nails are oriented for driving [ and I'm already assuming "point toward the wood" :-) ].

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Gooey TARBALLS]

"Hmm - I'd think that a pointed nail would do an even better job "

Yet, years of experience tell those who were taught the "dull the tip" technique in their youth that, it works. Do screw with success."

But the approach is an "in the field" substitute/work around for pre-drilling to prevent splitting - another tried and true approach that succeeds.

If you pre-drill the holes and clip the pointy ends off the nails, then dip each in a glue before inserting them you will succeed without splitting the work and the "pegs" should hold as well as if simply nailed into place.

[Australopithecus scobis]

I have enough original stock left over to make a replacement for the split arm. I'm not going to reshape a hundred nails, but I'll certainly drill, drill deeper, and try some glue.

I think this sort of loom would look fantastic with brass pegs instead of nails. There isn't the high tension found in other sorts of loom, so the brass would be strong enough. And yes, an inlay strip would add mightily to the aesthetic.

[lwasserm]

I always heard the explanation as the opposite: The pointy tip of a wire nail goes bewtween the wood fibers and then the body of the nail wedges them apart as it is driven in. A wire nail with a dulled/flattened tip, or a cut nail, cuts the fibers as it is driven in and has less of the wedging effect that splits the wood.

[George]

Drill real close to finish diameter. Since a cylinder exerts equal force in all directions, it's a split looking for the path of least resistance to drive them without making room.

[Unquestionably Confused]

You're probably right. It makes more sense than what I was remembering (or DISremembering as the case may be). At any rate, it seems to work rather well.

Haven't used the technique with hardwoods all that often. More often than not it was was pine moldings.

This past weekend had me trimming out a french door unit I'd installed with oak trim. Of course I used my PC nail but only had one problem with splitting and that was pure misplacement on my part. The rest of the nails caused no problem whatsoever even though some were quite close to the edge of the trim stock. Naturally, the nails are squared off rather than pointy so...