Primitive Archer
Main Discussion Area => Bows => Topic started by: russell on January 31, 2015, 08:45:37 pm
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I've done some searching, so I'm not being lazy - just want to make sure I've got this right. It looks like the general consensus is quartersawn as opposed to plainsawn. And 1/8" - 3/16" thick depending on type of wood. Is that about right?
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Sounds about right
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Make sure you cut them a little heavy so you can get the saw marks out
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That makes sense. Didn't think of that one - thanks.
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I cut mine with a tablesaw and run them thru a surface planer
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That's kinda what I was thinking. I guess my main concern is plain vs quarter sawn. I think flat vs edge grain means the same thing - I think?
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Make sure you cut them a little heavy so you can get the saw marks out
Yep, just learned that the hard way! By time get saw marks out these maple backing strips will be so thin that they'll only be useful for red oak bellies! :o
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Flat sawn, quarter sawn, rift it doesn't matter the key thing is straight grain. A flat sawn board is the easiest to read and 1/4 the hardest but at first glance it looks like it should be the other way round! Even a tiny deviation from straight on a 1/4 board can mean very bad things.
Some people think flat sawn backing don't work but think about a decrowned stave...that's essentially flat sawn and they don't break as long as you keep the lines parallel = straight grain.
I prefer flat sawn.
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Mike it right here. I'll take a flat sawn hickory back, for sure. The hard thing about quartersawn is there is actually no way to tell if the grain runs straight back to front. The lines are nicely parallel, and SHOULD be just fine, but that is examining the rings from the side. The radial grain could be doing what the heck ever it wants.
In Torges TBM series he shows how to take a large flat sawn board (4/4ths at least) and turn it into several blanks for kids' bows. He showed how ripping down the center of a perfect flat sawn board, with parallel ring lines on the faces, will give you several perfect quartersawn backings. That method is great. But, I have had several failures of backings, even with hickory and white oak, where I bought QS stuff that looked good, but which had radial grain running through diagonally.
I once bought a 4' long, 8.5" wide, 3/8" thick hickory board off ebay (advertised for scroll saw work) with perfect grain lines running straight and parallel the whole width of the board, back and front. I cut it into 2" wide strips, then ripped each of those into 1/8" plus thicknesses. The grain ran through fron to back on those that they snapped when bent just a few inches, before even being glued to a bow. The grain ran back to front diagonally in less than 1" through the 1/8" thickness.
Just saying, quartersawn isn't magic by itself. You gotta pay attention to how it gets there.
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Thanks mikekeswick and Springbuck. I kinda thought plainsawn had similar attributes to peeling a stave down to one growth ring (grain-wise anyway) - just wanted someone with more experience than me to confirm it. I understand watching what the grain does is important. Wood is an amazing thing. Thanks guys.
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You want the grain to run no less than 2& 1/2 " from back to belly/core side on a 1/8th " thick backing. A little less might still be useable with a wider strip. 2 and 1/2" = 20 x 1/8"= 20;1 ratio. If you backing was 1/4" thick the grain should be no less than 5", to keep the 1:20 ratio.
Grain orientation is not too important. Flatsawn can cup a bit, but it will clamp flat.
Hamish.
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Do you mean where a grain line "leaves" the back of the strip (looking from the side) and travels to the belly side? That distance the grain travels should be no less than 2 & 1/2"?
Sorry for all the questions. I've worked with wood since I was a kid, but only fiddled with a few board bows. No shooters yet, but gettin antsy to have a real go at it.
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I always cut mine a bit thick to begin with, and then run them through the thickness planer to an exact 1/8". I then glue it on with Aerodux Resorcinol that I get from amazon for about $64 a quart. It's expensive, but after having problems with Titebond 3 stretching and giving up on a hot day, I decided to go industrial strength.
When it comes to hickory, you really don't NEED quarter sawn stuff. Hickory is actually pretty forgiving, even if you have less-than-optimal lumber, it will still make a great backing strip.
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How hot was it when the tb3 gave up on you, during the summer here it is routinely above 110 deg and i have not had that happen
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How hot was it when the tb3 gave up on you, during the summer here it is routinely above 110 deg and i have not had that happen
It was a balmy July day in North Georgia. Around 95 degrees but with 100% humidity since we were camped next to a creek all weekend. It was like this for 3 days, and our bows were under a fly tent. Most of the day, the bows were being used and in the sun. At the end of the weekend it exploded in my hands.
Iv'e had it happen to a couple bows, and Titebond 3 just doesn't seem to ever dry solid - it always stays flexible. So, for safety sake, I switched to a non-water based glue, Resorcinol, and I haven't had a problem since. Actually, during destruction testing of the glue, the resorcinol actually ripped apart the wood fibers of the bow. It's used back home in coastal NC to build boats, so if it'll withstand being submerged in saltwater with no degredation, it should be fine for hot and humid weather up here.
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Thanks mikekeswick and Springbuck. I kinda thought plainsawn had similar attributes to peeling a stave down to one growth ring (grain-wise anyway) - just wanted someone with more experience than me to confirm it.
Yeah, that's right, and that is why a plainsawn board with nice parallel rings visible toward the edges is a great choice for a board bow. The TL:DR of my post is that not all QS stuff is the same. I would use a really nice flat sawn backing, too. I just saw a bow here where one of us PA guys just took the wood under the bark just like a stave bow, and made an elm backing.
Let's say you took a nice, straight, round hickory log and split it exactly across the rings, so that every ring in both halves was now a semicircle. The best possible hickory backing would be obtained by smoothing the flat, split sides, and taking your backings from right there on that surface. Got it?
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Do you mean where a grain line "leaves" the back of the strip (looking from the side) and travels to the belly side? That distance the grain travels should be no less than 2 & 1/2"?
Sorry for all the questions. I've worked with wood since I was a kid, but only fiddled with a few board bows. No shooters yet, but gettin antsy to have a real go at it.
Yep.
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if one is not sure of the reading of the grain on a board, the board can always be split to see just how the grain runs
better to loose some usability of the full board than to put soooo much work into something that doesn't hold up. odd pieces get used up on something or another sooner or later. some species actually have grain that can be seen if you look hard enough, and in some boards the grain can be traced with a sharp knife tip
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Got it Springbuck :)
Thanks again Hamish and everyone else for the help.