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Main Boards => The Bowyer's Bench => Topic started by: Zradix on February 26, 2015, 12:45:00 PM
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ok wood bowyers...
I don't have a toothing plane.
I've used a new fine toothed hacksaw blade in place of one.
I just watched a vid of a "pro" using an actual toothing plane and he cut diagonal across the grain in two directions so as to put a bunch of little diamond shaped scratches on the surface.
I've only used the blade to scrape down the limb lams with the grain.
Which way is best for bows?
I'm definitely afraid of tear out going across the grain.
...and a little fearful of the extra fiber violation..ie fibers not running the length of the limb
Thanks
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I think a sanded surface is best for making limb laminations at least for most of the common glues.
Do you have a certain glue you want to use?
I can't help you with the best way to use a toothing plane.
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On my last sinew backed bow I used a hacksaw blade to score the back of the bow down it's length with the grain and not across the grain. That's how I did it with a toothing plane too when I had one.
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using unibond 800.
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I just give it a swipe with the grain.
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Thanks guys!
:thumbsup: :thumbsup:
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Using that hacksaw blade you are breaking up splinters.Broken splinters are just that broken splinters.Do you want your glut to hold onto broken stuff that can break even more.A god clean sanded surface is whats recommended.Look at clear glass bows.Do you see broken up stuff under the glass.Nope the lams are just sanded smooth and glued.SmoothOn says a good clean sanded surface and I think they say with 120 grit sand paper.They do way more testing on their stuff to see that it meets specs than we do.Those broken splinters you just cant get glue completely down into every crack and crevasse completely.
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X's 2 what snapper1d said! Buy a toothing plane, about $100.00's, will last forever... You "are" going to keep making bows, right? Do it right there Mr. Engineer! Don't scrape across the grain on a bow limb, scrape the bow along the limbs length. I use 60 grit paper on my drum sander, that eliminates the need to toothing plane my lams. Some guys use even coarser sand paper, like 36 or 40 grit. Unibond800 is good stuff...
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:thumbsup:
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To answer your question Roy....that remains to be seen..
..I keep trying to make em..but all I get is kindling...
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Some folks use hacksaw blades, some use a corner edge of a big double cut ba$tard file, and usually they do ok. I've used both to prep glue joints and yes they tear, but I've never had a problem because of it. Then I got a toothing plane, and an extra toothing plane blade (so I don't have to keep removing my only one from the plane body to use by hand) and I never used anything else. Properly sharpened, set, and used, toothing planes cut very clean, AND they level surfaces. They don't tear.
I grind my cores and lams now with 40 grit, so don't need the toothing plane for them, but I always use it to thin and taper bamboo and prep its gluing surface. I generally run the toothing plane mostly parallel with the bamboo's length... but it depends on what I need it to do at any given moment. Sometimes I use it on slight angles as well.
I also use just a toothing blade, held by hand, to prepare gluing surfaces of handle pieces, overlays and such... run parallel... and I'll explain why.
Here's the thing(s) with the toothing plane, and this might explain why the fella mentioned above was seen using it at various angles to the work...
Assuming the blade depth is properly set... if run only in parallel passes, the teeth will tend to run in previous grooves, and cut less and less until they practically stop cutting and the plane will seem to 'float' over the work. That's not necessarily a bad thing, in fact, used as such on a narrow piece of bow wood, you can tell a piece is all leveled off and adequately grooved when the toothing plane quits cuttin'.
If you need to level and/or remove less material, go ahead and run it parallel. If you wish to remove more in one or more areas, and not just groove it to prepare a gluing surface, then changing angles will allow the teeth to cut ACROSS the previous peaks and grooves and continue to remove wood. As with any other, with experience you learn the vagaries of the tool and use it as your needs dictate.
Another thing... they work best when sharpened by grinding their cutting edge in a slighly convex shape. This allows us to better focus our efforts and is especially helpful with backing pieces because, if on the last several passes the tool is ran centered right down the middle and parallel with the piece, it will create a very slight concave and nicely grooved gluing surface from end to end, then when clamped, it flattens out and the glue lines on the edge of the bow are mated perfectly together and are virtually invisible. Sometimes when the bow's done I know right where they're at and I can't find them.
I love my toothing plane and wouldn't be without it.
Tooting planes are best used with glues that have good gap filling properties like epoxies. I use Smooth On. I have never had a toothing plane prepped glue joint fail, including those in working dips and handle areas.
Dean Torges covers the toothing plane's use, care, and even shows how to make one on his dvd, Hunting the Bamboo Backed Bow.
Hope this helps, Zradix.
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Thank you for that great reply Jeff.
:thumbsup:
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I don't think snapper1 was endorsing a toothing plane instead of a hacksaw blade, it sounded like he was saying to only sand and do not otherwise modify the surface.
I think this should be the real question,
Is there any evidence that a smooth sanded surface does not result in a sufficient glue-wood bond?
And secondly, does use of a toothing plane and/or hacksaw blade or other means improve that bond at all?
I don't know the answer, but I've never used either, I just sand the surface and wipe away dust and I've never had a delamination of any kind with smooth-on or Titebond.
I'm not trying to be a troublemaker here I'm just wondering if this is actually true or if we all just do it because someone decided that was the way to go 100 years ago without testing or with vastly inferior glues.
I know horn bows are grooved so that the surface area between horn and wood is increased, but those bows were also being made with hide glue, not modern 2part glues.
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It really depends on the glue you are using. With gap filling glues adding grooved surfaces increases the surface area of the glue joint. Glues that are not gap filling generally require smooth glue surfaces and a well sanded surface with the dust removed seems to be as good as any.
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SmoothOn is a gap filler but its used with a smooth sanded surface.You sure dont want to see marks on your lames under clear glass do you.SmoothOn recommends a smooth sanded surface.
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"Is there any evidence that a smooth sanded surface does not result in a sufficient glue-wood bond?"
Like Pat said, it depends on the glue. Which type of glue are we disussing here? Also, how smooth is "smooth sanded"?
"And secondly, does use of a toothing plane and/or hacksaw blade or other means improve that bond at all?"
Again, depends...
Smooth On and similar glues will work with sanded surfaces, but the smoother the surface, the easier it is to apply too much clamping pressure and starve a joint. Sanded with 36 grit or surfaced with a toothing plane... it would be almost impossible to starve it of glue due to the rough surfaces, and as Pat eluded to, the grooves offer extra surface for the glue to adhere to and improves the bond similar to how a Z splice offers a stronger joint than a butt joint in the handle.
I have had smooth sanded joints fail in the dips/fadeouts of all wooden bows(with Smooth On) as the handles began to 'pop off'. Since I've used the toothing plane blade on all such joints, I've never had another fail or show even a miniscule separation... even when those areas flex during the draw. I use no power lams or 'pedestal' of core wood. I allow them to work. In my mind, this is evidence of an 'improved bond'.
If I were going to use a glue like Titebond, I would prep my glue joints much differently, and perhaps design my bows a little differently as well.
This is a good article on various glues and gluing surfaces...
http://www.bowyersedge.com/glue.html
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Have you ever thought how much pressure you are getting on a glue up on a glass bow when you put 60-80 psi on your air hose.It stays constant even when heated where a clamped joint will shrink under heat.With heat your SmoothOn will even get thinner till it starts to cure under heat.With handles popping off you are having too much bend in the handle helping that situation.The stiffer the handle area is before adding the handle the less
chance of bending pressure for it to pop off.
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If you're using it to prep for sinew, traditionally you would want lengthwise grooves, most I see are about 2mm deep, same for horn. This is for a horn composite, though.