Primitive Archer
Main Discussion Area => Bows => Topic started by: LaBill67 on June 20, 2017, 08:28:43 pm
-
Ok fellas, here is the situation. I have a r-d bow that has a IPE belly backed with pecan. The riser is made up of IPE and pecan in that order. What is happening is the riser is starting to separate just above the handle shelf. Everything was glued up with Smooth On EA40 epoxy. So before it completely separates I plan on going ahead and taking off the portion of the riser below the belly and after cleaning up the surface of the belly regluing new wood in place of the old that I just removed. I'm not sure why this happened but I cant see any other way to save a well tillered and smooth shooting bow. What say you all?
-
To stop this you need to use a thicker belly lam (and then taper into the working limb thickness as normal) so that the portion under the riser block does not flex. Or use a powerlam to start with, again to stop any flex in the center section.
The reason it came off is too much flex into the handle.
Unfortunately this can really only be fixed prior to glue up by selecting the correct thickness belly lam/powerlam.
you can try building up the riser with many thin pieces but it is likely it will happen again down the line.
-
Thanks Mike.
-
How were the gluing surfaces prepared prior? I use Smooth On and prep them with a toothing plane blade the full depth of the teeth. They don't separate even if they're flexing. I leave no added thickness or 'pedestal' under the handle piece, and use no power lam.... additional, unnecessary work with a good bond.
-
How were the gluing surfaces prepared prior? I use Smooth On and prep them with a toothing plane blade the full depth of the teeth. They don't separate even if they're flexing. I leave no added thickness or 'pedestal' under the handle piece, and use no power lam.... additional, unnecessary work with a good bond.
you've been lucky then. ;) It is a well known fact that a flexing handle will pop off any handle/riser no matter what glue used. Smooth on don't recommend preparing surfaces like that. Also a toothing plane will leave an ugly blend from riser to limb.
-
Hey Mike do you think reducing the weight of the bow from 65+ down to 45 will help keep the riser in place? If so I may do that and just rebuild.
-
Poor Jeff, being lucky rather than good for over 20 years. lol
-
Post more of your ugly, lucky work Jeffro. People deserves to see it first hand. Ive seen enough to know that 95% of us will never be at that level.
-
Well Mike, that's not the only "well known fact" in bow making that I've found to be something else, so call it that if you wish, but calling it a fact doesn't make it one.
If we're going to have a fair conversation about this, a few things should be noted.
Toothing plane blades are made in a variety of teeth per inch. So yes, the most coarse ones would show their effects at the fadeouts of their joinery. They could be made perfectly smooth, but would be visible unless they were dyed or otherwise hidden. BUT, the irons with more teeth per inch leave glue lines that can be invisible if the pieces are well mated. I made the danged things so know right where they should be, and sometimes I can't find those glue joints myself. Same with horn tips, overlays, underlays, and such. Ugly blend? No. There are NO ugly blends on my bows and I wouldn't use them if that was the case.
By the way, someone mentioned draw weight... I've made bows like this with draw weights over 70 pounds... no pedastals, no powerlams, flexing well into the added handle pieces... glue lines still as tight, tidy, and hard to discern as the day I made em. Just sayin'.
Smooth On is made to flex and maintain the bond. It holds flexing limbs together just fine, right? In fact, I have used the toothing plane on countless, flexing full limb joints without a single failure. So it obviously isn't "the flexing" of an added handle piece that causes the joint to fail. Imo, most commonly, poorly designed or executed transitions from handle to working limbs are the cause... which is to say, halting the flex from the limb too abruptly. So it may be more accurate to say then that a non-flexing handle is the cause, not a flexing handle. Toss in another issue like a joint a bit starved of glue, or not enough working limb or limb taper, etc, and off she comes. The use of a toothing plane to prep the joints simply helps swing the odds back in our favor a bit by creating more gluing surface and making it practically impossible to starve the joint by clamping. Not a cure all, but a big help. If we add to that a good design and a smooth transition, the handle piece can flex and stay tight... and that's a fact. :OK
-
How about a pic of the culprit. I'm with Mike. There are ways to get a riser to flex a bit with a handle area that bends but generally in my experience if the center of the bow flexes the riser will pop off. If a bow is designed properly to begin with a handle riser popping off isn't an issue.
-
I dont use a toothing plane, but i use 36 grit to rough it up before useing smooth on. I do think the biggest problem with handles popping off has to do with the bend too close to the riser on a stiff handled bow. While the area to let go may be in the center of the handle i think that is more the cause of the limb acting as a lever and the riser as a block to add pressure, just like pulling tee posts
-
I dont use a toothing plane, but i use 36 grit to rough it up before useing smooth on. I do think the biggest problem with handles popping off has to do with the bend too close to the riser on a stiff handled bow. While the area to let go may be in the center of the handle i think that is more the cause of the limb acting as a lever and the riser as a block to add pressure, just like pulling tee posts
Wow never though of it that way....that's what happen on my first couple of handle glue ups....
Bub.. sometimes you amaze me for an old beat up cowboy :) ;)
DBar
-
If using all lams a power lam between the back and belly at the handle will prevent the handle area from flexing, keeping the riser from popping off. If you are only using a back and belly leave enough thickness at the handle of the belly to keep the handle area from flexing.
-
If using all lams a power lam between the back and belly at the handle will prevent the handle area from flexing, keeping the riser from popping off. If you are only using a back and belly leave enough thickness at the handle of the belly to keep the handle area from flexing.
What keeps the power lam from popping? Its length? After all it's just held on with glue too.
-
Can a good glue joint be stronger than the wood itself???
DBar
-
If using all lams a power lam between the back and belly at the handle will prevent the handle area from flexing, keeping the riser from popping off. If you are only using a back and belly leave enough thickness at the handle of the belly to keep the handle area from flexing.
What keeps the power lam from popping? Its length? After all it's just held on with glue too.
It's the accumulation of thickness that adds up to a stiffer midsection.
-
"Bend too close" is another way of saying the flexing of the limbs isn't gradually and adequately quelled before the handle by the design and execution of the dips/fades.
Can the bond be stronger than the wood? Sure.
-
Well Mike, that's not the only "well known fact" in bow making that I've found to be something else, so call it that if you wish, but calling it a fact doesn't make it one.
If we're going to have a fair conversation about this, a few things should be noted.
Toothing plane blades are made in a variety of teeth per inch. So yes, the most coarse ones would show their effects at the fadeouts of their joinery. They could be made perfectly smooth, but would be visible unless they were dyed or otherwise hidden. BUT, the irons with more teeth per inch leave glue lines that can be invisible if the pieces are well mated. I made the danged things so know right where they should be, and sometimes I can't find those glue joints myself. Same with horn tips, overlays, underlays, and such. Ugly blend? No. There are NO ugly blends on my bows and I wouldn't use them if that was the case.
By the way, someone mentioned draw weight... I've made bows like this with draw weights over 70 pounds... no pedastals, no powerlams, flexing well into the added handle pieces... glue lines still as tight, tidy, and hard to discern as the day I made em. Just sayin'.
Smooth On is made to flex and maintain the bond. It holds flexing limbs together just fine, right? In fact, I have used the toothing plane on countless, flexing full limb joints without a single failure. So it obviously isn't "the flexing" of an added handle piece that causes the joint to fail. Imo, most commonly, poorly designed or executed transitions from handle to working limbs are the cause... which is to say, halting the flex from the limb too abruptly. So it may be more accurate to say then that a non-flexing handle is the cause, not a flexing handle. Toss in another issue like a joint a bit starved of glue, or not enough working limb or limb taper, etc, and off she comes. The use of a toothing plane to prep the joints simply helps swing the odds back in our favor a bit by creating more gluing surface and making it practically impossible to starve the joint by clamping. Not a cure all, but a big help. If we add to that a good design and a smooth transition, the handle piece can flex and stay tight... and that's a fact. :OK
Yes I know saying something doesn't make it a fact ;)
When I started out with lam bows I made this mistake myself a few times - therefore it isn't just what I am saying - it is linked to my direct experience and as I'm sure you know many other peoples experience. Judging by the amount of times this question has come up over the years it isn't 'just me' making things up.
Yes I know about toothing planes but you didn't mention what tpi you where using. I'm glad you make nice transitions :) If a fine graded iron wasn't used you would see the joints - that is what i'm saying.
Draw weight makes no difference if the design is correct for the weight.
Virtually any epoxy will flex. Yes the limbs stay together but the forces on the gluelines in a limb are not the same as the forces on the glueline/s on a riser placed on top of a limb stack....comparing apples to oranges ;) No is isn't JUST the flexing it is the combination of flexing combined with the riser ending on a working part (if designed incorrectly). Of course staving glue joints will causes problems, as will a bad tillering job BUT that isn't the issue I was talking about. To not starve a joint of glue just don't tighten the clamps too much! A toothing planed joint with over tightened clamps will still be half starved...
One thing I will say because it was implied above is that I respect anybody and everybody who makes bows of any quality and was not meaning in any way shape or form to degrade yours or anybody elses work. Nobody is perfect....most of all...me.
-
Mike, my experience is very similar to yours. Not bragging but I have done hundreds of lam bows and boo backed bows. Sometimes a couple of hundred per year.
My preferred woods are osage, ipe, massaranduba, and even though it chrysals I like to play with jatoba. The white woods I have done plenty of also but less frequently.
I look at it like this. If I have a 5/8 slat of osage that I am gluing a boo back on and an 8" riser block I don't like to go over about 64" long and 50#. I much prefer to use a 3/4" belly slat. Massaranduba is the same as these woods are really not what I call stiff woods.
Ipe is a bit stiffer and I will tend to go heavier or longer with a 5/8 thick belly slat but I still prefer at least 3/4 or close. If I feel I am marginal I will usually use smooth on but normally use tightbond 3. Multi lam bows that run the belly slat over the fades into the handle are far more secure but I seldom do that. Instead of power lams I will very often just use thicker boo and taper the thickness toward the tips seems to work well.
-
Relevance is in order in these discussions, or there's no sense having them. The shortest added on 'handle piece' I've glued on was a 9" piece.... and I was really trying to conserve length on a blind bow, on a boo/yew/osage trilam, 58" ntn, 58# @ 28", d/r... and I'd bet the bow itself that it isn't shaped how most folks would shape it. I've glued the handle piece on other such bows, albeit longer ntn, up to 15" long, but usually they're at least 11-12" long.
Heck, who knows if we're even talking about the same kind of bows here. Probably not.
Bottom line is, there are many considerations and tradeoffs... handle design, thickness, width, shape, fade length and shape, limb cross section, limb action, working limb length, and more... should help determine what length piece we decide to glue on for the handle area. If we don't pay heed to such considerations, we'll learn to... or our bows will suffer their consequences.