Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: bigbob2 on April 15, 2019, 10:48:33 PM
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Decided to post these shots as a tribute to KennyM and his awesome design work. Circumstances might prevent me from building any more bows, that is for time to decide, but the form for this bow had already been made and I really wanted to try one so this was thrown together from shop scraps, no veneers just green glass on the belly and black glass on back.It came in at 54# and is a lot easier to draw than my 52# recurve. Also even though for simplicity sake, I went without power lam or reverse tip wedge, this thing is fast! It is also quiet, smooth and zero handshock. All in all everything i would look for in a bow. Take a bow Kenny!.
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That looks great Bob. I have two of Kenny’s bows and love them.
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thanks, it is a terrific design isnt it/
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Awsome Bob I have been curious how one would work with out the power lam ,did you still use .001 total taper ? Also how does the full draw profile look , but most of all I hope every thing works out for your future bow building Mate !!
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Looking good Bob. I hope you will be able to continue building bows and have a good health.
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Very nice Bob.
Wishing you the best.
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thanks Bue, Roy and forwardhandle, appreciated.Forwardhandle it is total of .001 taper. I will try and get a friend later this afternoon to take shot of bow at full draw, and post it.
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Looks pretty good for a bunch of scraps. Nice work :thumbsup:
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Thanks for the info Bob ,don't go out of the way for the FD I'm just curious !
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I hope to get a full draw shot later today, and will post it then. Inverting the form seemed to help with the fit up too. With the belly down and curve of back upward it seemed to press together very well.Bit of a pain to keep it all together on the form before the top half and hose went on but worth it I feel. If I get to do another, I would incorporate the super lam and a carbon strip just to see the difference.
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Got a friend to take a shot at full draw. I am at about 30 -31' draw in this shot and around the 60# mark.As you can see even without the tip wedges or power lam the string angle is very good. For a short bow to have this ability is indeed very good. The bow finished at 54# and is easier to draw than my 52# recurve. Such a good design.
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Very nice, Bob.
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Awsome looks great , nice to have another Bro exspermenting with the design , Im going to try one like yours with carbon next after I finish the curent FHLB thanks for the info nice that you have the same draw as me must be somthing about us grey bearded guys that like these bows :goldtooth:
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Bob I did the same thing putting the belly on the form. It was easier for me to get the belly curve to fit the form and let the hose take care of the big hump. It is a good design.
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thanks Roy Ritchie and Crooked Stick. Ritchie, surprisingly for a guy 6'4'' --- with a trad bow my draw is really only about 29''. This shot is drawn back behind mouth to demonstrate string angle. With a 'cough cough' compound my draw is actually 31.25. re the grey whiskers, I am actually senior to Roy by few months so am really ancient!.
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re the form. I saw your way with inverting the form Crooked Stick, and could see the logic so went that way too. Harder to "package " everything on form until airhose is in place but agree it seems to allow a superior fit once inflated.
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Well this sucks! I have had probably 150 shots through this bow when utterly without any warning signs she just blew apart. From looking at the result, it would seem it went just after one fade and ripped back toward center. Forward risers do impart a lot of stress on the riser , but my glue lines were impeccable, tight as with zero gaps etc and fades transitioned very well. [ You are not allowed to view attachments ] [ You are not allowed to view attachments ] [ You are not allowed to view attachments ] BIG argument for using the power lams.Damn it grieves me, loved this bow!.
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Nice bow, what a waste of labor of love. Looks like the fade transition was a little on the short side. Not enough meat in that area. But then again I have never built a glass bow.
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After mulling over your comment about the fades, Wolftrail I had another look at the bow, and actually I now think the transition was such that it actually had a little too much " shoulder" and probably a little stiff under load.If one masured back 2'' from end of fade the dimension there was closer to a .25' than ..125. This could have made the fades a little too rigid, setting up a higher than normal stress area, and acting as a fulcrum which caused the glass to shear as it did.
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I agree with your analysis. In the picture of the riser the fadeout area looked very short and too steep.
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Well that blows :biglaugh: for sure I had the one last year do the same ,do to bad form pressure, I use Kennys recepe of 2 in fade , .140 at 2" , .065 at 1" & paper on the end I have been exstending the fades back farther lately sense Im pulling 31" there is a lot of presure on the fades in this design I always hand lap the fades with sanding blocks to make sure every thing is dead flat and smooth but I seriously dont think those fades bend beyound the 2" mark so every thing needs to be perfect in my mind , after blowing one I spend a lot of time on the riser area & riser fit & havent had any more issues !
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Damn Bobby that sucks.
Glad you didn't get injured when it left go.
You going to put another one together?
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thanks guys. Yep going to try again Roy. Got lucky when it went, just a small rap on the snout from the bow arm but nothing really.I did have some small doubts about the fade area but it fit so well on the form I decided to go with it as is.It is the correct length etc, just that the ramp heading back from the tip of fades is just a little too deep at a given point,. not a big thing in the scheme of things but with this design, that "little" thing was surely enough.Any one building one of these would be advised to spend time making sure the fades are spot on, with a shallow curve away from tip, I believe the standard .1/16' @1'' and .1/8' @ 2'' is the right dimensions. Mine were perfectly flat, true etc but the radius just a little insufficient, loading up an area of high stress. Unreal the way the belly glass just sheared strait across about an 1'' in front of fade.That to me denotes the fades were too rigid and acting as a fulcrum point causing the shear and resultant tearing of lams and glass.Bummer, too good a design to just leave it at that so mark 2 will happen. just have to wait for some more epoxy.
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I never seen glass break clean across like that. I agree that the fades could be thinner. I also wonder about the thick belly over lay maybe too close to the fade and not allowing that area to flex enough. A way to cure that would be a G 10 ibeam. Even a PL just a couple of in. past the fade. The superlam.
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Definitely going to use super lams on next one. I have never seen glass do that either. Bit bizarre actually. I don’t have access to suitable thickness of G10 at the moment , might just have to go with super lam.
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Just looking at the pictures (hard to tell) but the fade outs look ok to me, it may be your 31" draw lots of bows cant take that long draw length . I used to have a 31" draw length when I was young and I broke lots of bows . I finally started shooting a 66" bow and they stood up .
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Could it be the last couple of inches in the fades that reflex opposite from the limb when flexed at full draw might be to stressed.
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I think this design can hold up to long draws fine I have been pulling the glass 60" to 31" for 800 or more arrows & got about 450 arrows threw the carbon 60" with no issues, I have been exstending my fades out a little bit farther on current bows like in the pic but all where made with the SL in the stack , The PL part of the super lam exstends the fade out aprox 2 1/2 - 3 " depending on where you start the front profile having made the 60 & 64" version my guess is the winner for 31"
Draws is going to be the 62 " but just speculation the 64" is a amazing bow the down side is a little higher brace height , Bob sorry you had to be the pioner on the no SL but at least you answered that question ! I see another in your near future :cheesy:
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Thanks guys for your input. Re the long draw, my own draw with stick bow is only 29” , I drew to 30- 31 just for illustrative purposes. I will extend the fades a little, add a power lam and see how that goes. This is why it was made from shop scraps anyway.
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Man that sucks Bob!! I don't have any theories that haven't been offered up, wish I did!
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I really dont think your draw is too long. I would be more worried about maybe that glass had a defect. If you look at this Shrew riser fades and they are bragging about being able to go past 30 in. on them.
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Yeah see what you mean. Fades are actually thicker than mine! Going to start on mark 2 soon.
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Mike do you know what taper rate they use on the Shrew ? Bob the more of these you make the more questions you get then answers :goldtooth: but Mike poped some veneers, I poped one & you did so we know the fades/ riser are critical the Devils in the details...lol Im thinking with the SL the riser fade angle might be a bit less critical with the SL fade exstention
but any relief in that area probably helps ! All speculation on my part but glad we can share notes :thumbsup:
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The weirdest thing is the way the glass first sheared, before it then delaminates. I have seen quite a few destructed bows over the years but this almost looks like it was cut clear across the glass. Definitely strange. I have started on mark 2 so let the fun begin.
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Dont have a clue what the taper would be on the Shrew.
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Wonder if the shrew has a power lam?
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I dont know but bet it does, Bob mine blew do to poor form design I used wood pegs with the topless @70 psi and some pegs broke while it was baking Im not saying its a issue with the design just some thing that needs a critical eye !
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Nothing wrong with the design. I got one prolly close to 800 arrows thru it. Two buddys and two 35 lbers. out all working fine. The second one I done delamed while building it
. I blamed it on the form that had the hump on the face. That is when I changed the form.
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All fades should be real gradual IMO, some bows can get away with less gradual, others not so much. Power lams are great to help this area...
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I have often wondered how far the fades bend back in to the riser on this bow but sandwiched between glass or glass carbon I really dought it moves back any farther then 2" it might be a feel good move on my part smoothing them back but can't hurt when I get my risers all thinned I put them on a clean flat surface and flex them to see if there bending the same but even with the light pressure doing that they stiffen up quick with in a in. or so !
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Looking at the full draw pic on my fone, that top belly overlay does look close to the fade. Mark may be on to something with the overlays needing to be back a bit?
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They finish about 1.5 “ below end of fade but may be within the zone of influence definitely consider that with new one.
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Not sure if it would affect it Bob , I’ll try to post a pic of the original bow
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(https://uploads.tapatalk-cdn.com/20190421/6ffbc681270e3f4d1e5a67d19d2f9f1d.jpg)
Sent from my iPhone using Tapatalk
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Mine are pretty blunt .
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My industrial background would say that your overlays would be far more prone to set up stress on that area due to abrupt change of plane, so if it remained intact then it might be there is another reason for mine’s demise.Still am bemused about the abrupt transverse shear on the glass. I did do a lot of sanding in weight reduction so perhaps the integrity of the glass may be the culprit.
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I usauly terminate mine where I figure the limb is thick enough not to interfere with the fade flexing nothing scientific just a guess !
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I Will definitely take particular care in this area for this next one. I will have to say this design is without doubt the best bow I have shot. Forward handle risers have the potential to creat a lot of stress, so attention to detail is paramount. I just see it as a challenge to get right.