Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: skeaterbait on January 03, 2019, 05:24:45 PM
-
As a few of you know I have jumped on the FH wagon and made my form. I have the risers somewhat fitted and starting to do dry runs but came screeching to a halt. How do you keep your scarf joints from snapping?
My best guess is that my joints are way to short. I would say the scarf area is only about 1/4" long. Will a longer scarf bend better or is it going to break as well?
-
Longer joints will help.
I’ve had trouble with some maple and walnut lams. If using super glue.....try putting a thin coat on and letting it dry before you glue them together. (Recheck your fit before glueing)
-
Maple is what I am using. Would bamboo be better suited for the drastic bend? Since it's a grass I can't help but feel it might bend better than wood.
-
Is the wood breaking or the glue joint failing?
-
A bit of both.
-
Good topic. Not to go off topic but what is the big advantage of having a forward handle/riser.
-
I haven't had that problem yet my scarfs might be a tad longer then yours I'm using the blue cap gorilla supper glue , I'm just curious how thick are your lams my current bow I'm using some .050 parallels and I noticed how nicely they bend around the radius the others have been thicker.
-
Good topic. Not to go off topic but what is the big advantage of having a forward handle/riser.
There may be other reasons but I think (notice I said "think" :help:, not my strong suit) it allows you to get a shorter bow and not compromise performance.
-
Many moons ago, in the dim ages o the past, I was taught that a scarf joint should be 6x longer than the thickness of the 'planks' being scarfed. Works perfectly with planks for boats; I dunno why it wouldn't work for bow laminations...
-
I haven't had that problem yet my scarfs might be a tad longer then yours I'm using the blue cap gorilla supper glue , I'm just curious how thick are your lams my current bow I'm using some .050 parallels and I noticed how nicely they bend around the radius the others have been thicker.
Both are in the neighborhood of .080-.082. I redid the scarf and stretched it out to 1.5". I didn't push it too far since the epoxy isn't fully cured but I think the longer joint will do the trick.
-
I agree with Skeats you can get a shorter bow for longer draw length with great performance to name few ! Wow Lonnie that's a long joint that one should give you no issue especially using epoxy :thumbsup:
-
Many moons ago, in the dim ages o the past, I was taught that a scarf joint should be 6x longer than the thickness of the 'planks' being scarfed. Works perfectly with planks for boats; I dunno why it wouldn't work for bow laminations...
I like that, and mine are at least that long. Probably more like 8x
-
Put a thinner parallel on the back (like .040) and the two thicker tapers on the belly. Then you don’t have to force it to fit.
-
Many moons ago, in the dim ages o the past, I was taught that a scarf joint should be 6x longer than the thickness of the 'planks' being scarfed. Works perfectly with planks for boats; I dunno why it wouldn't work for bow laminations...
Yes... Back in the day I also did a lot of research on boat building... The figure 7 to 1 stays in my head... Pretty close to 6 to 1...Anything around there or longer should be fine...
Make sure you mark your center after you glue and before you sand... If you sand a little more on one side you could lose your center...
-
Put a thinner parallel on the back (like .040) and the two thicker tapers on the belly. Then you don’t have to force it to fit.
After this last one with the thinner lams under the riser I agree & it seems to fill in any imperfections in the riser to Im going to glue this one up tomorrow I will let you know !
-
I agree. Putting two thin lams under the riser will help hide any imperfections in the shaping of the back of the riser.
-
longer joints and keep thin stuff on the hump.
-
I agree. Putting two thin lams under the riser will help hide any imperfections in the shaping of the back of the riser.
IMPERFECTIONS?????? You must have seen my previous bows... :jumper:
-
Its almost imposible to get them perfect I have tried but but your dealing with material thats not perfect and the end result you cant tell but some times the light you see threw is microscopic thin optical allusion I think because after you glue up you cant see it and there usually in the center non working area at least for me !
-
Also make the form so the hump under the air hose not on the form.
-
Also make the form so the hump under the air hose not on the form.
I think I follow you Mike but have you got a pic for a dense old Show Me boy?
-
(https://i.imgur.com/zJZiKYH.jpg)
(https://i.imgur.com/IO15ayk.jpg)
-
Thank you. Not what I pictured at all but I can see where that would conform better.
-
Forwardhandle, another thing you can do is line your form with 1/8” rubber. I use the black roofing rubber. I starting using it 15 years ago when I was hand profiling the back of the riser to fit the form for the same reason you mentioned. I don’t need it anymore but still use it cause I don’t want to change anything after hundreds of bows.
-
I have a bunch of rubber like that , that I use for bamboo backed bows but Im like you on these FH bows I dont want to change it now that I got all the bugs worked out but Im sure it would work fine !
-
If you shape every riser by hand to fit then you need a profile sander. play with one and get it perfect and make a jig.
(https://i.imgur.com/r8mTbWz.jpg)