BBH twins build along (For testing).

[superdav95]

Hey guys. I’ve had a few enquiry about my bbh bows so I figured I’d do a build along while I’m building my current test bows.  So it’s Another build along sort of…. It’s a series of tests and ideas I’m trying with these two.  So they are not actually twins bows but pretty close.    One will stay slightly wider further up the limbs.  Only slightly.  As far as the reflex both will be very close.  Both will be boo backed with toasted boo strip.  I’ll post some dimensions here as we go but generally one will be 1.4” wide out of the fades narrowed to about 1.25”  for about 16” up the limb then narrowed to about 1/2” at the tips.  Finished tip width with be closer to .4” or less when done.  As far as the other one it will be similar but limb width will got from 1.4” out of fades to about 20” to where it is narrowed to 1.25” then narrowed to 1/2” tips.   Both will have toasted boo strips as my other test bows.  The strips dimensions are as follows.  Same outline top profile of the bows with the tips at .090” thick tapering up towards the handle to about .13.  This is repeated for both limbs.  I space out the nodes to match up on back of bow blank.  I orient the bottom limb B with the nodes that are slightly closer together which happens to place the first node out of the fades area closer and thereby stiffer slightly due to that node.  This planning ahead of time my not be necessary but that’s what I’ve done.  Anyway more to come.  You can see in the pics so far that I’m using a belt sender to make short work of these.  I’m using a 36 grit 6x42 table top sander.  For those who want to do one of these it’s indeed still possible with rasps and file and drawknife but I’m wanting to get these done quickly.  The glue I’m using smooth on ea40 epoxy for my glue up.  I use a vice and various clamps to add reflex on glue up.  As like many do here I use narrow 26” inner tube from bike tires as my wrap up.  Some use a wrap that’s  cut lengthwise up the tube but I like the extra strength of the full inner tube for my wrap.  Just my preference but I’m sure as long as you get good glue up with minimal glue line your good.  I also tape up my boo backing node side to protect from glue. Before I wrap a put a layer of Cir-an wrap to protect my inner tips for most of the glue squeeze out.  Doesn’t stop all of it but works pretty good.  I no longer do hot box for ea 40.  Didn’t find it made any difference for me.  I do mix 2 parts a and 1 part B when mixing my glue.  I just eyeball this.  I do also make sure I degrease my glue surfaces with acetone wipe down prior to glue up and also ensure I glue the same day I grind and flatten my glue surfaces.  You can see that in the last pic I’ve stayed within 1 growth ring to getting the back prepped for glue up.  Not sure if this will make any difference we shall see.    Hopefully this helps someone out there think of one of these builds.  They make great bows.  Stay tuned 🌝

[Selfbowman]

I’m watching!

[PEARL DRUMS]

yes sir, me as well.

[mmattockx]

I'm watching with curiosity as well.

BBH = ??


Mark

[superdav95]

I'm watching with curiosity as well.

BBH = ??


Mark

Sorry mark.  I should have clarified that in initial post.  BBH = bamboo backed hickory

[superdav95]

Here you can see me splitting off my boo slat.  I use a big knife for this like a machete working my way down the length of the pole.  I make sure I inspect my boo for any checks and cracks.  Most bamboo will have some minor scuffs that don’t affect anything functional but is more aesthetics. I split out my slat to about 1 and 3/4” wide.  I use a hammer on the back of my large knife to split through the nodes.    I use large diameter moso bamboo pole.  At least 4-5” in diameter if you can get it.  Using large well seasoned moso pole bamboo will yield better results as the crown will be kept to a minimum.    More to come.  Stay tuned 🌝

[superdav95]

Let’s talk bamboo a bit.  As mentioned earlier I use large diameter moso bamboo.  The poles I get are in 10’ lengths seasoned about 2-4years.  I’ve used greener poles too but it’s more work to get the moisture out.  It’s doable but more work.  Here you can see some poles showing how the nodes are closer together as you go down the base of the pole.  In the last pic I show a slat that I bought online.  It’s not usable in my opinion.  You can see the uneven back on this slat.  Obviously this will be an issue getting an even backside that gives consistent bend if used. Watch out for this.    I find that using poles and making my own slats gives me the quality control I need.  I have found that commercial slats 2” wide can be good but it’s hit or miss depending where you order from.   Lots of guys here use them just fine. Just look them over well.   For me I use the large poles for other bow projects anyway so it works out for me.   

[superdav95]

I toast my slats after I grind them down to about 1/8” thick.  For a length of about 69-70” it takes about 20mins each side.  I use radiant heat source.  A hot plate like a stove top or single burner type would work.  I go till I see steam coming out the ends hovering over the heat source about 3-4”. I keep it moving and pay attention not to hover over an area too long to scorch it.  This will make it too brittle.   Heat tempering boo strips I believe has a performance benefit.  I’m still testing out some theory on this with these bows.  I also weight my bow strip just prior to heat tempering it and after.   I’ll see a drop in mass of around 30-40 grams.  This is seasoned 3yr dry bamboo.  If using greener stuff be prepared to lose a lot more mass in the form of moisture.   The last pic you’ll see how the boo strip swells a bit after heat tempering it.  This is due to the loss of moisture.  This is not a problem and this is why I start this process at 1/8” thick.   I’ve tried heat tempering the strip thinner but found it checks and splits more in me.   Keeping it at least 1/8” saves this for the most part.  A very light Color may be seen on the belly.  This is fine and won’t affect anything. 

Here’s video link for the heat temper process.

https://photos.app.goo.gl/NS34tXRfrtpwbNt8A

[superdav95]

For this slat I went with a taper from about .090” thick at the tips to center line of .125” thick.  You can see that I used clamps to get my outline penciled on from my hickory bow blank. I do this step when I get the thickness of entire strip down to about .150” thick.  I use my 36grit belt sander for this.  This gives a good glue up surface too.  Once I draw on outline and head back to the sander and get the outline shaped out.  This is where I then taper down to my finished thicknesses.  For this one I went .125-.090.  Center to tip.  My other test bow I went a little thicker .150”-.100 center to tip.  I’m testing out some theories with various boo strip thicknesses.    After I get my tapers done and outline the way I like I tape up the back in prep for glue up.  This protects the boo back from epoxy squeeze out.  The 36grit belt sander gives good glue surface but I’m sure other hacksaw blade methods or rasps or files work too.  I thin use a clean rag with acetone to wipe down both back side of hickory bow blank and the belly of the boo strip. I also mark the A and B as a reminder which side it which along with a center line for alignment on glue up. Trust me you’ll only forget to do this once.  Don’t t ask me how I know this 😉  Epoxy is messy slippery stuff!  Where gloves.   I’ll post more tonight when I get back of the glue up set up I use.  Stay tuned.  🌝

[Will B]

Thanks for taking time to document your work. Very helpful

[Selfbowman]

Looking good

[superdav95]

Ok here’s my glue up.  I clean the sanded and prepped surfaces with acetone and let it dry.  As mentioned before I use ea40 smooth on 2 part a and 1 part B for my mix ratio.  I’ve done it with 1:1 ratio without issues too but the can says 2:1 for best resistance and performance.  I mix it well for about 5 mins.  Then I spread it on both glue surfaces ensuring proper alignment. 

[superdav95]

This is what your 2:1 ratio mix should look like mixed.  This is an eyeball quantity that gives enough glue for good squeeze out. I put a liberal amount of glue on both surfaces then lay them in place.  I tape around the fades and tips and at the bends to hold slat in place while I lay the Curran wrap over it.  It protects your inner tube wraps from squeeze out of excess glue. 

[superdav95]

I wrap with two 26” long inner tubes.  Some may think this is overkill but I like the results and gives nearly nonexistent glue line.  The coarse 36grit belt sander marks in the glue surfaces give plenty of grab.  You’ll notice that too that I wrap the limbs with 1/8” gaps to allow for squeeze out.  Will it work well without doing this?  I suppose it would but I made sense to me to do it this way and I get good glue ups.  I use the full tube also and don’t split it in two halves lengthwise.  I use a ruler to measure the height of the tips from the table to ensure they are the same.  In this case I added an inch to existing reflex.  Should have about 5” reflex after glue is cured.  I’ll clean up bow a bit tomorrow stay tuned.  😁

[Aaron1726]

Thanks for sharing this.  I'm definately following along!