Yew billets belly drop build with sinew backing.

[Selfbowman]

My experience with sinew and tb3 has is it takes for ever to dry. But I only did one so don’t count on my experience.!🤠and by the way I was laughing my butt off at your trying  the chew thing. I’m sure it worked 5000 years ago and would work today but why and if those guys had the knowledge of today they might do it differently. 🤠enjoying Dave

[Gordon]

The benefits I foresee could possibly be:

1. Increased water resistance
2. Increased adhesive properties.
3. Easier to repair if repairs needed in the field.
4. Water soluble and easy clean up and application.

A few questions. Why do you believe that Titebond would possess superior adhesion qualities to hide glue given that the latter will naturally fuse with the sinew matrix and wood surface? Why would Titebond be easier to repair than hide glue given that the latter can be easily debonded by simply heating and/or applying water unlike Titebond? Why would Titebond be easier to cleanup than hide glue given that both are water soluble in the liquid state (and the latter while also in a solid state)? I do agree with that a Titebond/sinew matrix would likely be more water resistant than a hide glue matrix.

[superdav95]

The benefits I foresee could possibly be:

1. Increased water resistance
2. Increased adhesive properties.
3. Easier to repair if repairs needed in the field.
4. Water soluble and easy clean up and application.

A few questions. Why do you believe that Titebond would possess superior adhesion qualities to hide glue given that the latter will naturally fuse with the sinew matrix and wood surface? Why would Titebond be easier to repair than hide glue given that the latter can be easily debonded by simply heating and/or applying water unlike Titebond? Why would Titebond be easier to cleanup than hide glue given that both are water soluble in the liquid state (and the latter while also in a solid state)? I do agree with that a Titebond/sinew matrix would likely be more water resistant than a hide glue matrix.

Thanks for the questions Gordon.  I’m not certain just theories.  My reasoning and theories may in fact be flawed and am willing to accept that.  I’ve had great luck with hide glue, fish glues and such so that much I know to the level I can know it’s capabilities.  I’ve also used titebond with good results for some things.  I’ve seen great adhesion with both.  The problem with hide glue or most protein based natural glues is the time it takes to cure especially in the field during a hunt. For a minor repair that requires no water and just little heat if possible might be the exception to what I’m about to say…  Drying time does become an issue with hide type glues compared to commercial glues and epoxy.  In the field even a water soluable glue like tb3 may get you back up and in the hunt in a day or two depending on the repair.  On the other hand Having to rehydrate layers of sinew by adding more sinew or a patch of sinew I suspect would be longer to dry out and then seal up to get it ready for the hunt again.  Even if I were to speed dry each repair over mild heat source I suspect that the tb3 or the like would dry and cure faster then a similar patch of hide glue and sinew to be usable.  I could be wrong but that’s my guess.  Having built many sinewed backed bows and doing patch repairs here and there at the house I've observed that it may feel dry to the touch but is still cool to the touch indicating that it still not fully cured and dry even a week later.  Don’t get me wrong I love the obvious benefits in performance the sinew and natural glues gives.  Part of me is just curious if the benefits are overrated to some degree and negated somewhat by the rapid moisture absorption that happens with sinewed bows in higher humidity.   The tb3 may offer similar performance results and be less affected by moisture then the hide glue option.  I’ve done my very best to seal up my sinew backed bows and it helps for sure but the longer I’m out in the open outside air it shows a noticeable change in draw weight and recovery to its reflex especially in high humidity.  I guess I’m hoping the results are going to be favourable if I go the route of using tb3.  I suspect it may be a toss up in the end when it comes right down to it.   We shall see. 

[Gordon]

Dave, to be clear, I am not questioning the utility of your experiment. I am only questioning some of the assumed benefits. That said, as someone who has ruined two sinew backed bows by exposing them to hard use over several days of heavy rain, I am most interested in what you discover. Regarding the ability to perform field repairs, what sort of issues do you anticipate might arise that are specific to a sinew back that might, as a practical matter, be repairable in the field - I honestly can't think of any. My advice, based on hard experience, for anyone that hunts with a sinew back bow is bring a spare non-sinew backed bow with you in the event that weather conditions take a turn for the worse.

[superdav95]

Dave, to be clear, I am not questioning the utility of your experiment. I am only questioning some of the assumed benefits. That said, as someone who has ruined two sinew backed bows by exposing them to hard use over several days of heavy rain, I am most interested in what you discover. Regarding the ability to perform field repairs, what sort of issues do you anticipate might arise that are specific to a sinew back that might, as a practical matter, be repairable in the field - I honestly can't think of any. My advice, based on hard experience, for anyone that hunts with a sinew back bow is bring a spare non-sinew backed bow with you in the event that weather conditions take a turn for the worse.

Gordon.  It’s hard to convey meaning over text in a reply.  Never thought you were questioning the utility of this hair brained idea.  I too question the assumed benefits so I guess I’ll join in on that!  Lol.  I’m really not sure what will happen actually.  I’ve heard guys on the net posting their results and what not but I haven’t tried it myself so I’m basing my assumptions on what I believe might happen with using the tb3.  This is based on my limited use of it mind you.  I had good hard results as far as it setting up.  Others on here mentioned it was not as hard and even rubbery or flexible.  As far as in the field,  yes it would definitely be better to just bring another bow as a back up if the primary one is sinew backed.    This is not the scenario I’m thinking of.  The scenario I’m thinking of may not make sense to everyone as I explain it here but it’s a specific scenario that I’m going to allow myself to be in as a participant.   to only have one bow preferably made by me and don’t want to use a fg trad bow.  In this situation it will be exposed to various weather mostly cold.  The bow would need to be very durable and hard hitting  enough to take big game.  My thought on this originally was to get a good Osage bow backed with sinew covered with snake skins or something poss thin raw hide. I still may do that depending on how these do…  I would seal this up well prior to embarking.  It’s by choice and design to have only one bow.  That being said in the end depending on the repair both variants would be easy enough to repair in the field.  The major benefit would be the moisture resistance of tb3 version.  I may build one with hide glue and one with tb3 and test them out to see what I get.  I may see about different coatings like even epoxy coatings possibly.  I know there are some activated epoxy sprays that are good too.   The initial test is seeing differences in performance of the two.  I’ll deal with water proofing it later. 

[superdav95]

My experience with sinew and tb3 has is it takes for ever to dry. But I only did one so don’t count on my experience.!🤠and by the way I was laughing my butt off at your trying  the chew thing. I’m sure it worked 5000 years ago and would work today but why and if those guys had the knowledge of today they might do it differently. 🤠enjoying Dave

Lol.  Glad you are enjoying the visual.  I couldn’t do it.  I guess if I was Hungry enough.  😂

[Gordon]

Dave. I have experience with epoxy-based finishes. On the plus side they are extremely durable and weather resistant. On the negative side, unless you have a properly ventilated spray booth, application is difficult and seamless spot repairs are nearly impossible to perform. For me, the negatives outweigh the positives.

[superdav95]

Dave. I have experience with epoxy-based finishes. On the plus side they are extremely durable and weather resistant. On the negative side, unless you have a properly ventilated spray booth, application is difficult and seamless spot repairs are nearly impossible to perform. For me, the negatives outweigh the positives.

Ya figured that.  Thanks Gordon.  I’ve tried one bow finished with a home made version epoxy spray and the finish was less then desired as far as asthetics.  Your right though it is very hard and durable.  I got a lot of bleeding and blending of Colors when I tried it.  I posted the end result here last year and it was just ok.  Bow wasn’t ruined or anything but I obviously need to play around with my thicknesses I suspect.  I made mine using 2 part epoxy ea40 then added acetone to thin.  What mixes have you tried?   

[Gordon]

I've used Thunderbird Epoxy Bow Finish. I've not experienced any issues with bleeding, but you really need to spray it on to get the best results. After the finish is applied you can buff it out just like Tru-Oil and it makes a very nice and durable finish. But spot repairs are nearly impossible. If you care about aesthetics (and I do), then you need to remove the old finish, make your repair and refinish the bow. After having to do that a few times, I went back to my old standby Tru-Oil - people are always banging up their bows and want them repaired...

[superdav95]

I've used Thunderbird Epoxy Bow Finish. I've not experienced any issues with bleeding, but you really need to spray it on to get the best results. After the finish is applied you can buff it out just like Tru-Oil and it makes a very nice and durable finish. But spot repairs are nearly impossible. If you care about aesthetics (and I do), then you need to remove the old finish, make your repair and refinish the bow. After having to do that a few times, I went back to my old standby Tru-Oil - people are always banging up their bows and want them repaired...

Awesome thanks.  I may see about getting some of this to try it out.   

[superdav95]

Still working on these bows….  I got the sapwood one sized with watery thin sinew glue I made from my scraps from processing the moose sinew for these bows plus a few extra scraps from previous.  It took about 20 coats!  Letting each dry to the touch each time till I got to the point of a noticeable shine when dried.  This yew sapwood soaked it up like a sponge!  Should hold very well indeed.  The glue was very thin so good penetration into the wood pours and surface fibers.  I also used a Grobet gimping file from my knife making days to put my surface grooves in. Ive used this technique a few times now and it’s a very good consistent way to get clean fine grooves on your glue surface.  I do this with sinew and horn belly lams too.  For the horn lams I use the courser grobet file. I use the finer one for sinew.  Not sure where I bought these but they work awesome.  I have used hack saw blades and other blades mounted in a scraper with success too.  The key is to get them smooth and clean.  Most important thing in my opinion is adequate sizing of very thin glue.  Can’t stress that enough.  The failures I’ve had on earlier build in past I attribute to lack of proper sizing.  I grooved both bows with same fine file.  I wire brushed after each and wiped down with damp cloth with acetone.  I let them dry and started sizing.  Like I said the one with sapwood took 20 coats of thin sinew glue and the heartwood only bow took three coats of 50/50 mix water and tb3.  I used a burner in the stove to warm up the surface of each bow before sizing.  The tb3 seeped into the grooves and fibers of the heartwood well and followed up with two more subsequent coats which hardened up nice yet still leaving the fine grooving visible.  I will use this same 50/50 mix to soak my damp sinew bundles prior to applying on the bow.  I will follow up with full strength glue and then wrap it tight with a cloth wrap.  I will likley hot box this tb3 and sinew bow overnight.  I’ve not done this before with other instances of using tb3 and it may not be necessary but I’m thinking at this point that I may.  As for the sapwood one I’m going for one layer with a handle overlap into the fades.  Sinew for Both limbs will be weighed and measured for length to balance out the sinew applied to each.  I will likley do 30 grams on each limb and a handle section of 5-10 grams. 

The two bundles seen in the pics are what I’ve got for the 2 bows.  The big bundle is 104grams of good long moose back strap.  The other is 19grams of washed moose back strap med- long strands.  This is the bit that I started with on my chew experiment that ended in disaster.  I rewashed it all and dried it out again and will reuse it.  I hope to get them both backed today.  Thanks for following along.  Dave

[superdav95]

Here’s a pic of those file for those interested and the sinew I’m using and glue I made with the scraps.  For the glue I just use a crock pot on warm setting for 2 days.  I then blend it all up with a Braun mixer and let it go another 6 hours.  Temps were kept below 80-90 degrees.  I then cut up the gelatin into small chunks to dry for a few days with a fan blowing over them.  This has made me great glue in the past.   

[GlisGlis]

For the glue I just use a crock pot on warm setting for 2 days.  I then blend it all up with a Braun mixer and let it go another 6 hours.  Temps were kept below 80-90 degrees.  I then cut up the gelatin into small chunks to dry for a few days with a fan blowing over them.  This has made me great glue in the past.

what water/sinew ratio do you use to make glue? do you have to add water during the 2 days of slow cooking?

[superdav95]

For the glue I just use a crock pot on warm setting for 2 days.  I then blend it all up with a Braun mixer and let it go another 6 hours.  Temps were kept below 80-90 degrees.  I then cut up the gelatin into small chunks to dry for a few days with a fan blowing over them.  This has made me great glue in the past.

what water/sinew ratio do you use to make glue? do you have to add water during the 2 days of slow cooking?

I kept this batch quite thin so that I could use it for my sizing coats.  But normally I make it little thicker.  As far as ratio it really doesn’t matter in the end so long as you get a fairly firm gelitan mass that you can cut up into small chunks and let dry to 100% glue.  It will be rock hard.  I like to keep it fairly this so that it strains well too to get good clear glue free of most of the little bits and floaties.  So no measurements on water to sinew.  I just had basic estimates of 200-300 grams of sinew scraps and filled my crock pot up with water.  I added another 500 mls by day two.  Hope that helps.  Here’s a pic of what I ended up with after 3 days of a fan blowing on my little chunks on drying racks. 

[superdav95]

So I got my bows sinewed yesterday and wrapped.  Here’s what I got after removing the wraps this am.  See last 2 pics.   As far as my set up and bundles pic one shows that laid out.  Again as I mentioned earlier I sized both bows very well before getting here.  I think this is key to success with sinew.  I got a criss cross pattern on the sapwood one a bit more then I wanted but not a huge deal. I’ll smooth that out a bit more when it surface dries a little more.  So. Here is where I’m seeing a difference already.  I had suspected that the tb3 variant would have more mass retained.  This seems to be the case so far. Time will tell.  Both bows were weighed before sizing coats and laying down sinew.  The weights recorded the following day includes the the addition of the back set string.  The sapwood bow weighed 645.55gr before sizing and sinew.  The day following sinew it weighed 797.07gr.  That’s a difference of about 151gr give or take.  The heartwood tb3 bow weighed little more to start at 675.25gr then 833.63 respectively after sinew.  That is about 158.gr give or take.  So we shall see how things go as the days go by.  Gonna see how these measurements drop each day and record them down.  I suspect it will take several weeks if not months to get to the point of bending these again.  Anyway here are some pics.