Hold my hand when I sinew my first bow

[jameswoodmot]

So my laminates have started over as I found out the hard way my cascamite had gone off and my yew is still drying. My 100lb roving bow still isn’t down to low enough moisture so I started another bow!

I’ve been waiting for the right elm stave to practice sinew backing. This one is 43” from the top of a sapling I took down. 1 5/8” in the middle down to 1” at the tips

Gave it a cook over coals, it’s ready for a short string.

It’s got a little bit of snakeiness and a little knot in the middle and quite high crown. Are these likely to cause an issue?

My tendons are roe deer leg tendons so pretty short but it’s all I can get.

Any suggestions as to weight of sinew and how many layers? I know it’s an open ended question but it would be good to have a guide for the first one

[jameswoodmot]

Little knot and the reflex

[superdav95]

It’s a great candidate!   What are your longest strands?  I would lay down a brick pattern with shorter sinew strands.  This allows for staggered and methodical approach to laying it down.  I measure in dried pounded and stranded sinew bundles.  I then lay down either a single combed bundle premeasured by dry weight for each limb.  I save the shorter strands for over the handle area to overlap a bit.  The brick wall pattern would be good for shorter strands.   Ask away any questions. Lots of experience guys on here. 

[bjrogg]

I’m going to be watching this one to. I still haven’t done a sinew backed bow. I know Dave knows a lot about not only applying it, but also preparing bow for it, making glue for it. And knowing how to use it all.

Bjrogg

[jameswoodmot]

Thanks guys!

Averaging about 6-7” long, tearing it up now.

I’ve found if I shred it too much it starts to turn into a curly mess so I’ve left it slightly coarser.

Going to use commercial hide glue bought as dried granules.

I was thinking about tbb with the diagram of the brick pattern. Are two layers ok for this or would three thinner layers be better? I’m thinking also that because of the crown that perhaps applying slightly more to the centre of the crown and less to the outsides.

[superdav95]

If it were me I would really clean the sinew very well. Your hide glue will work just fine.  Separating bundles of strands into short medium and long can work well if using a brick patters.  I would measure the amount of sinew you want for each limb.  The last couple I did that were a little longer then your bow here each took about 70 grams dry.  So basically equal mass in glue general rule of thumb.  Depending on your glue and how it’s done can be a little less glue but risky.  I always mix up a little more then I need at approximately 25-30% strength.  If using granule glue just start with small mason jar with 75 grams of water and then add your granules till you reach 100 grams.  This will give you 25% glue.  If preparing the back for sinew I use a fine toothed hacksaw.  And run parallel grooves up and down both limbs.  I then take a stainless wire brush to clean out any debris.  I size coat with 5-10% glue about 10 times. This allows the pours of surface to really open up to accept the glue and adhere well for sinew.  Basically coat with a brush letting it dry to the touch warming slight the wood.  It will be shiny.  It may be overkill for sinew but you won’t regret taking the time to get it sized well prior to sinew.  Measure each pile for each limb to be as prices as you can to not end up with way more sinew on one limb then the other.  I comb my sinew and clean it well with my fingernail its entire length dry first to pull into finer strands.  I then comb it with a dog brush to even finer strands.  Doing this will give a very clean surface.  These bundles when layed down can be smoothed out with fingers dabbed in some water.  I use a heat lamp to keep things warm aimed at my work.  Another trick I’ve done with brick pattern sinew to get a smooth finish is to let the sinew gel up well and start to just be dry to the touch on surface only and then wrap it is with a t shirt stripped out or some sort of bandage.  I don’t use tensor bandage as it has a little too much elastic but instead I use horse leg wrap.  This stuff is very thin and leave virtually no wrap marks and compresses just enough the sinew to make it smooth even with brick pattern or laying it down.  Works well.  I’ve posted on this method using wraps.  If you search my yew bow builds last year or so I show it.  I know it’s there I just sent link to someone else recently with similar questions.  Anyway.  Don’t be afraid to get messy.  The sinew will stick to you and be like playing with wet spaghetti noodles.  Is you sinew fairly clean when pounded up?  Leg tendon is good for giving clean sinew dry.  There will be some pieces that will have extra bit that would need to be washed and combed for best results. 

[jameswoodmot]

Fantastic thanks Dave you’ve already answered many of my questions.

When you say is it clean are you referring to the oily/residue or how cleanly the stands come apart? It definitely has some oiliness to it it I don’t have a lot to compare it to as I have only used one piece of roe back strap before. I have pulled out the short strands where the tendon splits into branches and done my best to pull out any short bits.

I will strip it down further into smaller pieces and  I doing so sort them into length (currently between 5” and 8”)

What do you recommend washing with?

[superdav95]

I use a dawn dish soap.  I wash it well in Luke warm water.  I’ve also soaked my bundles overnight for some of my moose backstrap as it has bigger strands.  I use a small stainless steel brush for final brushing to root out the clumpy bits that are sinew and remnants of casing.  The soap will help cut the oils too. Back string your bow too when you lay it down.  You can do one good layer or 2 smaller layers.  I’d let it dry a week or so between.   This may also give you the chance to fill in any voids or sand down any clumpy spots.  Keeping all the fibers is key to not have the fibers twist when drying under top layers of fibers.  I like to comb it the flip it and comb it again to be certain all the fibers are parallel

[jameswoodmot]

Thanks again!

Man, my hands know I was shredding sinew last night!

I’ve got 46g (1.6oz) of long 5-8” and 11g (0.4oz) of 3-5”. 2-2.5oz seems average for a 60” bow so I should have plenty there. As it’s Elm I would rather not over power the belly.

Later I’ll go through it all and sort the long bundles into two sizes and pull the longest pieces out of the short pile. Break down any larger looking bits and give it a brush through to pull out any stragglers.

I’ll get this bow to brace height and a bit further, score up the back with hacksaw blade, clean.


Does the sizing need doing at the same time as the sinewing or can I size one day and then re wet it and warm it back up again?

[Robert Pougnier]

Yeah is sinew is about as tough on the hands as it gets!

That's about the amount I added to my 60" hickory bow and It pulled an inch of reflex on it's own initially as it cured.

I've had no problem doing either. I prefer to let the sizing dry but you can size it just before you apply the sinew too. If the back seems to absorb a lot of the glue you could give it a couple of coats to make sure there's a nice solid base for your first layer to key into.

That's looking great so far and I can't wait to see how it turns out. Nice job!

[superdav95]

Thanks again!

Man, my hands know I was shredding sinew last night!

I’ve got 46g (1.6oz) of long 5-8” and 11g (0.4oz) of 3-5”. 2-2.5oz seems average for a 60” bow so I should have plenty there. As it’s Elm I would rather not over power the belly.

Later I’ll go through it all and sort the long bundles into two sizes and pull the longest pieces out of the short pile. Break down any larger looking bits and give it a brush through to pull out any stragglers.

I’ll get this bow to brace height and a bit further, score up the back with hacksaw blade, clean.


Does the sizing need doing at the same time as the sinewing or can I size one day and then re wet it and warm it back up again?

Ya it’s hard on the hands.  The way I do sizing for sinew prep is heating the bow slightly to open up the pours to better accept the thin glue.  I let it dry to the touch each time and with a little warm heat. Radiant heat.  I use a hot plate burner.  Do not over heat.  If you do see it bubble up let it dry and scrape it off and restart.  I go as many times with warming it and adding another size coat till it looks shiny but still thin.  This can happen on same day as laying sinew.  I would scrape the back and size coat the same day.  Sinew can wait to be done as long as you want after sizing.  Just wet it slightly with warm water just before starting to lay your bundles.  It’s also good to have a system written down.  You’ve spent all that time and energy get to this point so keep good notes.  I like to draw out a diagram even of how i plan to lay out my staggered bundles with check boxes. This way if something happens and I have e to leave and come back I can pick up where I left off.  Notes are good to keep for future builds too. I’ve often referred to my old notes as my memory is t what it used to be and I also can spot irregularities later to be improved upon. Sounds like you made some progress.  Don’t worry about measuring out too much glue.  You can always freeze it to be used later.   When you are about to lay sinew it will all be laid out in measured bundles that are damp, clean, combed straight and brushed of debris.  I dip my bundles right down into the glue and squeeze out the excess glue and lay it down. Best of luck and keep us updated.