Turkish Bow Beginner Project

bheggeseth · Post by **bheggeseth** » Tue Aug 14, 2012 2:13 am

Yesterday I was able to get some more shop time in. I started with preparing two horn strips from raw horns. I was able to make quick work with the use of a band saw and table top belt sander. I then used my custom router bit and jigs to groove the horn. The finished horns measure 19.5 inches long, they are 5mm thick at the tips, 4mm in the sal area and then tapper down to 3mm. I also was able to groove the core as well. The router bit works very well but I had to make a new jig for the core as the core shape did not match up with the last bow I was working on. For me that still is better and grooving by hand. 3 hours start to finish for the horns and approx 1 hour to build the core jig and all of 2 minutes to mill grooves. I then went right to applying 1% glue to the core and horns. I will plan on applying 20 coats.

To be fair I first practiced milling grooves with some scrap material and in the past have destroyed a set of good horns as part of the learning curve. I have an addendum log to Adam's great book that I have been keeping for this entire composite bow project. Both are invaluable to me.

Adam Karpowicz · Post by **Adam Karpowicz** » Tue Aug 14, 2012 11:06 am

The grooves look very nice and this is a good option if one plans on making many bows. I machine cut grooves for a couple of bows years ago, but was very worried about the potential burnishing of the wood and horn, which could interfere with adhesion later.

Adam

Arry · Post by **Arry** » Tue Aug 14, 2012 5:59 pm

Adam, but did you actually encounter this problem? I am also contemplating using a router bit...

Adam Karpowicz · Post by **Adam Karpowicz** » Tue Aug 14, 2012 8:52 pm

I have not used a router bit, but toothed blades mounted on a moulding head - the type used with a table saw. There were slight marks from burnishing on the wood, these would be hard to see on horn. Perhaps the burnishing can be avoided with router bits made of carbide.

Adam

bheggeseth · Post by **bheggeseth** » Tue Aug 14, 2012 9:51 pm

Yes the router bit I am using has a carbide cutting edge. I would guess there is an optimal router speed and material movement speed, both of which I paid no attention to. I don?t think any of the material showed signs of burnishing but I have some scrap material that I will examine tonight, what should I be looking for; I would guess I am looking for polished shinny surfaces? If the router bit does burnish the material could you follow up by cleaning the grooves with a matching grooved scraper, ect?

This brings me back to why deviate from what worked back hundreds of years ago? For me I found great difficulty in grooving the horn by hand, this was followed up by the horn delaminating, note this was probably from very poor glue sizing and less due to the poor grooving. To eliminate the problems I moved to using the router bit and applying 20 coats of 1% glue.

I will report back after examining the scrap material.

bheggeseth · Post by **bheggeseth** » Tue Aug 14, 2012 11:17 pm

Using a magnifying glass I examined the router made grooves and then added and examined some handmade grooving. I could not tell if the wood or horn was burnished. I could tell that the router bit leaves a very clean crisp edge but I don?t know if this will be a problem. Time will tell. I am hopeful that I will have the bow done and curing by mid September.

bheggeseth · Post by **bheggeseth** » Thu Aug 16, 2012 1:36 am

Over the last three days I applied 20 coats of 2% glue. I let the core and horns dry for the last day and now tonight I glued the horn and core. I used 100% fish bladder glue at 30%. While the glue was warming up I used three halogen lights to warm up the horn and core, I also was boiling a pot of water in the work room to bring up the temperature and humidity, the room was at 84F. When the glue was ready I quickly applied a heavy coat of glue on the core and horn. I quickly clamped the horn using C clamps with a leather backed strip of blocks to help apply even pressure. This was followed up with the second horn. I had no problem with glue gelling before I was done clamping.

Arry · Post by **Arry** » Thu Aug 16, 2012 5:26 pm

bheggeseth wrote:Over the last three days I applied 20 coats of 2% glue. I let the core and horns dry for the last day and now tonight I glued the horn and core. I used 100% fish bladder glue at 30%.

Great job! Thanks for the pictures.
Did you use fish bladder glue also for the 20 coats of 2% glue?

bheggeseth · Post by **bheggeseth** » Thu Aug 16, 2012 10:06 pm

I have always used 100% fish bladder glue for my attempted composite bows, mostly because I wanted to remove as many unknown variables as possible. Fish bladder glue is the first natural glue that I have used, only recently did I make some sinew glue and found out that I have been spoiled. I was surprised how much quicker the sinew glue gelled. Note strength test showed the sinew glue was real close to the fish bladder glue. I am hoping to use the sinew glue for a 48? Native American ash sinew gull wing bow.

bheggeseth · Post by **bheggeseth** » Sun Sep 16, 2012 2:40 am

I spent some time over this weekend and have shaped the two most recent bows I am working on. Both have approx the same dimensions. The horn extends into the kasan and ends just before the tip transition. The horn is 5mm thick at the handle, 4mm for most of the sal and then reduces down to 3mm for the kasan. I am using Adam's advice for the sal thickness dimensions. At the start of the sal the thickness measures 8.5mm and then the sal tapers down to 6mm. From here the core thickens into the kasan. Currently the width of the sal only tapers 3mm. Note the full dimensions are listed below, I am open to all suggestions so please share your thoughts. I will need to spend a few days preparing sinew so there is time for any corrections.

bheggeseth · Post by **bheggeseth** » Sat Dec 15, 2012 8:30 pm

It has taken me several weeks but I finally have the sinew ready. I am using rear elk leg sinew and it is quite time consuming to process, I figure 20 to 25 hours. Also I would be curious as to how much waste sinew everybody generates. For 100 grams of sinew I ended up with 150 grams of scrap, note it is not really waste as I can use if to make sinew glue.

Now for the bow, it is shaped to the dimensions listed in the above post. I am open to suggestions for the amount of sinew to use and how it should be divided. For this bow I though I would use all 100 grams split into three layers as seen below. As for the 250 gram core weight I think it is heavier due to the horn extending right up to the tips. My last core shared similar dimensions and came in at 200 grams.

All advice is welcome, I hope to get the first sinew layer applied this week followed with a week of drying in-between each additional layer.

Kviljo · Post by **Kviljo** » Sat Dec 15, 2012 9:14 pm

I think this looks extremely promising

I have not measured the amount of scrap, but I have a feeling that I don't end up with as much waste. The reason is probably that I tend to use shorter fibres for the first layer.

Arry · Post by **Arry** » Sun Dec 16, 2012 6:29 am

I am also experiencing a lot of scrap, processing deer sinews.

Do you guys separate the sinew fibers by hand, or do you employ some sort of automation?

jack farrell · Post by **jack farrell** » Sun Dec 16, 2012 6:16 pm

I think I could make a bow out of what you are throwing away. Mostly the outer sheath is useful in Elk.

bheggeseth · Post by **bheggeseth** » Tue Dec 18, 2012 12:57 pm

So I have applied the first layer of sinew which covered the handle and the outer edges of the sal, ending just at the transition to the kasan. Once the glue gelled I pulled in 12 inches of reflex as described in Adam's book. My concern is the un-evenness of the bending. This is the third bow that I have applied sinew to and but the previous bows have never looked this uneven. Prior to the sinew each bow limb was shaped to the same dimensions.

My question is should I reduce some horn on the right limb to get the sal bending to match the left limb or do I just keep adding sinew and fix this with final tillering? It seems as the sal/kasan transition on the right is where all of the bending going on. Where as on the left the entire sal is bending nicely.