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Most recent revision 3 March 2003

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Horn & Sinew III

3 March 2003

SMESSAGES posted to thread:

bluelake                             14-May-99   
ttt                                  14-May-99   
Adam Karpowicz                       16-May-99   
bluelake                             16-May-99   
Sam S                                17-May-99   
Adam Karpowicz                       17-May-99   
Sam S                                19-May-99   
Adam Karpowicz                       19-May-99   
Sam S                                19-May-99   
Adam Karpowicz                       19-May-99   
Sam S                                20-May-99   
Adam Karpowicz                       20-May-99   
Sam S                                21-May-99   
Adam Karpowicz                       21-May-99   
Sam S                                25-May-99   
Sam S                                25-May-99   
Adam Karpowicz                       25-May-99   
Sam S                                25-May-99   
Adam Karpowicz                       25-May-99   
Sam S                                27-May-99   
Adam Karpowicz                       27-May-99   
Sam S                                28-May-99   
Sam S                                02-Jun-99   
Adam Karpowicz                       02-Jun-99   
Sam S                                02-Jun-99   
bluelake                             03-Jun-99   
Adam Karpowicz                       03-Jun-99   
bluelake                             03-Jun-99   
sam S                                03-Jun-99   
Adam Karpowicz                       04-Jun-99   
Sam S                                04-Jun-99   
Adam Karpowicz                       04-Jun-99   
Sam S                                07-Jun-99   
Adam Karpowicz                       07-Jun-99   
Sam S                                09-Jun-99   
Adam Karpowicz                       10-Jun-99   
Sam S                                14-Jun-99   
Adam Karpowicz                       15-Jun-99   



Subject: Horn & Sinew III
From: bluelake
Date: 14-May-99

As with the first thread, the second took off and (consequently) took a long time to load. Let's try it again.

Thomas


Subject: RE: Horn & Sinew III
From: ttt
Date: 14-May-99

ttt


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 16-May-99

Sam:

I found a picture of a Turkish bow on the net for you: it is an item # 103860956 on Ebay. It seems to be genuine, although I am a little suspicious about the leather belly wrap at the grip.

Adam


Subject: RE: Horn & Sinew III
From: bluelake
Date: 16-May-99

Adam,

Interesting item.

Thomas


Subject: RE: Horn & Sinew III
From: Sam S
Date: 17-May-99

Adam:

That bow does not have the great amount of reflex that I would have thought that a Turkish bow would have. I guess that varies.

Glued up the siyahs to core over the weekend. Went ok but I did end up with small gaps of 1/8" or so between point of male splice and bottom of female. Probably due to the fact that I had let a sizing of glue dry. Didn't get anything else done as I wasn't feeling well over much of weekend.

I had not really realized how short this bow was gonna be. Finally a bow that I can get into the cab of my pickup. May even fit it into the glove compartment! ;~)

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 17-May-99

Sam:

The bow on the picture has been used and lost some of the reflex, this is normal.

The 1/8" gap is ok, nothing to worry about, once you file the core with horn to shape and cover with glue it may even go away.

Check the core for twist by laying sideways on the flat surface. Prop up the ears for the centres to be at the same distance from the surface as the centres of the grip and limbs. If you see any twist, you need to warm the section and untwist it. Once ok, file on the horn side to make the belly surface perfectly perpendicular to the plane of the core's curvature. It is important to have everything well prepared before gluing horns.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 19-May-99

Adam:

One end has slightly more recurve (5 deg or so) than the other. One is at an angle of about 80 deg, the other at 75 deg or so. I did as you said above and everything is in perfect alignment to me. Maybe I should get somebody else to eyeball it. Sometimes the eye sees what the eye wants to see.

I've got a 3 1/2" splice. The part of the ear above the core is 4" to tip with nock cut in 1/2" from tip.

Thinking about working with some gemsbok horns that I've got for this first bow. The are straight (as in minimal curl with plenty of length) and therefore less intimidating than the water buff horns!

Do you recommend grooving on this first horn bow? If so, can I use a broken part of a 3/8" bandsaw blade for grooving tool made similar to the one that is used in Scmhidt video?

I'm not sure how these bows are made to bend in only the upper third of the limbs.

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 19-May-99

Sam:

You can check if the limbs are the same by placing one on a board, drawing the outline with a pencil and checking if the other matches. I not matched, I would slightly open the one with 80deg with dry heat on the siyah section and bending by hand until the same as the other one. If too difficult, you can adjust the curvature by cutting the ear in a little more open configuration if you have enough room.

The length of the ears is ok, no need to cut nocks yet.

The 3/8" bandsaw blade is too thin, would flex too much. A heavier saw blade or a scraper blade would be fine. You will of course need to re-cut the teeth to make them exactly even-sided triangles, every 1/12 - 1/16". I think it is a good idea to do the matching grooves for the first bow, that way you are sure it will hold up better.

The bows bend in the lower half of the limbs mainly, the siyahs are rigid.

I understand you would need to heat flatten the gemsbok horn after cutting in half. Fot working with horn, not only before heat treatment, but also for sawing, filing etc., it is good to pre-soak in water. This softens the horns a little.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 19-May-99

Adam:

Would a piece cut out of an old handsaw do for an grooving tool? Hate to use one of my cabinet scrapers. I'm thinking about making a form for grooving similar to Scmhidt's. I've got one of those Workmate benches that he uses. His method looks simple enough.

Probably should mention that I got hide glue all over the siyah portions. Guess that needs to come off. Also, I take it that I'm to file of the ridge of the siyah on the horn side even to the core so that the horn can cover up the splice.

The 80 deg angle was the more open of the two. I was measuring that by the plane of the core extended. Or the outer angle in other words. So I'll just heat up the 75 deg recurve and give it a little more bend. Just a little.

Thanks, Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 19-May-99

Sam:

Be careful heating the siyahs, if the glue is not completely dry, you may get separations. I meant to heat and open the 75deg, not 80, sorry.

Yes, you need to file the siyah section on the core's belly too. The horns go all the way up to the knee, where the string bridge is later placed.

The core is filed/sanded flat. Make sure the filed surface is exactly at the right angle to the plane of the overall curvature of the limbs. There must be no bumps, very smooth and even.

The old handsaw is perfect, just make sure the teeth are properly spaced for re-filing. A small triangular file is used for this. Of course when you file, do not rock the tool, otherwise you will have rounded cutting edges, I am sure you know this.

The fixtures in the video are good, I used something similar too.

I think it is better to have the horns cut and filed flat too before the grooving. This way you will know where you are heading.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 20-May-99

Adam:

After I arrived home yesterday I placed the thing on a flat surface and looked at it and well .... I thought the recurves looked equal. Did your trick of drawing the outline of one and comparing it against the other and they were identical. How about that? One must have gave some.

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 20-May-99

Sam:

Good. You need to worry only about equal curvatures of siyahs with ears, really. The rest will be made equal when you use a form for gluing horn. In any case, the nonbending sections should be equal. Now, the horns.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 21-May-99

Adam:

Yes, the horns. I've gotta get to work on them.

Been doing some thinking. Is this bow to have the "double curve" feature that was talked about on an earlier thread? I know that some horn bows [Kassai (sp?) for example] has this feature. Am not sure about the Korean bow. In other pictures this feature is missing in many (most?) horn bows. Just curious.

BTW, that grooving tool I going to make is going to see double duty use for add on risors on selfbows. The kind that always popping off.

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 21-May-99

Sam:

The double curve you mean reflexed at grip too? The Turkish bows sometimes have this to a lesser degree than the Crimean Tatar, Korean, Manchu/Mongolian or Sind. Some bows acquire this reflex during drying/contraction of sinew, depending how flexible were the sides of the grip. Normally Turkish bows do not have it. For the very short bows, like the Turkish, such reflex would add to stack. I would not recommend this for a first bow anyway.

Good idea about the grooving tool.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 25-May-99

Adam:

I haven't had as much time to spend lately on this project as I would have liked because of getting sidetracted by unexpected priorities. However, I have worked on the Gemsbok horns by sanding down the outside rough and then steaming to flatten. Really it did not go well in that the horn tended to split. I stopped my effort then to keep from ruining that particul half. In rereading some of your earlier posts ( I saved them on the hard drive) you wrote that a rounded, concave horn could be glued to the core.

Oooops gotta go. Sam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 25-May-99

Adam: Continuing from above-

You wrote "If you end up with a rounded, concave strip at one (base) end, you must allow for greater thickness along the rest of the strip. In such case the entire cut strip will need to be rounded in the inside to match the end. The wood will of course be convex in cross-section to fit." In my particular strip I do not have 19" of concave length. More like about 14" of concave and about 12" of solid. Of course I'n going to cut it down to 19" with it being 3/4 at tip. Can I have one end cancave and tapering to flat at about 1/2" of length of horn? I know this is not what you wrote, but I don't know how to otherwise. The base will be at the handle, btw. The inside of the horn is to be the gluing surface to horn. Keep in mind that Gemsbok is narrow and rounded on top. Will it be ok for it to be about 3/4" at tip with a more or less rounded surface? A concave cross section would negate grooving for at least part of horn? If it is concave why must I have greater thickness along rest of strip?

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 25-May-99

Sam:

The horns, if concave at one end, must be concave at the other end too. In short, must be concave all the way. The reason is you will be in this case using a grooving scraper, concave for the horns and convex (at the same curvature) for the core, both with teeth cut as usual. The curvature is normally no less than at 3" radius, pretty flat. There is no way you can have the partial concavity along the strips, matching the core to fit would be an impossible task.

This is why I said the other end should be thicker to allow for scooping the concavity without loosing width. The 3/4" width is about the minimum for the horns at the siyahs ends.

The rounded horn belly is ok, although the thickness of the horn strip at the siyahs is no more than about 1/8", concave or not.

I would try to soak the gemsbok horns in water for a couple of days, dip in boiling water for a short time, heat further over a stove to very hot and flatten fast. It may be desirable to bend over a curved form (a little more open curvature than for the core). I think it may help to thin the sides of the cut horns a little for more even flattening, also cut the sides to more narrow than half circle at the base. Again, I have never used gemsbok, only bent some cows horn with reasonable success. Slight splitting should not be too bad.

It may not be a bad idea to practice on a scrap piece to see how much heat you can use to plasticise the horn without ruining it.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 25-May-99

Adam:

I think your right in that that I had the base end of the horn too wide before steaming. I'll try making them no more than 1 1/4" or so at base. How can a grooving scraper be used for a concave surface(horn) and convex (core)? Would a grooving scraper need to be made for each?

These were the inside curves of 2 Gemsbok horns so I still have the outsides in case I ruin these. I'll try it again!

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 25-May-99

Sam:

Yes, for concave horns you need two scrapers, one convex for horn and another concave for the core. Both must have exactly the same radius of curvature with teeth. It is much easier to have flat horns!

Try to have the horns really hot. If the sides of the horns are a little thinner, they may flatten with less stress in the centre. You could try doing it in stages.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 27-May-99

Adam:

Trimmed a strip and soaking. More I look at it the more I think that the base of horn should go at tip of bow because tip of horn has more thickness. I had always kind of assumed the other way with base of horn being at handle. The horn is 1" for nearly all of length. I think in a earlier post you stated that this would be aa acceptable minimal width. It has been reduced to a max thickness of about 1/4". I'll reduce it down later to about 3/16" with handtools. My question is how narrow can horn be at handle?

Also what is the best way to cut the old handsaw for making grooving scraper. Would a metal cutting blade in a heavy duty jigsaw work? Or hacksaw? Or break it up with some kind of chiesel?

Thanks, Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 27-May-99

Sam:

Yes the 1" width is an acceptable minimum, although it is easier to have a little wider strip, since some trimming may be needed later. Bear in mind, wider limbs are more stable and easier to tiller. For a first bow 1 1/4" would be better.

The horns at the grip's centre are about 9/16", widen to the full width about 6-8" from the centre of the bow.

The 1/4" thickness is ok for the handle section, the horns taper from there to 1/8" or even less at knees. This is for a finished horns, for glueing, greater thickness gives you more room for mistakes. On the other hand, the horns must be flexible enough, when hot, to follow the curvature of the form/core. The w.buffalo horns are quite flexible, I am not familiar with gemsbok.

To cut the blade you need an abrasive blade in a table saw or a grinder. Or a dremel tool with a grinding bit to score and then break the blade. The blade can be locally annealed with a torch and then cut with a hacksaw.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 28-May-99

Adam:

I'll follow your advice and work with both the remaining Gemsbok and W. Buffalo horns to get least 1 1/4" width strip. Wouldn't want to have a reenactment of the Persian prince incident!

Sam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 02-Jun-99

Adam:

Another Gemsbok horn strip is somwhat flat. I have trouble flattening the part the is hollow near the solid tip. The first 8" or so from base is fine but the rest will not flatten. I boiling it in a roasting pan so I know I'm getting it hot enough. It is reasonable that I would have the some problem with W. Buffalo horns. Any advice?

Also, I've got 2 pieces cut fron handsaw for grooving scrapers. The existing teeth are at spacing of 8" tpi. Will it be necessary to grind these flat and refile at 12"-16" tpi?

Thanks for the help, Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 02-Jun-99

Sam:

To have it flat, you would need to file/shape the solid part of the tip to become somewhat concave and then do a little more bending. The strips narrow down towards siyahs, perhaps filing only is sufficient?

It is not necessary to flatten the water buff. horns, since they are normally wide and thick enough to allow only filing the inside flat to shape. I never needed to do it, if horn was concave for the most part, I would just make the rest concave too and glue it to a convex core.

I think you will be better off to find a finer blade, the 12 tpi is the widest spacing for the horn. If the teeth are too wide and deep you will be cutting dangerously close to the outside and risk splitting. Bear in mind the thickness of the horns is less than 1/8" at siyahs. I suppose the big teeth could be filed more flat for less depth, but I have never done it.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 02-Jun-99

Adam:

The depth of the existing teeth is 3/32". I think what I will do is grind these teeth flat and refile the teeth at 1/16 tpi at about 1/16" depth. Just don't know how difficult that will be to do.

I not at all sure that I have thick and wide enough w. buff. to file flat. I'll work one of them tonight. I would think that one would always want to match the work on one to the other (i.e. if one flat the other flat; if one concave the other concave).

Sam


Subject: RE: Horn & Sinew III
From: bluelake
Date: 03-Jun-99

FYI, the Korean scrapers are, about, 8tpi.

Thomas


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 03-Jun-99

Thomas, the Korean scraping does not go as deep as in the Turk style joinery.

Sam:

Good luck with the w.b.horns, actually as I am writing this you are probably done. I hope you followed some of the advice at the beginning of this thread.

It is not hard to file the blade, you need a small triangular file with sharp corners. Perhaps you know this, but try not to drag the file back in the cut, just even pressure strokes forward, without rocking the blade (keep the elbow stiff while doing this).

Adam

Adam


Subject: RE: Horn & Sinew III
From: bluelake
Date: 03-Jun-99

Just making a mention.

Thomas


Subject: RE: Horn & Sinew III
From: sam S
Date: 03-Jun-99

Adam:

Did some work on the rougher of the two W. Buff. horns last night. This one horn has significant twist about 2/3 from base and I'm not sure that I can get 19" without boiling/steaming the twist out of it after working it to a strip. Schmidt mentions on the video about doing this by twisting the strip in the opposite direction when hot. I'm working slow and causiously on it.

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 04-Jun-99

Sam:

The twist should be much easier to eliminate than the concavity in your gemsbok. However. When the horns are later glued, they must be quite hot to extend the glue fluidity and make them softer to conform to the core. It is possible that the horns will try to "untwist" again at that time. To prevent this, the horns should be untwisted at a higher temperature than later heating during glue-up. Just make them very hot when you do this.

Horns conduct heat well, there is no point boiling for too long, it may actually weaken them. Boiling for only a couple of minutes + heating further over a stove is ok.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 04-Jun-99

Adam:

Put plenty of W. Buff. horn dust in the air last night (cough, cough)! But I'm not sure that I understand how the ancient bowyers were able to do this work with what they had.

I'll trim this strip down to about 5/16" max thickness and then try untwisting. Does this sound about right?

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 04-Jun-99

Sam:

I'd be careful thinning the strip at this point, you may need more thickness to have more room if something goes wrong.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 07-Jun-99

Adam:

The better of the two W. Buff. horns is down to 3/8" thicness. I know to take it down to 3/16". The twisted one is coming along too but I have to be more careful wih it. It has good width which should help. Would to be better to take out the twist at the same time that I heat it to make it conform to the core?

Another thing that I've started wondering about the curvature of the horn strips relative to curvature of core. I've always assumed that the outside surface of the horn would also be the outside of bow and the inside of horn would be the gluing surface to core. Yet the direction of curvature of the horn and core seems th dictate otherwise. The horn strip will have to be flexed in the opposite direction for what I had assumed. Please comment.

Also have done 2 grooving scrapers and a fixture similar to Schmidt's for holding horn while grooving. It was tough to get identical teeth by freehand but I think it will do. I've got 12 tpi.

Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 07-Jun-99

Sam:

About the horns: yes the outside curved surface of the horns will be the outside of the bow's belly. How did you get it the other way? Is is gemsbok you are talking about?

The horns do not have to be curved exactly as the core, it is better to have them curve less. This way, when you press the horns down onto the core's belly, the contact is assured with no air pockets, and the grooves in the horn allign to the grooves in the core easily. This is important when you use the gelling glue, like hide glue, you have less time for corrections.

If the horns are too curved, I'd straighten them a little. Yes, you pretty much have to do all corrections with heat at the same time, since heat may undo what you did before.

If you for some reason must use horns curving "the other way" as you suspect could be the case with yours, you would do better to make the core's matching surface on the concave side, if possible, too. Both strips must of course come from the same section of the original pair.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 09-Jun-99

Adam:

Still reducing thickess of horns. In rereading former threads, strip is to be 3/16" at handles and 1/8" at siyahs. What should be the thickness at middle of strip? Where will taper start? Width will be 1 1/4" and taper to 3/4" (7/8 to finish down from) at siyah. But would 1 1/2" width be better if I can get it? Where should taper begin for width?

I think I got confused about the horn and core curvature relationship. Or maybe I was thinking about what if I was using cut from concave edge of horn or something.

If I understand correctly gooving will be the next step once horn is to correct diminsions. What will follow?

Thank you very much, Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 10-Jun-99

Sam:

It is best to leave the horns as wide as possible for grooving. This way you have more width to play with if there is some misalignment betw. the grooves in horn and core. Try to leave them as wide as you can all the way to the tips at this stage, do not trim the sides at all now.

After the horns and core are grooved and pressed together (dry, no glue), the sides of both can be filed down, but not to the target widths yet, just until they are level. With the edges level, it is easier later to line-up the horns with the core during glue-up. Since I use clamps, I file only one side, if the rope method is used, both sides must be filed.

The thickness at this stage is best left 1/4" at the grip and half way into the limb, then taper to 1/8" at siyahs. If not enough thickness left after cutting, 3/16 is ok, but this will be the final thickness, try to leave the horn smooth on the belly. After grooving, some thinning on 1/4" end may be needed for more flexibility.

As to the final (after glue-up, do not do it now) taper for width: the limbs are best left parallel from about 6" from centre of grip to the beginning of siyahs. Modifications may be needed, depending on how it all turns out after gluing horns.

After that, the limbs must again be un-twisted if necessary, a center line drawn, limbs and siyahs trimmed, and the back side, together with ears, shaped for sinew.

Adam


Subject: RE: Horn & Sinew III
From: Sam S
Date: 14-Jun-99

Adam:

Finished sanding thickness to 1/4" at handle to mib limb and then tapering to 1/8" at tip on both strips. Tips are now 1" in width. Base is not cut off to length just yet. The strips have some flex but doesn't *seem to me* to be enough for a bow or even to flex to glue onto core. Its hard (for me anyway) to know how much they can bend before risk of breaking in tension. All in all they look good, though.

I'm not sure about my grooving scrapers. Did some experimenting with 2 softwood strips. The triangular file that I used did not exactly place a sharp point in the gullets (they were more like rounded) and the grooves in the 2 strips of softwood did not match well. Thinking about doing some more work on them or something.

Also, the strip from the horn that was twisted is wide enough that that 1 1/4" width of 19" length can be laid and cut out of it without boiling and steaming. Could be difficult to groove straight before hand, though. Should I rough the width out before trying to groove this particular strip?

Did glue up siyahs and core on a second bow (that has more reflex) but the siyahs do not look as nice as the first bow (they looks too thin in thickness where they shouldn't). Can a horn ridge be inlaid on the back of a siyah strip for strenghtening purposes?

Thank ya, thank ya very much! Sam


Subject: RE: Horn & Sinew III
From: Adam Karpowicz
Date: 15-Jun-99

Sam:

My last night post did not go through.

The thickness of horns:

The horns can be made thinner for more flex after grooving. Also, during glue-up the horn will be hot and more flexible. Do not worry about breakage, the horn is a very tough material, unless defects are present, such as cracks, which are difficult to see sometimes. In any case it is better to loose the horn now, than have a crack in the belly later.

I used a small "needle" file with very sharp edges to make the cuts in the scraper. They are cheap. Softwood can be messy as the practice material, use hardwood.

For the (now un)-twisted horn: press it flat and lay a ruler over it to check for the lack of twist now. With twist there will be more sideways curving. If all is ok, the sides can be filed a little, but it is better to leave as much material as possible now.

The siyahs on your second bow: wood is only 1/2" thick at the bend and a sinew ridge is formed on it later for more thickness. So, the siyahs may not be so bad. If necessary, a sliver of hardwood (not horn) can be added on the back side. Sinew sticks to wood much better.

The surfaces of the horns and the core must be flat with no bumbs or dips before grooving. Try to mate the surfaces now, the contact should be good now (if horn is too stiff, bend it in sections). I usually finish the mating surfaces for grooving with #80 sand paper.

Adam

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