Primitive Archer
Main Discussion Area => Horn Bows => Topic started by: duke3192 on October 19, 2014, 11:04:45 pm
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Have horn, need some guidance on how to cut it to get the most out it.
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It's the outer curve you need. Glue the horn to a piece of ply so that this outer strip is as square as possible to the board. More than likely you will just get one strip.
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and what tools would you use to work the horn down to strips suitable for a bows belly? Belt sander, rasp, surform?
Russ
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any and all of the tools mentioned will work,, you can also use a very small hatchet and/or small hand daze to rough out the horns. then switch to rasp/ and heavy scraper
if you using power tools,as mike said.. hot glue the horn down to a PC of 1/4 " plywood, square the horn as good as possible, make your first cut, just skimming the surface of the horn, but make a good continues first cut,, then make a cut for the strip,, if the horns are thick enough you may get lucky , to get a second cut,, it wont be as long as the first strip, but can still be used for another bow.. DONT use the fence it wont work... take your time and use a new or sharp blade . James
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Last nite I began working the horn and I found, like you said, that all of those tools will work. I found the best non tailed tool was the heavy saw rasp - but even still, it will take quite some time to work the horn to where it needs to be using only these hand tools. I would be too chicken to use an axe and I don't have a small adz. I did put it up against the belt sander, and that did work, but the smell was too bad for me to continue.
Your idea of using the band saw makes sense. I could tape a paper template to the outside of the horn to use as a 90 degree guide or just set up the ply board like Mike says, or both. I have also seen a thread here where a guy (maybe Beadman) worked the horn down on a drill press with a grinding bit to a uniform thickness, then flattened it with heat and pressure. It would seem with this method, you can get a wider strip than with the band saw, due to the spreading sides becoming part of the finished strip. Of course, this method excludes the possibility of getting a second strip from that piece of horn.
So, I ask you - - which method would you suggest I take a stab at? Since I am working in the dark (cant find Adams book in English for less than $150), I dont really know what size (width and thickness, I mean) strip I should be aiming for. I just assumed I should get the largest (width) strips I can manage, then make the core to match the strips. In this vein, I was leaning towards the drill press method due to the larger width strip theory. The band saw approach seems much easier, though, and with less steps. Any advice would be welcomed. Thanks.
Russ
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what kind of composite bow are wanting to build? it will be such a waste of horn to just grind it away, for the sake of width alone.. the Turkish bows do not require great widths. you will want more thickness down the center of the belly.. but other styles require more width ,but less thickness,,
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The Beadman was using Gemsbok horn, which is fairly straight, but a smaller diameter, he cuts through the solid tip and hollows it out to flatten it. Very work intensive. Beware, too much heat and you will break the horn. Personal experience, get the lazer thermometer, it is about $25.00 at an auto parts store and it is infra red tech.
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So, I found the paper template idea to be useless -- but the horn, once hot glued with shims to a piece of ply, stayed put well enough to skim the outside edge of the horn past the band saw blade creating a nice flat reference surface. Off that surface, I marked a fat 1/4 inch in thickness and cut again. This, done to two horns, has left me with 2 thick strips which taper in width, about 22 inches in length (not all going to be usable) and the left over horn from each cut is plenty thick enough for two smaller strips (with more work) of about 14 inches long.
Now for flattening and grooving. I think I said it before - but here it is again - - man that horn stinks when machining it.
James - as to what kind of bow I plan to make - - not sure -- I have wanted to experiment with horn and now have the opportunity - but not a sufficient knowledge base. I am doing my research as I go, as I am able to, and for this first horn bow, I will let my eye and the advice I receive guide me. I do not care so much what type or style I end up with, so long it is looks nice to my eye (if it survives at all). I hope you don't find this thought "sacrilegious" :-)
Russ
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Put a 50 grit belt on the sander. Works faster and does not snell as bad, and get an extension cord so you can work outside
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Funny you should say that - - I got extra belts today at lunch - and I started hooking up the shop vac to the back of the sander last nite. As bad as the smell is, it is not worse than machining antler - which to me smells like the dentist.
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I would definitely try to decide what style bow you want to make first. Magyar style bows with less than normal grip reflex might be a good place to start.
What wood do you have for the core? Sinew and horn are easy enough to get but perfect straight grained wood...well that can be another matter!
Your strips are long enough to make most styles of bow and say 35 - 40mm width, 5mm thickness will likely be enough.
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Hi Mike
I was thinking along the lines of Magyar style bow, mainly because I have been able to find more information and pictures about that style over the others. Also, they are dynamite looking. Although not decided yet, I was thinking of 160 - 170 degrees of set back at the handle with ears coming off the limb at 45 degrees. I was thinking that the limbs would be as long as the finished horn pieces turn out to be.
I had planned on making my core to match up well with the finished horn pieces. I thank you for the rough horn size estimates, as I will know if I am in the correct ballpark when thinning what I have. Currently, my horn pieces are clamped flat after my attempt to straighten them with dry heat. We will see how well they keep. If they spring back too much, my next attempt will be with steam and boiling. I am unable to use the belt sander to sand the inside of the horn pieces until they are relatively flat.
Do you think I will be able to straighten the horn at all? I mean, as opposed to flattening it. Maybe I should have tried prior to cutting the strip? If not, the finished length and width of the horn pieces will be even more limited than I thought I would get.
You asked about the core. I have a very nice piece of 8/4 rock maple, very straight grain. I had thought it was 44 inches or so in length, but your query sent me to the measuring tape. Turns out it is 36 inches in length. Think that is going to be long enough or should I seek alternative core material. I guess it depends on the horn? Was going to use the maple for the ears as well - but I am now thinking of finding a naturally curved piece to splice in. Getting ahead of myself.
Russ
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Sorry i've only just seen your reply.
As for straightening horn i've only ever use boiling water for about 10 mins. Then clamp between something flat, if you want them dead flat then you will have to account for springback. Don't worry about getting them dead flat though it doesn't matter.
How thick is your maple? Doing some quick mental arithmetic it does seem to be long enough to cut in half. Finding a natuarally curves piece for the syhia's is a good bet...funnily enough i've just been out trying to find recurves for one of my Turkish cores. Also look to find something hard, dense and plum straight (no knots at all) for the grip piece. Ideally it wants to be flat sawn and the same goes for your maple core. Flat sawn wood is more laterally stable than rift or quarter.
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Russ. Glad you are working on the bow already.
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Hi Randy - Yes, jumping in with both feet, no net. How was the trip?
Mike -- I get the advice on the flat sawn wood. I am not sure I follow the bit about cutting my board in half? I was thinking the length of the core sans the ears would be about 36 inches in length, slightly bent in the middle around the handle piece. However, slicing a piece off the end of my board as I was originally thinking would not give me flat sawn lumber, so I will have to cut my core piece out of the face of the board and then thin it to thickness. Is this what you mean? And was your mental arithmetic a metric conversion thing?
As to the horn, I hope you guys can answer some questions and / or confirm my assumptions.
The portion of the horn that was the inside of the horn before cutting (also the inside of the natural curve of the horn since I took the strip from the outside curve) is the side of the horn that gets grooved and glued to the core, right? In this way, if the natural curve reasserts itself, it would tend to increase the reflex of the bow, right?
My pieces of horn are not yet finished being turned into strips. The ruler is 12 + inches long and the last picture is the outside of the horn. Th other two are the inside.
The wider side of the horn was the hollow end near the head. The thin spots still need a little more thinning to remove completely. As a result, this end, while wider than the other, is much thinner. The tip end, while full in thickness, is less wide. Should I maximize the strip length and end up with one end very narrow but full thickness and the other thin and wide? Or should I trim them shorter and aim for a uniform thickness and width throughout?
Which end typically gets glued closer to the handle, the thin wide one or the thick narrow one? I am assuming the thinner wider one, as the handle will be non bending, and the thinner horn here would be less troublesome to the whole here than in the area backing up the ears?
The outside edges of the horn, as you can see from the pics, still have some undulations from the original shape of the horn. In addition, due to the original curve of the horn, the outside face of my horn strip is less wide than the inside face. I would say it is naturally "trapped", like you would do to a hickory or bamboo backing. Should I trim it all away leaving a strip with square edges, or leave it as wide as I can, maintaining a nicely trapped semi uniform width for the length of the finished strips?
Hope you guys can shed some light. I have been staring at the stips for a few days now not knowing what to do next.
Russ
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James must be hunting :).
I'd say square up the horn. Only thing you can do is grind the ridges off. How much width do you still have it you take the narrowest point there? Should still be plenty from the looks of it to me.
My understanding is that the tips go in the handle area butted together. Don't cut them off too much as the handle will be thinner anyway. Wait for more experienced guys on horn bow to sound off here before doing much else though. Good luck
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This is the shape the stripe should look like at the end of the process:
The thicker end goes to the grip.
Your pair of horn is a real challange I am afraid.....
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Tc, is that one cut from each horn, where did you get your horn from, if you don't mind telling us. Can I get you to do mine those look great.
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After the snow in NC, James probably doesn't have internet. He lost it and power last year, also. I'll try to call him tonight.
Johnny, come on down and use my grinders. They'll eat that horn up. I'm getting ready to grind two 30"+ horns.
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Duke, pm sent
Tc
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Nice pictures Tc.
The reality is that every pair of horns is a bit different. Some like Russ's there have some deeper grooves near the end. If you can't get the length/width then you would have to cut them shorter and change your bow design to a shorter style horn bow for a given set of horns. I work pretty hard with people to find the right pair for the design they want to make. Long horns 26" plus are getting pretty hard to find but everyone seems to want them regardless of actually needing them. Unless you are making a Chinese style bow. Turkish horn bows only need 18"
But Russ if they don't work out for you I'll get more in Jan.
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Randy is right. Once you have the horn you can choose the hornbow style you can make out of it. Generally a 50-55 cm stripe should be good for any type of horn bow (even for a manchu bow). But the stripe must be perfect, otherwise you are just suffering with it....
One more thing:
Although the turkish is one of the shortest type of bow it needs longer horn than e.g. magyar (the siyah is covered - normally- by the horn)
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I think you have cut your strips too thin. I normally get the outer surface ground to shape, flat and smooth before I cut them if i'm working a full horn.
From here you need to get the strips cut/sanded dead straight. Then you can assess your width/thicknesses. Sides square not trapped.