Primitive Archer
Main Discussion Area => Bows => Topic started by: Judson on January 19, 2009, 09:38:27 pm
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First let me say that I will not use the spell check as lots of times it freezes up this thing for some reason and I have to start over.
The bow in this build along was built by Seth Penney as a senior project. I talked him thtough it and gave him some help but he did most of the work.
For a Penobscot bow I like to use a stave wide enough to give me around 2" to 2.25" limb width at the fade outs. I know that this seems wide but it works. The lower and mid limbs of these bows are highly stressed and the additional width is needed. This bow is being built from white Elm and as you can see we have lots of width in this stave. With white Elm just remove the bark and this will be the back of the bow. Seth is laying out a center line on the stave and then finding the center point. It will work best if the lower limb is 1" to 2" inches longer then the upper limb. Even length limbs will work but build one or two of these bows before you try it.
The main bow is layed out in a pyramid patern with 6.5" for the grip and fade outs. The lower limb is 31 inches and the upper 29 inches long from the fade outs. A band saw was used to roughout the stave and the limbs were left 3/4" thick. Further thinning of the limbs was done with a stock makers rasp until the bow could be floor tillered.
Once we got Seth to this point he cut the nocks and sanded out the back of the bow starting with 100 grit and then going to 220 grit wet and dry paper. With the wet and dry paper mineral spirits is used for a wetting agent and each sanding uses a finer paper up to 600 grit. At this point the back of the bow should be like glass. Since this bow is of Elm, which is rather soft it is here that we stained the bow. We also used a coat of Rod wrapping epoxi on the back of the bow to toughen it up a bit. This will not change the performance of the bow one bit but it does make t more durable. If you want to do this, heat the bow to 100 to 150 degrees before applying the epoxie. After using the epoxie place the bow in a cooler area, say 70 degrees, this will draw the epoxie into the wood and harden up the back.
Once the epoxie is fully set sand the back of the bow again to even out everything but this time start with 400 grit and work up to 600. Be careful not to sand through the stain under the finish.
(http://i543.photobucket.com/albums/gg465/Judson127/bowstave.jpg)
Laying out the center line
(http://i543.photobucket.com/albums/gg465/Judson127/bandsawing.jpg)Seth cutting down the stave.
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Looking forward to this. Thanks, Judson
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Watching closely. Bring it on.
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Now, before we really get into this let me explane a bit. Several years ago, (more like 10) I was tillering a bow and the tillering board slipped off the scale and I damn near knocked my self out!!!! My wife, Barbara yelled at me. "What did you do that for?" The tillering board had sliped and the tillering board, bow, and all came down onmy head. I was on my knees and looked up at her and dazed said. "I thought it might be a new experiance and stimulating." It was not! The tillering set up I use now allows me to check the pull and also step back and check the bend of the limbs. It is safe, and also easy to store, and since I build custom rifles for a living easy to hide. (sorry about that, but rifle customers can be funny if they find you building bows)
My tillering board is now attached to a bath room scale. This set up lets me see both draw length and draw weight at the same time. It also lets me step back and check the tiller of the bow. Here are two views of this set up.
(http://i543.photobucket.com/albums/gg465/Judson127/build%20along%20Penobscot%20bow/IMG_0145.jpg)
(http://i543.photobucket.com/albums/gg465/Judson127/build%20along%20Penobscot%20bow/IMG_0146.jpg)
This next picture shows how the tillering board is used. I mark the limbs from the nocks back to the grips in either 4 or 6 inch incriments. Then using elastic from nock to nock the bow is drawen with the tillering string. Measuring from the marks on each limb down to the elastic will give you a real picture of the tiller. Measuring to the tillering string will not give you this as where the limbs are not of equal length the measurements are deceptive.
(http://i543.photobucket.com/albums/gg465/Judson127/Sethtillering.jpg)
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Very nice Judson.
I will let this build along stay here for a couple days so that people will see what you are doing and get a taste for it then I will move it to the How to's and build a-long forum
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Very nice, Judson. You are the Judson from ME? :) Jawge
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this is way cool,thank you
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Yes, I am the Judson from Maine. After the bow is roughed out the grip is shaped. I leave the bottom of the grip flat at this point as it sets better on the tillering board.I have found that on these bows, (for that matter on any bow) you never want to draw the bow further then the final draw weight. One advantage of this is that by the time the bow is finished it is for the most part broken in. At first you will only be drawing the bow a few inches to reach the target draw weight. (This bow was tillered to 65 pounds@ 28") The tillering string used in the begining of this process is untwisted to give only one or two inches of brace height at first. As the tillering process continues and the bow can be drawn further the string will be twisted up increasing the brace height to the bows full 6.5".
Where this is a Penobscot bow all tillering of the main bow is done on the belly of the bow, never the edges. What we want is an eliptical tiller with no bending in the handle and none for the last 6" of the tips. For the early tillering I use a course stock makers rasp. Go slowly, I use a pensil to mark stiff or flat sections of the limb and only cut enough off to remove these marks then theck the tiller again. When we are finished tillering the main bow we wanted the upper limb to bend slightly more then the bottom limb' about .250". This helps to lift the nock of the arrow some during release making for a much quieter bow then if the nock of the arrow is forced down into the arrow rest.
Now that the main bow is tillered to the full 65 pounds it is time to rough out the back bow, sand it out like was done to the main bow and "mate" the two togther. When this is done it is time to retiller the bows as one. One note here about this bow, it is Elm and though a hard wood a bit soft. Once the main bow was sanded out the back of the bow was stained and finished with two coats of the rod wraping epoxie. Like I mentioned, this will not change the performance but it does toughen up the bow a great deal. Scratches or nicks on the back of a bow are like lines from a glass cutter on glass. This is where the bow will probably break.
Here Seth is cutting the nocks in the main bow, yes I know that is not a primiyive tool.
(http://i543.photobucket.com/albums/gg465/Judson127/thinninglimbs.jpg)
The main bow is now ready for the back to get finished and the tillering to get started.
(http://i543.photobucket.com/albums/gg465/Judson127/readytotiller.jpg)
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that may not be a primitive tool,but that phone behind him looks pretty primitive
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That phone is no longer there. It has been replaced with a cordless crank up model, Ayh up here we are a bit behind at times, but If yall want a dangerous game rifle, some thing like a double rifle in .450 #2 Nitro, or a Penobscot bow we can help you out.
Now don't get bent that I mentioned rifles, that is how I make a living and get enough time to build bows, please for give me!!!
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Ok, now that we have the main bow tillered to 65 pounds at 28 inches it is time to mate the back bow to the main bow. Let me degress for a bit. When I talk of draw length I am talking about the distance from where your hand holds the bow to your anchor point. I am not refering to the AMO draw length. When we build a bow all that counts is actual draw length. Now ack to building the bow.
Find he center of the back bow and the main bow and drill a half inch hole around .75" deep into the center of the grip on each bow. A piece of half inch dowel is fit into the hole, this is what holds the back and main bow togther. Now cut the back bow grip down to match the grip on the main bow. Later a leather spacer will be put between the two bows but for now it is not needed. This spacer quiets down the bow when shooting. Even though you may not think the bow bends in the grip, it does and the leather eliminates the noise of the two bows slapping togther.
In this picture you see the components of a Penobscot bow.
(http://i543.photobucket.com/albums/gg465/Judson127/maincomponentsofaPenobscotbow-1.jpg)
There is the main bow, the back bow, a leather spacer the lace that holds it all togther and the alinement dowel right below the laces.
I will scan in a picture of Seth mateing the back bw to the main bow but I think you get the idea of that. Once the two bows are mated string them up and go back to the tillering board. On all but the static recurve bows twist up the back bow strings untill they will stay on the nocks. At this point we do not want a lot of tension on them. On the static recurve bows leave them loose enough so they can be pushed down to touch the main bow with out bending either bow.
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I think most everyone loves rifles too. :)
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Seth is working on the grip of the back bow in these pictures. The idea is to match them up and also get the grip to be comfortable in your hand. One point to keep in mind though is that the grip gets wraped in a leather lace. The lace actually adds a fair amount of diameter so as you shape remember that or the grip will feel to big.
When you start tillering the bows togther do not lace it up, let the back bow float free. There should be nothing holding it other then the dowel and the strings. As before, use the elastic from nock to nock on the main bow and measure from your marks on the limbs down to the elastic not the bow string. You do not want any bending in the tips of the main bow for around the first 6". Watch the back bow, it may tip towards one limb or the other this shows which limb of the back bow is stiffer. If you run into this then lighten the back bow limb.
(http://i543.photobucket.com/albums/gg465/Judson127/mate2.jpg)
(http://i543.photobucket.com/albums/gg465/Judson127/mate1.jpg)
In this picture you can see the elastic that we are measuring to and also notice the stiffness of the tips of the bow.
(http://i543.photobucket.com/albums/gg465/Judson127/tilleringboth2.jpg)
Sorry about this picture it is the double rifle I built. but from here on I will behave!!!
(http://i543.photobucket.com/albums/gg465/Judson127/double%20rifle/left.jpg)
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Your a very talented man. I wish I lived next door to you.
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Please feel free to PM me any more rifles your proud of. I never get tired of drooling at those ;D
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Sorry I have been busy for a while I will get back to this build along I hope either tonight or tomorrow. Here is a little tantilizer for you!
(http://i543.photobucket.com/albums/gg465/Judson127/Tilleringastaticrecurvemainbow.jpg)
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Again when tillering the bow NEVER draw the bow further then the desired draw weight. Using the marks on the main bow again you measure down to the elastic stretched from nock to nock on the main bow. You want the last six inches of the main bow tips to have minimal bend if any. All the bend should be in the lower and mid sections of the main bow limbs. The radius of the bend of the back bow is not of much concern. If it does not rock to one side or the other things are fine. I try to get it's minimal bend to look right but it is the tiller of the main bow that will tell you if all is well.
Do not be suprised if when tillering the main bow togther with the back bow you find some interesting changes. The back bow will force the main bow to shorten which forces the mid limb area of the main bow to "bow" out. This is not going to be found on a more convential bow. Once every thing is even with the upper limb bending about 1/4" more then the lower limb, and we are within 3 to 4 pounds of our desired draw weight it is time to sand the bow out and start finishing.
Oh yes one morething you might be intrested in. I was talking to Don Pummel at LL Beans the other day and he is thinking about having me do a talk and demo on building these bows. If you would be able to come you might want to let him know as he is looking into it and seeing how much intrest there is out there in primitive archery.
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you'd better get working on it since it looks great and I really want to see more of it! hehe :)
very interesting post Judson!
why are you shaping the handle like that? is it some kind of a double-2level shelf or so? haha I don't have a clue :p
Nick