Primitive Archer
Main Discussion Area => Bows => Topic started by: sound maker on March 20, 2012, 03:32:11 pm
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So I'm in the middle of doing a mollegabet bow from a red oak board
(6' 5" long, 3 1/2" wide, and 3/4" thick) and I going overbuilt the limbs
(about 65" end to end, 5" handle with a fade of 2", working limb of 14" thats about 3 1/2" wide,
with another 2" fade going to a 12" static limb thats going to be either 1" its at now or less).
My question being is can I do a reflex on it or should I not???
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I would not make a mollegabet design with red oak... It cannot handle the stresses. I made a similar bow last summer and the belly chrysaled terribly after 1000 shots. And I had a perfect tiller. JMO..
Jon
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I'm going for low weight (somewhere under 50#) and I'm going to back it with either silk or cotton. So far I got it to where I'm getting the limbs even and I'm not really getting any kind of issues yet.
This bow is going to be mainly for target shooting.
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You may have better luck than I did... Plus your limbs are an inch and a half wider... Mine were 2 inches wide... The bow still has not failed in tension (it was unbacked), but the belly is chrysaled from one end of the working limb to the other, showing a perfect tiller, but a over-strained design. Also the bow was only 46#... ;D
Jon
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Truth be told I got a bigger board then what I was going to start but said to myself "Well lets just make this into a bow. The only thing that could be bad is its going to me a bit longer to make and when I drop it onto my foot by accident its has a chance its going to get stopped before it lands." >:D >:D and if something goes bad I can always gets some thin wood backing onto it. ??? (like bamboo or something) and if it breaks :o :o my friend can use it was a paddle so I just look at this as something that going to be use for something other then firewood project. ;D ;D ;D
The only thing worrying me the fading from from the handle to working limb and from working limb to static limb. though I'm going to add a riser and a backing so it should hold together!!! ::) ::)
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I would not make a mollegabet design with red oak... It cannot handle the stresses. I made a similar bow last summer and the belly chrysaled terribly after 1000 shots. And I had a perfect tiller. JMO..
Jon
Honest to god, red oak has been very different from board to board with me, some have chrysalled terribly and some have been ridiculously good bow wood for board lumber red oak. The boards that have been good for me, have been denser than the ones that have chrysalled (probably pretty obvious that they would though, :laugh:). I too have had a red oak molly chrysal on me, but that was more my fault than the boards, as well as the board being very light feeling. I was very happy to find it though at the time (at menards) as it had absolutely ZERO run out. Shoulda made a better designed bow out of it.
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I was doing this because I liked the look and after spending a month or so looking around followed a build-along but when a bit over with the board (was going to be a 3" wide board but got a 4"). If I did this right the grain should be good (I'll post a pics on where I'm at when I have some good light and I'm not going for a high poundage here so no worrys).
I got it to where I can tiller but have to do some work on the fade area (some areas are not good due to some rasping ::) ::) ). Right now I'm working on removing tool markings and getting so both working limbs are 1/2" thick (I got about 1/32" I think to remove from both sides but done that for the most part) and making sure theres no points that will cause any problems. I'm think about reducing both inner limbs (near the static limbs) a bit so stress is less on the area near the fade. (for the most part thats where I believe if its going to break thats where it will happen) It seems that I'm going to burnish the back and sides a bit so it lower chance of splinters and add the backing after tillering (mostly because I haven't gotten my fabric yet :'( :'()
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I got it to tillering now and it seems to be twisting and thats mostly because the handle area I believe (one side was more in then the other ::) ::) went a little too far) so I'm going to move the other side in so they match. Going to work the limbs more and round the edges so theres no lift and then going to try backing in a few days. Still haven't gotten the backing though :o :o (procrastinate somehow sneaked up on me but I will get the backing).
On the backing I can use gorilla wood glue or no?
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pics!! ;D first time posting pics here so not sure how it will turn out. I am still gettting the handle right and making the the static limbs narrower.
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<snip> On the backing I can use gorilla wood glue or no?
I would not use Gorrilla glue for the backing. It is not elastic at all when cured, and it turns to a foam sort of consistentcy. I'd use TB2 or TB3.
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I've made a bow using that exact layout, and I think your working limbs are much too thick relative to the handle area. I had a first attempt snap in the handle during tillering. It was rather violent and sudden. I wound up thinning the working limbs to 3/8" thick and significantly lightening the static limbs to 0.56" thick. I also glued on a riser to guard against breakage and dull any handshock. It turned out around 35# in draw weight - less than the 50# that I wanted - but it shot about as fast as my 50# ELB.
Best of luck.
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you can use gorilla wood glue, it's basiclly titebond 2, their outher glues foam and expand, that's not good for bow making, Bub
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onebowonder- At the moment thats all I got and wanted to be sure it would work.
ryddragyn- I do realist that and I am thinning it (more due to some areas get a little overwork due to getting the fade and edge right ::) :o ::)) but I'm right now trying to get the handle equal and I'm trying to to get more flat-ish since its not fully flat. I'm also going to glue a riser onto it with fabric backing to make sure I don't have it break or something else ::). The only thing that kind of worrying for me is I got a friend to draw it for me and after I was doing more work and drawing it seem like the working limb (the 14") its not all bending alot otherwise it seems to be going.
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If the working limbs aren't really bending then it's probably bending in the handle and getting ready to break. Try putting the bow with the back down on the ground and pulling it from there to see if the edges of the handle area come slightly off the ground. I would add a riser forthwith, or thin the working limbs a LOT more. Or both. Just my two cents, I know some people have gotten this template to work with no riser and half inch thick working, but it seems kind of risky to me.
Also don't forget to lighten the static limbs, otherwise I think the bow is casting a bunch of dead weight.
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thanks I'm going to do both and I am lightening the static limbs but I'm not sure how far red oak can go without it breaking. right now its about a 1"-1" 1/8" wide and 3/4" deep and about 12" to the end.
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On mine I have static limbs tapering from 3/4 to 1/2 inch wide and the same dimensions for the thickness. Plenty strong... With static limbs the size you have now you are severely limiting the effectiveness of this design.
Jon
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Once you get the bending part of the limb thin enough to actually bend, you'll be surprised how much you can remove from the static parts and have them still remain stiff. You have a ways to go in the thickness of the bending limb since you have such a wide limb. I'm just guessing but it'll probably be about 1/4" to 5/16" thick by the time it's bending good. I got one out of quarter sawn hickory I'm working on and it is 3/8" thick an still not bending much yet. And It's only 2 1/4" wide at the widest part tapering in a pyramid fashion to 1 5/8" at the start of the static limb. The static limb is 3/4" tapering to 1/2" wide and 1/2" thick tapering to 3/8" thick. I plan on backing it with rawhide.
Make sure and round all the edges and corners good (in the profile corners as well around the grip area they look a little angular)
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Ifrit617-I am making them thinner (they're about 1" or so) I'm just going slow to get them right. Maybe I will just get them going from about 1" or so and lower it too about 1/2 or so.
randman- I am bending it right now (mainly to see how its going) and I'm getting bend there but seems to be more bending to like mid then less to fade.(limbs are 3/4" thick. thinking of taking off maybe 1/16 or so but I'm thinking of lower the thickness near the static limbs since I want it all to bend) I am sanding / rounding and I said earlier in the post I went a little overboard ::) ::) and one side is not equal to the other (got them to be more equal buts still just a little off and its kind-of too bendy there so I stop until riser is on). Now after I get this all set I might forget about the fabric backing (haven't gone to a fabric store so ::)) and just do paper bags. question?!?! can I just do the backing on the working limbs and join them together at handle and put some wood on it??? the wood because I want the handle a little thicker with the riser on it.
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So I got it down to 7/16" thick on both limbs and kind of gotten the levers down but its 1" or so at the tips (most likely going to lower it to maybe 3/4" - 1/2", rather have it big and slow then narrow and broken ::)). I just finished backing it with 2 layers of burlag with lots of glue (would have it with too much glue rather then too little glue O:) ;D O:)) after I got it with a riser glued on and it bend with what I feel comfortable with it being draw to 20" with about 30# or so there. also I was getting worried so I decide I will put the backing on now rather then too late ::). this is going to make it harder to measure the thickness isn't it :o. I'm thinking of just staying here with it with maybe lowering the width of the levers with a tapering to that 1/2" or close to it. Since they're still like long blocks with the corners rounded could I just sand down the corners so its more diamond like? wouldn't that both reduce the weight, size, and shape so its going faster and has less air resistants? I would like to draw it more but I woulkd rather have it lasting, it does fling those random arrows nicely though ;D >:D ;D.