Primitive Archer
Main Discussion Area => Bows => Topic started by: Wooden Spring on February 23, 2014, 01:08:37 pm
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I just finished up my first mollegabet. It came in at 1 pound, 7 ounces, a little heavy, but the ipe will do that every time!
It's a tri-lam of hickory (1/8"), ipe (1/8"), and jatoba.
She's 67" nock to nock, 1 1/2" at the fades tapered to 1 3/8" at the levers. Bending limb is 1/2" thick at the fades tapering to 7/16" at the levers. Levers are 10" long. I tillered her so that the upper limb is about 1/4" stiff to compensate for shooting above center. I finished it with (so far) 4 coats of teak oil and steel wool.
She came in at 65# @ 28" and boy does this thing shoot FAST!!!
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You could WWWAAAYYY lighten those outer tips and reduce your overall and tip mass. I'd probably shorten those static tips a bit, too.
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Also, according to the mass principle, an ipe bow and an osage bow (for example) of similar design and poundage, should weigh the same, if the design is correct. Ipe is dense and heavy, so it therefore takes less of it to make a bow.
Have you shot it in? How's the handshock? I made a bow similar to that outta osage (overbuilt) and it loosened my fillings when I shot it the first time. After lightening the tips, it was tolerable.
IMO, I think this design really excels with the lighter whitewoods... elm, ash, maple, hickory, etc. Tip mass is less. You just have to make the bending limbs a bit wider and flat to get the required mass to reduce stress and minimise set.
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I won't lie, it does have some hand shock, but then again I use a .375 H&H to plink at squirrels in the back yard, so a little "recoil" never bothers me...
The levers are 10" long, and taper in width from 3/4" to 1/2"
They start at 3/4" thick and taper down to 7/16" at the nock.
It works out to be about a 60/40 ratio of bending limb to lever.
I know I could reduce the levers a bit, but I'm still playing around with the numbers. I've got another board glued up that's just 2 lams - hickory over jatoba, no ipe in that board.
It's remarkable to me just how smooth a draw this bow is. It's 65 pounds, but it feels like I'm pulling my 40 pound pyramid bow. It looks like it's all in the string angles, the pyramid bows are almost at 90 degrees, but the mollegabet is not even close to that.
I'll make the next bow with a little smaller levers, but this one, as heavy as it is, is a SWEET shooting bow. This shoots faster than my 65# pyramid bow with the same arrows and seems to be a little more accurate too. I can't wait to see what a MORE efficient design will do!
I told my wife that she has competition to her throne, I think I'm in love. I haven't seen that look in her eyes in a long time, and the doctor says that I'll be able to drive again as soon as the swelling goes down. ;)
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LOL... my wife has a "look" too! I think they all do!!
This design is smooth drawing and shooting due to the low string angle.
I think you're on the right track with your next glue up.
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I agree with lightening the levers/tips.
These make for my fastest and smoothest shooters.
(http://i.imgur.com/y9iMncA.jpg?1)
(http://i.imgur.com/INKqHeG.jpg?1)
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I agree with lightening the levers/tips.
These make for my fastest and smoothest shooters.
OK, so what is the size of your levers? They look like they've about 1/4" wide at the tips,but how wide are they at the beginning of the levers? How thick are they?
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they only have to be a fraction thicker not to bend, but ascetically some want to see the change in width
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they only have to be a fraction thicker not to bend, but ascetically some want to see the change in width
Gotcha, so if the bending limbs are 1/2" thick, then the levers should probably be around 5/8" then, not 3/4"
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OK, so what is the size of your levers? They look like they've about 1/4" wide at the tips,but how wide are they at the beginning of the levers? How thick are they?
~11" long
1" x 7/8" just out of the fades
1/2" x 3/4" at the middle
1/4" x 5/8" at the nocks
These levers are completely static, but sometimes I work the levers down to where they just barely bend at full draw for maximum efficiency.
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As a firm believer in all things holmegaard and mollegabet... I love this! Nice job!
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It's up to you but I'd reduce close to that 5/8" mark
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Looks to be very nicely tillered. How much reflex did you glue in? Has it taken much set? I've had a bow like that on my to-do list for quite a while now.
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A bow should NOT have recoil..... ;)
No matter what the design is. Adb - these bows wether made or hazel or ipe should not have any handshock...
Regarding thickness of the levers - 1/8th thicker is ample to make them static. Picture your working limbs.....if you had left a section that was an 1/8th thicker would you expect that spot to be working!?
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Looks to be very nicely tillered. How much reflex did you glue in? Has it taken much set? I've had a bow like that on my to-do list for quite a while now.
Well, that's the downside to THIS particular bow. I glued in a core lamination of ipe that I now know is not necessary... (hey, that's why I do this type of thing, to find out WHY we do or don't do the things we do!) And because I had the core lamination glued in, it made the belly so thin that it's not able to resist compression very much, therefore forcing the hickory back to stretch a bit more than it normally would...
SO, I actually started with 2" of glued in reflex. I made a form that kept the middle 12" flat, then made gentle sweeps out towards the tips that curved down 2". Due to set, it has kept 1" of reflex, but it's only in the tips. The working limbs lay perfectly flat.
When I make another mollegabet with just a backing and a belly woods (no core) I have every idea that it's going to keep more reflex.
As it is, it's still a sweet bow (for a prototype). ;)
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The only two Mollegabet style bows I have made were quick. I made the levers a triangular section in both, so that they had the depth/thickness to resist bending, but less mass even than plain narrow tips. That is, the back of the bow is one side of the triangle, and the sides of the bow make up the other two. It seemed to work for me.
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A bow should NOT have recoil..... ;)
No matter what the design is. Adb - these bows wether made or hazel or ipe should not have any handshock...
Regarding thickness of the levers - 1/8th thicker is ample to make them static. Picture your working limbs.....if you had left a section that was an 1/8th thicker would you expect that spot to be working!?
I agree. A properly made bow of any design should have minimal or no handshock.
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"I agree. A properly made bow of any design should have minimal or no handshock."
I never said it was PROPERLY made... Just that it was MADE. ;)
Nah, I think the next one with really minimalist levers is going to be much better...
I love the idea of a triangular cross section on the levers too... That will make them lighter, but be stiffer to resist bending. LOVE IT!
Thanks for all the comments folks. That's how we build better bows - more minds in the game means less mistakes we have to make and learn from!
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You are likely already DONE with this bow, ...but just to add something else to consider, even in this Tri-Lam configuration, I would think you could 'TRAP' the hickory back a bit to reduce the compression strain on the too thin belly lam.
OneBow
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If your happy with it and it makes ya smile then cool,and that's all that matters....so I'll leave my two cents in my pocket 8)
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OK, so taking all the comments into consideration, here's my thoughts on my next attempt...
1) Levers will be reduced to: 10" long and 1/2" wide at the fades, tapered to 1/4" at the tips, and be 5/8" thick at the fades tapered to 7/16" at the tip, with a tip overlay for the string groove.
2) hard lines will be removed, and instead the back will be a series of smooth curves.
3) Hickory backing over a belly wood yet to be determined - NO core lamination
4) bow will be 68" tip to tip
Something like this sketch...
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Looks pretty good to me, though I thought (don't take my word for it) one of the distinguishing features of a mollegabet was the flat/no-taper working limbs. Looks like a holme/molle hybrid. A holmollegardet?
I establish the side profile of the levers and then work down the thickness bit by bit to be sure I'm not going to fold them over while reducing mass as much as possible. Just a thought ;)
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Looks good, but a lot of what has been said would make it better!
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Bushboy just made one similar to that..http://www.primitivearcher.com/smf/index.php/topic,45038.msg609774.html#msg609774
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Here's a hickory lever with most of the fat trimmed!shoots quite fast with no hand shock.I really like this design for performance!
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Whoops thats the one! Damn phone screens!! Both great bows. That hickory looks fast!
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This is based on a tim baker design.eiffel tower bow.at least my take on it.
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Great job man and I wholeheartedlly agree with blackhawk!
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Looks pretty good to me, though I thought (don't take my word for it) one of the distinguishing features of a mollegabet was the flat/no-taper working limbs. Looks like a holme/molle hybrid. A holmollegardet?
I establish the side profile of the levers and then work down the thickness bit by bit to be sure I'm not going to fold them over while reducing mass as much as possible. Just a thought ;)
You're probably right... It's really hard for me to find much information on this bow. (The google-fu is weak with this one) So my take on it was to lay out a typical pyramid bow like I normally would, but then reduce the tips.
I assumed that since the distinguishing characteristc of this bow was the stiff levers, and the shape of the bending limb tends to define it's draw weight, so those could be of any functional design.
By doing it this way, it kept the final poundage of the bow predictable for me since it has basically the same shape and working length of my pyramid bows, but since the tips are forced not to bend, it makes the bow limb analogous to swinging a baseball bat versus swinging a foam pool noodle. The baseball bat is a still, massive lever, and the pool noodle is a light and flexible lever. The stiff and massive lever is faster than the pool noodle.
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great job! love it!