Author Topic: Tri-lam Mollegabet  (Read 9036 times)

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Offline Wooden Spring

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Tri-lam Mollegabet
« on: February 23, 2014, 01:08:37 pm »
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!!! 

"Everything that moves shall be food for you..." Genesis 9:3

Offline adb

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Re: Tri-lam Mollegabet
« Reply #1 on: February 23, 2014, 01:18:22 pm »
You could WWWAAAYYY lighten those outer tips and reduce your overall and tip mass. I'd probably shorten those static tips a bit, too.
« Last Edit: February 23, 2014, 01:26:32 pm by adb »

Offline adb

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Re: Tri-lam Mollegabet
« Reply #2 on: February 23, 2014, 01:22:51 pm »
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.
« Last Edit: February 23, 2014, 01:29:08 pm by adb »

Offline Wooden Spring

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Re: Tri-lam Mollegabet
« Reply #3 on: February 23, 2014, 01:41:51 pm »
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.   ;)
"Everything that moves shall be food for you..." Genesis 9:3

Offline adb

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Re: Tri-lam Mollegabet
« Reply #4 on: February 23, 2014, 02:37:57 pm »
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.

Offline huisme

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Re: Tri-lam Mollegabet
« Reply #5 on: February 23, 2014, 08:56:42 pm »
I agree with lightening the levers/tips.
These make for my fastest and smoothest shooters.

50#@26"
Black locust. Black locust everywhere.
Mollegabets all day long.
Might as well make them short, save some wood to keep warm.

Offline Wooden Spring

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Re: Tri-lam Mollegabet
« Reply #6 on: February 23, 2014, 09:34:25 pm »
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?
"Everything that moves shall be food for you..." Genesis 9:3

Offline bubby

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Re: Tri-lam Mollegabet
« Reply #7 on: February 23, 2014, 09:36:26 pm »
they only have to be a fraction thicker not to bend, but ascetically some want to see the change in width
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline Wooden Spring

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Re: Tri-lam Mollegabet
« Reply #8 on: February 23, 2014, 09:47:46 pm »
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"
"Everything that moves shall be food for you..." Genesis 9:3

Offline huisme

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Re: Tri-lam Mollegabet
« Reply #9 on: February 23, 2014, 09:51:22 pm »
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.
50#@26"
Black locust. Black locust everywhere.
Mollegabets all day long.
Might as well make them short, save some wood to keep warm.

Offline Almostpighunter

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Re: Tri-lam Mollegabet
« Reply #10 on: February 23, 2014, 11:08:00 pm »
As a firm believer in all things holmegaard and mollegabet... I love this! Nice job!

Offline bubby

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Re: Tri-lam Mollegabet
« Reply #11 on: February 23, 2014, 11:40:56 pm »
It's up to you but I'd reduce close to that 5/8" mark
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline Cameroo

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Re: Tri-lam Mollegabet
« Reply #12 on: February 23, 2014, 11:54:41 pm »
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.

mikekeswick

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Re: Tri-lam Mollegabet
« Reply #13 on: February 24, 2014, 02:47:50 am »
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!?

Offline Wooden Spring

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Re: Tri-lam Mollegabet
« Reply #14 on: February 24, 2014, 08:26:54 am »
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). ;)
"Everything that moves shall be food for you..." Genesis 9:3