Author Topic: mollegabet dimensions question  (Read 12877 times)

0 Members and 1 Guest are viewing this topic.

Offline webrx

  • Member
  • Posts: 47
mollegabet dimensions question
« on: March 28, 2013, 10:00:33 pm »
I have a question, on the limb dimensions for a Mollegabet bow as I am considering this for my next build. 

In checking this thread:

http://www.primitivearcher.com/smf/index.php/topic,17521.msg245951.html#msg245951

I see the recommended dimensions are 50% working limb, 50% static limb, but when I look at the pics of the "found" mollegabet bow, and actually take the measurements (albeit on the screen with a ruler), it appears the original is more like a 2 to 1 working limb to static limb ratio. 

I would think having more working limb would make the tillering a little easier, i.e. for a 30" limb you would then have 20" to work with vice 15 if it is an actual 1 to 1 ratio.

Is there a reason why the "modern" builds are using/recommending a 1 to 1 vice 2 to 1 ratio?

Thanks

Dave
Experience - that thing you get just moments after you needed it.

blackhawk

  • Guest
Re: mollegabet dimensions question
« Reply #1 on: March 28, 2013, 10:19:24 pm »
Are you wanting to make an exact type replica?

Ive made "lever" bows with a 30% lever 70% working limb to 60% lever 40% working limb and oodles of em in between those numbers. If making your first "molly" and don't have a lot of bows under your belt id stick to 30-40% lever and no more

Offline Joec123able

  • Member
  • Posts: 1,769
Re: mollegabet dimensions question
« Reply #2 on: March 28, 2013, 10:50:22 pm »
A proper mollegabet is 50% working 50% static if you go to boarriorbows videos on YouTube he has to bow builds one called high performance bow for under 10 dollars and the one he has in the process called how to bud a high performance bow for under 25$ he shows how to make a proper mollegabet but he makes them with boards in those two videos but you could get an idea of dimensions from there
I like osage

Offline Cardboard_Duck

  • Member
  • Posts: 282
  • Winter Haven, FL
Re: mollegabet dimensions question
« Reply #3 on: March 28, 2013, 11:22:42 pm »
I have made two mollies so far -

This one was 65 TtT and had just about a 50/50 ratio - Forgot to mention this one was HBERC and has 2" wide working limbs.

-

This one has 16" working limbs and 13" levers (this was my first molly) This one is hickory, 68" TtT and has 1.75" working limbs.

I could have made the levers narrower on both of them, but I was chicken  :laugh:
« Last Edit: March 29, 2013, 09:57:22 am by Cardboard_Duck »
>>>---------->

Offline webrx

  • Member
  • Posts: 47
Re: mollegabet dimensions question
« Reply #4 on: March 29, 2013, 12:53:23 am »
Thanks, and those are some nice bows Cardboard_Duck.

I wasn't arguing that a 50/50 wont work, I was questioning why the current philosophy was a 1 to 1 vice the original dimensions which appear to be 2 to 1. 

Again, I am new to this, but it seems to me that the 70/30 or 60/40 split (closer to 2:1) as noted by blackhawk, is closer to the original design, and I was curious, before I start laying one out, if the 2:1 was easier to tiller than the 1:1, and what the reasoning was for the 1:1 performance improvement aesthetics, buildability, etc.

I have looked at the videos by Boarriarbows, and did notice he was building them closer to 50/50 as well (his static limbs included the 2" fade).  He says in his video that they are supposed to be 1:1, but, it is pretty apparent in looking at the pics (link in my first post), that 2:1 or maybe 70/30 is closer to the original found bow dimensions.

d
Experience - that thing you get just moments after you needed it.

Offline Newindian

  • Member
  • Posts: 734
Re: mollegabet dimensions question
« Reply #5 on: March 29, 2013, 02:47:28 am »
Give me a long enough lever and I could lift the world- it the same principle a longer lever is more efficient, so long as properly designed.
I like free stuff.

mikekeswick

  • Guest
Re: mollegabet dimensions question
« Reply #6 on: March 29, 2013, 04:34:21 am »
Make the levers 30 - 40 % of limb length.
Make it wide out of the fades - at least 2 inches wide. Keep this width for 4 -6 inches then taper into 1 1/4 at the levers fade.
The levers do not need to be much thicker than the working limb. They can also be narrowed to 1/4 at the tips with little danger.
Good luck.

Offline DarkSoul

  • Member
  • Posts: 1,315
    • Orion Bows
Re: mollegabet dimensions question
« Reply #7 on: March 29, 2013, 07:01:51 am »
Is there a reason why the "modern" builds are using/recommending a 1 to 1 vice 2 to 1 ratio?
Is that really the case? What builds do then recommend a 50/50 ratio?

There is a difference between a true Möllegabet and a mollie-inspired bow. Do you want a true replica? Then you need to stick to the actual artefact and take measurements from them. If you just want a lever tipped bow, mollie inspired, than the lever length is a matter of choice. I'm sure even 40% working length and 60% lever would make a decent lever tipped bow. However, most people choose to make the levers between 25% and 50% of the total limb length.
The first bow Cardboard Duck showed is a great example of a lever tipped bow (mollie inspired). However, the shoulders are too abrupt to qualify as a replica, and the ratio is also not accurate to the original artifact. Myself, I prefer a 60% working and 40% lever ratio, just because this looks aesthetically pleasing. It's close to the Golden Ratio and stuff...
"Sonuit contento nervus ab arcu."
Ovid, Metamorphoses VI-286

blackhawk

  • Guest
Re: mollegabet dimensions question
« Reply #8 on: March 29, 2013, 09:34:05 am »
Do you believe everything you see,hear,and read on YouTube or the internet for that matter?

The longer ratio lever the wider you will have to make the working limbs to compensate for the extra added stress.....and the longer levered ones are a much tougher act to balance and pull off without it blowing up or taking to much set....if you can please specify what wood species you will be using and the intended draw weight/length I'm sure we can give you good starting dimensions....also let us know how many good successful bows you have made.....this will help determine what will be best for you

Offline BowEd

  • Member
  • Posts: 9,390
  • BowEd
Re: mollegabet dimensions question
« Reply #9 on: March 29, 2013, 09:56:08 am »
I think what the fellas might be saying is it's really not a question of design all together but tillering skills as well, as it always is with these self bows.For the first go at it it's probably best to be safer then work your way to more stressfull designs[longer levers & shorter working limbs],and that's just the beginning.Types of wood do make a difference too.Don't let this sound like it's darn near impossible to build but with time and builds it's possble.They're fun to shoot for sure.Good luck.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline Cardboard_Duck

  • Member
  • Posts: 282
  • Winter Haven, FL
Re: mollegabet dimensions question
« Reply #10 on: March 29, 2013, 10:13:21 am »
Also... I didn't think that the tillering process was any more difficult than a normal selfbow, but maybe I just got lucky  >:D



but I am still a rookie so take my advice with a grain of salt.
>>>---------->

Offline BowEd

  • Member
  • Posts: 9,390
  • BowEd
Re: mollegabet dimensions question
« Reply #11 on: March 29, 2013, 10:36:53 am »
I like that nice HBERC there Cardboard_Duck.I assume those initials mean hickory backed eastern red cedar.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline webrx

  • Member
  • Posts: 47
Re: mollegabet dimensions question
« Reply #12 on: March 29, 2013, 11:12:08 am »
Thanks guys,

I am new at building bows - I have successfully built 3 board bows from red oak as that is what is available to me readily - and have yet to have one fail on me (knock on bow wood). 

One longbow, my first, came in under weight, and was shortened (it actually now has 3 sets of nocks) 28@27 first nock, 35@27 second nock, and 41@27 third nock.  It actually is kinda cool cuz I can hand it to a newbie on the first nock (after warming it up) and not worry too much about them breaking it.

First pyramid (2nd bow) - pulls 47@27 right now, has a pistol grip type handle and arrow rest.

Second pyramid (3rd bow) - pulls 31 at 23 (built for my son), pistol grip handle, arrow rest, and we are staining and trimming to be similar to the "Katniss hunting bow" from hunger games (not exact as it has a grip and arrow rest).

To be clear, I do not think 3 bows that did not break makes me an expert, just noting that I have successfully done this.

I am a tinkerer by nature, a trained and experienced engineer by trade (nuclear, mechanical, and computer), and have been around the block once or twice in my life so no, I do not believe everything I read on the net, as with many things I have learned a little skepticism is not a bad thing. 

I posted this question for the experts here, as I enjoy understanding the why as well as the what when doing things. 

My suspicion was that the shorter working limb to lever ratio would increased the stress on the wood, and would require a more precise tillering effort. where the longer working limb with shorter levers would be a little easier build, and also be more true to the original.

I have actually spent serveral hours researching the Mollegabet vs Holmegaard bows, and from what I can find, the actual found Mollegabet bow was only a portion of a bow that was only around 13.5 inches long, the rest of the Mollegabet we see in pictures is the "experts opinon" of what the bow looked like, so nobody really knows how long it was, how long the levers were, or how the handle area really looked, actually some are not sure it was even a bow - the best we have is an educated guess. 

For the Holmegaard bow, on the other hand, they have found full bows. 

I will most likely build my first "mollie inspired" attempt out of red oak, as I have a 2.5 inch piece that is 6 feet long, sitting in the garage I ripped from the 5.5 in piece I originally purchased.  Unless the guy at the hardwood store has some elm that looks decent and usable, as if I am going to try to build this bow, whether a wall hanger or actual working bow to the specs and measurements of the found piece, elm appears to be what it was originally made of.

Thanks again for your advice, I will take it slow and let you know how it comes out if your interested.

dave
Experience - that thing you get just moments after you needed it.

Offline gpw

  • Member
  • Posts: 149
Re: mollegabet dimensions question
« Reply #13 on: March 29, 2013, 11:29:36 am »
   Dave , just sayin’ ... precise tillering is the name of the game ... always ...  no matter what bow you make or what you make it out of , your Best tillering effort is  mandatory !!!  ;)

  JMHO.. It would seem you’d want a more arc of a circle tillering in the bending areas of the limbs... the thin wide wood doing all the work ...   ???

Offline Cardboard_Duck

  • Member
  • Posts: 282
  • Winter Haven, FL
Re: mollegabet dimensions question
« Reply #14 on: March 29, 2013, 11:39:56 am »
Here is the final tiller of the HBERC i did -

>>>---------->