Mollegabet design question - Now with pictures!

[MatthewMeredith]

Hey everybody! I'm about to start building my first bow after buying a cheap recurve and falling in love with the sport! I picked up a 1"x3"x6' oak board with very nice straight grain (note: actual dimensions are .75"x2.5"x6'). I have been doing a lot of research and decided to go with a Mollegabet design with the following dimensions:

Riser: 1.5" wide, full depth plus 1.5" deep birch handle, 5" long
Taper to active limb will take place over 2" for width and 3" for depth
Active limb: full width, .5" depth, 13" long
Taper to static limb, same as riser taper
Static limb: .5" wide, full depth, 11" long to nock

My main question is: do you think .5" wide by .75" deep will be enough for the static limb not to bend? I want it to be as light as possible to fully use the "lever" action. Any other thoughts on my measurements? I decided to fade the depth in and out of the active limb over a 3" distance to add a bit of draw weight, give it a bit more strength, and avoid a hinge. Thoughts? Am I crazy?

I'm shooting for 55#-ish at a 28" draw

Cheers!

[lesken2011]

The only molle style red oak bow I made cracked. The failure was probably a combination of a lack of experience and the materials. I'm not saying that is can't be done, but that design puts a lot of stress on the limbs since the bend is concentrated on a smaller area. Personally, I think the pyramid style is a good bow to start with if you have red oak as a material. Hickory would be a better choice for a molle style to begin with since it is more forgiving. Of course there are a number of woods that would work including hard maple, osage, and others. Of course almost everyone on here has more experience than I do.

[scp]

All depends on the board you got. Even though I work with oak staves, I usually start as if I'm making a pyramid style bow, but leave the tip halves of the limbs at least half inch thick and work only on the lower halves until the bow can be braced. Then I decide whether I will go for a mollie, if so how long the static lever would be, or just for a pyramid bow. Good luck.

BTW, even for the 5" handle, I would glue on a piece of wood at least 10" long.

[half eye]

for what it's worth I've make a whole bunch of mollegabets....all the way up to 75# (white oak)......all my levers are 3/4" deep at the working limb fade and taper to allmost 1/2" thick at the tips.....haven't had any of 'em bend at all. 1/2" thick at the fade  WILL start to bend some so ya should be good with your idea of the 3/4" thickness for the levers at the intended draw weight.

Thats my experience with the little darlins, except that they shoot real well with heavier arrow weights.
rich

[MatthewMeredith]

Thanks for the replies folks! Half eye, I'm glad you chimed in; I know you have a lot of experience with the Mollegabets I was planning on not tapering the static limb at all and just having the whole 11" of it be 3/4" deep by 1/2" wide... Just wanted to make sure it won't bend being that skinny! Also, as far as snapping limbs, I'm hoping that the board's 2 1/2" width should prevent that... Just in case, I'll most likely be backing it with raw-hide

[bubby]

if you dont taper the levers thats a lot of mass that will end up as hand shock, if you go to the how-to's halfeye has the layout for molly's right there, good luck they are some sweet shooter's, Bub

[half eye]

M2, In my experience the working limbs dont need to be more than 1-1/2 to 1-3/4 wide....any wider and the working limbs will be so thin it will scare ya. Also consider tapering your working limbs about 1/4" total in width and also thickness (about 1/8")......that will "round out" the working limb bend .....otherwise most folks tend to get too much force right out of the grip fades. When that tillered limb lets go most times it's chalked up to "the design overstresses the limbs".

By making levers that are close to half the limb's length you increase draw length and actually stress the working limbs LESS. Think about an arrow spine tester.....the arrow moves very little but the long lever (indicator needle) moves a lot so that you can read it easier on the graph.......so basically the longer levers (within reason) give more draw length for less movement in the working limb than does a typical long bow where the entire limb has to bend to get the same draw length. To me it's common sense, but the flack will be comming, so ya can decide for yourself....but give it some thought, eh? couple that with a more "round" limb bend profile and them babies will flat fling arrows.

Like I said though, just my thoughts on the design, so take it for one old guys opinion.
rich

[MatthewMeredith]

M2, In my experience the working limbs dont need to be more than 1-1/2 to 1-3/4 wide....any wider and the working limbs will be so thin it will scare ya. Also consider tapering your working limbs about 1/4" total in width and also thickness (about 1/8")......that will "round out" the working limb bend .....otherwise most folks tend to get too much force right out of the grip fades. When that tillered limb lets go most times it's chalked up to "the design overstresses the limbs".

By making levers that are close to half the limb's length you increase draw length and actually stress the working limbs LESS. Think about an arrow spine tester.....the arrow moves very little but the long lever (indicator needle) moves a lot so that you can read it easier on the graph.......so basically the longer levers (within reason) give more draw length for less movement in the working limb than does a typical long bow where the entire limb has to bend to get the same draw length. To me it's common sense, but the flack will be comming, so ya can decide for yourself....but give it some thought, eh? couple that with a more "round" limb bend profile and them babies will flat fling arrows.

Like I said though, just my thoughts on the design, so take it for one old guys opinion.
rich

Thanks so much for the info, rich! When you say to taper the working limb, is it tapered from riser to tip? I'm going to take a closer look at your posts and make some more pencil marks on my board I'm  working the night shift right now, but I'll get some pictures of the board up tomorrow! Again, thanks to all the folks who replied!

[half eye]

no sir, I was referring to the working limb......taper from the grip fade up to the lever fade.....both thickness and width.....just helps distribute the bending load and not all of it near the grip fade.
rich

[blackhawk]

There are easier designs to make for a first bow than a molly from a red oak board(like a pyramid,flatbow,D bow etc....)......but if your dead set on it then who am i to say dont do it...im just happy your giving it a try,but i wood also like to see you succeed on your first attempt as well.....soooooo

As long as you chose a good board then the most important part that will make or break it will be in the tillering.....that is key and very important in this design...it must be dead nuts or it will fret and or eventually fail on you...there is very little margin for error with such short working limbs,and if the load isnt evenly distributed it will spell disaster. The hardest part to learn in making bows is tillering....so,keep us posted with pics and progress and it will help you tremendously more in succeeding. Also use a tillering gizmo to help you see flat areas that need to be scraped.....and if ya got time on work to peruse the internet,then do a search on how to make a gizmo,and read,read,read, read on how to tiller properly.

Good luck

[Fred Arnold]

Matthew, I'm glad to see you working on this one and will watch your progress.
I cut an elm sapling last fall and couldn't decide what to do with it, Started to make a D bow but changed direction as the stave was drying and decided to attempt a Mollegabet style bow.
So far still in the floor tillering stage and have run into some stiffness in the working limb section probably because of the crown and knots.
I'm using basically the same dimensions you posted but so far it's all a bit stiff while checking the tiller. It seems to bend good but heavier than projected. I spent a a couple hours today slowly rasping and calculating. Because of the heavy crown I may end up trying to go thinner in depth on the working limbs.
I just spilled a glass of wine on my mouse trying to clap a pestering fly, I got him but don't think it was worth the mess I just cleaned up. I forsee mouse problems! It's already sticky.
My project may not work but I've got a shop full of wood and time on my hands.
Post pics if you get a chance and good luck. > Fred

[blackhawk]

And just for fun i have to disagree with Rich about the working limbs being less stressed in this design.....does it lessen the string angle and promote a longer draw...absolutley......but in my opinion the working limbs are acually more stressed as compared to a normal faltbow persay. There is less surface area carrying the load,and distributing the bend. Think about it,if you have a normal flatbow and a molly both are 50 pounds,and the molly has to carry that 50 pounds with less surface area to cover the bearing of that load. Now usually we make a molly wider to compensate for the difference,but i do beleive it is more stressed than a normal bow. And its why we see it fretting more than a normal design because of two things,either improper working limb width,or improper tillering. And thats why its so sensitive to fretting more is because its a more stressed design than a regular flatbow persay.......

But hey...what do i know...

[MatthewMeredith]

I have to say, I'm glad this is getting so much discussion! I think I'm going to stick with my original dimensions, contrary to all the sage advice I'm getting, simply to discover what the end result will be! The board was only $12, so I really don't have a lot to lose I'm going to do the whole thing with a rasp and sandpaper, and I'll be sure to post plenty of pictures!

Side note: does anyone here use Google SketchUp? Could be a neat idea to share designs, if anyone is interested! I have a model made to the dimensions in my first post.

[sound maker]

So I read what you wrote here and all I saw was you said you picked oak board, just to make this clear did you get red oak, white oak?? From what I understand the working of those 2 are different on how you go about it and so far we are guessing on your wood type. I'm just wondering because I am currently making a red oak molly bow too but a little bit wider and shorter though not sure if its going to be ok since I let a friend use it to show some young kids about bow making and it gots some damage to it under 3 hours but luckly I'm fine with it  though it most likely be under poundage as long as its nice and shoots well. If its red oak  this guy here
 
http://www.youtube.com/watch?v=bjiPXuuKFa4
 is doing a red oak molly bow build along thats similar to what you are doing so I would say this would be a good guidelines to be near and then do as the other suggested so your chances are higher of making it and getting it there. he says long bow but its a molly and I think its about 35# or so, so check as you get near.
good luck

[Jude]

Matthew, great to see you building your first bow.  What Blackhawk said about the tillering doohicky is right on; it helped me immensely.  In a pinch, I just use any flat block 2.5-3 inches long, and run it along the belly as I tiller, looking for flats or hinges.  My last bow was a sort of Molle-Pyramid hybrid, hickory, with pyramid limbs for 2/3 and the last 1/3 to the tips 1/2 inch wide X 5/8 inch thick.  It turned out to be a nice shooter, but I plan to taper the levers in width and thickness, like Half-Eye suggested, to see if I get more speed out of it.  Good luck with it and with red oak I would back it, regardless of the design.  I nearly lost an eye to a white oak board that I thought had perfect grain.  I found out I was wrong when the tip smacked me in the temple and took my glasses off.  Have fun.