mollegabet board bow

[Zedd]

Finally, after lurking here (yeah, I'm one of those fellas) for years I took the plunge and made my first bow. First, I have to thank all the thousands and thousands of tips and advise given on this forum. It is amazing how folks are so willing to share information so readily for so little money....
The bow I decided to make was a home depot red oak board mollegabet bow. I had to go to many different home depots, loew's, and other shops that sell timber, multiple times to find a board with a proper (I think) linear grain structure. I have shot the bow 30-40 times and it seems to be holding up fine (my first consideration). When I realized it wasn't going to blow apart on my, I started to enjoy it. Wow. I mean, wow. I have a 50 lb samick sage recurve, and this mollegabet bow is much much much smoother than that bow. Not trying to disrespect the sage, just saying. Here are the numbers on the how it ended up:

47#/28"
65" ntn
1 3/4" string follow
rawhide backed with a cobra skin on top

Pulling this back was so smooth, I immediately checked the pull weight several times. (The scale was calibrated by picking up several 50 lb bags of fertilizer at the hardware store and surprisingly it was spot on). I can't feel much in my hands even on bows I have shot other folks say have hand shock, so I can't address that, but at 30 feet I was hitting 5 arrows inside a 6" circle.  Anyway, my son picked out the skin. I have read and realize there is a risk the TBIII might not bond tanned cobra skin (personally I find the cobra skin a bit gaudy, but hey, no accounting for taste) to the raw-hide adequately, but honestly, I don't figure my son will be shooting it a lot anyway. Question...does anyone have any input on using tanned leather as a backing, or is my understanding correct and this is risky? Here are some pictures...

[gfugal]

I loke it a lot!

[Zedd]

Thank you for the kind comment!

[Pat B]

All of the bend is at the fades. Get the rest of the "working" portion of the limbs bending evenly and together.

[Zedd]

All of the bend is at the fades. Get the rest of the "working" portion of the limbs bending evenly and together.

A sense of proper proportion is obviously not something I am familiar with yet. So, if I were to make the ovals with the foci closer together so the oval becomes more 'circle' like, the limb as a whole would work better? The belly and back of the working portion of the limbs are currently perfectly parallel. Doing this would mean making the middle portion between the two fades slightly thinner than at the fades. Am I understanding you correctly?

[bubby]

Get rid of the ovals and circles, get a six inch straight edge and use that as your guide. You should have a even gap between the belly and the straight edge then the tiller will be correct. Where is the set anyway do you have a unbraced pic?

[mikekeswick]

Bubby - the limbs are parallel width - the tiller should be elliptical. The set is at the fades from what I can see so yes a little overstressed there but this is a first bow Well done.

[bubby]

Mike the profile doesn't change the fact that a gizzmo or a straight edge especially with a board bow will give a proper tiller. That said this is a tough first build design i hope i didn't come off too harsh good job so far but tiller could use some tweaking

[Zedd]

I'll see if I can't get picture of the bow laying flat on a table. I appreciate the feedback on the bow. Can't get better if I don't know what is wrong and how to correct it. Bubby, geometrically speaking, the sagitta of a chord moving across an arc (i.e., the gap between a strait edge and the curve) will be constant for a circle but variable for an ellipse. My understanding was that for this type of bow, the tiller should be more elliptical than for other types of bows. Granted, I see how a 'fatter' ellipse will move more of the work into the limbs. Are you suggesting the tiller should be circular?

If someone wanted to know what a straight tiller looks like @ 7/16" with backing is, here you go.

 I am thick skinned enough to accept the critics while recognizing not only did I make a functioning bow, but a rather handsome one as well. I am very pleased with my first try.

[High-Desert]

I would have been stoked if my first bow looked like this. Mine was only worthy of firewood, and the fire didn't even want to burn it. This is a tough design to start with.
As far as tiller, the tiller should be elliptical, but the bend should increase as you move out on the working portion of the  limbs. What you have is an ellipse, but backwards, is bending the most aybyhe limbs, then decreasing as you move out. To see it, use a single ellipse for both limbs, instead of a single one for each limb. If that makes any sense.
Great job, you have a bow that you should be proud of. Now, start your next one.

Eric

[Zedd]

I would have been stoked if my first bow looked like this. Mine was only worthy of firewood, and the fire didn't even want to burn it. This is a tough design to start with.
As far as tiller, the tiller should be elliptical, but the bend should increase as you move out on the working portion of the  limbs. What you have is an ellipse, but backwards, is bending the most aybyhe limbs, then decreasing as you move out. To see it, use a single ellipse for both limbs, instead of a single one for each limb. If that makes any sense.
Great job, you have a bow that you should be proud of. Now, start your next one.

Eric

Thanks, I am pretty excited about it. Is this what your talking about?

[Zedd]

Eric,
What do you mean by " is bending the most aybyhe limbs?

[bubby]

Zedd elliptical or circular tiller the gap between the straight edge and belly should be even, a circle tiller may have more gap than ellitical but the gap should remain constant. I don't need geometric theory to know that if that gap isn't consistently the same the limbs aren't working equally from fade to fade
 

[High-Desert]

Sorry, I should have proof read that. I meant to say is was bending most at the fades, then progressively less outward. Yes, that's what I meant by a single ellipse. Your ellipse should be a bit smaller, it shouldn't go out into Non bending portion  of the limbs. The circular and elliptical tiller refers to only the bending portion.

Eric

[High-Desert]

What bubby said is very useful method of determining you tiller. I have trouble seeing elliptical tiller when it's subtle. If you run the straight edge across the belly. With an eliptical tiller, the gap will gradually get larger as you move out on the bending portion of the limb. With a circular tiller, it will remain the same.

Eric