Mollegabet tip thickness

[loneviking]

For you folks that have built these bows before, how thick (top to bottom) were your finished tips?
I'm building a Molly out of a Red Oak board, and the finished thickness of the tips is about the only parameter I'm not sure of.

[PEARL DRUMS]

Don't let them bend. Remove wood until you THINK its about to budge, then stop. That's how thick your tips will be.

[John Scifres]

5/8" should be about right.

[PEARL DRUMS]

The length of your levers and desired draw weight play a huge role in thickness.

[monterey]

I too am in the process of building an oak board molly and have concluded that they should be as thin as possible without bending.  That way you are getting as much tip weight reduction as possible.  What I'm working on now is how to get the correct fade between the narrowed thicker tips and the working limb.

Sorta ran your thread off the road here, but hope there is no harm done!

[Rdog]

Hey Loneviking, as you know I am a beginner and don't know squat, but here is a close up of mine, and I really wish I did not do it like this...
 
 

I don't care about it being a bit heavy, its pine and can't weigh much, but it has in effect shortened my overall length a bit and worse made it a pain to string up.

the static limb was 3/4 sq. but I have smoothed and shaped it more oval, with the back staying the flattest.  It is still 3/4 back to belly, but side to side its a little thinner.

Post up some pics of yours, I'd love to see it.

[LittleBen]

There's no real answer to how thick in inches or anything. As PD said, it's going to depend on things like bow length, draw weight, width of lever etc.

I think PD's advice is right on. You want the least wood possible without it bending.

I would personally start removing wood slowly until it's just barely-ever so slightly-almost bending at full draw. That way they're basically stiff, but you know you have the minimum weight.

[PEARL DRUMS]

You can always give the levers a toasting if they decide to give a bit too much. Unless its broke, there is always a way out! Just keep your eyes open.

[loneviking]

Thanks guys! I guess I'll wait until final tillering to start shaving them down and keep that 5/8ths number in mind.

Rdog, thanks for the heads up on the tip shape. The shape looks nice and I was thinking about doing something like that. After hearing from you, I think I'll pass!

Some have said that the tip thickness depends on the desired draw weight.  That puzzles me a bit as I didn't think you tillered to a desired weight.  I was thinking to tiller until the limbs are bending well and even and then stopping.  The range of possible draw weights would vary with the width of the board and how good the grain is along with whatever backing I might use.  Am I wrong?

[LittleBen]

You're out-thinking yourself here. Everything depends on everything else, just don't think about it or you'll end up hurt.

Tiller the bow, leave the levers thick. When you're satisfied with the tiller ... start removing wood until the levers just seem like they wanna start thinking about bending.

Regarding tip overlays ... In my opinion less is more. tip overlays add weight if they're bulky and frankly i think can look silly. All you need is 1/8" piece of hardwood or phenolic or something ... well really you don;t need any overlays, but if you put them on 1/8" is probably enough.

[John Scifres]

Of course you tiller to a desired draw weight.  You design your bow from the start for a desired draw weight and draw length.  You are the master here.  Within the limits of the specific piece of wood you have, you decide what it becomes.  If a specific piece of wood has limitations that don't fall within your desires, find a piece of wood that does.

[PEARL DRUMS]

Exactly like John said. Depending on your skill level? You can get a bow bending evenly and smnoothly at 80-90# every time, but not many want that. Therefore you tiller it down to your target weight, all the while maintaining that same smooth, even bend you had at 80-90#.

[John Scifres]

But...never bend a bow past your desired draw weight or draw length.  To do so invites unnecessary set.  In fact, I don't bend past 16" until I am about 10# under my target weight and the tiller is spot on at 16".  

Here is how I tiller:   http://hedgerowselfbows.webs.com/fromblanktobow.htm

[loneviking]

John, thanks for your link.  I do have several questions for you from that link.  

The first is that in the 'blank to bow' example, you have the bow pulling 39 lbs at 18 inches. You also say to figure on 3lbs for every inch of pull.  18x3 is 54lbs, not 39 lbs.  And with the bow at 27 inch draw, you're projecting a weight of 65 lbs. But 27x3  is 81lbs!  

What am I missing here?

[John Scifres]

I'm only getting an additional 9" of draw over my 18".

27-18=9

9x3=27

27+39=66 (which is about 65. Remember this is rule of thumb math, not engineering.)

You don't get 3# of draw per inch in the early part of the draw.  i.e. 18x3 does not equal 39.

[loneviking]

A second question is why 18 inches and not the 16 inches mentioned above?

[John Scifres]

You are very literal aren't you  

Remember, wood bowmaking is often more art than science.  I frequently take artistic license with the process.

And I don't always remember how I get from Point A to Point B.  Those who wander are not always lost.

[takefive]

John is spot on with his 3# per inch average if you factor in brace height.  If his bow is braced at 5", he's pulling the string 13" (13 X 3 = 39) to get to 18" on his tree and 22" (22 X 3 = 66) to get to his full draw of 27".

[loneviking]

Quote:
John is spot on with his 3# per inch average if you factor in brace height. If his bow is braced at 5", he's pulling the string 13" (13 X 3 = 39) to get to 18" on his tree and 22" (22 X 3 = 66) to get to his full draw of 27". Quote:

Nope, his brace at the 18" point was only about two inches.  And the final weight of the bow was 50, not 66.  Not looking for a fight, but some of you guys and and your math really need some help.

And John, I only took you literally because you seemed so adamant in your post.  It does seem to me that things like 16" and 3" per inch should be general guidelines.  So, I guess we agree.

[takefive]

Go back and reread your post.  I'm just going off the numbers you provided.  Then again, if you'd rather quibble over the math than actually make the bow, that is your choice.