KennyM's form for BBO or HBO?

[razorsharptokill]

I have a KennyM 62"-64" longbow form made out of MDF. The top half bit the dust due to moisture. I was thinking of trying a BBO or HBO using the lower half of the form and converting it to inner tube pegs. Think it will hold? What size dowels?

What about the design? Too much deflex?

[Dmaxshawn]

I too have been wanting to try this Idea after seeing Davids bows from  http://www.primalneedarchery.com/index.html   for a BBI.  I dont see why it wouldnt work with dowels and inner tubes.  When I had a tube press I used 1/2 inch dowels worked fine and didnt break any.  


Shawn

[No-sage]

Here's my form.  The dowels are 1/2" and go all the way through in 1 piece.

I use 2 bar clamps just at the end of the handle deflex, put on all the bands, then the 2 bar clamps can come off and the bands hold everything.

 

[GREG IN MALAD]

It will work but a design with less deflex would be better. I used my 64" longbow form for a hickory backed cedar. It shot nice but took a bunch of set, about 2" if I remember correctly.

[Swissbow]

You have to consider, that an all wood bow will not hold the form like a glass bow and will always loose some of the reflex. Therefore a form that is perfect for a glass bow might not be the best choice for an all wood bow.

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Andy

[bjansen]

I was going to say the same thing as Greg about removing the deflex...and I actually used Kenny's design the other day to make a BBO form.  I also took about 2 inches of deflex away...and If I were to do it again I would probably take a little more.  

We used 1/2" oak dowels and went all the way through and that worked great.

[razorsharptokill]

I'm thinking I can add a block in the valley to reduce the deflex some. Should make it easier to fit the powelam and handle too.

[Dmaxshawn]

Can you post up some pics of the form when you get her blocked up.  Thanks

Shawn

[broketooth]

i wouldnt use mdf for anything structeral or induced stress. i would use any kind of lvl(laminated veneer lumber) whether it be 3/4 a/c ply with 7 plies. or a full 1 3/4" lvl header material you get from truss companies. the 1 3/4" is some tough stuff let me tell ya. it mashines pretty good for making forms too. 16" width or bigger is what i would use. 6' or shorter i guarentee no flex the glue in these lvl's is tougher than the glue used in glass recurves. its made not to flex. short answer dont use mdf. ruddy

[razorsharptokill]

I have an piece of angle iron that I bolt to the bottom of the form. With the reduced stress of the rubber bands I think it will hold. I think I'll also run some half inch plywood down both sides also.

I will post some pics as I make progress.

[razorsharptokill]

I took 1/2" plywood and traced the contour of the valley in the center of the form then cut it out on the bandsaw. I'll laminate it and two more pieces together and then cut them out and sand to fit.

When it does I'll drill pilot holes through it into the face of the form and counter sink some wood screws through it into the form. I should have a two in one form.

I think I'll lay a piece of formica across the top of the block to make a smooth transition at the ends.

[razorsharptokill]

Here is the plywood I put on the form to take some of the deflex out.



I secured it with counter sunk wood screws. Now I need to figure out how thick of a power lam I need. The Dryad Hunter uses a .300" x 18" power lam. I think I'll need a thinner one to conform to the curve.

[Dmaxshawn]

Looks good and Thanks for posting the pics.  

Cant wait to see the rest.

Shawn

[razorsharptokill]

The problem I foresee is getting a good glue line between the boo and the power lam/taper lam as it will have the convex side down. The nodes may interfere with getting it to lay flat.

[razorsharptokill]

May have to glue the boo on after I have the two lams of osage glued into reflex/deflex. That would mean two forms to do one job. May not be the best option using this form for boo backed bows.

[kennym]

Hey Jim, how about a pc of like 1" thick foam under the boo to crush it into?

[razorsharptokill]

Good idea! Maybe like the black pipe insulation.

Glue up should be fairly non violent with the rubber bands. I could ensure proper positioning as I add bands.

I was also thinking of two pieces of 1/4" rubber mat, 1/2" wide that I have. I'd place them a 1/2" apart. This mat is pretty squishy.

[razorsharptokill]

Was looking at my form and lams and playing with the idea of putting the power lam in between the taper and parallel lam? What do you guys think?

The boo backing would then be glued directly to the taper core.