What kinda material for a bow form?

[bowhntineverythingnh03743]

So I have been using LVL headers for my bow forms but am curious if there is anything else out there that will work just as well and be dead straight.

Any thoughts or ideas on what may be another suitable material for a form? This new form will be another air hose design for Kenny's 58 inch pattern.

[MoeM]

I still use MDF; 2x19mm= 38mm~1 1/2". Easy to route and I get it straight when I lay the Forms together on a straight surface and screw them together.
I haven`t had any issues with using them in my heatbox though.

[Roy from Pa]

Birch plywood 3/4" glued together gives you 1.5" wide. Glue it and screw it.

[Bowjunkie]

I like the LVL beam matrial... but I've screwed various sizes of plywood together to get the thckness I needed too.

[wandering monk]

I always used 1/2" douglas fir plywood  AC grade...but the russian or other birch plys would be fine...MDF is for sure flat, I just dont know how durable it would be after repeated 150 degree kiln operations...

whether or not you use a "fire hose" or clamps, there is a lot of stress put on a form...especially after mutiple glue-ups...

the LVL idea sounds great...especially since its already the 1 7/8" thickness usually...cutting and sanding perfect 90 degree curves would be a lot more work I think,thats why I always like lamming up (4) 1/2's for a little extra width, especially for take down or recurve limbs.

here is my old shop with some of the forms...a relex longbow, def/fefl flat bow and a one piece recurve...all DF 1/2" 4 ply forms...

   
   

[scars]

One of the best ply hibreds is MDO It is a multi ply Plywood with a medium density over lay. You get the strength and fastener capabilities of ply wood with the flatness of MDF.

[jess stuart]

I have had good luck with the MDF.  I do put a layer of plywood on the outside makes the form a bit heavy but, for takedowns not bad at all.  Haven't used it for a one piece yet.

[kennym]

The  MDF forms I've seen broken did so in the bolt hole. Heartbreaker!!

I have one that I lined with 1/2" ply down an inch from form surface. It is a bear to handle alone!!

Another we put about 6" squares of 1/2" on at all bolt holes. So far so good. Still be a heartbreaker if it goes.

So I guess I would still say plywood to get thickness.

If it is a little too thick, could you use a strait bit in a router set to depth to narrow for an inch or so down if you don't have a planer?

[bowhntineverythingnh03743]

Ok guys I will attempt a high grade plywood. I will head to the big orange store here this weekend and pick up a piece. I only ask because I started with a straight LVL header and now when I look down the side it has developed a little bow in the thing. I even stored it inside the oven so that it wouldn't collect moisture and the form was all put together during storage.

I had a metal shop in my town build me some brace pieces that cap the top and bottom and have 1 1/2 inches of over hang on both sides. I plan on connecting them with some plates and bolts on each end. i just have to weld on some handles because it will be quite heavy when all put together but I think that they will keep their straightness for the long run with this setup.

We shall see tho.....

[Crooked Stic]

MDF will collect moisture and swell if not protected properly-It does not handle dings well either. I guess maybe a coat of paint or sealer may be good whatever the material is.

[Dan Bonner]

I use laminated oak stair treads from Home Depot for take down forms. They are about 1" thick and I glue and screw 2 together. I take a router and make grooves where I put my zip ties for the width of my lams. They have held up for years.
 
 


I like a form that is wider than my limb stock so the hose can spread out more and apply more even pressure to the lams. I also space my steel brackets so they are wider than the form for the same reason.
Bonner

[Robertfishes]

I have only used 9 or 11 ply cabinet grade 3/4 inch birch plywood for 1.75" forms along with a piece of .25? Inch ply and a door skin..I used tite bond 2 glue and at least 2 lbs of 1 5/8 inch drywall screws for each form. My 3 one piece bow forms and one 80" form blank were glued up July of 2009 and are all straight. I have one 1.5 inch wide form, I used birch plywood from Lowes. Seems like I had to use 3 pieces to get my width, tite bond2 and at least two pounds of 1.25" drywall screws