squaring a form surface w/ limited tools?

[styksnstryngs]

Hey guys, I'm building a T/D longbow and I have a form planned out. It will be a rubber-band form, and I have the rough profile cut out from laminated pine. I'm not worried about the form warping because rubber band forms tend not to warp as much because of the even nature of the pressure. However, I need to get the gluing surface on plane with limited tools. I do not have a router, spindle sander, or a drill press. Has anyone made a form without these tools? Or should I try to borrow a router from a friend?

[kennym]

Or should I try to borrow a router from a friend?

^^ This, if you can. Be sure your router template has smooooth curves, because you will se it in the limbs if not.

Bend a pc of something reasonably stiff around the curves, like a pc of fiberglass. Look at it closely and make sure it is in good contact with the template. Block sand as needed.

Much easier to sand a 1/4" plywood than a 1.5" form!

And if your limb pads are flat, make sure you have a flat on the limb there.  

[M60gunner]

I take it you have a square? If not a piece of fiberglass laminate works. When I made a form I got it square but put a strip of flat steel on the surface. Maybe overkill but it was flat.

[Dazzad]

if you can borrow a router, this is by far the best course of action. I can relate - had to save up to buy one, but once i had it and an mdf template a smoothly curved, square, flat surface was easily and quickly achieved.
I'm a firm believer that the earlier in a making process you compromise or employ a shortcut, the more grief or 'payback' will come due for payment down the track:)
Go to the extra time, trouble, expense etc. to get your form great - it will be worth it! Best of luck mate

[stickmonkey]

Check with local tool houses and rental outlets if you can’t borrow one.

[LittleBen]

A relatively easy way imighf be to mix up some epoxy with a lightweight filler (I.e. Microballoons or something similar). When you mix it into epoxy resin you get a very lightweight very thick paste that can be used for fillets and is common in small boat building.

You could cover the surface of the form with this, then sand it smooth and square by hand. It sands pretty easily but is plenty strong for a form. I would probably make a sanding block (or a set of sanding blocks) that have basically a fence at a right angle that you could run along the side of the form while you Sand to maintain square. (Kind of like the fence you might see on a hand jointer plane)

Lastly, you could probably use a strip of wood to make the epoxy mix smooth, flat and faired.

Cut a pressure strip of wood the width of your form, and maybe 1/4" or thinner depending on the curvature of your form.
Spread the thickened epoxy onto the form.
Cover in plastic wrap or wax paper.
Place the pressure strip over the wrap/paper.
Clamp the pressure strip down.
Let it cure.

That should get you pretty close. Then fine tune by hand.

Using multiple pressure strips stacked on one another will smooth out any bumps better than a single strip.

I fixed a small portion of my form using this method.

[monterey]

When I have one edge of the form perfect and the rest cut too deep, I take Elmer's Wood putty and goop it on the surface then bring it into square using a...yup, a square by drawing it down the "good" edge and essentially filling the low portion of the form surface.  Takes a couple runs but it works!  

If you saw the form I initially with a saber saw it will tend to cut on the line but deeper on the offside.

So, my advice is to buy, borrow or rent a router. One of my favorite tools!  

[bamboo]

https://www.harborfreight.com/power-tools/routers/2-hp-fixed-base-router-68341.html

cheap enough