Routing out forms ???

[Pat B.]

I've made a template of 3/16 masonite and used it to make a line to cut to with the bandsaw.

Then I came back and screwed the template down 1/8 shy of the line and used the router and a top bearing trim bit to run against the template.

Maybe the the third time's the charm, because I messed up and cut a divit in the form the first two times...

Any tips to make this a more predictable effort ??

                Thanks !!

[kennym]

I've had trouble with Masonite giving and cutting the form deep in places(hate that when it does it).

I use good 1/4" plywood now.

Clamp the form to a solid bench and use both hands firmly on router taking care to not let it tip (makes a divit) .

Bend a pc of glass around the curves on your template first to see flats and bumps you can't see without it. Also shows stuff I can't even feel .

Lots easier to sand a thin plywood than 1.5" of it!!

[Pat B.]

Thanks Kenny!

I hate making the same mistakes over about 3 or 4 times in a row, lol...

[Bruce Martin]

Do you guys have a particular pattern  or top bearing trim bit to recommend? Thanks also for the heads up with Masonite vs plywood for a pattern!

[kennym]

I use a half inch bearing and cutter bit. Long nuff to do the whole width is good but you can do part and run the bearing on the just cut surface also.

[Robertfishes]

If its a small divit just fill it in with auto body bondo.

[BigJim]

When I have my forms finished, I add an 1/8" aluminum strip as a surface for the back of the bow. It will dramatically smooth out any minor wash boarding

bigjim

[Pat B.]

Jim, how do you attach the aluminum stip to the surface of the form ??  

Glue or ??

   Again, thanks everyone !

[LittleBen]

Originally posted by BigJim:
When I have my forms finished, I add an 1/8" aluminum strip as a surface for the back of the bow. It will dramatically smooth out any minor wash boarding

bigjim

X2

[Robertfishes]

5 years ago I bought a couple of 2" pattern bits from MLCS. They were $12 each then..

[BigJim]

I don't attach it to the form...tried that several times and ruined several forms and sluminum strips.

I use scrim tape and tape it down in place in the riser section and then again on the tips.

I have never noticed and issue with the thickness of the tape but then again, I put overlays over the areas in the riser where the tape was and cut the tips off of the bows where the tape was...but sure it wouldn't have mattered anyway as I have never so much as felt a groove or mark from the tape.

I have to clean up the aluminum every so often and replace the tape.
bigjim

[skeaterbait]

Hope not too lame a question and please forgive the shameless plug... :-) Jim, it was nice to meet you at ETAR.

What is Scrim tape?

[BMN]

Mount your router to a jig like shown below and it will help it from tipping and putting a divot in your form. One hand on the router and the other hand on the black knob on the jig.

 

[BigJim]

nice jig!

Scrim tape is just the super tough packing tape with the fibers in it.

bigjim

[Pat B.]

Great idea !!!

         Thanks

[BenBow]

Same as Big Jim only i use 1/16" aluminum and glue it on with smooth on. I use the air hose and a stack of lams to shape it to the form then cook it in the oven extra hot. Haven't had any trouble with it.