My latest bow form is haunted! I've made 7 forms so far and never had this problem. I pull the bow from the new form, sand off the glue globs, and run it through my 12" drum sander so the edges are perfectly parallel. But when I lay it on edge a flat surface, one limb tip is always about 1/8" to 3/16" off the surface. The form is perfectly straight. The surface of the form is perfectly 90 degrees along the entire surface. Any suggestions?

It must not be straight

Glulam?

Form may be warping from the heat in box. The comes back straight when cool?

How are you applying pressure to the limb during glue up? uneven pressure could cause the problem you're describing even though your form is perfect.

How do you keep it perfectly straight going thru the drum sander? Carl

Fire hose @ 60 psi.

Obviously something is different to your previous forms.Then as mentioned earlier your glueing them up with uneven pressure.Have you checked the integrity of your hose.Those things can get a bit of a hideing cause they have to do quite a bit of work.If its none of the above than God only knows. Best of luck OSR.

Unintentionally quoted a Beach boys song.Sorry.

Carl, infeed and outfeed table extensions which the riser rests on before the limbs enter the sanding drum. The riser is squared up before gluing and is dead on. Oh well, life goes on. I can compensate for the limb twist during tillering. OSR....."All I want to do is have some fun"....

You cant get a bow straight with a drum sander you have to scribe the bow out and sand it down to the marks with an edge sander or belt sander.

sounds like you are experienced-the form must be a tad off-I have 1 form that does that every time and I can allow for it when cutting blank out and its OK.

sometimes lining the form with 1/4" rubber allows it to be more forgiving of flaws-I have used the rubber strips from Binghams or cut your own,or use the pickup topper foam each time.

Tim Finley is right, my advice is to lay out your pattern on a .050 piece of glass and lay it on the glued up blank. It's pretty easy to get the pattern cut out almost perfect. If your pattern won't center up you have a form problem. A pattern makes your bows repeatable and straight.

I agree I have a glass pattern cut out for every type of glass bow I make.Good tip.

One explanation is that the bow form moves during it's time in the heat box. I learned bow making from Ric Anderson's' directions here on this web site, and cook my bows for about 7 hours. So......let's here from all you laminated bow makers........how long Should I cook my bows??

TTT

Nemah, The bow presses I've designed in the past were made of 1/4" steel and trued up using a dial indicator with plunger to within a thou of an inch ..No lateral twist..no variances in bend from upper to lower limb.. Always used a 1/4" rubber pressure pad on the form next to back glas..and another one atop the belly glas-reiser components..

Have used seran wrap and then inner tube wraps after positioning all for the cinching down of the components for the glue up..

All that said..I discontinued use of a hot box for curing years ago..The G-2 epoxy is far better..better in tech specs for strength/shear etc than the smooth on..

I use the G-2 Epoxy which cures very nicely at 70F room temerature...Jim pic of my press for the replication of the old Bear early 5-'s statics..It has a new home now..:)

and tho you have prolly seen this pic before..one of the finished Bear-Grumley staics from that press.. This one is 77#@30" draw..A fine well tillered balanced fast shooter..with some color..:) Jim

Damn interesting bow form Jim! G2, room temp. Like that idea hate heating up a bow. Holds a static together. Might have to look into that sometime if I build another bow.

Nemah can understand your disappoint, know the amount of time it takes to build a form. Only thing worse is when your bright idea, work, and material ends up being BTU's because the design was just good on paper! LOL. I've not seen this suggestion and don't know if you done this.. Get your bow and lay it belly side down on a nice FLAT hard service i.e. tips pointing up bow laying on its arc. See if the bow rocks. If it rocks, then sorry Bro. your form is bad. If she don't rock then it can be hard telling what caused your problem. 1/8th inch or so not really a big deal. Take your straightest side, centerline her for your templates and build your bow. It will come out in the laundry just fine. Leaving your bow in a hot box for 7hrs, guess this would depend on what the temp of your box comes up to, but think this is a bit of over kill. I ran about 190 or so. Once the form and layup came to temp about 2 hrs. or so is plenty for smooth-on. But would not unwrap the bow till next day.

Still liking the sound of the G2, fellow could save some on his light bill also. LOL Y'all take care

Oldbowyer..Todd.. The G-2 from Industrial Formulators LTD in Burnaby Canada..Is a great two part epoxy..( I'm not their salesman or spokesman)..:) There are folks who sell it stateside..:)

Non critical 2:1 mix of resin and hardener.. Do a search and look at the TECH SPECS..Jim

heat cured smooth-on 6 hours at 150F

here's some of Bear's forms still in use from Grayling-heat cured with heat strips built in I think.

Here is the bow form I'm having so much trouble with.

After careful examination, the form IS twisted, just about 1/8". Look at the bottom of the form in the previous picture: you'll see both ends are warped upward about 3/16". Here's an end view:

When turned upside down, there is a definite twist, as shown when I slid a rule under the formica on the form.

Oh, well. Life goes on. It's off to the lumberyard tomorrow to buy more plywood. Here's a photo of the bows I'm making. I have a long way to go to finish these bows. Do they look familiar??

That picture is not mine. Here's mine, I hope.

And three more waiting in the wings!

Oooooh! ...Kodiak Deluxe clones! Got any deals on a twisted L/H 64 incher? ;)

Your shop is to neat LOL. Man sorry about your form. Your work looks top notch.

Nemah, Looks like a ine design for a recurve!..When I said I trued up the form I used..I used what is called a bendmeter.. Basically I made an aluminum block with feeet on either end that are 6" apart..In the center I mounted a dial indicator with plunger that contacts the surface ..

So I can true up the form so both limbs not only bend the same at any given point-station, but also keep the form PLANE side to side..

It's not perfect..we're dealing with thousandths of an inch..BUT useing the bendmetr sure gets it closer to perfect than the eye and a leven can..Jim

NICE Nemah-once you make a 59/60 form its hard to make others!

4nolz..I'm hittin' the "LIKE" button on those pics..:)

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