Form Build Question

[Cruiserpilot]

I'm building my first glass bow and am building it with 1 3/4" limbs.  
I may at a later date build a 2" bow and was wondering if it matters if I build this form 2" wide or need to make the form 1 3/4" for this bow??
It doesn't seem to make a difference to me but I know I have seen threads with people building 1 3/4" forms and talk about sanding it down and taking micrometers to the lumber yards to get the plywood the exact size to make it exactly the width they are looking for.
I'm a super newbie here so just don't want to overlook something.
I can see making a form too narrow being a problem but is there an issue with making it wider than the limbs your building (2" for a 1 3/4 bow)???? I guess I could see making sure the lams are straight in the form would be slightly easier with a matching width....??

Thanks in advance for helping the new guy on the block.

[Trux Turning]

Having the width of you form match your bow width is important- stuff likes to slide around once you add glue. You could make a 2" form for 1 3/4" bows if you build in some stops for the smaller width. To narrow a form and you could get some limb cupping- to wide and your stack could slip around in the form.

[kennym]

Yep on what Dave said!

My stuff wants to slide with the right width form!

Welcome to the building sickness!  

[Cruiserpilot]

As I look at the design of the form I don't see what would keep the lams from sliding around either way??  There is a plywood spacer to keep the metal bars away from the lams.  
In the plans the picture shows a gap between the lams and really nothing holding them in from the sides.  All the pressure comes from above and below and no side pressure to keep it from slipping in the form.  Does the narrower form just allow me to see if it has slipped in the form before it goes into the oven???
I will follow your advice and just go with the 1 3/4" design.  Just trying to wrap my mind around what I'm doing and why.
Thanks again!

[Cruiserpilot]

Thanks KennyM. Posted last response before I saw yours.
I will take your and Dave's advice and just build a new form down the road if need be for a 2" bow.  I could see how things could get out of sorts in there and not be able to see whats going on.

Its good to be part of the building sickness!

[kennym]

Use some fender washers with a new hole drilled off center so the washer will swing up as needed to keep lams in place. Just screw to form at proper height so you can hold all the lams.

I use 4 pairs on a 64" bow , to hold the fades of riser in place and then at midlimb.

[Cruiserpilot]

That sounds good.  I will go pick up some.

[Trux Turning]

Originally posted by kennym:
Use some fender washers with a new hole drilled off center so the washer will swing up as needed to keep lams in place. Just screw to form at proper height so you can hold all the lams.

I also use washers to keep everything from sliding side to side on my forms.

[Robertfishes]

I used these wood pieces in place of washers on my last form, they worked fine but the washers might be eaiser to use.

[Robertfishes]

This form has the offset drilled fender washers, they work good.  

[Cruiserpilot]

Thanks guys.  
Those are both great ideas.  Definately got me going in the right direction for the form build.
I like the idea of the form stand in that last picture.  
Do you guys have those in the overn too???

[kennym]

Here is how I build a form, it might help ya!

 http://www.kennyscustomarchery.com/Bow_forms.html

[Cruiserpilot]

Kenny.
Love the link.  Hadn't considered using the router to make sure the cut was square.
Great info.

[Robertfishes]

No stands in oven, the form would be too close to the heat source (light bulbs)..I just use the stands on the bench,it helps when taping pieces down. if you look on the bottom left side of form you can see a 6 inch piece of plywood..that keeps it from tipping over in the oven, I could screw one on the other end but havn't. I had trouble getting my first form perfect, I found kenny's web site and saw how he does it.. I bought a router and a 2 inch bit and have had no problems.

[7 Lakes]

A little extra trouble but you can always build a 2" form and use the pattern for 1.75" to cut out a smaller width bow.

All in all, it's best to make up your mind first.

[rmorris]

I got an idea for you on how to use a 2" wide form To make 2" and 1.75" bows. You will need to be very accurate but here is my idea..... The difference between 2"and 1.75" is .25" and if you place half of the difference on each side of the form you are only dealing with .125". So , if you were to take something like a 1.5" foresner bit and drill .125" into each side of the from with the foresner bit hanging the. It about 1/3" off the form. You would then be able to use 1.5" washers to keep the 1.75" wide limbs from slipping on the 2" form and then remove the washers and also be able to make 2 " wide bows. I would do a set of washers every 9-12" along the entire form. I don't believe the small gaps of approximately .125x 1" long would be noticeable in the final product. This is how I would tackle your problem, hope it helps.