Plywood form question

Bvas · December 27, 2016, 08:06:00 PM

The BIL hooked me up today with some 3/4" plywood to build a form with. I need to build an 1-1/2" form. Problem is the plywood is actually 23/32". So if I laminate them together I will end up 1/16 narrow on the form.
I have steel banding strips that I could use as spacers to get proper thickness, but then I would lose that wood to wood glue bond.
Would just screwing the two halves together be sufficient? Or should I use wood strips as spacers to maintain a glue bond as well?

Walt Francis · December 28, 2016, 03:19:00 PM

I would recommend using a wood spacer. Most of the glass I purchased came slightly over 1.5 inches. I use LVL's for forms and run them through the planner & thickness sander to match the thickness of the glass.

kennym · December 28, 2016, 08:15:00 PM

I like the wood to be glued and screwed on mine. Like Walt said, slightly over 1.5", a few thousandths at least.

Crooked Stic · December 29, 2016, 08:53:00 AM

On my 1 1/2 forms I use a 3/4 -1/2 and 3/8 plywood screwed and glued. Ir comes out a bit over 1 1/2 Most times I have to run it thru the drum sander to match the glass.

kennym · December 29, 2016, 09:16:00 AM

Heres a wild thought....

Make the form a bit thick, and then take a router with straight bit and your form pattern and bring it to the exact thickness you want for an inch down from the face. You have spacers under your lock straps anyway so a small step won't hurt anything.

Trux Turning · December 29, 2016, 10:13:00 AM

QuoteOriginally posted by kennym:
Heres a wild thought....

Make the form a bit thick, and then take a router with straight bit and your form pattern and bring it to the exact thickness you want for an inch down from the face. You have spacers under your lock straps anyway so a small step won't hurt anything.

This is how I've done a number of my forms and it works out well.

Bvas · December 30, 2016, 05:56:00 PM

QuoteOriginally posted by kennym:

Make the form a bit thick, and then take a router with straight bit and your form pattern and bring it to the exact thickness you want for an inch down from the face.

Great idea!!

December 30, 2016, 09:55:00 PM

I been putting my forms in a vacuum bag... Saves a lot of time on screwing...

Robertfishes · December 31, 2016, 10:03:00 AM

I like to put alot of screws in my forms. I use tite bond 2 glue and I just don't trust this glue by itself. Make sure your plywood is not warped, I think it would be very hard to get a straight form if you start with "crooked" wood. I try to buy my Cabinet grade birch plywood from a local cabinet shop..but I did buy some from Lowe's once.I still use forms I built in 2009 that are straight.

Walt Francis · December 31, 2016, 11:02:00 AM

Kenny,

Good idea, I will give it a try on my next form.

I always put angle iron on all my forms, never had any issues with them warping.