Darryl Keil Last Activity 2025-05-12 11:03 AM
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mike mcnerney

Posts: 87

Joined: 2003-07-17
Location: ottawa ontario

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Subject : bending form
Posted : 2010-12-07 8:50 PM
Post #36214
I am making a bent lamination using the curve ply (bendy, wiggle..) plywood. The ply I got is .250 thick, and I am making an 8 ply piece so an end product of around 2" thick. My curve is very gentle for about 18" and then gets fairly sharp maybe a 3" radius. The stuff does bend but just barely. I would like to make a form and not put a skin on it and just tie the ribs together with cross pieces notched into the ribs.
Is this feasable? I'm thinking about putting the ribs on 4" centres & if necessary fill the cavity with foam although I have heard foam can collapse under vacuum.
Can I glue all 8 plys at one time in the bag or should I do say half at a time.
Mike McNerney


 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: bending form
Posted : 2010-12-08 7:15 PM
Post #36218 - In reply to #36214
Darryl's 2nd video spends a lot of time on making bent laminations. It might be very helpful.
If the plywood bends but just barely I'd drop down to 1/8" plywood so that you can coax it through the bag as the vacuum builds. I wouldn't want to try to spread glue and get under vacuum more than 3-4 layers the first time, and only after confirming in a dry run I could coax them into shape as the vacuum builds.
Just my two cents.


 
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Darryl Keil

Posts: 1454

Joined: 2003-05-22
Location: Maine

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Subject : RE: bending form
Posted : 2010-12-09 3:10 PM
Post #36219 - In reply to #36214
Mike,

A 3" radius is pretty tight for 1/4"bending ply. You may have to do it in a couple of pressing.

If you want no dishing between ribs then I suggest ribs every 2" OC. For 3/8" bending ply I usually do 3" on center. If it was me I would skip the foam and go 4" OC and glue two layers of the 1/4" bending ply to each other on top of the ribs. Dont put it in the press to glue the two layers together otherwise you'll end up with permanent dishing between ribs. I just think it will take less time to put a skin on the form than putting foam in between.

Darryl Keil


 
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mike mcnerney

Posts: 87

Joined: 2003-07-17
Location: ottawa ontario

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Subject : RE: bending form
Posted : 2010-12-09 4:47 PM
Post #36221 - In reply to #36219
I have been looking for the 1/8" bendy but can't find it. I guess I don't think it would be easy to glue 2 .25 skins on the ribs & without any humps or valleys, that is why I am considering no skin so if I have to put the ribs every 2", so be it. I'm resigned it will have to be at least 2 or 3 pressings. I've come up with a method to mechanically clamp the first laminations tight & after about 10" they bend real easy. The clamp will be able to stay in place until all laminations are complete.
I hope to photo it all and post at a later date.
thanks


 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: bending form
Posted : 2010-12-10 7:24 PM
Post #36226 - In reply to #36221
Mike:
The only source I've found for 1/8" Ital poplar bending ply is Distributor Services Inc (DSI) and fortunately for me they have a Cincinnati warehouse.
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