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Thread: Bending Tight Radius in Ply
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30th October 2018, 11:17 AM #1Novice
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Bending Tight Radius in Ply
Hi,
I have a project to do which involves some really tight radius bends. The project isn't too big (would fit in a 300x150mm box). I have;
- Bending bucks made from MDF and coated with PVA to seal (I hope), and,
- Some sheets of 0.8mm ply
What I'd like to do is locally steam on the curves, wrap the ply in plastic (to stop moisture getting into the MDF) and gradually bend the ply in the bucks until they close up.
Has anyone done this, should I just soak the ply instead of steaming. There will be a bit of trial and error but i'd prefer more trial than error.
Cheers,
Andrew
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30th October 2018 11:17 AM # ADSGoogle Adsense Advertisement
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30th October 2018, 12:11 PM #2rrich Guest
The only thing that I can think of is to saw grooves to allow the plywood to bend. Even heated, plywood is not going to bend very easily. Maybe it would be better to laminate your own steam bent timber to fit the radius needed.
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30th October 2018, 02:34 PM #3Novice
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30th October 2018, 04:21 PM #4Taking a break
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Umm....grooves in 0.8mm ply? You're keen
Normal plywood generally doesn't like bending, but I've never used anything that thin.
My old work had 2 type of 3mm bendy ply; one 3-ply for general work that would comfortably bend around a 100mm radius, and one super-flexy 2-ply that was specially done by Plyco for us which you could pretty much fold in half - it'd take a 10mm radius no problem.
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30th October 2018, 04:47 PM #5GOLD MEMBER
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Welcome to the forum Andrew.
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30th October 2018, 05:05 PM #6Novice
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30th October 2018, 05:16 PM #7
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30th October 2018, 05:55 PM #8Novice
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Ply is 0.8mm Birch. Don't know if that makes any difference. Radius is about 6-8mm inside.
If I bend along the grain (so the middle ply is across) and cut the top layer with a knife/bend/fill with PVA while on the bending buck for the top layer (there are 4 sheets at 0.8mm) would that work? What have I got to loose really?
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30th October 2018, 05:55 PM #9Taking a break
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I think the key word there is "old".
If I'm not mistaken, pretty much all plywood now is bonded with thermosetting resins, which don't soften with heat.
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30th October 2018, 06:00 PM #10Taking a break
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30th October 2018, 11:16 PM #11
Lee Valley sells 0.8 mm ply which they advize will form to a 38 mm diameter. 6 to 8 mm is too small.
I think you should forget about using ply and investigate other options such as using veneer and laminating.
you might be able to steam (or heat bend) 0.6 mm veneer around your form.
I suggest you protect the form with packaging tape.regards from Alberta, Canada
ian
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31st October 2018, 11:51 AM #12Novice
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31st October 2018, 12:31 PM #13
I've not looked at or done it, something that comes to mind that makes me wonder if a similar approach might help or work is like the Luthiers do with a bending iron to form the sides of say a Violin etc
It's Ripping Time!!!
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31st October 2018, 04:42 PM #14Novice
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Hi Mick.
I'l look at that too. You Tubing on the weekend for Luthiers techniques.
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31st October 2018, 09:57 PM #15GOLD MEMBER
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Have you got a sketch or image of what you are trying to achieve? I have started building ukuleles this year and as part of the process built a bending iron, I have also used a steam iron from the laundry with great success. Luthiers usually bend timber at or around 2mm thick (or less) and no where as tight as you are proposing to do.
I have a few threads in the musical instrument section of the forum if you wish to see what I have done.
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