Bendy ply. hd15 curve
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Category: Plans
Forum Name: HD 15 horn
Forum Description: Discussion / Questions about the HD 15 horn
URL: https://forum.speakerplans.com/forum_posts.asp?TID=1428
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Topic: Bendy ply. hd15 curve
Posted By: ashnono
Subject: Bendy ply. hd15 curve
Date Posted: 20 February 2005 at 9:45am
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Went to bend me 4mm ply today for the new hd15's and discovered it'd
been cut the wrong way. This meant it didn't want to bend in the direction I needed it too. Are there any ways around this, steam etc? Or is it a bin it and do it again jobby. |
Replies:
Posted By: mans1000
Date Posted: 20 February 2005 at 1:21pm
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prolly easier to start again as ur gonna have a tough time trying to bend it,especially if u have to do a few curves to get the thickness u need. |
Posted By: ashnono
Date Posted: 22 February 2005 at 6:15pm
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Can anyone recommend the best way of doing the curved section on
hd15s - What glue, screw use (will I need many?), clamping etc. thanks in advance ash |
Posted By: Dom
Date Posted: 22 February 2005 at 6:30pm
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It's really a lot easier than everyone thinks. As long as you get the plywood cut the right way round, you just bend the first sheet into position. It will naturally form a smooth curve, just as a soap bubble forms a sphere... Glue and tack it into place and then laminate more layers over the top. When we built ours we cut the ply to be just short of the back of the box and then clamped it down by clamping to the back of the box. The excess was cut off once it had dried... PVA works as well as anything for glueing. Some people have used curved battens on the sides to use as formers which they screwed the ply into, but we never needed to. ------------- "It sounded like a million fire engines chasing ten million ambulances through a war zone and it was played at a volume that made the empty chair beside me bleed." |
Posted By: ashnono
Date Posted: 23 February 2005 at 4:14am
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Cheers, I've put curved sections on the sides to help fix the curve in
place. In the past for other curved stuff i've always used loads of screws. Are you saying you only need to screw the bottom layer then all the tops are just glued. Did you use a batton at the top or/and bottom to fix the 4mm too? ash |
Posted By: loophole
Date Posted: 23 February 2005 at 5:28am
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dom's method will work fine, but the advantage of using formers (both curves along the sides and a batten at the bottom front) is that you can wack on two or more sheets at a time. just glue them up, screw them all to the bottom batten, then apply weight to them over the curve until they're lying flat, and wack a few screws down each side. work from the bottom with the weight and screws and you won't get any ripple in the curve. its all kinda obvious once you start doing it.
the problem is this is all only really possible if you get the ply cut the right way. if you've got the grain running along the curve, you'll probably need steam to bend it round and you can only do one laminate at a time. its certainly possible, i did our first 2 hds this way, but its pretty time consuming, and if your times worth anything to you then its probably cheaper to buy some new ply. especially once you factor in the costs of broken kettles.... ;) are the drivers out of customs yet btw mate? |
Posted By: ashnono
Date Posted: 23 February 2005 at 6:05am
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Cheers lads, Its my own retorded fault for not telling the timber yard which way I wanted em cut, cant be bothered to try and bend em, so new ones it is. @loophole-Drivers are in the hands of some customs clearence agent, havn't hard from em yet. No luck on the Vat but got 3 yrs to claim back if I become Vat registered. Will let you know as soon as. |
Posted By: Dom
Date Posted: 23 February 2005 at 11:34am
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Just make the batten that you screw the removable panel onto so it doubles up as a batten to screw the bottom of the curved section to... ------------- "It sounded like a million fire engines chasing ten million ambulances through a war zone and it was played at a volume that made the empty chair beside me bleed." |
ashnono wrote:Posted By: moss
Date Posted: 24 March 2005 at 1:56pm
| Is there any point in crossing the direction of the grain of each layer when laminating up the pieces of ply or will the curved section be strong/stable enough with the grain running in the same direction? Im using a jig to construct the curved part first then fitting it into the cabinet. |
Posted By: mans1000
Date Posted: 24 March 2005 at 2:48pm
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[QUOTE=moss] will the curved section be strong/stable enough with the grain running in the same direction? On my scoops I slightly modified Rog's design by having the curved ply running all the way to the front of the cab,therefore leaving out the x-brace.I was suprised how tough it was (4mm Ply) even when I had only applied 2 sheets on the curve at quite a long length and I did not use curved formers.(wish I did,It would have been a lot easier!).So 4-6 sheets will be 'solid as a rock'(as Sizzla says |
)Posted By: mans1000
Date Posted: 24 March 2005 at 2:51pm
| Oh,Forgot to mention the grain was all in one direction.You will have one hell of a job trying to cross the grain on curves! |
Posted By: moss
Date Posted: 29 March 2005 at 4:47pm
| cheers man!! |