Vacuum curve forming

[flanajb]

Hi,

If I am going to form a curve using bendy ply or thin birch ply, do I need to add a layer between each of the ply sheets which has the grain going 90 degrees to the ply or is this not required ?

eg, do I buy sheets that bend in the 8' length plain as well as in the 4' plane and then alternate the layers

Thanks

 

[jasonB]

No you don't need to alternate the grain. Once you have 2 or 3 bendys stuck together they will be quite rigid so you only need to buy a long grain or short grain sheet. If you did alternate the bendy you would find one would not bend easily.Same with the skinply just keep the face grain the same way.

Jason

 

[flanajb]

No you don't need to alternate the grain. Once you have 2 or 3 bendys stuck together they will be quite rigid so you only need to buy a long grain or short grain sheet. If you did alternate the bendy you would find one would not bend easily.Same with the skinply just keep the face grain the same way.

Jason

Thanks Jason, really appreciate your help.

If you can get away with 4mm Birch ply would you use that over bendy or are there other factors that I need to consider when choosing to use either birch ply or bendy ply ?

 

[jasonB]

I prefer birch, its that bit more solid.

J

 

[flanajb]

Hi, this what I am planning to make as my first piece.

What I am trying to to deduce is whether you would make the rounded rectangular carcass in one or multiple parts and if you do it in multiple parts how do you then join them?

Thanks

 

[jasonB]

What sort of sizes are they? And is this teh bed or the front of a draw unit?

 

[flanajb]

What sort of sizes are they? And is this teh bed or the front of a draw unit?

That is a drawer unit, and I thinking dimension wise of 900mm*1500*600mm

Given the dimensions I suspect that it is too big too attempt in one hit.

 

[JonnyD]

I think you will need to use 1.5mm thick ply to get around the corners easily then you will have to do it in probably 4 sections with a split half way across the top/bottom and either side because the sheets are only 1525mm square i think. The other option would be to make the 4 corners separately and then join into flat board sections to make up the carcase.

I would also consider making it as an mdf box and then veneering it in a vacuum bag. You can do the corners with a router using the biggest cutter here it will give a 70mm diameter corner http://www.wealdentool.com/acatalog/Onl ... lo_187.htm

cheers Jon

 

[flanajb]

I think you will need to use 1.5mm thick ply to get around the corners easily then you will have to do it in probably 4 sections with a split half way across the top/bottom and either side because the sheets are only 1525mm square i think. The other option would be to make the 4 corners separately and then join into flat board sections to make up the carcase.

I would also consider making it as an mdf box and then veneering it in a vacuum bag. You can do the corners with a router using the biggest cutter here it will give a 70mm diameter corner http://www.wealdentool.com/acatalog/Onl ... lo_187.htm

cheers Jon

I think making the 4 corners separetely will be the easiest route. My only concern is how do you get a strong joint when attaching the corners. Do I biscuit joint or use a tongue joint ?

 

[jasonB]

I agree with Jonny do the 4 corners as separate parts that way you won't get problems with springback.

I'd cut a groove full length and use a ply spline, you can do it with a slotting cutter or run the biscuit jointer along the length.

J

 

[flanajb]

I agree with Jonny do the 4 corners as separate parts that way you won't get problems with springback.

I'd cut a groove full length and use a ply spline, you can do it with a slotting cutter or run the biscuit jointer along the length.

J

Ok makes sense. Just need to make sure that I dont make it so big that it won't fit in the vacuum bag once assembled, otherwise, I won't be able to apply the top veneer.