Sharp radius bends in plywood

[TobyT]

How do they do it?
A design website was touting a office carry-tote for your laptop and office stuff for hot desking. As someone who is being encouraged to return to such an environment on a more regular basis it tickled my fancy, until I saw the £175 price tag. Gustav Original
I will be sticking with my laptop bag.

I did wonder about the construction though, particularly the small radius corners on the bottom of the main frame. The construction is listed as American oak veneer, plywood & aluminium. Having played around with bending plywood for a roman shield these corners look to small to just be 6mm-ish ply bent on a former. Have they used multiple layers of thin ply, or is it in fact some special kerfed stuff with just a veneer all over? Zooming in on the picture suggests it is a single piece of ply, but I assume that is design trickery.

 

[Jones]

It's made that shape from veneers pressed in a form similar to many ply chairs in the 60's and 70's. You'll need a vacuum bag to do it at home.

 

[TobyT]

Thanks.

I did vaguely think about making one, but I have a very long tuit list and I even if I did build one I probably would just get annoyed with it.

Having looked at the price of veneer presses I won't be buying one in a hurry either.

 

[TRITON]

Bagpress do one without the vacuum pump. You use a standard compressor to achieve the vacuum.
Priced at £235
https://www.bagpress.com/Venturi_Presses.html
A small compressor is going to be about 7cfm
Small compressor is probably about 150 quid.

All in all it adds up to not far off the cost of a basic bagpress which includes the basic pump, as well as bag etc etc, which is £450(I have this one)
https://www.axminstertools.com/bagpress-minipress-mk2-vacuum-press-951656
However if you dont have a compressor - You should have bloody got one by now

If you dont have one you build a former two piece. an inner and an outer. The inner is the shape you want, which the veneers are going to be bent around, the outer is the size of the finished shape, calculated by how thick your finished ply with be.
So basically draw the shape, then (eg 8-12mm thickness of finished ply) you draw a second shape, so that the veneers are sandwiched in the middle. This applies enough pressure with clamps to squeeze the shape you want between them.
If you dont understand, and lets be honest, I'm pants at descriptions, then look for laminating former's on You Tube and you'll get the concept from there
Some examples -
This bloke is taking things to extreme though. You really dont need to add bolts, and glue on extra strengthening panels on the sides. Glued up its going to be pretty strong and the forces are pulling/pushing it together, not sideways. Totally overkill in my humble opinion.
I think he's just mad



But you get the idea. The shape built up from pieces of mdf, as accurate as you can, perfection is nice but im sure it will be ok if theres a bit of discrepancy.

Even a child can do it.


This one is showing a better curve, more the type of thing you want. Obviously a lot deeper than this, more like the other vid but its the same, just more layers

You should find other vids from these two that are more similar to what you want.

 

[Cooper]

If it just the shape you want rather than the ply look at the front edge you can make a very cheap bend like that from softening and bending hardboard.
As they said it is very much a 60s and 70s design, when I was in Art school. I wanted to make a box with that sort of shape and managed to achieve a 25mm radius on a single skin of hardboard. My design was about making it as cheap as possible, so I only had one layer of the hardboard. It was pinned to a ply back so it held its shape. (Birch ply was much cheaper in those days). I think that I soaked the hard board first and bent it around a chip board former and left it to dry, I may have had a strap around the outside, so the curve was about compressing the inside of the bend and not stretching the shiny outside, as that tended to crack if it wasn't supported, though my memory is hazy.

You would need to experiment on scrap before making your finished piece but I think a U shape, as on the website image, is entirely doable.

When I was teaching, students made similar shaped boxes by heating and bending perspex around a former, with a hot air gun. They even made them bending that foam board, sign writers use, as we were given piles of scrap.
Good lick
Martin

 

[KiwiChris]

It's made that shape from veneers pressed in a form similar to many ply chairs in the 60's and 70's. You'll need a vacuum bag to do it at home.

 

[Richard_C]

Bending sounds complicated for a one off job. You could redesign a little, make the "chassis" a conventional box with right angle corners and sit the long sides on it rather than in it, so you simply cut the curves on the bottom corners.

Were I doing it my worry would be over-building, easy to make it too heavy to be nice to use.