Steam bending walnut. Do I steam sawn or can I steam PAR?

[flanajb]

I have been making my lamp armatures for the lamps shown below using 1.5mm ply and paper backed veneer.

It is quite a time consuming process and I am now thinking of steam bending solid walnut instead. What I want to understand is whether I would bend the walnut in the sawn state and then finish when curved or whether I could par the walnut to finished dimensions then steam so that any post bending finishing is kept to a minimal?

 

[custard]

You're a talented man Flanajb. There's a great deal to admire in your lamp, not least the way you've sweated over even the tiniest detail, it's very Apple and very 2016!

Personally I'm sceptical that steam bending will be better than laminating. I've done a fair bit of both and I suspect you'll encounter three issues.

Firstly, springback is more random and more pronounced with steam bending than with lamination. If you laminate then the spring back will be relatively consistent at say +/- 5%, with steam bending that can jump to +/- 20%. If you want your lamps to be displayed in pairs then that's too much variation.

Secondly, even though steaming doesn't bring the glue squeeze out issue of laminating it does bring it's own finishing problems. With high tannin woods like walnut you'll frequently encounter staining and there'll always be a lot of scraping and sanding to make the component smooth.

Thirdly, you'll always lose a lot more components in steaming than in laminating, and the drier the wood the worse the problem.

However, to answer your question, if steam bending I'd definitely finish pre steaming as removing machine marks cleanly on that inside curve would be a bit of a mare.

By the way, I'm just over the county border from you in south west Hampshire, I don't know your workshop set up but I've got a decent vac bag system plus a drum sander so if you wanted to try vac pressing solid walnut lamina as a solution you'd be welcome to drop by and give it a go.

 

[marcros]

laminating solid walnut may reduce the finishing that ply and veneer would require.

sadly I cant see your images at work due to a block on imaging sites and therefore links to the same.

 

[flanajb]

You're a talented man Flanajb. There's a great deal to admire in your lamp, not least the way you've sweated over even the tiniest detail, it's very Apple and very 2016!

Personally I'm sceptical that steam bending will be better than laminating. I've done a fair bit of both and I suspect you'll encounter three issues.

Firstly, springback is more random and more pronounced with steam bending than with lamination. If you laminate then the spring back will be relatively consistent at say +/- 5%, with steam bending that can jump to +/- 20%. If you want your lamps to be displayed in pairs then that's too much variation.

Secondly, even though steaming doesn't bring the glue squeeze out issue of laminating it does bring it's own finishing problems. With high tannin woods like walnut you'll frequently encounter staining and there'll always be a lot of scraping and sanding to make the component smooth.

Thirdly, you'll always lose a lot more components in steaming than in laminating, and the drier the wood the worse the problem.

However, to answer your question, if steam bending I'd definitely finish pre steaming as removing machine marks cleanly on that inside curve would be a bit of a mare.

By the way, I'm just over the county border from you in south west Hampshire, I don't know your workshop set up but I've got a decent vac bag system plus a drum sander so if you wanted to try vac pressing solid walnut lamina as a solution you'd be welcome to drop by and give it a go.

Many thanks Custard. I just need to get on and start trying to sell the lamps now.

As to the merits of steam bending and laminating, your feedback has put my mind to rest as to which way to go. The spring back with steam bending has far too much variation and I cannot run that risk, so laminating is the way.

I have my own vac bag setup which is what I have been using to date with the paper backed veneer and 1.5mm ply.

Regarding veneering solid walnut lamina, what thickness do you reckon I could use for the bend radius I need to achieve?

ps - If you fancy a look, my web site went live yesterday www.theconcretelab.co.uk

Thanks

Justin

 

[Sgian Dubh]

I'm with others - I wouldn't go down the steam bending route for the same reasons already given.

I'm guessing the bends are somewhere in the region of 100 - 150 mm radius, so you could probably get away with a dry bend in walnut veneers of 2 - 3 mm thick - a test bend or two will soon prove it one way or another. Walnut is one of the 'classic' woods for steam bending, and if you find this is too tight for a dry bend, in whatever thickness you decide to use, you could steam and pre-bend your laminates, let them dry, then do a dry glue up in your former. This way, you would be able to get away with thicker laminates at, say, three pieces 4 mm thick to get what looks like about 12 mm thick armatures.

You'd probably have to make your own laminates at this (4 mm) thickness, which might be wasteful of time and material. Better I suspect to buy 2 mm thick constructional veneers from a veneer merchant and accept a few extra glue lines. You'd also be able to join sequential leaves of veneer which, if done well, would almost disguise the fact the curve is laminated. You could, too, make a former that's wide enough to bend three or four at one time, and split this into narrower sections after bending.

Glue choice for me would probably be epoxy resin with a slow acting catalyst, and some colloidal filler, although you could use urea formaldehyde type glue too, and others. I'd avoid creepy PVA.

I've done quite a few wood bending jobs over the years, both steam and laminate bends, and I guess I've picked up a few tricks! I suspect you don't need too much guidance on technique, but just in case it's useful, here's a link to a lamination job I did fairly recently. Slainte.

 

[lurker]

Love the stuff on your site, hope products take off and sell well



One thing............. The word is grey unless you think your main market is across the pond.

 

[flanajb]

I'm with others - I wouldn't go down the steam bending route for the same reasons already given.

I'm guessing the bends are somewhere in the region of 100 - 150 mm radius, so you could probably get away with a dry bend in walnut veneers of 2 - 3 mm thick - a test bend or two will soon prove it one way or another. Walnut is one of the 'classic' woods for steam bending, and if you find this is too tight for a dry bend, in whatever thickness you decide to use, you could steam and pre-bend your laminates, let them dry, then do a dry glue up in your former. This way, you would be able to get away with thicker laminates at, say, three pieces 4 mm thick to get what looks like about 12 mm thick armatures.

You'd probably have to make your own laminates at this (4 mm) thickness, which might be wasteful of time and material. Better I suspect to buy 2 mm thick constructional veneers from a veneer merchant and accept a few extra glue lines. You'd also be able to join sequential leaves of veneer which, if done well, would almost disguise the fact the curve is laminated. You could, too, make a former that's wide enough to bend three or four at one time, and split this into narrower sections after bending.

Glue choice for me would probably be epoxy resin with a slow acting catalyst, and some colloidal filler, although you could use urea formaldehyde type glue too, and others. I'd avoid creepy PVA.

I've done quite a few wood bending jobs over the years, both steam and laminate bends, and I guess I've picked up a few tricks! I suspect you don't need too much guidance on technique, but just in case it's useful, here's a link to a lamination job I did not fairly recently. Slainte.

Many thanks. I tend to use cascamite, but also have epoxy to hand and have used it before. Will give the 2mm constructional veneers a try.

 

[flanajb]

Love the stuff on your site, hope products take off and sell well



One thing............. The word is grey unless you think your main market is across the pond.

Thanks. When typing gray I was thinking should it be grey.

 

[marcros]

nice website, products and photography. well done indeed, i can see these selling very well.

 

[Wizard9999]

Love those lamps, good luck with the website!

Terry.