Laminating for beginners

[nev]

Evening gents

Is it feasible to use a few sheets of wood veneer to create a small rigid (ish) shape?

Making another scooter but slightly larger this time and wondering if I can create the leg shields by laminating?

The bends are only in one plane and size is approx 50mm X 360mm (2off) and anywhere between 4 and 6mm thick.

TIA

 

[Phil Pascoe]

You are making plywood. Why not?

 

[Chrispy]

If you go with veneer you would need 9 or ten layers which will give you a problem using a water based glue it just won't dry because of all the water.

 

[dickm]

Depending what timber you are using, MIGHT be feasible to steam bend? Just done some 6mm thick edging for some shelves in beech and was pleasantly surprised how tight a curve was possible after about 20 minutes steaming.

 

[Sgian Dubh]

Evening gents
Is it feasible to use a few sheets of wood veneer to create a small rigid (ish) shape?

Yes, although you will probably struggle to achieve the two relatively sharply angled bends (particularly the one in front of the knees) because the veneers will naturally want to form themselves into a sweeping curve: trying to achieve too sharp a bend is likely to lead to tension failure (ripping) particularly on the outside of each lamination in the curved part.

Chrispy is incorrect to say a water based adhesive won't cure if used for a job like this. He is partially correct if he's referring to using aliphatic resin or PVA adhesives, and where the layers aren't pressed together firmly meaning that each layer of veneer isn't intimately touching the adjoining piece(s) of veneer. Voids filled with these adhesives appear much the same as the rubbery dried dribbles of the stuff you often find on the outside of the glue bottle - neither PVA nor aliphatic resins are gap filling strength conferring adhesives. They're also creepers and often not ideal for laminating because the bend tends to want to straighten out, especially tight bends.

On the other hand, hide glue will fully cure in gappy joints and does offer some (relatively good) gap filling structural strength. Urea formaldehyde adhesives, e.g., Cascamite, another adhesive incorporating water provides significant gap filling ability as well as structural integrity. Urea formaldehyde adhesives are a common choice for laminations because of this gap filling characteristic, and their non-creepy nature. And, there are other possible adhesives, e.g., epoxy resin, but for something as small as you're doing I suggest you go for the urea formaldehyde option, at least to start with.

Ensuring your laminations are pressed firmly together is likely to incorporate an accurately made male/female former, although other techniques would work, e.g., a vacuum bag or press (overkill probably), or possibly some sort of strap (metal or strong fabric, even possibly strong elastic) to pull the layers down firmly over a male only former. Slainte.

 

[worn thumbs]

Easy job actually.Use the thickest laminates that you can get to conform to your sharpest radius.Before spreading any glue have a dry run to be sure you have enough cramps and you may find it prudent to cover the laminating former with parcel tape to be sure of releasing the cured assembly.I wouldn't recommend steaming as the risk of breakage and the general increase on work for constructing a steambox really isn't justified.If you use a water based glue the prophecy about the laminate staying wet may come true.When I had to do a job that needed 33 laminates of furniture veneer 30 minute polyurethane glue worked brilliantly,but it did require a shaped outer form in addition to the inner former in order to prevent the foaming distorting the thickness of the laminate.for half a dozen laminates I would expect PVA left overnight to be satisfactory.

 

[Rob Platt]

saw cuts across the bend lets say 90% of the thickness number and spacing trial and error and then glue the shape.

all the best
rob

 

[nev]

so...
If I smooth the curves a little similar to the below diagram, and use Cascamite or similar, clamp in a block? as per diagram?

Had a quick gander for veneers and they seem to be approx 0.6mm or construction veneer at 1mm.
Will a 1mm veneer in something plain like oak, ash, walnut, cherry or even sapele etc bend to this degree?

 

[worn thumbs]

Without an idea of scale its not easy to tell.If you use a minimum bend radius of 50 times laminate thickness it should be ok.Tighter than that may need special preparations.

 

[nev]

Without an idea of scale its not easy to tell.If you use a minimum bend radius of 50 times laminate thickness it should be ok.Tighter than that may need special preparations.

Ta.
The diagram above is approx to scale.

 

[Sgian Dubh]

so...
If I smooth the curves a little similar to the below diagram, and use Cascamite or similar, clamp in a block? as per diagram?
Had a quick gander for veneers and they seem to be approx 0.6mm or construction veneer at 1mm.
Will a 1mm veneer in something plain like oak, ash, walnut, cherry or even sapele etc bend to this degree?

Clamping in a male/female former as you've drawn with curves using Cascamite will work, although the visible variation in the space between the formers should be attended to. You'll need to make sure you can achieve even clamping pressure all around the curve area and the flat part.

0.6 mm veneer would be easier to bend than thicker material, and some experimenting will tell you how tight a bend you can achieve without fracturing using different thicknesses of material. You could make the veneer more supple if needed by soaking in hot water and then fixing whilst still hot and wet in your former, then leave in clamp until dry enough to glue - perhaps 24 hours or so. As to species, just try to avoid very brittle material. Beech, walnut, ash and oak for example are rather good for bending, but wenge can be a bit of a bear. Slainte.

 

[ComfortablyNumb]

Make yourself up some formers and get a vacuum bag press for best results

 

[profchris]

A 1mm veneer would bend to fit your drawing if heated - I'd use a heat gun. I can bend close to that in 1.8mm solid wood using a hot pipe. For 1mm construction veneer, warm the wood to hand hot, and as it relaxes, ease it to the curve.

Oak has (so far) bent for me ridiculously easily. Walnut has a good reputation for heat bending. Softwoods can be very tricky (except yew). Mahogany of all kinds (including African substitutes) is usually OK, but some boards are just ornery.

All this assumes the grain direction runs the length of the piece. If you're happy with grain running across, 1mm veneer should bend without even heating for most species. The resulting laminate wouldn't have so much structural strength, but this looks like a decorative piece so that might be no problem.

 

[dickm]

I wouldn't recommend steaming as the risk of breakage and the general increase on work for constructing a steambox really isn't justified..

Agree with risk of breakage, though a well fitting former should help, but not much increase in work to make a couple of plugs to go in the end of a bit of ventilation tubing connected to a wallpaper steamer!

 

[Inoffthered]

I have just made a bracelet using various layers of veneer and started by soaking the veneer in water for a day, after which it was extremely bendy, I was surprised at how tight the curves without any hint of splitting.
With regards to your Lambo leg guards, (I'm no expert but...) I'd suggest cut your veneers to length, soak and dry fit between your formers to take the shape (ish) while it dries. Then put cling film or packing tape on the former and then use super glue to join each layer of veneer.

 

[nev]

Thanks for all the advice gents.

I had a quick experiment yesterday with what I have to hand, cut a few slices off a block of oak and clamped them between two thin formers with a film of titebond original between each leaf. It worked! to a degree anyway. Spot on where the clamps were, a little flared at the edges, but the resulting piece was very rigid and will do the required job.

Experiment 2 is in progress at the mo.
Cut some more leaves but these were a little thicker, about 1mm, so soaked them in hot water for 5 mins (not long enough but they didn't fracture) and cut a lump of 8x2 for the former. Clamped up minus the glue to see if they take the shape before gluing.
Haven't been out to the shed to see the results yet.

Thanks again.

 

[worn thumbs]

I'm glad it worked quite well.If you are open to suggestions,I would cut the lower right hand corner off your jig and glue it to the inside corner so that its easier to apply pressure square to the glue line.I have often read of the "glue starved joint" but have never regretted fitting all the cramps that can be fitted to ensure good and small glue lines.