Veneering

[kelvaden]

Hi all, bit of an unusual question. how would you go about veneering a car bumper something like the new vw beetle . this is the best way i can describe what i need to do. Sorry i cant elaborate but customer very secretive about the project
thanks

 

[Droogs]

The main problem you're going to have is the fact that you are trying to veneer a compound curve. my suggestion is:
1: Don't - it's a nightmare BUT if you really want to then try this
2: Choose a veneer with a really wild pattern - anything with linear grain won't look right
3: decide to use either what i call the wedge method or the template method
4: Wedge method - a: Veneer the single radius portion of the bumber ie the middle bit first. Trying to make sure you have a gnarly bit at the end where the second radius starts
b: cut the veneer into long slim isosceles triangles shapes and apply each piece with the pointy bits meeting at the gnarly bit
c: place each carefuly and try to match the edges along the join and don't worry so much about the gnarly bit
d: trim the edges and then scrape smooth and apply whatever finish you are using
5: Template method - a: get some thin paper
b: as "a" above
c: use the paper as a template and tape it to the edge of the already applied veneer
d: careful fold paper, making little pleated dart creases until it conformes to the shape
e: cut out the pleats and you should then be left with a template of how to trim the veneer before you try to apply it
f: once you've cut the veneer give it a damn good soak in softener and apply
6: best glue to use is hide as you can re-trace your steps if you go a bit wrong using a steam iron

Hope this helps and good luck

 

[Racers]

How about water transfer https://www.youtube.com/watch?v=pKuXyeAGzEU if they do wood effect.


Or carve it out of solid!

Pete

 

[kelvaden]

thanks droogs, should of added not actually veneering the surface more laminating up that shape plywood style, other problem is we are using western red cedar not the easiest.
pete ,solid not an option as needs strength.
will let you know how i get on.

 

[Racers]

Birch ply?

Pete

 

[Droogs]

Then i would suggest you treat it as if it were GRP.
make a mould slightly undersize of the under side and lay up each layer in strip with epoxy, rotating each layer by 30 deg until its basically what you want. then sand to final shape and size. Then use the either of the above to put final layer of veneer on.

Will take a while but you'll get there.

edit
Also just had a thought. Depending on how patient you are.

If you cut your wood into blocks say 30/35mm wide and long enough to be longer than the radius. Before you you re-saw into .5mm thick strips, you could drill 1 or 1.5mm holes every 5mm. This would have the effect of making the veneers once given a good soak in softener act a bit more like GRP matting, the build up of each layer a bit easier to get round the 2 radii. Then just sand to final shape/smoothness and apply the final layer of the veneer.
probably not practical from a commercial point of view but interesting to try

 

[kelvaden]

droogs thats sounds like the way i need to go, there is talk of the final surface being vinyl wrap but this is not confirmed. would think that would stick beter than to bare cedar.

pete , i have mentioned birch in the past but customer insisting on all cedar.
thanks great help guys

 

[worn thumbs]

Maybe you should have a talk with the people who build wooden rowing shells.They have to persuade veneer to take curves and might be able to help.

 

[James-1986]

I'm guessing the customer will want the grain running horizontal and the bumper to wrap around the sides of the car? Cedar bends well with steam or heat, you could plane up some staves, bend the ends so they 'wrap round' then glue it up to whatever width. Then you can easily work it to shape with hand tools. If you want the job to be thin then you can always glue a tough fabric to the back of the timber to give it more strength, this is what was done with curved and wreathed stringers made of up staves.

I don't think I will ever try compound veneering!

 

[kelvaden]

Thanks for your replies, when i get two mins will post a pic of first attempt. turned out quite good.

 

[dickm]

Probably larger radius curves, but the guys (and ladies, presumably) who built the DH Mosquito did some fantastic 3d shapes with veneer.

 

[Droogs]

Probably larger radius curves, but the guys (and ladies, presumably) who built the DH Mosquito did some fantastic 3d shapes with veneer.

The fuselage of the mosquito, although the the eye looks like a compund shape is infact a mash up of many paneled pieces of ply which were relief cut to a template and then bent in one plane only and form a truncated cone. Once in position on a former jig they were then glued. the fuselage was then covered in doped fabric after being sanded smooth. the nose cone being made up of wedged pieces

You can see one being made here:
https://www.youtube.com/watch?v=ZdSOmA7DHdM