Vehicle clamping (we'll sort of !)

[RonA]

Hi to all,
Bit of a misleading title but I am looking for a clamping solution or ideas.
Problem revolves around the coach work I'm replacing on my post vintage sports car, specifically the rear wheel arches. The body is classic aluminium skin over ash framework.
I have fabricated new wooden wheel arches (see photo) which are in three pieces & they are joined together by finger joints (see photo). These will be glued together with prefere 4050 (previously known as Aerodux & allegedly used to glue WW2 mosquito airfcraft together) which is a two part adhesive with high strength combined with good water resistance/gap filling qualities. The joint will be then cross drilled & dowelled.
However I would like to pull the joints together as firmly as possible while the glue sets & therein lies the problem, how to pull the curved sections together, whilst maintaining the curve.
So far I have thought of putting screws either side of the joint & tightening binding wire round them while holding then on the old arch frames to keep the curve right.
Anybody any better ideas?
RonA

 

[WorkshopChris]

What about a MDF or Ply base with a few pegs in to locate then a ratchet strap to tension.
Have used the technique in the past to clamp curved sections.

 

[RonA]

What about a MDF or Ply base with a few pegs in to locate then a ratchet strap to tension.
Have used the technique in the past to clamp curved sections.

Hi Chris,
I like your solution. I have a ratchet strap & can soon lay my hand on some MDF sheet to hold it down. May give it a whirl unless somebody comes up with anything better.
RonA

 

[clift_d]

I'd probably get a piece of 18mm plywood and fix some blocks to it exactly following the outside curve of the finished arch as a kind of formwork. Then I'd add a couple of stop ends firmly fixed about 20mm away from the ends of the overall arch sections and use pairs of opposing wedges at each end to push the arch into the formwork and force the joints together, a bit like this:

 

[RonA]

I knew it would be good idea to put it on the forum. Two great ideas already.
RonA

 

[gaz1]

heres the proper way 6" oak bending

 

[wristpin]

A bit off topic but back in the late 50s I used to do a bit of boat building and the glue of the moment was Aerolite 306 made by CIBA and was said to have been used in WW2 aircraft construction. As CIBA were (are?) based near Duxford is Aerodux a development of the original Aerolite product?
Incidentally, Araldite was another CIBA product but is now, I believe, licenced to another manufacturer.

 

[CompoSimmonite]

These will be glued together with prefere 4050 (previously known as Aerodux & allegedly used to glue WW2 mosquito airfcraft together) which is a two part adhesive with high strength combined with good water resistance/gap filling qualities.

Late father-in-law was aircraft mechanic during WWII and for a while with a Mosquito squadron in Middle East. He loved the aircraft but said they suffered from delamination in the humidity. All they could do was strip the affected aircraft of anything useful and then tow them to one side where they were quickly swallowed by the sand. He reckoned they'd still be there today !

 

[colnerov]

Hi, I was going to suggest similar to WorkshopChris, the same way a brick arch is done with a former inside and the ratchet strap round the outside. Have a few sheets of newspaper between the former and the frame to so you don't glue them together. It will also do for the other side.

Colin

 

[RonA]

A bit off topic but back in the late 50s I used to do a bit of boat building and the glue of the moment was Aerolite 306 made by CIBA and was said to have been used in WW2 aircraft construction. As CIBA were (are?) based near Duxford is Aerodux a development of the original Aerolite product?
Incidentally, Araldite was another CIBA product but is now, I believe, licenced to another manufacturer.

Apparently Aerodux changed to Preferé 4050 when they stopped making it in the U.K. & production moved to France. As with most stuff in France it's also bloody expensive.
RonA

 

[RonA]

Hi, I was going to suggest similar to WorkshopChris, the same way a brick arch is done with a former inside and the ratchet strap round the outside. Have a few sheets of newspaper between the former and the frame to so you don't glue them together. It will also do for the other side.

Colin

Thanks for the suggestion but have already discovered it doesn't stick to polythene sheet, so will be putting that under the joints when I glue them.
RonA

 

[arther dailey]

put a bit of 4x2 on the open section to fill the gap, then ratchet strap or twist strig around till dry.

 

[mike os]

For adhesive take s look at using epoxy, it has largely replaced resorcinol for general work

 

[Parm]

If your using specialist gap filling adhesive, don't over do the clamping. You don't want to squeeze out all the adhesive and have the wood under any spring tension once clamping is relased.

Sometimes less is more, particularly if using modern adhesives and dowelling too

 

[Mee]

You could use steam bending then you can bend tighter radii or use larger sections to form the same radii. Simple gas bottle burner, top tank with outlet, and a sealed box to hold the timber and covered with old blankets to insulate it, then follow Chris's suggestion and it retains its shape.

Thicker sections mean less expensive glue.

 

[RonA]

For adhesive take s look at using epoxy, it has largely replaced resorcinol for general work

Apparently the buffs on coach work still go with resourcinol based glues, the reasoning being that as well as being strong, water resistant & gap filling it also has a bit of give in it. I had intended to use Cascamite when I set off on this project, also extremely strong, water resistant but inflexible.
RonA

 

[RonA]

You could use steam bending then you can bend tighter radii or use larger sections to form the same radii. Simple gas bottle burner, top tank with outlet, and a sealed box to hold the timber and covered with old blankets to insulate it, then follow Chris's suggestion and it retains its shape.

Thicker sections mean less expensive glue.

I had considered steaming or lamination as a way of making the wheel arches but timber availability in the required lengths in Ash put paid to that idea.
RonA

 

[clift_d]

For adhesive take s look at using epoxy, it has largely replaced resorcinol for general work

If you can get your clamping right and have really tight joints then I would suggest going for resorcinol (RF) adhesive. If you can't get a good clamp setup or your joinery is a bit sloppy then epoxy will be easier, but you need to be aware that epoxy joints can be sensitive to UV, moisture and heat, and so are more likely to fail in the long term if they aren't looked after or protected. For example if you heat stripped your arches at a future date to refinish then that might effect an epoxy joint but would have no effect on a resorcinol joint.

http://www.classicboat.co.uk/practical-advice/adhesives-for-wooden-boats-structural-glues/

 

[normspanners]

could you form a 'D' shape in flat steel 30x3 on edge to match the radii require then at the corners of the D in line with wooden arch have two 8mm bolts that screw in and push on the very ends of the wood pressing it not only together but into the shape required you could use some sacrificial blocks to save marking the arch at the end, it would be easy to bend to match the shape, weld the two ends of the steel that would form the straight part of the 'D', drill two holes weld 8mm nuts for the bolts and not take long to produce.

ps sorry bout the drawing just did it quick

 

[Mee]

I had considered steaming or lamination as a way of making the wheel arches but timber availability in the required lengths in Ash put paid to that idea.
RonA

What lengths are you bending, or looking to bend? friend works on boat restoration and he had a long steam chamber on his bending equipment as I made it in sections for him, over 30' with all the sections on.