Bending Composites To Radius

ClemS

Does anyone have any amount of experience bending composites to a radius? I'm bidding a job that's all curves out of trex brazilia. The curves are very slight, about an 18' radius at the sharpest. I feel pretty confident getting the bends - the only trouble area may be butt seams.

This is what I'm thinking of doing.

Glue and pocket screw the boards together and then bend. Any thoughts on the process from people with a little more experience in this greatly appreciated.

clem

loneframer

I'm not familiar with the properties of Trex, but I bent Correct Deck around an 11' radius, but needed to rip it to 3.5" first. Still broke several boards in the process. I'd suppose a 100% vinyl product with no wood fiber content would give better results. I don't know if the radius will be obvious but these are the steps.

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BreyerConstruct

Take your time.
Keep the boards in the sun.
Consider using a heater to warm them.
Work with help.
Use ratchet straps to hold them in the shape till screwed AND COOL!!




Buy extra boards.


Realize that you most likely underbid it, if you're asking this question.
It will most likely be a learning experience... but you'll know for next time!


~Matt

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Teetorbilt

My experience with Trex is zero other than seeing the docks around here and noting that 16" centers is not enough support in the SoFL sun. Heat is definitly a factor.

I have an upcoming project that involves forming 4" SH 80 PVC pipe to contours. I plan to build a 20' oven to bring the 18' PVC up to temp for bending. I have done this before for curing thermoset epoxies for spars. It really helps if you have a turkey fryer or lead smelter (same thing here).

Build watertight box, attach heater unit and recirc pump, find the magic temp. You can do this with scraps and gloves and it gives you the most even temp.

Plan 2, Air system. Same box, needs lid, heat control uneven even with booster fan. Can be done with Ol' lady's hair dryer over time.

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ClemS

I want the job so I'm not going crazy with the numbers even though there's a lot of bending. There's 5800 sf of deck to be done so I think I'll get a system going after a day of putzing around.
Thanks!

ClemS

Because of the volume I'm leaning towards the hot air approach. I can rig 2 or 3 kerosene heater to melt this stuff in bulk as I'm installing. Thanks for the info. I'm bound to be closer that 16oc on most of the deck due to the radius.

ClemS

yes I can kind of see the curve. I think the new trex is much like the other composites so if I heat the stuff up thoroughly I shouldn't be in much worse of a shape than laying it straight. If I win the bid I'll post pics

John Hyatt

Teetor, I have some tract time bending wood ,none with manmade stuff. With wood the whole idea is to mimamize stress on the final outcome so you get less spring back and as little as possible lams coming lose or big cracks down the road.

I see pictures of fancy spancy composite projects with radical radis going on and Im just wondering how they do the first year. It should be the same as coming out of the extruder but even that has to be cooled down slowley. In fact the cool down would seem to be more important than the heat process. J.

Five Star

you can buy temp controll heating blanket pads ive read work great!! IN JLC MAG
5800 sq ft..What did they hit a LOTTERY!!???

or did they knock down the house and decided to live on a deck?

LOL GOOD LUCK Make sure you get payments on a steady basis!!

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ClemS

thanks. it's some sort of a municipal compound. the deck and a full half circle with a couple of handicap ramp to go up the levels. right now i'm still waiting to get the job, getting payments will be the next battle

SSCOTTCONST

Heatcon makes a heat forming blanket system that heats pvc composite boards to the correct temperature to bend any radius necesarry. But boards shrink while they cool so it is a good idea not to seem anything for at least a few hours.