How much heat to bend Royalex

Advice
#1

Near as I have been able to figure out, the melting point of royalex is somewhere around 220 degrees F.



How hot do you figure royalex needs to be to be pushed into a new shape?



I got the Chipewan hull up to about 130 last night, which is not enough to do anything. I’m guessing a canoe sitting on a hot car in the summer gets that hot.



~~Chip Walsh, Gambrills, MD

#2

Melting point 220?

– Last Updated: Feb-16-07 11:51 AM EST –

I think the melting point is much higher.

Edit: OK I looked it up here:

http://www.plasticsusa.com/abs1.html

You are right. If it is similar to most other ABS plastic it is only 221 Degrees F.

My limited experience is that you can set you canoe out in the sun for a few days in the summer and it will pop back into shape.

#3

It doesn’t take much heat to bend.
One of my canoes has a scar on it from where I left a “trouble light” laying in the boat for just a few minutes. The 100-watt bulb was about 2 inches from the hull, and in those few minutes, a spot about 2 inches in diameter sagged down under its own weight. I propped it back up and let it cool, but the scar is still there.

#4

Ya, but oil can is the shape
At the age of this boat, I suspect the oil can has been there most of its life. I heard heat will make it return, but after oil canning 15 years, the material’s memory is of an oil canned shape.



I just wonder if royalex is one of those materials that doesn’t change gradually. Seems like I remember a spec that it was good to 220, and that the melthing point was 221.



Did that light bulb make it sag or drip?



~~Chip

#5

Reverse oil canning
I wonder if you could support the boat from the ends and pour really hot water into it. the weight of the water and the heat might reverse the oil can.



The spec I saw said that it is useful from -40 to 194 so I think you have to get it pretty hot to change the plastic memory.



Come on over and I put some water in the double turkey fryer.



Oh and um… bring beer. We;ll either be celebrating or crying.

#6

Considering rocks

– Last Updated: Feb-17-07 11:17 AM EST –

or bricks.

A small amount could be heated in the kitchen oven, or I might try to heat up a big can of gravel.

I think I could put gravel into one of those big metal cans that pop corn or chips come in, almost 5-gal sized. Heat it up in a kiln I have for pottery. Spread it on the bottom of the boat as you suggest with water. Lay a blanket of r-11 fiberglass over it, and see what happens.

If I have patience, I could start with lower temps and then if I don't get a result, add 10 degrees the next time I try it. I think it would be a one or two day cycle to heat and apply the rocks. But I am considering an approach similar to what you suggest.

But, that will need to wait until the boat has gunwales on it, which won't be for at least a few days, assuming I make good progress and can get my hands on a hundred or so ss screws of the proper length. I bought 1.25 inch screws. But the old royalex is thick, maybe 3/8", and 1.25 isn't going to be long enough. So, one challenge at a time.

~~Chip