Kitebuilder.com

[stevef]

Documentation of the Heat Specifications of Kite Studio's Plastic Stock

MAXIMUM RECOMENDED SERVICE TEMPERATURE (INTERMITENT USE)
ABS = 220 Degrees F
UHMW = N/A

MAXIMUM RECOMENDED SERVICE TEMPERATURE (CONTINUOUS USE)
ABS = 180 Degrees F
UHMW = 163 Degrees F


COEFFICIENT OF LINEAR THERMAL EXPANSION:
ABS = 5.7 X 105
UHMW = N/A
_________________
Steve Ferrel
Measure once, buy twice!

[Dorsal]

[knotronda]

In other words, it doesn't expand like the little capsule Sea Monkeys when tossed in water, or grow with heat like bread does in an oven??


How technical do we have to be when making parts? You build them, we use them. We break them, you sell us more. A system that works doesn't need fixing.

KR

[Dorsal]

[Spence602]

[Dorsal]

Actually, it's usually written CTE, whenever I read it in technical papers, or reports generated by our Materials and Processes Engineers.

Oh, for those of you who may ask, CTE is a means of expressing just how much expansion or contraction can be expected from any material as the temperature changes. A fitting with a high CTE might expand enough, on a hot day, to come loose from the rod it is hanging on to. Or if it were internal to a tube, might expand enough to burst the end of the tube. Carbon tubes are generally too strong to actually burst, but it can make an internal ferrule might tough to remove.
As an aside, the Carbon fibers in rods and tubes actually have a negative CTE , meaning they actually shrink as they get hotter. The epoxy holding the fibers together has a positive CTE , and they balance out. The number I usually associate with Carbon/epoxy laminates is .09 to .12 X 10-6 in/in/°F. Aluminum is 12.9 X 10-6 in/in/°F.

[Doug LaRock]

Very good info Dorsal. Running a machine shop I often run into engineers who seem to forget about CTE. I once got a drawing where the designer wanted holes 30 ft apart held with in .005. We had to have a little discussion about CTE, and what did he really want and how much money did he want to spend. Even in a steel part the distance would change .022 for every 10 deg. change

Doug

[Dorsal]

Yeah Doug - I've got some engineers who can't understand why I want them to fix a blueprint that calls for an aluminum ring, 15 feet ID, 16 feet OD and 8 inches tall to be machined from a forging to within .005 flatness and parallelism. 95% of the forging is to be machined away.

[Progcraft]

main (int argc, char **argv)
{
if(Whatchotalkingboutwillis == true)
{
print("HUH???")
}
else if(Whatsthisgottodowithkites == false)
{
print("HUH????")
}
else
{
print("You guys lost me at hello ")
}
return 0
}


P
_________________
There is no box.

[300M]

Cte ==> Thermal expansion or how much the material will shrink or grow depending on temperature. A good example of this is water. When frozen, water expands to occupy move volume. What Doug and Dorsal are talking about are Engineers requesting to much tolerance and not alowing for expansion or contraction of the material. Remember the water to ice.
What does this have to do with kites.... Say you design a kite using 2 rods that slide through another. The rods are designed to slide across each another. You could drill the hole that fit at room temp, but you go fly the kite today in the cold and the material contracts and a pinch fit. Now the jig that you build to contorl the kite jams and you have a problem.

Casting vs forging is a long topic that would bore you Forging is way stronger, but maching away 95% and then looking for flat is dumb!

John an ME that was a tech first.
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John M