RIB - Impluse heat sealer for thermal urethane

[kach22i]

I need to source an Impluse heat sealer for thermal urethane.

For use on RIB or hovercraft skirt................please help; us "full of air" guys have to stick together, right?

I have some samples of heat sealable fabric for making waterproof bags (nylon base 420 denier with a nice thick urethane coating one side 0.30mm). They said you can just iron it with a household iron, but that leaves something to be desired. Problem is both sides should be heat activated at the same time and pressure kept on after the heat is removed and until it cools. An iron can't do that, and an iron has a hard time doing straight lines (mine are two feet long). By the time I get it to seal well, it starts to bubble and ruins the finish. If I go over it several times it ends up stiffing the fabric (bad for my application).

My first product choice would be the T-Clamp a $3,000 Vertrod Style by Therm-O-Seal, but I can't afford it.
http://www.therm-o-seal.com/equipment.handsealers.html

My last choice is $40 from Harbor Freight, might be better off with the iron.
http://www.harborfreight.com/cpi/cta...emnumber=43477

The local rental place has nothing to rent me, the local tent and awning place only sews things and is expensive.

Any suggestions besides Craig's List and E-bay?

[Pericles]

This may sound like something from a mad scientist, but I visualise this to solve your need. Take a suitable length of smoothed 2" X 4" and support it horizontally. Stick some aluminium foil to the wood to reflect the heat. Align the two edges of the material you wish to join along the timber and pin or staple them down. You said pressure must continue after the iron has fused the two edges together. How about using a heavy saucepan filled with ice and salt and sliding it along behind the iron? Two pairs of hands will be required, but I think it might work.

I would also consider hand stitching the completed seams with mono fish line with sailmaker stitches as well.

Good luck,

Pericles

[TerryKing]

The Harbor Freight heat sealer is typical of many of that configuration. They are available from "Packaging" suppliers.

These work by putting pressure on the two layers of (plastic, fabric, etc.) you want to heat seal, and quickly heating and cooling a small area.

They have an insulating material strip on the bottom which has a little resilience, often a foam backing. Good ones have some high-temp red rubber.

On the top hinged bar there is a exposed strip of resistance wire, typically flat nichrome like in a toaster, so the sealed area is a narrow strip. That heating element is backed by a hard heat-resistant strip of insulating material that holds it against the fabric etc.

A variation has heating elements on both top and bottom, for heavy materials.

The two bars are pressed tight against the fabric/plastic and the heating element is activated for a short time (A "Pulse").

The timing of the pulse is done by a variety of methods. I have one with what seems like a thermal delay relay with a control knob. Recent ones seem to have some electronic control.

I think you can make these of any size, and even of curved shape if you work at it.

Where are you, what electrical/electronics resources do you have? The 'controller' could be more or less complex. The high-end ones control both timing and heat intensity I believe.

If you can build a Hovercraft you sure as heck can build this.

[thudpucker]

Watching "how its made" on the History channel, they went over the building of a RIB.
When it came to seams, they overlapped the two pieces about 1" and ran the two pieces through a pair of wheels, similar to an 'english wheel'.
Both wheels were heated.
Both wheels were held at the specific distance apart.
During the process the Ureathane could be seen welding itself together. A little puddle of the stuff went out ahead of the rollers.
No glue was used.

Then they put a backing strip on the welded seam from the inside using the same method.

You can see that your going to be experiementing a bit with the welding process.

[kach22i]

Watching "how its made" on the History channel, they went over the building of a RIB.
I'm reading right now how Zodiac in France uses radio frequencies (different materials though). It's in the October 2007 issue of "Boating" magazine.

[thudpucker]

Yes, there was something they 'welded' using Radio Frequencies in this TV program.
Beyond my back yard ability though.

I gatherd it was sort of like Micro-wave cooking.

[wet-foot]

Perhaps a modified ( cut off the second side ) carpet seamer would work ..... would heat both inside surfaces ...... apply pressure behind joint. one person operation too!