Thinking outside the weld

[milkman]

since the material was SSSSOoooooo thin (no mesh) this year.

I'm curious what you mean by this? Are you saying that the boat's plastic was thin? Has Esquif started making Preludes with thinner plastic? Or did Gonzo wear it down? I was among one of the early buyers of Preludes when Esquif started making them and thought the original boats were pretty much perfect in terms of thickness and weight.

[PAC]

I'm curious what you mean by this? Are you saying that the boat's plastic was thin? Has Esquif started making Preludes with thinner plastic? Or did Gonzo wear it down? I was among one of the early buyers of Preludes when Esquif started making them and thought the original boats were pretty much perfect in terms of thickness and weight.

Glad you asked to clarify... this is a Pyranha Prelude that has had multiple owners, been more than well loved and way past its life expectancy! If the Esquif boats hold up as this Pyranha (and its original air bags) then you purchased well! I still creek it but with more of an eye on the line of flow. Its a sweet ride when things are going right.

[Einar]

a friend with a cracked L'Edge took it to a plastic water tank manufacture/installer for R.V.'s and had it professionally done. Bring cash.

[milkman]

And just who are you calling an amateur, Einar? You don't think I can melt and play with the goo with the best of them?

All kidding aside, I'm looking forward to the challenge and have just purchased a heat gun complete with LCD temperature control. Can't be any harder than all the repairs I've made on Royalex over the years.

Much thanks to the great crew at cboats for all the "been there, done that" advice.

[the great gonzo]

As Dave said. What I meant to say was to make sure that the notch/groove is deep and wide enough to get a good weld and full penetration. The cross section of the groove should look like an X, with just a sharp ridge there the 2 grooves meet. If in doubt, cut out too much, with a little practice you can easily fill plastic back in. I once had to fix a boat where someone did a real hack job and just tried to weld some plastic on top of the crack, without grooving, cleaning or even dry the crack out. The obvious had happened, the water was evaporating during the attempted welding, forming huge steam bubbles. The boat cracked again soon after. I ended up having to cut about 1/2 inch of plastic full of bubbles out along the entire 4 inch length of a crack. Didn't have enough of the same color material, so I cut welding rods out of a plastic deck plate and used the material to fill the hole in, using a roller to smooth the plastic. To keep the plastic from flowing out on the other side I duct taped a scrap piece of sheet metal on the outside of the hull (it was in Costa Rica, you have to work with what you got...). The repair still holds and the boat has gone down class 4-5 rivers and over a 30+ ft water fall numerous times.
Before you start welding on your boat, try to find some scrap pieces of HDPE to practice with until you got the heat gun settings and tyour technique right.

TGG!

[Larry Horne]

Before you start welding on your boat, try to find some scrap pieces of HDPE to practice with until you got the heat gun settings and tyour technique right.

TGG!

That's some good advice. I made such a huge mess of my first welding job that I decided it would be my last..

[Einar]

Outing the amatuers.

Looking forward to seeing your welds Milkman.
It's gotta be better than my g flex slathering although it all held together on my pin balling the Fish Ladder on the Rogue last weekend. Barely.
e

[yarnellboat]

deleted. P.

[milkman]

The author of the book Outliers talks about how it takes 10,000 hours of practice to become an expert. Guess I better order a lot of plastic welding rods ...

Does anyone know the best temperature setting for PE welding? I did some poking around on the web and found two sites recommending a temperature of 575F, a lot of sites saying "until the rod melts" and another site recommending around 260-275F. Obviously, I'll start low and gradually go up in temperature in my practice sessions until I find the ideal temp, but I thought I'd see if anyone knows the best approximate temp to try. I'm thinking some of the difference here might be that the lower temp range is the actual temp at which PE melts and the higher temp (575) is just what you need the welding gun to be to bring the rod to around 260 quickly as you work.

[the great gonzo]

300 deg C (572F) according to BAK:
http://www.bestmaterials.com/PDF_Files/ ... lding2.pdf" onclick="window.open(this.href);return false;

TGG!

[milkman]

I just got off the phone with a friend who talked to someone at Esquif that has done a lot of their boat welding. The Esquif guy recommends cleaning the area to be welded with MEK. He strongly cautioned against using acetone--that will melt the plastic. But apparently MEK won't. He said you'll get a much better bond.

[the great gonzo]

Not sure about your friends statement. I have researched this a bit and done some trials with the solvents that we have at Esprit (MEK, Acethone and THF [Tetrahydrofuran]), and I found that they all do some minor dissolving of PE at ambient temperature, THF maybe a bit more than the other two. This seems to be supported by literature. PE is a pretty inert plastic after all. I have even seen shops where acetone was stored in PE squeeze bottles, with no apparent detrimental effect. Some plastic suppliers actually state that acetone is less of an issua as far as dissolving PE than MEK is:
http://menda.descoindustries.com/PDF/Ch ... eChart.pdf" onclick="window.open(this.href);return false;
http://www.cdf1.com/technical%20bulleti ... _Chart.pdf" onclick="window.open(this.href);return false;
http://www.premierplastics.com/Adobe/Ch ... hylene.pdf" onclick="window.open(this.href);return false;
I have used all 3 of them, each one sparingly. I do the basic cleaning with soapy water and then only use solvent or alcohol for the final de-greasing. I have not found any difference in weld strength, whatever dissolution that occurs during the short final de-grease does not seem to have any detrimental effect, all welds seem to hold equally well.
If potential dissolution is a concern, then I would suggest to use alcohol for the final cleaning.

TGG!

[milkman]

Good call on the alcohol. I'd rather go with that then use MEK or acetone or any other nasties. I use 99% rubbing alcohol for all gluing and have always had great results ... so I think I'll use it as the final cleaner before welding.