# Learning to plastic weld; tips? suggestions?



## Dave Frank (Oct 14, 2003)

How big is the crack? The standard method is to drill the ends to stop propagation, and then tape the inside with vycor.

The one time i tried welding (an'01 pyranha) the weld held great, but the plastic cracked badly about an inch away from the weld on day one.

I know some folks have succeeded in welding, but it is very finicky, and can easily render a boat useless.


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## spenceuiuc (May 28, 2008)

There are multiple cracks; one is an inch long near the bolts that adjust the seat near the cockpit lip, and then there are 2 U-shaped cracks, one near each of the thigh braces on the cockpit lip.

Honestly, if the boat doesn't make it out alive, it is alright because it was free and it will be a learning process for when my main boat gets a crack. I will get some pics up before long (I actually haven't seen any pics amidst the slews of posts on EZG problems anyhow).


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## spenceuiuc (May 28, 2008)

*pics of cracks*

Here are some pics of the damage.


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## JCKeck1 (Oct 28, 2003)

Get ahold of xacker or [email protected] Far and away the best plastic welders I've met. I don't think either one of them has had a proper boat this summer. Alex Kilyk is good too, but I'm not sure he reads the buzz since he hit the PNW.
Joe


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## arkriverrat (Apr 11, 2005)

*Plastic Welding*

We do a lot of polypropylene welding at work, and while I have never welded on a kayak, I think that most of the principles hold true. I agree with all of the above, and would just add that I believe resin is VERY important, to the extent that I would get welding plastic right from the boat manufacturer or from a donor boat of same make and color. At work we have also had problems with welds being contaminated because the surfaces were not cleaned properly prior to welding. Surfaces really need to be as clean as possible, and weld contamination will weaken even the best weld. While welding (I would use a forced hot air wellder on a boat) If you see smoke, you are too hot, and contaminating your weld. Lastly, in our buisness, we fill out finished tanks with water and beat all of our weld seams with a rubber mallet to stress test... If I had a welded boat, I would want to make damn sure it was strong before I relied on it in water of any consequence...
My 2 cents... Best of luck!
Tim


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## spenceuiuc (May 28, 2008)

Right on. I will definitely make sure the area is good and clean before I go at it. I am also getting plastic directly from Wave Sport for welding. Thanks for the tips. Keep the tips coming if you have any more for me!


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## Theophilus (Mar 11, 2008)

arkriverrat said:


> We do a lot of polypropylene welding at work, and while I have never welded on a kayak, I think that most of the principles hold true. I agree with all of the above, and would just add that I believe resin is VERY important, to the extent that I would get welding plastic right from the boat manufacturer or from a donor boat of same make and color. At work we have also had problems with welds being contaminated because the surfaces were not cleaned properly prior to welding. Surfaces really need to be as clean as possible, and weld contamination will weaken even the best weld. While welding (I would use a forced hot air wellder on a boat) If you see smoke, you are too hot, and contaminating your weld. Lastly, in our buisness, we fill out finished tanks with water and beat all of our weld seams with a rubber mallet to stress test... If I had a welded boat, I would want to make damn sure it was strong before I relied on it in water of any consequence...
> My 2 cents... Best of luck!
> Tim


That's good tech information. I've been wanting to try this for sometime so I've been following this thread.


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## Theophilus (Mar 11, 2008)

spenceuiuc said:


> Right on. I will definitely make sure the area is good and clean before I go at it. I am also getting plastic directly from Wave Sport for welding. Thanks for the tips. Keep the tips coming if you have any more for me!


I'll be interested to hear your results. Keep us posted.


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## spenceuiuc (May 28, 2008)

I'll keep posting and get images up as well. 

I ran across some helpful tool for those who are interested.

KC Kayak weld kit. Seems pricey, but convenient.

Heat gun w/2 temps, one near 500F.

Heat gun w/many temps.

Multiple heat gun tips.

Plastic welder, specific, nice, more $$.


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## spenceuiuc (May 28, 2008)

Attached is a brochure w/specific temps for general plastic welding.


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## Snowhere (Feb 21, 2008)

Here is my plastic welder. I bought it about 20 years ago from an industrial supply house so it was not cheap. I got it for welding my motorcycle fairings and have only welded ABS plastic with it. You will find the better welders have a lot better temperature control and you will have better control of the weld quality.


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## spenceuiuc (May 28, 2008)

*after welding round 1*

So I went through and welded all the cracked spots. I haven't sanded anything yet to a finished product (and don't know if I will to be honest), but here are the pix of welding round 1. I know I know, it's sloppy.

I ended up using a variable temp heat gun ($35 @ Ace) for the heat supply and a set of tips for the heat gun ($6) which reduced the diameter of the tip of the heat gun for better accuracy. A crappy old spoon + fork were my only other tools necessary. This worked pretty well.

Since the EZG issue is that the cockpit rim flexes too much near the thigh braces, I came up with the idea to go ahead and weld a brace in the gap on the inside of the cockpit rim, as pictured. This really stiffened up the cockpit rim when you push where the thigh braces attach. I think this may help the issue of cracking on the EZG rim.

I just wanted to say thanks to Scott @ Confluence for the extra welding plastic from another boat--- it is really easy to go through a lot of plastic for a beginner at plastic welding. Thanks, Scott!
-Tony


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## kayaker (Oct 29, 2003)

If you want to fix the cracks right, talk to the pros at Boulder Boat Works 720-565-0789 (Andy or Chris). These guys weld up co-polymer dories every day. They have fixed four cracked kayaks for me and they know more about temperature specifics and how to do bomber welds than anyone else I've ever found or even heard of. 
I crushed the stern on a boat and cracked it in three places. Not only did they reform the stern, but the welds done on the cracks are now the strongest parts of the boats (three years afterward still holding strong). 
Tell Andy that Craig sent you.
The $ you spend on the repairs with Boulder Boat works will resolve the cracks, strengthen the integrity of the boat and help to lengthen the life of the boat.

Buenos suertes!

-Craig


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## rich1979 (Nov 6, 2008)

Hi all i have been plastic welding for about 6yrs now

I have found this company Tempatron Ltd - plastic welding equipment
to be the best equipment so far fast and cheap ( the way i like it lol)

Hope this helps 

Richard


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