Author Topic: Plastic welding  (Read 1317 times)

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1981cb650c

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Plastic welding
« on: January 01, 2009, 05:52:23 PM »
I need to repair a plastic bumper. I have done some reading on the subject and got what I hope is good information. Anyone ever tried it?

These are the welders I'm looking at (cheap units available from Harbor Freight and ebay)


http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592


http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=96712

and this is the procedure I'm looking at using. Instead of a true weld, it is more like plastic brazing
http://www.urethanesupply.com/step3c.php

Any thoughts or advice?

Here is some additional reading if your interested with lots of links
http://forum.doityourself.com/welding-metalworking/164855-plastic-welding.html

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Re: Plastic welding
« Reply #1 on: January 01, 2009, 05:59:36 PM »
I have done plenty of ABS plastic repair on my XVZ12DN - Part of owning that beast.  But not like that.  I have always done it by hand.  Having a setup like that I hear just fricking rocks.

I can stand that beast on its back wheel but scares me to death when she hits the ground coming down. I am afraid the plastic is just gonna explode.
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

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Re: Plastic welding
« Reply #2 on: January 01, 2009, 06:31:41 PM »
From my understanding the paint should survive with the plastic welding and rods.

It is really very simple, kinda like working with bondo and fiberglass sheet. 

-I wipe down the area(s) with acetone.  Makes it clean, porous and kinda sticky (no worries).
-Mix the two part ABS plastic repair (i get it from AutoZone).  Many parts stores will carry it, I think it is called permatex or something similar (pickish background).
-Put the mix over the crack or the two parts and let them dry a bit.  Wont take long.
-I lay a piece of fiberglass sheet while it is still soft and push it in. Trying to get it in the weave.
-I mix another small batch and lay it over the top of the area.  Push it into the weave.
-Let it dry.
-Dremel to clean it up and make it look nice.

This mix has never broke, hard as bujesus.  Now, high stress stuff will break around it but not what you have done (to me, there is no real amount plastic on em, early Honda's).  I have a bunch of tabs that like to break as it is is old weather beaten ABS.  Few have broken around the fix.  But then, when it comes down from standing her up on the back wheel, a tab likes to let go, lol.

I have filled holes like this that is about an inch radius.

If you have seen my XVZ12DN, there is SO much plastic, it is crazy.
« Last Edit: January 01, 2009, 06:37:51 PM by GigaWhiskey »
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

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Re: Plastic welding
« Reply #3 on: January 01, 2009, 06:35:17 PM »
You got me on the Canada thing.
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

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Re: Plastic welding
« Reply #4 on: January 01, 2009, 06:42:43 PM »
Now, that is a ton of plastic.  Like 27 pieces.  And 800lbs to boot with a V4 1200 (Almost VMAX motor).  It will run like hell too.

« Last Edit: January 01, 2009, 06:45:25 PM by GigaWhiskey »
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

eldar

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Re: Plastic welding
« Reply #5 on: January 01, 2009, 08:04:01 PM »
Problem with plastic welding is the composition. Certain plastics require a different rod or glue. Plus with the welder, you have to be careful of the heat. If you do a search, there was a thread on this like a year ago or something like that. There was a lot of discussion in it.