Plastics repair with ABS cement: Difference between revisions

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===Introduction===
===Introduction===


To state the obvious, the Ninja 250 has a good amount of bodywork. It is ABS plastic, which can be heat formed, or heat-welded. Most plastic repair can be done on the cheap, and without many exotic tools. So, if you are poor, cheap, or have made a terrible life decision to become a grad student making $600 a year, this article is for you.
To state the obvious, the Ninja 250 has a good amount of bodywork. It is ABS plastic, which can be heat formed or heat-welded. Most plastic repair can be done on the cheap and without many exotic tools. So, if you are poor, cheap, or have made a terrible life decision to become a grad student making $600 a year, this article is for you.
   
   
This process repairs the plastic, but does not address paint, or making it look good. This page will just cover the structural repair.
This process repairs the plastic but does not address paint or making it look good. This page will just cover the structural repair.


Make sure that you have a well-ventilated area for the noxious fumes to escape from.
Make sure that you have a well-ventilated area for the noxious fumes to escape from.
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*ABS Cement
*ABS Cement
   
   
::Use ABS plumbing cement with low VOCs (volatile organic compounds) . This is used as a sort of "bondo" to fill in cracks and deformations in the bodywork. Unlike bondo, the ABS cement will melt and fuse with the ABS bodywork, making a uniform repair material.  
::Use ABS plumbing cement with low VOCs (volatile organic compounds) . This is used as a sort of "bondo" to fill in cracks and deformations in the bodywork. Unlike bondo, the ABS cement will melt and fuse with the ABS bodywork, making a uniform repair material. Home Depot or anywhere that sells plumbing supplies usually carries something like [http://www.amazon.com/Low-VOC-ABS-Cement-Black/dp/B000UG3GJQ Oatey Low VOC ABS Cement].


*Sandpaper and a sanding block
*Sandpaper and a sanding block
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===Theory===  
===Theory===  


The theory behind the plastic repair is simple. A crack or a break in the ABS bodywork can be bonded back together by welding the plastic together. This can be done chemically, or by heat. Heat is used to make the primary bond, and then the surface imperfections are filled in with the ABS cement. This takes place in several steps.  
The theory behind the plastic repair is simple. A crack or a break in the ABS bodywork can be bonded back together by welding the plastic together. This can be done chemically or by heat. Heat is used to make the primary bond, and then the surface imperfections are filled in with the ABS cement. This takes place in several steps.  
   
   
The first figure shows the cross section of a break in the plastic. The top surface has a paint layer, and a relatively thick plastic layer.  
The first figure shows the cross section of a break in the plastic. The top surface has a paint layer and a relatively thick plastic layer.  


[[Image:theory01.gif]]
[[Image:theory01.gif]]
   
   
Start by sanding the paint off, to clear out the surface. This makes repainting REQUIRED. You can skip this step and only weld the break from the back. This makes a nice looking, but weaker, repair. If the paint gets into the ABS, it contaminates the bond, and you'll have to sand anyway.  
Start by sanding the paint off, to clear out the surface. This makes repainting REQUIRED. You can skip this step and only weld the break from the back. This makes a nice-looking, but weaker, repair. If the paint gets into the ABS, it contaminates the bond, and you'll have to sand anyway.  


[[Image:theory02.gif]]
[[Image:theory02.gif]]
   
   
A hot soldering iron melts together the two sides. Run the hot iron down the length of the fracture from the rear (unpainted side), with your finger on the painted side, moving gingerly up and down the surface. The idea is to keep the feeler fingertip from getting too hot. This is especially important if one is only welding one side. If your finger can't take the heat, neither can the paint. In this picture, both sides are welded.  
A hot soldering iron melts together the two sides. Run the hot iron down the length of the fracture from the rear (unpainted side), with your finger on the painted side, moving gingerly up and down the surface. The idea is to keep the feeler fingertip from getting too hot. This is especially important if you are only welding one side. If your finger can't take the heat, neither can the paint. In this picture, both sides are welded.  


[[Image:theory03.gif]]
[[Image:theory03.gif]]
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Next is a crack on the same piece.  
Next is a crack on the same piece.  
   
   
The lower end of this piece shattered, and left a fracture running up it. The crack is a good candidate for repair.  
The lower end of this piece shattered and left a fracture running up it. The crack is a good candidate for repair.  


[[Image:inner_crack.01.jpg|170px]]
[[Image:inner_crack.01.jpg|170px]]
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[[Image:Leftside_top.01.jpg|170px]]
[[Image:Leftside_top.01.jpg|170px]]
   
   
The lines show the fracture ran along the edge, which was reconstituted using ABS cement. As a result, the rounded edge of that corner is gone. It's now a sharp edge, which can easily go unnoticed. The Orange is also significant. That section was gone. Entirely gone. It was rebuilt by making a thin ABS layer, then rebuilding the surface. The rebuilt section was less than perfect, and cracked while back on the bike. This was because the shape it solidified into was not the same as the original shape. After welding the new crack to relieve the stress, it has been doing fine.  
The lines show the fracture ran along the edge, which was reconstituted using ABS cement. As a result, the rounded edge of that corner is gone. It's now a sharp edge, which can easily go unnoticed. The orange is also significant. That section was gone. Entirely gone. It was rebuilt by making a thin ABS layer, then rebuilding the surface. The rebuilt section was less than perfect, and cracked while back on the bike. This was because the shape it solidified into was not the same as the original shape. After welding the new crack to relieve the stress, it has been doing fine.  


[[Image:Leftside_top.02.jpg|170px]]  
[[Image:Leftside_top.02.jpg|170px]]


===Rebuilding plastic parts from molds.===
===Rebuilding plastic parts from molds.===
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The consistency of the plastic can be anywhere from a runny fluid (straight out of the can) all the way to something almost like a thick dough. A half empty can will solidify if left unused. Add some acetone to the plastic to thin out the cement. This can be done to completely solid plastic to make it a fluid again. This also means you have to keep the acetone and stuff away from the bodywork. Spill it, and it shouldn't do much damage right away. It takes a bit of time, and a good amount of solvent before your bodywork does a Salvador Dali impression. Still, don't take the chance.
The consistency of the plastic can be anywhere from a runny fluid (straight out of the can) all the way to something almost like a thick dough. A half empty can will solidify if left unused. Add some acetone to the plastic to thin out the cement. This can be done to completely solid plastic to make it a fluid again. This also means you have to keep the acetone and stuff away from the bodywork. Spill it, and it shouldn't do much damage right away. It takes a bit of time, and a good amount of solvent before your bodywork does a Salvador Dali impression. Still, don't take the chance.


====Links====
==Links==


To learn about ABS, its uses, and how to work with it:
To learn about ABS, its uses, and how to work with it: