Repair Broken ABS

[Charlie Gary]

December 2007 gave me a chance to see my bike laying broken in the street. Now the holes and broken bits are fixed. All I had handy was a piece of ABS scrap, some Methyl Ethyl Ketone (MEK) and hand tools. Before beginning your own repair, some things to know are:
MEK is flammable stuff, so don't be using Coleman lanterns for light. In fact, make sure there's no flame source anywhere. MEK is hazardous, so keep it separate from you and your body parts. Look for an MSDS online if you want to know more about MEK. If you die because the MEK killed you, tell your spouse to leave me out of it.

Here's how I did it.

1 ) Here's the damage

http://i229.photobucket.com/albums/e...er_missing.jpg

http://i229.photobucket.com/albums/e...r/HOLYhole.jpg

2 ) I began by finishing breaking out the piece holding the light and repairing the crack in it. I used MEK as a glue, and just let it wick into the crack.

http://i229.photobucket.com/albums/e...rack_glued.jpg

3 ) Before using MEK to glue the cracks around the big hole, I used a Dremel tool to make relief bevels for filler later.

http://i229.photobucket.com/albums/e.../glue_prep.jpg

4 ) Then I used a fine paint brush to control how much MEK I applied and let wick into the cracks.

5 ) A clamp and some craft sticks hold everything flush until the glue sets.

http://i229.photobucket.com/albums/e...lamp_flush.jpg

6 ) Once the glue is set, I prepped the edges of the hole and part by beveling them like I did for step 3. Then I put some tape on the back side of the hole to help hold the piece I put back in.

http://i229.photobucket.com/albums/e...ir/backing.jpg

7 ) After everything was in place to my satisfaction, I again used my paintbrush to apply MEK to the joints. I put the piece in and pulled it back out maybe ten times before I was happy with the fit. It might take more than ten seconds, but this is when it's important to take your time. Don't rush the fit you'll have forever after.

http://i229.photobucket.com/albums/e...epair/glue.jpg

8 ) Once the piece was back in, I needed some filler. After seeing a big price tag on "ABS Glue" at the local plastic supplier, I read the ingredients label and saw MEK and filler material listed as the main ingredients. I knew I had those two things at home, so instead I used a wood rasp to turn ABS solid into ABS fuzz.

http://i229.photobucket.com/albums/e...oncentrate.jpg

Mix it with MEK, and you get glue with filler. It takes a few days to completely dissolve. This stuff is in a jar that doesn't seal air tight, so over time it will thicken. More MEK fixes that.

http://i229.photobucket.com/albums/e...r_complete.jpg

9 )Here I'm using a q-tip to apply the filler.

http://i229.photobucket.com/albums/e.../main_fill.jpg

10 ) Here's how it looks after the first sanding. Not there yet, but much better than a hole.

http://i229.photobucket.com/albums/e...first_sand.jpg

11 ) After a second fill and sand, it looks like this.

http://i229.photobucket.com/albums/e...econd_sand.jpg

12 ) Fixing the upper part was a little more involved, since I had to make one from scratch. I started by hacking a piece from the corner of some scrap.

http://i229.photobucket.com/albums/e..._beginning.jpg

13 ) After roughing the shape close, I needed a way to hold the part while working on it. Hot glue saves the day.

http://i229.photobucket.com/albums/e...pper_held1.jpg

14 ) I shaped the inside first, making sure all parts fit together. The nails help me line things up the same way every time.

http://i229.photobucket.com/albums/e...upper_fit1.jpg

Once things fit, it was time to shape the outside. Again, hot glue to the rescue.

http://i229.photobucket.com/albums/e...pper_held2.jpg

15 ) One trick to roughing off material quickly is to make some fast cuts like these before shaping the rest of the part.

http://i229.photobucket.com/albums/e...r_roughing.jpg

16 ) Use one of these when you have to make a shape match one somewhere else.

http://i229.photobucket.com/albums/e...pper_check.jpg

17 ) This is as close as I got it before gluing it in.

http://i229.photobucket.com/albums/e...upper_fit2.jpg

18 ) Use a soldering iron for tack welding.

http://i229.photobucket.com/albums/e.../tack_weld.jpg

19 ) After gluing and sanding, I discovered the new piece was just a little too big. One hacksaw blade width, to be exact. I cut it in half, glued it again, and it was ready for final shaping.

http://i229.photobucket.com/albums/e...r_adjusted.jpg

20 ) Here it is, ready for some paint.

http://i229.photobucket.com/albums/e...epair/done.jpg

That's how I did it.

[KZQuixote]

Hi Charlie,

I enjoyed your plastic writeup. By coincidence, I wrote a similar piece for KZR last month.

Check Out: KZrider.com - Plastic body panel repair. First Time.Forever!

Don

[Charlie Gary]

Originally Posted by KZQuixote

Hi Charlie,

I enjoyed your plastic writeup. By coincidence, I wrote a similar piece for KZR last month.

Check Out: KZrider.com - Plastic body panel repair. First Time.Forever!

Don

Don,
Nice write-up. One thing I've learned about fiberglass and plastics over the years is if you drill holes through the area being patched and put fabric on both sides, the holes allow resin to flow through and tie the layers of fabric together. This really helps prevent peeling, which is fiberglass's main weakness. Having said that I love your use of ABS glue, because it actually eats into the base material, which should prevent peeling. Epoxies need a rough surface to stick to since they don't actually chemically attack the base material.
One thing I've learned about ABS is it can be bought in its natural color of beige as well as black. Here's a picture of a piece of ABS uncolored.

http://i229.photobucket.com/albums/e...a/DSCF0015.jpg