Lego bricks and Acetone

[rmd24]

Recently decided to have a go at fixing the two little cracks in the front corners of the central console. My research in the archives lead me via a devious route to a modelling website, perhaps I should say a model making website just in case anyone gets the wrong idea!
Several contributors suggested just acetone for sticking ABS as it slightly dissolves the plastic and the two pieces become welded together as it hardens. However because of the nature of the splits in my console I felt that would probably not be adequate so I followed another suggestion. I sourced a couple of black Lego bricks from an abandoned set and cut them into tiny bits with tin snips. I then poured a couple of tablespoonfuls of acetone on them and waited.
After about an hour almost all the acetone had disappeared and a sort of black mush remained and I used this to fill the cracks. Overnight it hardened and I was able to sand it lightly to the shape and finish required. This did cause the repair to become slightly greyish but a wipe with acetone brought it back to black (sounds like a song).
The result is slightly glossier than the original although that may be fixable and of course I can't vouch for its longevity ( I only did it yesterday) but for those planning similar repairs its a method worth considering.

Roger.

[john.p.clegg]

Roger

Excellent post,you will have to update us in a year or two about its longevity...

John

[ardee_selby]

Roger

Excellent post,you will have to update us in a year or two about its longevity...

John

+1 on that.

(BTW Roger...Any developments on the weber flat spot problem? Choke size?
Ref: elan-f14/weber-problem-t21985.html )

[rmd24]

I haven't done anything about the Weber problem except use some carb cleaning stuff in the fuel. Not sure if it made any difference or not! However the problem, although still there seems not to be quite so intrusive now. Maybe I've got used to it and drive around it. I don't feel it's bad enough to start dabbling.

Roger.

[bilcoh]

Adding another page to my "oddball repair techniques" binder.

Very creative. I don't have cracks on the dashpad, but both the lower corners have broken off over the years and it's just exposed foam. I wonder if this technique might have applications for such a repair.

Roger, any chance for some photos of the repair?

Thanks for sharing,

Dave

[reb53]

I just used a similar method to fix a bunch of cracks in my centre console.

Instead of acetone I used methylene chloride as I had several litres to hand.
Experimented on various bits of plastic to see which was melted by the meth.c.
Ended up attacking an old black tv case with a Surform, ( large file), and melted all the shavings into a black gloop.
It did a brilliant job of glueing up and reinforcing all the cracks when poured in from the back side where it can't be seen.

Word of warning though, ( apart from meth. c. being toxic.....).
I thought I could reinforce all around the gear lever by putting a flat piece of the tv case there and making up a heap of the gloop.
Worked a treat, apart from the fact there was now so much meth involved that it softened and distorted the top of the console......

Everywhere else was fine, just not the place where I got carried away.
Now has a nice little vinyl cover which looks OK but still p*ssed off that it was OK for 40 years until I messed it up...

Ralph.

[bilcoh]

That's a frustrating one, Ralph. Perhaps you should post that on the "bodges you regret" thread? Seems like it qualifies. Perhaps a better bodge will fix it?

Do two wrong bodges make a right?

Best of luck,

Dave

[rmd24]

Dave,
A couple of pics. I haven't yet got quite the finish that I want but I think that can be tweaked. I also put a good dollop on the underside which I am sure will prevent the split from getting longer.
I am mindful of the fact that I may be creating a market for black Lego bricks so for the sake of domestic harmony I would urge discretion in plundering these items from one's children or grandchildren.

Roger.

[cabc26b]

I like the ingenuity, however i don't have the patience - Awhile back I bought a tube of Evercoat MAXIM multifix plastic repair . its a two part epoxy system in a single tube. 4-6 min working time , 15-20 min to sand , 30 min to paint.

George

[bilcoh]

Thanks for the pictures, Roger. My kids are done with their Legos, so I think I'm safe on that front. I'll have to try and mix some up and see how well I can form it into the shape I need.

Hmmm. What other household items might be melted into durable repair substances? Could I use Coke and paperclips to create a metallic goo to smear on those pesky rust holes in the frame? Hypothetical, of course, as I'm lucky enough to not have any rust.

Gary, you've got a "test" frame laying about. What do you think?

Dave

[AHM]

For reenforcement - Use a hot glue gun - provides strength and flexibility.

Do several thin applications - it needs to be hot to stick properly but too much glue and the heat will soften the panel.

This is the only useful application I have found for a glue gun!

Simon

[Esprit2]

Many specialized plastic glues are simply the base resin disolved in a solvent, sos this approach is certainly on the right track.

ABS is a broad family of plastic resins. Some versions are formulated for a high gloss and brilliant colors, and others are formulated for high impact strength. ABS = Acrylonitrile-Butadiene-Styrene, with butadiene being a synthetic rubber. In simplistic terms, the higher the percentage of B in the ABS, the less brittle and more energy absorbing it becomes, and the less glossy.

The more glossy, colorful, cosmetic grades tend to be more brittle, however some specialty grades are quite strong while still managing to maintain a pretty nice gloss. Legos put more emphasis on cosmetics, color & gloss than ultimate impact strength, but they're still reasonably strong.

The high impact grades generally have far less to no gloss, and the colors tend to be more muted.

Given that the repair in the original message came out noticeably more glossy than the original part's material, it might be better to seek out a more high-impact grade of ABS. That would kill the gloss somewhat, and make for a stronger repair. One less prone to cracking again.

Don't expect the repair area to ever match the luster of the original Lotus part. Anytime you soften or melt dull ABS with solvent or flame, it will re-solidify with more of a shine. Flame-polishing is a common, easy way of cleaning up cut edges on fabricated parts.

Regards,
Tim Engel