I have used both acetone and mek to melt abs and they both work about the same so if acetone isn't doing anything noticeable to it mek probably won't either. I'm guessing it not abs.

Grem Five wrote on 2022-03-23, 14:02:

I have used both acetone and mek to melt abs and they both work about the same so if acetone isn't doing anything noticeable to it mek probably won't either. I'm guessing it not abs.

Howdy neighbor, thank you for the reply. Then I think I'm going to skip the ABS cement as I have no other use for it and it seems unlikely to work.

I should find some confirmed ABS though to see how acetone behaves on it.

I don't know about newer ones but old Legos are abs and will completely melt in acetone or mek. Same with left over sprues from like revel model kits. Many times I have used these as fillers when fixing abs.

On most parts there are injection markings (look like little clock dials) and near them there should be some letters that can give you a clue to what kind of plastic it is injected out of, not on all parts but many.

Grem Five wrote on 2022-03-23, 15:51:

I don't know about newer ones but old Legos are abs and will completely melt in acetone or mek. Same with left over sprues from like revel model kits. Many times I have used these as fillers when fixing abs.

On most parts there are injection markings (look like little clock dials) and near them there should be some letters that can give you a clue to what kind of plastic it is injected out of, not on all parts but many.

I have a quantity of various plastic project enclosures that have datasheets available, so I can check those.

And I did check the areas you're talking about because I've seen that before, but no luck.

Might have to use the Shoe Goo. I've used that stuff on all sorts of non-shoe items and it works on everything. I guess it's the best alternative given that plastic welding doesn't seem possible with this. The parts are small too, so I can't risk repair with a soldering iron if that would even work on this plastic.

Well I thought many products had the material listed that they are injected from but I Google it and came up with squat. I know last '90s pc case I had to fix some plastic panels had that info on it because when I started I thought it was abs panels but I was wrong.

At a previous place I worked we use to make industrial model mockups and for most of it we used sheets of .125" Virgin abs and we always bonded them together by using Mek.... nasty stuff and i have fixed the disk drive holder tray in my PCJr by using Mek as well so that was abs.

For internal dmg fix, you can try PVC glue it may work.. I normally use Moment glue (henkel) that thing is universal and it glues very well many things, metal to plastic, platic to plastic...

Radical Vision wrote on 2022-03-29, 21:36:

For internal dmg fix, you can try PVC glue it may work.. I normally use Moment glue (henkel) that thing is universal and it glues very well many things, metal to plastic, platic to plastic...

When you say PVC glue, are you referring to the purple stuff used to glue white PVC sewer pipe?

Is Moment glue not available in the US? I'm not finding it to be generally available here. Found several results with Cyrillic text on the package. I'm thinking this is some sort of rubber cement, similar to Shoe Goo.

eesz34 wrote on 2022-03-31, 16:36:

Radical Vision wrote on 2022-03-29, 21:36:

For internal dmg fix, you can try PVC glue it may work.. I normally use Moment glue (henkel) that thing is universal and it glues very well many things, metal to plastic, platic to plastic...

When you say PVC glue, are you referring to the purple stuff used to glue white PVC sewer pipe?

Is Moment glue not available in the US? I'm not finding it to be generally available here. Found several results with Cyrillic text on the package. I'm thinking this is some sort of rubber cement, similar to Shoe Goo.

I glue many things with this, i consider it very good, only downside is the fact it is yellow, so keep that in mind. It is German brand Henkel, so no idea if they sell it in the US, for sure they sell it in whole Europe. Yes the PVC pipe glue, should work very well with internal places. Or just look what type of glue that Henkel Moment is, and find similar good brand in US and use that instead.

Radical Vision wrote on 2022-03-31, 16:43:

I glue many things with this, i consider it very good, only downside is the fact it is yellow, so keep that in mind. It is German brand Henkel, so no idea if they sell it in the US, for sure they sell it in whole Europe. Yes the PVC pipe glue, should work very well with internal places. Or just look what type of glue that Henkel Moment is, and find similar good brand in US and use that instead.

product_13577.png

Henkel is actually a common brand here, usually under the Loctite brand. But I will look into the mentioned product!

Im a big believer in melting stuff

All Lego are ABS and acetone will definitely melt ABS as it is used to smoothen the surface of ABS 3D printed parts.

Revell glue is basically expensive acetone, I think.
Both basically just melt both surfaces and evaporate.

ABS is also infamous for being the material that tends to yellow.
IBM enhanced keyboards don't yellow as they are made from PTB, afaik.
But, I tested on the back of mine, it also dissolves in Acetone.
Then again, my old Logi cordless is yellowed AF and it doesn't mind acetone one bit. Their mice do, though.
So, it's complicated.
https://www.millerplastics.com/how-acetone-af … rtain-plastics/

But anyway, I'd guess that the broken part is some kind of "screw post", the hollow rod where a screw was meant to grip?
Or, if not, it's still bound to be load-bearing in some way, since it broke in the first place.

Chances are, even the best solvent-based superglue won't help you there.
All it does is connect the very limited surface that did break and exactly at the point where it broke, the one with the most stress on it.
So, that would be like trying to fix the St. Andreas fault line by pouring in a lot of concrete.

Think you'll need some solution that actually adds material to the structure.
So, not sure what that ABS cement would do, or maybe some two component acrylic.
This stuff:
https://wuehlbox.com/en/accessories/472-uhu-p … esive-33-g.html
is expensive AF but it claims to hold 300 kg per cm² (that's 661 booleywocks per 0.16 square glonkaflorks, for the Yanks.).
Once you heat it up with a hot air gun or something.

Minor offenses, torrents of hot glue will do. Worked well on the fire switch of a joystick once.

Feel free to improvise some structural aid like cuts from old credit cards or pieces or fine mesh of wire.

Also, this crazy f*cker (esteemed Vogons member scorp) has a neat trick with superglue and baking soda:
https://youtu.be/j1hGepWb6nY?t=770

Good luck!

Cuttoon wrote on 2022-03-31, 22:12:

All Lego are ABS and acetone will definitely melt ABS as it is used to smoothen the surface of ABS 3D printed parts. […]
Show full quote

All Lego are ABS and acetone will definitely melt ABS as it is used to smoothen the surface of ABS 3D printed parts.

Revell glue is basically expensive acetone, I think.
Both basically just melt both surfaces and evaporate.

ABS is also infamous for being the material that tends to yellow.
IBM enhanced keyboards don't yellow as they are made from PTB, afaik.
But, I tested on the back of mine, it also dissolves in Acetone.
Then again, my old Logi cordless is yellowed AF and it doesn't mind acetone one bit. Their mice do, though.
So, it's complicated.
https://www.millerplastics.com/how-acetone-af … rtain-plastics/

But anyway, I'd guess that the broken part is some kind of "screw post", the hollow rod where a screw was meant to grip?
Or, if not, it's still bound to be load-bearing in some way, since it broke in the first place.

Chances are, even the best solvent-based superglue won't help you there.
All it does is connect the very limited surface that did break and exactly at the point where it broke, the one with the most stress on it.
So, that would be like trying to fix the St. Andreas fault line by pouring in a lot of concrete.

Think you'll need some solution that actually adds material to the structure.
So, not sure what that ABS cement would do, or maybe some two component acrylic.
This stuff:
https://wuehlbox.com/en/accessories/472-uhu-p … esive-33-g.html
is expensive AF but it claims to hold 300 kg per cm² (that's 661 booleywocks per 0.16 square glonkaflorks, for the Yanks.).
Once you heat it up with a hot air gun or something.

Minor offenses, torrents of hot glue will do. Worked well on the fire switch of a joystick once.

Feel free to improvise some structural aid like cuts from old credit cards or pieces or fine mesh of wire.

Also, this crazy f*cker (esteemed Vogons member scorp) has a neat trick with superglue and baking soda:
https://youtu.be/j1hGepWb6nY?t=770

Good luck!

This is a NMB RT101+ keyboard I've had for over 20 years, and amazingly not very yellow. So maybe that means it's not ABS? Acetone doesn't do much to it though.

What broke are these little catches on the spacebar side of the top half. So the bottom half has something that fits inside of these. This is a picture of a set of intact ones, it has 4 sets and the ones at the ends are broke.

I've tried JB Weld Plasticweld on a test area and it peeled right off. My favorite all purpose glue, Shoe Goo, was better but also peeled off with some effort(probably not unexpected though considering it's a rubbery cement).

You guys across the pond have the good stuff apparently, since I can't buy Moment Universal or this epoxy you mention.

One good thing about this repair is I could fill in the space between the 3 little "fingers" with glue, so it would strengthen it considerably.

I really wish I could chemically bond this, but as acetone doesn't do anything but some slight discoloration I don't know if that's feasible.

And I don't think much of superglue. I actually bought one of these

https://www.loctiteproducts.com/en/products/f … dingsystem.html

but I haven't even opened because I later realized it's fancy superglue.

I thought this was an interesting read--

6 Ways to Repair Broken Plastic: https://makezine.com/2017/02/16/plastic-repair/

• Hot Water, Cold water
• Plastic Welding with Heat
• Plastic Welding with Friction
• Plastic Patches
• Using Acetone for ABS Plastic
• Good Ol’ Glue

Usually welding broken thermoplastics with the soldering station.

250 deg C is a good starting point for ABS, go higher if necessary. Be careful not to burn the plastic, you only want to melt it. Also, make sure you clean the soldering iron tip very thoroughly before starting, you don't want the weld contaminated by solder or flux residues. I'm keeping a dedicated chisel tip for plastic welding.

3D printer filament is very convenient to use as filler if needed, but basically anything made from the same material as the parts you're welding works.

If working with a plastic type that can be dissolved chemically without too nasty stuff (I'd recommend avoiding chlorinated hydrocarbons etc), the weld can be evened out and strengthened further with a plastic/solvent slurry. For ABS, ASA, etc acetone works well as solvent.

A hot air rework station with a small nozzle can also be used for the above. It's quite easy to screw up though, be careful. Many plastics tends to deform when heated above their glass transition point.

With some practice you can get very strong and clean looking joints 😀

Here's a serviceable, if somewhat sloppy repair I did today.

I got a combo 3.5 / 5.25 floppy in the mail that arrived damaged. After contacting the seller, I attempted a repair.

This plastic was not soluble in acetone. Since I had to rebuild some of the plastic, and the parts were small, I decided to go with CA & Soda

Three latches were broken off, the centering post was damaged, and one end of the 3.5 drive door was missing.
I already straightened the center post when I took this picture.

First I made a pile of baking soda ( Sodium bicarbonate ) and CA glue on some glossy, non-porous paper

Then I dipped the end of the drive door back and forth

Then I filed it down with my wife's nail file (and later freed the spring )

I needed to straighten some of the metal on the drives with pliers.

I glued the center post and clips back in place with CA glue, but two of the clips bent out of position when I was reattaching the face.
They were still attached on the far edge, so I applied additional glue, pushed them them back in place, and sprinkled with soda to make a fillet on the stress side.

Repair is a little sloppy, but looks fine from the outside other than that the 3.5 flap moves slower than expected. I hope that with time, the CA glue peg will smooth out and move more freely.

In hindsight, I would have left the spring off while building the new peg. it would have made the filing a lot easier.

kaputnik wrote on 2022-04-02, 16:41:

Usually welding broken thermoplastics with the soldering station. […]
Show full quote

Usually welding broken thermoplastics with the soldering station.

250 deg C is a good starting point for ABS, go higher if necessary. Be careful not to burn the plastic, you only want to melt it. Also, make sure you clean the soldering iron tip very thoroughly before starting, you don't want the weld contaminated by solder or flux residues. I'm keeping a dedicated chisel tip for plastic welding.

3D printer filament is very convenient to use as filler if needed, but basically anything made from the same material as the parts you're welding works.

If working with a plastic type that can be dissolved chemically without too nasty stuff (I'd recommend avoiding chlorinated hydrocarbons etc), the weld can be evened out and strengthened further with a plastic/solvent slurry. For ABS, ASA, etc acetone works well as solvent.

A hot air rework station with a small nozzle can also be used for the above. It's quite easy to screw up though, be careful. Many plastics tends to deform when heated above their glass transition point.

With some practice you can get very strong and clean looking joints 😀

I have a feeling heat won't work that well for this repair because of how small it is.

douglar wrote on 2022-04-02, 19:43:

Here's a serviceable, if somewhat sloppy repair I did today.

That's pretty impressive though, probably because it's a similar part to what I have to fix.

I've always thought of Superglue as sort of an inferior brittle glue with no shear strength, but if it's holding these clips in place that's amazing. Is this regular, standard CA? I do have Loctite plastics bonder that I believe is nothing more than a tube of CA and some type of prep chemical ("activator") that I perhaps should try. Have you ever tried that? I am curious what is in the activator.

eesz34 wrote on 2022-04-04, 01:26:

douglar wrote on 2022-04-02, 19:43:

Here's a serviceable, if somewhat sloppy repair I did today.

That's pretty impressive though, probably because it's a similar part to what I have to fix.

I've always thought of Superglue as sort of an inferior brittle glue with no shear strength, but if it's holding these clips in place that's amazing. Is this regular, standard CA? I do have Loctite plastics bonder that I believe is nothing more than a tube of CA and some type of prep chemical ("activator") that I perhaps should try. Have you ever tried that? I am curious what is in the activator.

This was regular “runny” CA glue with baking soda sprinkled on as a curing agent it to make make fillets. The replacment peg and the fillets were built up with 2-3 layers of glue & soda.

eesz34 wrote on 2022-03-23, 13:57:

Anybody here have considerable experience with plastic repair?

If anyone cares, I ended up using JB Plasticweld 2 part epoxy and it worked great. I sanded the sides so it holds better, cleaned the areas with alcohol and rigged up something to maintain pressure on the part and let it cure for a few hours. Then I applied it to the sides which should considerably strengthen it.

And despite the packaging claiming a 1 hour cure time, that's not at all the case. In tests I found it to be quite soft after 1 hour, and when left overnight it significantly improved.