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I need to attach a relatively small piece of ABS plastic to another. The small piece is about 4 mm wide, 1 mm tall, and I can make it between 3-6 mm long.

I need to attach it so that 1 mm of the plastic hangs out over the edge of the other piece.

This overhang will be subject to regular, small pressure. It's a catch for another piece, to hold it in place. It's not a lot of pressure to hold it, but the pressure of catching and uncatching it can be an issue.

enter image description here

If you look at this diagram, I need to fuse the blue parts, so that the red part can by slid on and off vertically. The red and blue parts that overlap are slightly rounded, and the red has some give, which makes the catching fairly easy.

If it helps, this is for a modification to an action figure. The catch is the kind you'll find on Transformer action figures, which gently hold pieces in place.

  • Is there a reason what you learned in this question: http://crafts.stackexchange.com/questions/384/can-i-melt-or-weld-broken-abs-plastic-back-together?rq=1 does not apply here? FYI I would have tested acetone. – Matt Aug 23 '16 at 01:14
  • @Matt For this one, I specifically need it to be able to withstand the pressure, instead of just having it be a decorative piece that needs attaching. I don't know if acetone will withstand that constant wear. –  Aug 23 '16 at 02:13
  • Just to close the loop, a solvent weld will fuse the parts together as if it was a single piece of plastic. It will withstand pressure as well as if the part had originally been molded that way. If there's enough pressure to break the plastic, it will break at its weakest point, which isn't likely to be the weld. – fixer1234 Sep 07 '19 at 21:13
  • @fixer1234 That would be ideal, but IME, welded ABS toys are still often weaker at the "seams" where they were welded, especially when the plastic is warmed. –  Sep 07 '19 at 21:58
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    The usual cause of that is either not letting the weld harden long enough (weaker when warmed is because there's still a little solvent present), or choice of solvent. ABS is a mix of resins that don't all have the same solubilities. If you pick a solvent that isn't good for all 3 resins, the weld won't be as complete, so it will be weaker than molding one piece. A mixture of solvents may work better. Also, once the weld seems hard, warming the piece without stressing the joint can help diffuse solvent away from the joint. Then let it harden again. Full strength can take days. – fixer1234 Sep 07 '19 at 22:54

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PlasticWeld is a hand-mixable, fast-setting epoxy putty that forms a durable bond to most major plastic types. *After mixing, it forms a polymer compound that can be molded or used to build up and repair just about anything made from plastic. When cured, it can be sawed, drilled, carved, sanded and painted. PlasticWeld has a 20-25 minute work life; functional cure occurs in 2-3 hours. PlasticWeld cures to an off-white color, is rated at a tensile strength of 350 PSI. Does not adhere to polyethylene, polypropylene or some other plastics. Test for adhesion first.

Great for: Rigid & Semi-flexible Plastic ABS, PVC & CPVC Pipes Automotive Trim & Bumpers Fiberglass Parts Vinyl Siding

Found at most automotive and hardware stores:Products link to O'Reilly's

DETAILED DESCRIPTION Repair and rebuild any rigid and semi-flexible plastic including ABS, PVC and CPVC Bonds instantly Superior strength Will not shrink or pull away Rebuild automotive trim, fiberglass parts and vinyl siding ADDITIONAL DETAILS Set Time (hr): 0.25 Hour Cure Time (hr): 3 Hour Volume (ml): 60ml Volume (Oz): 2 Ounce Cure Color: Off White Material: Epoxy Resin Color: Off White Solvent Resistant: Yes Temperature Range (Deg F): -67 To 300 Degree Strength Rating (psi): 350 psi Strength Rating At 400 Degrees (F): 350 psi Water Resistant: Yes Waterproof: Yes Weatherproof: Yes Type: Epoxy Stick

enter image description here

EDIT: Adding instructions here so it is not lost in comments.

INSTRUCTIONS CUT: Remove required amount of putty. MIX: Thoroughly knead putty with fingers to a uniform color. APPLY: Press putty firmly to the surface to be repaired.

norcal johnny
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  • Auto store! That makes sense. Any tips on applying it? I would need to put down a very small amount, and it needs to hang over the edge. Is there a good material it won't stick to that I can use to hold it in place? –  Sep 08 '16 at 08:02
  • It initially forms into a putty and so staying in place will not be a problem, especially with the shapes and formation of your parts. Simply apply pressure after following instructions and it will be fine. INSTRUCTIONS

    CUT: Remove required amount of putty. MIX: Thoroughly knead putty with fingers to a uniform color. APPLY: Press putty firmly to the surface to be repaired.

     – norcal johnny Sep 08 '16 at 08:12