Best "glue" for plastic frame

[44 AMP]

Looking for opinions on the best "glue" or adhesive/epoxy to use to repair a cracked frame on a Tec 9.

The frame is cracked to the point where, if I took the upper off, I'm sure I could snap it in two by twisting it in my hands, so I'm looking for opinions about what would be the best bonding agent to repair it.

Please don't respond with posts telling me how bad a piece of crap the gun is, and I shouldn't bother. I know very well what it is, and isn't. I just want to see if I can fix the thing to make it a LITTLE less likely to break apart IF it ever gets used again.

Thanks.

[Recycled bullet]

I use a commercial product called q bond to repair broken plastic stuff. It is cyanoacrylate glue AKA super glue with a separate tube of powdered plastic.
Sprinkle the plastic on the broken part then glue it and carry on.

The same objective can be achieved by pushing baking soda into the crack and then sealing it with the glue you can build the layers up this way then sand it down.

I don't know what type of plastic intratec make their guns out of however this technique works especially well to repair interior automotive plastics and automotive electrical connectors I've seen repairs on valve covers that held up to heat and vibration though I wouldn't recommend it for that purpose.

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[Unclenick]

That's a good suggestion. I used the baking soda approach to mend the weak molded plastic screw posts on our vacuum cleaner that kept snapping off due to bumping baseboards and what have you. I used it to build up small buttresses around each one.

For best effect, use the water-thin style cyanoacrylate glue. The thick stuff doesn't penetrate well into the baking soda. Also, you can use other powders, a powder coat powder that matches your frame color, for example, BUT try a test first. At one point I got the bright idea to try using some precipitated silica dust as the powder base. These particles are very fine, like one millionth of an inch, and the surface is crenellated, with the result that the surface area is huge and the bumps are sharp enough to nucleate crystalization, so, as you might expect, a huge area of thin glue all sets up at once, and the crystallization is exothermic, of course, so you get a rapidly heating and smoking pile of cooking glue that yellows and, in effect caramelizes itself. So, test the powder first. You want it to take thirty seconds or so to harden, and not three seconds.

That said, I will suggest another product called Plas-T-Pair. This is a plastic powder and a solvent. When you mix them, the powder turns to a soup that then sets and hardens a very short time later. The advantage is you can control how thin the soup is by the amount of solvent you add, so if it needs to run into a crack that is easy to do. The set plastic is very tough. A friend of mine broke his glasses at the bridge and patched it with this stuff and it never broke, and that is surprisingly tough duty.

Now I don't know how it will handle a polyolefin, like polyethylene. That stuff usually has to be lightly cooked at the surface careful sweeping with a propane torch flame for adhesives to be able to get a toehold. There is a plastic bonding epoxy that requires that, but epoxies have an especially hard time with plastics. But whatever you use in the end, try it out in an inside spot somewhere first, just to make sure.

[Shadow9mm]

Pics might help. I didn't realize the tech 9 had a plastic receiver, things you learn. Personally in fixing my kids glasses, with plastic frames, I have found that jb weld has worked the best. I have tried straight 2 part epoxy, super glue, and even rifle bedding compound once, but jb weld worked the best. Make sure to rough up the area a little and properly clean it so whatever you use can bond properly, I prefer brake cleaner.

While I would not say that a tech 9 is what I would consider to be a quality firearm, it certainly is a cool one. I hope you are able to get it repaired and back in good operating condition.

[44 AMP]

the Tec 9 does not have a plastic receiver, the bolt runs in a steel tube "upper" mounted on a plastic lower frame which does house several parts (fire control group, mag well, etc) but isn't technically the receiver.
(or didn't use to be, who knows what the ATF will change its mind about next week )

I was considering JB Weld, among other things. The gun was offered to me by a co-worker who was short of cash, back in the late 80s and I played with it enough to realize what it was, and wasn't. ITs buried in my stuff somewhere, not a front burner project, was just looking for opinions for what to use when I do get around to it.

Years ago, some writer called it a Walter Mitty gun, not good for a lot but fantasy fulfilment. Looks like an SMG but is legally a semi auto pistol. Mine ran well on decent ammo including handloads, when well lubed, and would run ok in all positions, including upside down.

Mechanically mine was decently accurate, but poor (and tiny) sights and a miserable trigger meant it could not be shot accurately but for spray and pray, it did work.

[Unclenick]

Wouldn't that be Walther Mitty? (Revisionist James Thurber, I know.)

[fisherman66]

Not sure how well it will work on this application, but I’ve used superglue and baking soda for projects where rigidity is important. There will me minimal flex. A little fiberglass can add strength along a plane.

[Unclenick]

We used to mix rock wool in with epoxy for that reason. Orienting the fibers perpendicular to the crack by wetting them and combing them with an old toothbrush might work, then applying the adhesive after it has dried. But I would experiment with anything like that on some scrap plastic first.

[Big Wes]

https://robart.com/products/zap-a-gap-ca

This product is amazing , I've been using it for years. Doesn't take a lot to do the job.

[Ricklin]

Since the project is not a priority, I would reach out to try and determine the exact polymer they used for that "lower receiver" part. Depending on the part a custom 3d print may be an option as well.
By knowing what Polymer was used to make the part, the best adhesive for that polymer can be selected.

[Bill DeShivs]

Ricklin's answer is the correct one.
Many glues don't adhere well to certain plastics. Many will melt plastics.
Some plastics need to be "welded" back together.
Using the correct glue is imperative.

[44 AMP]

I would reach out to try and determine the exact polymer they used for that "lower receiver" part.

The gun was made in the mid-late 80s, or at the latest in the 90s and the company that made them has been "dissolved" since approx 2001. Any suggestion on how to find out what exact polymer they used would be helpful.

[Shadow9mm]

Id try looking at the inside of the plastic part. May be some markings in the molding you can look up.

[Unkl Chuck]

I have had pretty good results using the Loctite 2 part 'Plastics Bonding System' on tough to glue plastics, it's a CA type glue with a primer. But it all depends on your plastic, some respond better to a solvent type adhesive and some do better 'welded'.
Good luck.

[Shadow9mm]

Try a test area inside the receiver where you cant see it and its not in the way. Clean it, apply some glue, let it dry, try and break it free with a screwdriver. Will tell you how well it bonds to your specific polymer.

My issue with super glue is that it tends to be brittle.

[Ricklin]

44 Amp,
Try inquiring on websites where folks may have an interest in that particular gun. I'm thinking there are still guys around who may have built them. My first guess would be a glass reinforced ABS material. From when it was made late 80's that was a hot ticket in manufacturing circles, cheap and strong.

[Shadow9mm]

Found this interesting video on "hot staplers" for plastic crack repairs. Not sure if this would fix your problem, but its an interesting idea.

https://youtu.be/dGveuYxwzg0?feature=shared

[paknheat]

May give Marine Tex a try. Build up a good layer on both sides of the crack & sand it down.


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