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I need to glue a plastic thingy inside a metal tube. There is a notch for it to fit in, and it is slightly tricky. Therefore I do not want the glue to soldify too quickly. Also, I cannot press on the surfaces where the glue will be, but it is pretty tight.

I do not know what type of plastic it is, but it is hard. It does not bend. The metal is stainless steel I guess.

Edit: it is not outdoors or under water. Normal house temperature.

What sort of glue should I be looking for?

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Epoxy. But forget brand. Look at speed.

Nothing annoys me more than people cheerleading for brand X, and completely ignore brand X's material characteristics and whether they are a good fit for the application.

Epoxies are sold in a variety of speeds from 1 minute to 48 hours. Some even will never cure unless autoclaved. You need to select a speed that is appropriate for you. Slower is better for a novice.

Additives to the epoxy are also appropriate to discuss, as they help epoxy be a strong filler, a bulky filler, stiffen up its flowability, etc. Any chandlery or plastics store should be able to help with that.

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JB weld is one of the best epoxies I've used. It's specially good for multiple surfaces. When gluing plastics, you want to roughen up the surface so the glue adheres to it better. If the metal is smooth, roughen it up too with some emery paper before gluing.

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  • @TomasBy This particular kind sets in 4 to 6 hours and fully cures in 15 to 24 hours. They have other kinds that set faster.
    – JACK
    Jul 17 '20 at 13:42
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    Epoxy takes minutes to hours to bond and has body so if it is not totally flat surfaces like super glue requires the epoxy will fill the void.
    – Ed Beal
    Jul 17 '20 at 13:44
  • There's no such thing as a "best" epoxy. It all depends on the speed, chemical makeup, and additives that are in it, vs. the application. For instance, bondo is epoxy, but it's stuffed with fairing filler additives, which makes it a poor choice for OP. Jul 17 '20 at 18:13
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Cyanoacrylate glue, commonly known as "superglue" will bond nearly any two types of material together. Usually it's thin enough to be pulled by capillary action into the thin space between two parts that have already been assembled. You simply put the plastic thingy into the metal whatsits then put a drop or two of glue on the joint line. The glue should disappear into the joint and it'll set in a matter of seconds and you'll be good to go.

You do not want to put too much glue in there - you literally only want one or two drops! If you can still see the glue at the joint line you've got too much. If you do get too much it will take forever to cure and you'll end up with it gluing your fingers on as well. You can get your fingers off by pulling. You'll pull skin off and it'll likely hurt, but you'll survive. If you move quickly, you'll get a bit on your fingers but get your fingers off before they're glued in place. Now you'll have some on your fingers and it'll wear off in a day or two of general living.

Purchase a package of very small, single use tubes. The stuff invariably dries and hardens at the tip of the tube once you've opened it, and just about nothing will reopen the tube, so even the industrial size tubes end up being "single use". May as well start out planning on throwing it out after the one use.

If you need to apply the adhesive before assembling the parts, you probably want to use epoxy to join two dissimilar materials like plastic and stainless steel. (You sure it's actually stainless and not galvanized or zinc coated?) Check the labeling on the package you're considering purchasing - most of the ones I've seen will contain a little matrix of materials with an indicator showing whether it will or will not work on any particular combination.

For small use, you'll probably end up with a small, dual-syringe dispenser. One push will expel the correct amount of resin and hardener. Squeeze it out onto a piece of scrap cardboard, wood, or other disposable surface. Use a stick (or the provided stirrer) to mix it thoroughly, then slather a bit on the plastic thingy and gently push it into your metal whatsits. Wipe off any excess and set it on a piece of wax paper to dry.

Be sure to read the instructions that come with the epoxy to ensure you've mixed your particular kind properly and to see what the setting time is. Don't use it until it's fully set.

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  • No I am not sure about the metal either.
    – Tomas By
    Jul 17 '20 at 13:39
  • Also, I believe I will have to put the glue on the metal towards the bottom, and then push the plastic in. Too tedious to explain the physics exactly...
    – Tomas By
    Jul 17 '20 at 13:41
  • FYI, there are slow setting super glues. Loctite makes one that works on metal and plastic and has a longer set time. Like 7$ for a bottle. Jul 17 '20 at 13:41
  • @TomasBy if you put a drop of glue at the joint between the metal and plastic, capillary action will draw the glue into the joint, no matter where the two pieces are in relation to each other. Assuming, of course, that they are tight against each other. If there are gaps, then epoxy is 100% your best bet.
    – FreeMan
    Jul 17 '20 at 14:38

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