Is waterproof glue my best option?
March 3, 2011 5:20 AM Subscribe
I would like to permanently reattach small metal fittings to their plastic housing- should I use waterproof glue?
I have some small plastic bodied mouthpieces with metal pieces that get regularly washed and soaked in cleaning solution. Looks like this-- the loose metal piece is supposed to be seated next to the other one in the plastic body. The two metal pipes are put inside rubber tubing and often experience pulling stress such that some of the mouthpieces have broken and the metal pieces have become detached from the plastic bodies.
When we sent the broken mouthpieces back to the company that made them for repair, they glued the metal pieces in place- and the metal bits detached again after light use.
I would like to permanently reattach the metal fittings to the plastic bodies. I probably shouldn't do anything that would deform the plastic or the metal piping bits. Any suggestions in terms of adhesive or how to better do this? I see that the original Gorilla Glue is waterproof. I did see the thistothat site but wanted to check if there's anything else I could do.
I have some small plastic bodied mouthpieces with metal pieces that get regularly washed and soaked in cleaning solution. Looks like this-- the loose metal piece is supposed to be seated next to the other one in the plastic body. The two metal pipes are put inside rubber tubing and often experience pulling stress such that some of the mouthpieces have broken and the metal pieces have become detached from the plastic bodies.
When we sent the broken mouthpieces back to the company that made them for repair, they glued the metal pieces in place- and the metal bits detached again after light use.
I would like to permanently reattach the metal fittings to the plastic bodies. I probably shouldn't do anything that would deform the plastic or the metal piping bits. Any suggestions in terms of adhesive or how to better do this? I see that the original Gorilla Glue is waterproof. I did see the thistothat site but wanted to check if there's anything else I could do.
Some plastics require very specific glues, and glues that say, "good for plastic and metal" don't stick at all. Can you call the manufacturer for a recommendation?
posted by StickyCarpet at 6:23 AM on March 3, 2011
posted by StickyCarpet at 6:23 AM on March 3, 2011
If it helps, the type of plastic you're dealing with here is almost definitely nylon.
posted by clorox at 6:24 AM on March 3, 2011
posted by clorox at 6:24 AM on March 3, 2011
Just a side remark: some glues can expand when setting (Gorilla Glue being one of these) so you may wish to test the glue prior to using it, lest you be surprised by a mass of rapidly-hardening foam that's going places you don't want it to go.
posted by aramaic at 8:25 AM on March 3, 2011
posted by aramaic at 8:25 AM on March 3, 2011
Are they ever getting hot or just washed in warm water? Hot glue would work really well, but it will probably release if temperature gets over maybe 50ish centigrade. The plastic looks like polyethylene to me and epoxies and the like work OK but have trouble gripping. JB weld or another two part might do well if you have a tight fit and a lot of bonding area. It would be nice to use a lower viscosity adhesive so you can build up an edge around the two parts and maximize the contact.
I'm also thinking superglue mmmmmmaybe if you have a tight fit.
Regardless, do a good joint prep - soap+water and then a wipe down with acetone/rubbing alcohol. Don't get fingerprints on of the sealing surfaces.
posted by Dmenet at 11:27 AM on March 3, 2011
I'm also thinking superglue mmmmmmaybe if you have a tight fit.
Regardless, do a good joint prep - soap+water and then a wipe down with acetone/rubbing alcohol. Don't get fingerprints on of the sealing surfaces.
posted by Dmenet at 11:27 AM on March 3, 2011
Response by poster: -these cost us ~$100 each so not too disposable in our case and I have 6 that I would like to put back together. I'm not sure the company who sold us the mouthpieces will help us talk to the actual manufacturer but I will check in with them again (they're the ones who tried some kind of glue in the first place)
-the metal tube sits about a quarter inch into the plastic piece, and I think there is a teeny rim in the hole in the plastic part that prevents it from going further
- that is a good point about the expanding glue
- we don't wash this in very hot water. I am going to guess that they don't get particularly hot although to be more specific, we have cigarette smokers smoking through them, so they are exposed to smoke which does come from burning stuff. But still, I don't think the mouthpieces really heat up from the exposure.
Thanks for the suggestions.
posted by tangaroo at 7:05 PM on March 3, 2011
-the metal tube sits about a quarter inch into the plastic piece, and I think there is a teeny rim in the hole in the plastic part that prevents it from going further
- that is a good point about the expanding glue
- we don't wash this in very hot water. I am going to guess that they don't get particularly hot although to be more specific, we have cigarette smokers smoking through them, so they are exposed to smoke which does come from burning stuff. But still, I don't think the mouthpieces really heat up from the exposure.
Thanks for the suggestions.
posted by tangaroo at 7:05 PM on March 3, 2011
I would use locktite. It's made specifically for hold threads together.
posted by I love you more when I eat paint chips at 8:14 PM on March 3, 2011
posted by I love you more when I eat paint chips at 8:14 PM on March 3, 2011
-these cost us ~$100 each
That's highway robbery unless this is medical equipment, in which case the price will be larded with liability insurance costs. I think you could have them (or an improved version of them) custom-made to your specifications for less, even in small quantities. That part has probably fifty cents worth of material, and the machining is not especially difficult. At that price I'd expect sterling customer service, which in this case would've involved the manufacturer saying something like "We are so sorry about our defective product. We will replace these at no cost to you." The fact that they tried to glue them back together at all is really disappointing. (BTW, I have some machining experience and used to work in prototype model making).
The holes into which the metal tubes fit should've been bored a few thousandths of an inch smaller to provide an interference fit. Glue should not be necessary at all. I'm sure that an interference fit is what the designer of this part intended, but something went wrong, i.e. the design was off a bit, or the manufacturer tried to save time by drilling the holes to size in one step instead of drilling undersize and reaming to a precise diameter. Regardless, I think "defective" is a more appropriate descriptor of these parts than is "fragile."
posted by jon1270 at 5:55 AM on March 4, 2011
That's highway robbery unless this is medical equipment, in which case the price will be larded with liability insurance costs. I think you could have them (or an improved version of them) custom-made to your specifications for less, even in small quantities. That part has probably fifty cents worth of material, and the machining is not especially difficult. At that price I'd expect sterling customer service, which in this case would've involved the manufacturer saying something like "We are so sorry about our defective product. We will replace these at no cost to you." The fact that they tried to glue them back together at all is really disappointing. (BTW, I have some machining experience and used to work in prototype model making).
The holes into which the metal tubes fit should've been bored a few thousandths of an inch smaller to provide an interference fit. Glue should not be necessary at all. I'm sure that an interference fit is what the designer of this part intended, but something went wrong, i.e. the design was off a bit, or the manufacturer tried to save time by drilling the holes to size in one step instead of drilling undersize and reaming to a precise diameter. Regardless, I think "defective" is a more appropriate descriptor of these parts than is "fragile."
posted by jon1270 at 5:55 AM on March 4, 2011
Best answer: When I said low viscosity I meant high viscosity...like syrupy instead of watery. Sigh. I really think hot glue would work like a champ on this, you can thinly (carefully) coat both pieces with a hot glue gun and then use a hair dryer (or heat gun if you have it) to soften up both parts and mate them. If you use the correct amount of hot glue the finished product will look pretty snappy. For $100 each you could pretty quickly buy the hardware needed to make these from scratch.
Or a two-part epoxy. That might work too.
posted by Dmenet at 1:21 PM on March 4, 2011
Or a two-part epoxy. That might work too.
posted by Dmenet at 1:21 PM on March 4, 2011
Response by poster: I think jon1270 is probably right about the fit-- historically we had some mouthpieces occasionally fall apart after we would leave one to rust overnight in solution (totally our fault), and then I think we got a poorly manufactured batch where the posts were sliding out on all the new ones.
Not medical, we just didn't realize that we had any other options (there aren't any competitors in the market for the equipment that these things work with).
I'd be interested in pursuing having a bunch of these custom-made but have no idea how this works- where should I start to look into this? I just googled "custom plastic metal prototype" and I need to be more specific but I don't know how.
Dmenet- are you thinking of a specific type of fancy industrial hot glue bc I am well acquainted with craft store variety hot glue but suspect that that's not what you're talking about.
posted by tangaroo at 8:59 PM on March 4, 2011
Not medical, we just didn't realize that we had any other options (there aren't any competitors in the market for the equipment that these things work with).
I'd be interested in pursuing having a bunch of these custom-made but have no idea how this works- where should I start to look into this? I just googled "custom plastic metal prototype" and I need to be more specific but I don't know how.
Dmenet- are you thinking of a specific type of fancy industrial hot glue bc I am well acquainted with craft store variety hot glue but suspect that that's not what you're talking about.
posted by tangaroo at 8:59 PM on March 4, 2011
Best answer: I'd be interested in pursuing having a bunch of these custom-made but have no idea how this works
You might be able to just drop into a small local machine shop and work with them in person. These parts do not require the latest technology to produce. The cuts are simple and most of the dimensional tolerances appear to be forgiving; a lathe and a drill press each made in the 1920's would be perfectly adequate to the job. I live in the rust belt, where small machine shops are easy to find. I also have 2 friends that own metal lathes and vertical mills, and I have my own woodshop; it would never occur to me to shop for such services on the internet, but I suppose not everyone has the local resources I'm used to.
The smallness of the order and your unfamiliarity with the materials might be your main obstacles, the latter because many shops that can competently make the parts will be unwilling to take responsibility for choosing what to make them from; you should probably spend a little time educating yourself on the properties of various plastics so you can approve a particular choice. The materials can easily be ordered from a company like McMaster-Carr, where the stainless steel tubing can be had for about $4 a foot and the plastic rod will be in the range of $1 - $7 per foot depending on which type you choose.
posted by jon1270 at 2:43 AM on March 5, 2011
You might be able to just drop into a small local machine shop and work with them in person. These parts do not require the latest technology to produce. The cuts are simple and most of the dimensional tolerances appear to be forgiving; a lathe and a drill press each made in the 1920's would be perfectly adequate to the job. I live in the rust belt, where small machine shops are easy to find. I also have 2 friends that own metal lathes and vertical mills, and I have my own woodshop; it would never occur to me to shop for such services on the internet, but I suppose not everyone has the local resources I'm used to.
The smallness of the order and your unfamiliarity with the materials might be your main obstacles, the latter because many shops that can competently make the parts will be unwilling to take responsibility for choosing what to make them from; you should probably spend a little time educating yourself on the properties of various plastics so you can approve a particular choice. The materials can easily be ordered from a company like McMaster-Carr, where the stainless steel tubing can be had for about $4 a foot and the plastic rod will be in the range of $1 - $7 per foot depending on which type you choose.
posted by jon1270 at 2:43 AM on March 5, 2011
Just plain old hardware store hot-glue. Properly applied it is stronger then you would think. I bet a cheap-ass gun + sticks might cost you $15, so you don't have much to lose.
posted by Dmenet at 8:57 AM on March 6, 2011
posted by Dmenet at 8:57 AM on March 6, 2011
Response by poster: Thanks all, I appreciate the suggestions and detailed answers. I'll try to get some made and experiment with the broken ones.
posted by tangaroo at 7:53 AM on March 8, 2011
posted by tangaroo at 7:53 AM on March 8, 2011
This thread is closed to new comments.
As noted on thistothat, it's hard to say what glue would work best without knowing what sort of plastic you're gluing to. I'd abrade both the plastic and the metal just a bit with fine sandpaper, and then try either superglue or some sort of epoxy. I don't think this is a great place to use Gorilla glue, but my experience with the stuff is minimal.
posted by jon1270 at 5:33 AM on March 3, 2011