Screws and Nuts vs Cyanoacrylate Glue
I'm working on a vent cover that will have a pipe I print sticking out from it. The vent cover is covering a hole in a wall and the pipe sticks out horizontally. The vent hole I'm covering is large enough I'll have to print the cover in halves or quarters, since the full cover size is too big for my print bed. I'm using a frame on the back to hold the vent cover pieces together.
Considering that the vent cover and frame will be supporting the printed pipe or tube connected to it, I'm working out how to connect the parts so they'll stay firmly joined and sealed together. Quite often when I have printed parts that fit together, I use screws and nuts to join them together, but sometimes use glue. I'll be honest: I tend to have a distrust of glue, overall. While I know cyanoacrylate glue works well with PLA, and I've heard of it working well with PETG (any experience otherwise please let me know), I remember trying to use "superglue" in the 70s and finding it often did not hold what it claimed it would. But I've also read that the glue can often hold so well it'll hold up better than print filament.
I'm trying to decide whether to use screws and nuts to join the frame and cover plates, or to use glue instead. I figure part of the issue with glue is how large a surface area is used for the joint between two pieces.
The vent is in a foundation wall, so it's roughly 8" high by 16" wide (roughly 200mm x 400mm). The frame will be in 8 pieces around that and extending about 40mm out from the edges, to allow enough room to drill into the surrounding cinder blocks, put in anchors, and make sure those holes aren't right near the edges.
I'm interested in hearing not just what people would prefer to use to join the frame and cover plates, but also any background on factors to consider or any pros and cons of using either method to join printed parts either way.
RE: Screws and Nuts vs Cyanoacrylate Glue
From.my experience cyanoacryl glue tends to wear out over time due to weather conditions - few times I saw parts to break due to water usage.
But it really depends on the materials you have, some plastic and glue will turn itno a more resistant structure than the originally printed part, because glue will literally melt the plastic and allow better bondings - such as ABS/ASA and acentone.
Screws are good if tou need to disassemble it from time to time, and also allow adjustments.
Certain holes and joints can be filled with a silicone, especially if this needs to be air/water tight with low pressure.
See my GitHub and printables.com for some 3d stuff that you may like.
RE:
I use ASA and glue parts with glue for plastic models, which in my experience is effectively welding the parts together.
I try to give answers to the best of my ability, but I am not a 3D printing pro by any means, and anything you do you do at your own risk. BTW: I have no food for…
RE: Screws and Nuts vs Cyanoacrylate Glue
I sell a couple of products where I use CA glue to fuse ASA parts, and I've never seen or heard of any issues with it. In general I have found CA to work well with PLA and ASA, not so much with PETG. I also found some brand to work better than others. Currently I use "GH1200" as well as "HFT" off Amazon.
Formerly known on this forum as @fuchsr -- https://foxrun3d.com/
RE: Screws and Nuts vs Cyanoacrylate Glue
The vent is in a foundation wall, so it's roughly 8" high by 16" wide (roughly 200mm x 400mm). The frame will be in 8 pieces around that and extending about 40mm out from the edges, to allow enough room to drill into the surrounding cinder blocks, put in anchors, and make sure those holes aren't right near the edges.
Slightly off-topic -- but is this really a use case for 3D printing? What's wrong with a board, either wood or plastic, with a circular cutout? (Or two boards with semi-circles, assuming the pipe is already in place and you need to fit the cover around it.) Maybe 3D-print a narrow circular mask that fits around the tube and covers the cutout in the board, to give you a bit more tolerance there.
Glues are a whole science of their own ... and sometimes a black art as well.
@_kaszpir_ Ordinary cyanoacrylate is not waterproof - but waterproof versions are available, look for superglues sold for boatbuilding or perhaps fishing.
@tango Despite the above, cyanoacrylate is not particularly good with FDA parts, it works best with intimate contact and the interlayer surface texture causes voids - often the failure is not a glue failure but looser surface strands being ripped out of the part. Better grip can be had by sanding both surfaces but not cleaning away the last of the dust before gluing.
Superglues are extremely good glues but acquired a poor reputation because many users didn't put in the effort to prepare the surfaces and just used far too much and expected miracles.
For your vent cover I would use PETG and screws although the right adhesive would work well - you would need a petroleum based one with a heavy gel texture (next time you buy something in a PET bottle peel off the label and notice the adhesive.) Because it's to be used outdoors you must paint the part, UV light slowly degrades PETG but if it's painted it will last a very long time.
If you are using other filaments - look up the solvent. If it is volatile a good 'cement' type glue can be made by dissolving a few scraps in solvent but take care with ventilation.
Cheerio,
RE: Screws and Nuts vs Cyanoacrylate Glue
From.my experience cyanoacryl glue tends to wear out over time due to weather conditions - few times I saw parts to break due to water usage.
This is a vent under a deck and in an area where it won't be getting that wet and won't be getting exposure to direct sunlight, but when I design something like this, I try to make it a "general use" design instead of a "specific use" design. In other words, I don't like designing something for this one case and having to redo it if I need another. With that in mind, and with what others say, I won't count on the glue.
But it really depends on the materials you have, some plastic and glue will turn itno a more resistant structure than the originally printed part, because glue will literally melt the plastic and allow better bondings - such as ABS/ASA and acentone.
Read that and recommendations for ABS/ASA in other replies here - but I looked it up. I will be building a vent hood over my print station at some point. It'll connect to a system I've already made, using designs from the same line as what I'm doing now (and I use AC Infinity's 4" vent fans that can be controlled with some simple hacking). Until then, after what I saw about those filaments, I'm going to hold off. When I start using those, I want to be able to have the print in a hood that I can vent once the print is done.
Screws are good if tou need to disassemble it from time to time, and also allow adjustments.
That's one reason I often like screws. I've found too many of my "permanent" designs reach a point where, after use, I think about changes I want to make and often am glad I haven't glued parts, because I can pull off one part and replace it with a new design and just put the screws back in and have a new version. I like screws for that and other reasons.
Certain holes and joints can be filled with a silicone, especially if this needs to be air/water tight with low pressure.
Since this is in the foundation vent to my house crawlspace, I'll be using silicone to seal the place where the vent goes up against the hole in the foundation wall. While it doesn't have to be air tight, I find myself in that crawlspace to add new ideas I have way too often and prefer to keep the bugs and spiders out of there!
I use ASA and glue parts with glue for plastic models, which in my experience is effectively welding the parts together.
I'll hold off on ASA until I get my vent hood over the printers, so it doesn't make my entire shop (and maybe my wife's studio, next door to my shop) smell!
The vent is in a foundation wall, so it's roughly 8" high by 16" wide (roughly 200mm x 400mm). The frame will be in 8 pieces around that and extending about 40mm out from the edges, to allow enough room to drill into the surrounding cinder blocks, put in anchors, and make sure those holes aren't right near the edges.
Slightly off-topic -- but is this really a use case for 3D printing? What's wrong with a board, either wood or plastic, with a circular cutout? (Or two boards with semi-circles, assuming the pipe is already in place and you need to fit the cover around it.) Maybe 3D-print a narrow circular mask that fits around the tube and covers the cutout in the board, to give you a bit more tolerance there.
Yep, off topic. I'm asking a specific question and I don't want to redirect the discussion to my reasoning for printing vs. something else. That's another discussion.
Glues are a whole science of their own ... and sometimes a black art as well.
@_kaszpir_ Ordinary cyanoacrylate is not waterproof - but waterproof versions are available, look for superglues sold for boatbuilding or perhaps fishing.
SO glad you mentioned this here! That's somethign I need to know!
@tango Despite the above, cyanoacrylate is not particularly good with FDA parts, it works best with intimate contact and the interlayer surface texture causes voids - often the failure is not a glue failure but looser surface strands being ripped out of the part. Better grip can be had by sanding both surfaces but not cleaning away the last of the dust before gluing.
FDA parts? Not sure I get what you mean, unless you mean the US FDA and you're talking about parts that might be used for food! But your point about the reason this glue fails is well taken - it comes down to just another reason to avoid using the glue if I have options.
Superglues are extremely good glues but acquired a poor reputation because many users didn't put in the effort to prepare the surfaces and just used far too much and expected miracles.
With a printed surface, I prefer not having to sand or do much work like that on a surface, since it always seems I get strange results more than I get a smooth surface from sanding.
For your vent cover I would use PETG and screws although the right adhesive would work well - you would need a petroleum based one with a heavy gel texture (next time you buy something in a PET bottle peel off the label and notice the adhesive.)
I get that - yes, something that would cover a surface area more and "stretch" a bit more than just something joining to really flat surfaces. Can you give me more detail on just what I'd look for if I want something like that?
Because it's to be used outdoors you must paint the part, UV light slowly degrades PETG but if it's painted it will last a very long time.
I brought this up a while back (at least a year ago). While this part will be under a deck and not get any direct sunlight, I have some vent pipes that would be exposed to sunlight and a few people specifically said to use PETG for it and definitely NOT use PLA. I'm not saying you're wrong - I'm bringing that up and saying I'd really like more info on that. For one thing, I have two vent outlets that are exposed to UV light and I'd like to know what to replace that with when I have time to reprint them.
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I think my bad experiences with superglue come from the fact that I was using it with PETG, and apparently this is not the best idea.
I remember also using other glue with PETG and oh boy, this one melted the PETG nicely and the parts looked like welded, the name of the glue was a generic 'Universal plastic glue' so... 😀
Thanks to the others for the recommendation, wasn't aware there is a CA version for wet appliances.
See my GitHub and printables.com for some 3d stuff that you may like.
RE: Screws and Nuts vs Cyanoacrylate Glue
Yep, off topic. I'm asking a specific question and I don't want to redirect the discussion to my reasoning for printing vs. something else. That's another discussion.
XY problem. 😉
RE: Screws and Nuts vs Cyanoacrylate Glue
I prefer not having to sand or do much work like that on a surface, since it always seems I get strange results more than I get a smooth surface from sanding.
With almost all thermoplastics use wet and dry paper - wet; otherwise the friction heat melts the work.
Can you give me more detail on just what I'd look for if I want something like that?
Er, the one I've been using recently is a UK shoe-repair trade adhesive called 'Gripsotite'; I don't know about international availability but there will be similar alternatives.
exposed to sunlight and a few people specifically said to use PETG for it and definitely NOT use PLA. ... are exposed to UV light and I'd like to know what to replace that with
PLA does not survive UV for long - in the order of a few months. PETG does much better but the surface will begin to degrade in around a year and the damage will creep inwards, a coat of paint stops that.
I have been experimenting with a filament called 'BioPro' from 3DTomorrow and so far it has survived, unpainted, for 3 years attached to a south facing wall here in the UK.
Cheerio,
RE: Screws and Nuts vs Cyanoacrylate Glue
You don't randomly glue two things together. You design the interface to be a glue joint in terms of surface area and stress, then glue it. I also have a mistrust of glue. I've had really good results putting a dovetail on edges. If it's tight, I don't even need glue, but if glued it would never come apart. I did a weathervane where the front and rear blades go into dovetail slots in the round center body and they've been banging around outdoors for months now without any glue at all.