How to mount standoffs without drilling the enclosure? - Page 1
Forum section: electronics / general

author: caprider
author_rank: Contributor
timestamp: January 31, 2022, 11:17:50 pm
content: How can you add/stick nylon M3 female threaded standoffs to a plastic enclosure without drilling the enclosure?I assume superglue won’t last. Are you using another piece of plastic just to glue it in the box and have standoffs mounted with bolts on it?Those snap on/adhesive standoffs are one way to do it. But I prefer bolts instead of snap-on system.What would be some smart ways to achieve this?Or what is your preferred way to mount a PCB in an enclosure? besides 3d printingThanks.

author: TimFox
author_rank: Super Contributor
timestamp: January 31, 2022, 11:36:11 pm
content: In general, the nylons (along with the Teflons) are difficult if not impossible to attach using adhesives.Can you get acrylic (Lucite) or polycarbonate (Lexan) standoffs?

author: rob77
author_rank: Super Contributor
timestamp: January 31, 2022, 11:55:54 pm
content: make a base plate from a sheet of plastic - drill and mount the standoffs, then glue the base plate with strong double sided tape to the enclosure.the standoffs alone have way too small surface area to make it work with adhesive. blob of hot snot works for very light loads but not usable for anything what doesn't sit on a shelf

author: caprider
author_rank: Contributor
timestamp: February 01, 2022, 12:14:13 am
content: Quote from: TimFox on January 31, 2022, 11:36:11 pmI think so. How would that make attaching different?

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 01, 2022, 12:55:18 am
content: Solvent glues and even normal glues can be used with those plastics, they don't work well with the 'greasy' plastics like teflon, nylon and polyethylene.How about using the standoffs that have a square pad with some double-sided tape? I've seen those used in commercial products.Google image search 'adhesive PCB standoff' and you'll see what I'm talking about.

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 01, 2022, 01:26:06 am
content: Buy an enclosure with slots or mounts for PCBs already molded in.Or, if it's just because you don't like screw heads sticking out, use countersunk screws instead.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 01, 2022, 01:26:13 am
content: Just get some decent wood. Balsa, Asian white wood, etc. I would use a square section that fit the inside width. Drill for the standoffs. Press the standoffs into those holes and glue the strips to your enclosure. A little CA/superglue will ensure the standoffs stay in the wood. CA reacts poorly with some acrylics and causes brittleness. If the enclosure is ABS, I think they CA would be OK, but I would probably use an epoxy. As for nylon and epoxy, roughen the nylon and clean well (e.g., use MEK or acetone). Nylon fixtures are used extensively in model airplanes with epoxy. If you do not like the wood idea, I would use epoxy and be sure there is a good fillet around the nylon standoff.

author: geggi1
author_rank: Frequent Contributor
timestamp: February 01, 2022, 06:36:34 am
content: Make a baseplate that can be glued down to the box.I have done this several times with an aluminium baseplate.Buff the back of the aluminium plate with sandpaper or similar.Install the standoffs.Clean the back with IPA or some other degreaserand repeat in the box.Glue the plate down with two component epoxy that is not to liquid and let it harden for the required time.

author: SMTech
author_rank: Frequent Contributor
timestamp: February 01, 2022, 09:38:06 am
content: Quote from: Kim Christensen on February 01, 2022, 01:26:06 amThis. And unlike some of the other suggestions, this isn't a random thought or a nasty hack, its how commercial products that are mounted in an off the shelf enclosure are put together.Most enclosures have a set of studs and grooves in the bottom. You use these to mount your PCB in the base of the box, if you need spacers you can temporarily tack them onto your PCB with a glue of your choice to hold them in place. Often enclosures will have a pre-cut base plate you can buy separately, galvanized steel but sometimes wood or some kind of composite and you can drill that to match whatever you like, adhesives are also more likely to work with the base plate.Adhesive latching spacers work OK for very light PCBs even when stuck to ABS enclosures but can come unstuck at random IME.However if you are mounting in the lid, suck it up and drill holes.

author: TimFox
author_rank: Super Contributor
timestamp: February 01, 2022, 02:56:28 pm
content: Quote from: caprider on February 01, 2022, 12:14:13 amPMMA (acrylic) and polycarbonate are easy to glue.

author: caprider
author_rank: Contributor
timestamp: February 01, 2022, 03:30:52 pm
content: Looks like ~all standoffs from TME are of polyamide:https://www.tme.eu/ie/en/katalog/plastic-standoffs_112547/Does that mean “nylon” and the glue won’t last?Or which is a good glue for polyamide?Thanks.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 01, 2022, 07:34:08 pm
content: Quote from: caprider on February 01, 2022, 03:30:52 pmWhere did you get that idea? Yes, it is true that polyamides, of which nylon is one, cannot be solvent welded. Neither can Teflon (as an example). But both can be "glued" with epoxy and other adhesives very effectively. With nylon, you have a choice of chemical primers or just using cleaning and abrasion (usually the order is clean, abrade, clean). With Teflon, abrasion is much less effective, but chemical primers are really quite effective.The most important part of "gluing" anything (v. welding) is joint design. Butt gluing wood doesn't work particularly well either. It also can't be solvent welded. You have had several suggestions to improve the butt joint of the standoff to the plastic case. Why ignore them?

author: tszaboo
author_rank: Super Contributor
timestamp: February 01, 2022, 11:16:47 pm
content: There are standoffs with adhesive bases.Like these:https://www.essentracomponents.com/en-nl/p/self-adhesive-pcb-supports?cacheBust=true

author: free_electron
author_rank: Super Contributor
timestamp: February 01, 2022, 11:27:39 pm
content: put in a screw on the opposite side and glue that down using two component epoxy

author: BrokenYugo
author_rank: Super Contributor
timestamp: February 02, 2022, 12:25:56 am
content: Why not just use metal standoffs and a thickened epoxy?

author: SmallCog
author_rank: Frequent Contributor
timestamp: February 02, 2022, 02:00:48 am
content: If for some reason countersunk screws through the case aren't an option (IE water ingress issues) then I'll either use a box that has threaded posts built into it or if there's no suitable box like this available I'll glue in a base plate with my mounts on it. I tend to do this a lot when building/packaging inside of "pelican" style instrument cases where the closed lid water/dust proofing can't be risked by penetrating the base and sides.Very rarely I'll have a board to mount in a box with the threaded posts in it that it doesn't match up. I combine the 2 then with a board screwed to the box that has mounts for the other board.Example of the type of boxhttps://www.tro.com.au/Polycarbonate-Enclosure-Clear-Lid-IP66-200H-x-120W-x-90D?gclid=EAIaIQobChMIt7ecsvXf9QIVU5lmAh2PHQA6EAQYASABEgKAL_D_BwEThat said I do a lot of boxes up with countersunk holes to attach boards if there's no perceived risk associated with this method. Often hide these behind the rubber feet for aesthetic reasons

author: ledtester
author_rank: Super Contributor
timestamp: February 02, 2022, 02:33:03 am
content: My interest related to this topic would be to hide the screw heads from showing when mounting a display module, e.g.:(pic comes from this PDF:http://www.diyleyuan.com/JC/3B1E.html)One idea is to 3D-print a bezel such as this:https://www.thingiverse.com/thing:3459425For small 7-segment LED displays I've even thought of repurposing those snap-in bezels used in all of those cheap volt/amp meters, e.g.:Maybe there's a way to just buy those bezels w/o the meter or 3d-print your own.