How do you keep nuts in holes without blocking the threads?
 
Notifications
Clear all

How do you keep nuts in holes without blocking the threads?  

  RSS
Tango
(@tango)
Estimable Member
How do you keep nuts in holes without blocking the threads?

I remember talking about this in a topic in the past and I can't remember for sure, but I think someone mentioned some kind of glue they used for this. I have parts with square holes to fit nuts in, like this:

I have some cases where I want to keep nuts fastened in a hole like that long term, so I can unscrew the screws in it and the nut will stay in there on its own, without me having to worry about it dropping out or getting pushed out when I try to put a screw in it again.

I know some people like heat set inserts, but I don't want to use them for this situation, since I can't hold a soldering iron perpendicular to this surface, since it's inside a cylinder. I can use masking tape, but this will have air blowing through it and, over time, the tape could dry out or lose its hold on the surface. I thought about glue, but I see that as a problem because I can see how the glue would easily spread and possibly end up in the threads or over the hole so it's hard to get a screw into the hole when I need to.

Posted : 12/05/2024 2:57 am
Brian
(@brian-12)
Estimable Member
RE: How do you keep nuts in holes without blocking the threads?

Can we see more of the part?  And reason you can't pocket a square nut like is done on meant if the Prusa parts?

Another option could be to pause the print at the top of a pocket and drop the nut in and print right over the top of it effectively making inside the print.

Posted : 12/05/2024 4:27 am
JP Guitars
(@jp-guitars)
Estimable Member
RE: How do you keep nuts in holes without blocking the threads?

Pocket or internal position is probably the best solution, but you could do heat set from the outside if it is not going to have too much load.

 

Or if you want to stick with glue us CA/super glue with a micro applicator: https://www.amazon.co.uk/dp/B07W5V8LFC

Posted : 12/05/2024 5:21 am
Tango
(@tango)
Estimable Member
Topic starter answered:
RE: How do you keep nuts in holes without blocking the threads?

This particular part is a pipe. I've considered making a pocket, but that would change the pipe thickness. Since it's a pipe, that's also why I can't get a soldering iron to go straight into it.. It's also why I can't put a heat set insert on the outside. For some joints I can reach in and hold the nut, but for others, I can't get to the inside area to put a screw in there or hold the nut.

It may or may not help if I include what I'm trying to do. This part is attached to a wall plate. The pipe that fits over it has flexible ducting attached. When cleaning or working in the area, I want to be able to take the duct off the pipe - but flexible duct is not durable, so I don't want to have to frequently undo the pipe clamp than redo it. It won't hold up to that. So I have a very short pipe adaptor that I can screw to the wall plate with thumb screws. That make it easy to quickly detach that pipe adaptor from the wall plate and to move the flexible duct out of the way, so I can clean or move the printers (and CNC) that are in vent hoods when I need to.

Then, later, I can re-attach the adaptor with the flexible duct to the wall plate with just tightening two thumb screws. Those screws would go into the nut in the photo, which is located in the pipe interior.

Posted : 12/05/2024 7:35 am
fuchsr
(@fuchsr)
Famed Member
RE:

I'd use CA glue. Just put it carefully on the outside four walls of the recess. Even if a tiny bit spills into the threads when you put the nut in place, a few cycles of screwing the bolt in and out will take care of it.

Posted : 12/05/2024 10:47 am
Zappes liked
Chris Hill
(@chris-hill)
Estimable Member
RE: How do you keep nuts in holes without blocking the threads?

I'd be tempted to make the hole slightly undersize for the nut, then screw in a screw from the outside until the tip is flush with the surface of the nut or just beyond.  Hold the screw head with a pair of pliers so that you can gently pull the nut into position, then apply the side of a soldering iron tip (preferably a flat tip) to the tip of the screw.  As the plastic melts, gently pull the nut into the hole, and keep it perpendicular with the pliers on the screw.  This would probably work with a threaded insert too, and would give a better grip into the plastic than a square nut.

Posted : 12/05/2024 12:26 pm
Tango
(@tango)
Estimable Member
Topic starter answered:
RE: How do you keep nuts in holes without blocking the threads?

I'd use CA glue. Just put it carefully on the outside four walls of the recess. Even if a tiny bit spills into the threads when you put the nut in place, a few cycles of screwing the bolt in and out will take care of it.

So the main point of control there is where it's applied. I can handle that.

As the plastic melts, gently pull the nut into the hole, and keep it perpendicular with the pliers on the screw.  This would probably work with a threaded insert too, and would give a better grip into the plastic than a square nut.

A couple concerns there. One is that the soldering iron is used at an angle. While I'd be holding the screw, that still means there could be issues with the nut ending up akilter. Also, if it's hot enough to melt plastic around the nut, the screw holding it in place could melt some of the hole as well.

Posted : 12/05/2024 6:22 pm
Crab
 Crab
(@crab)
Reputable Member
RE: How do you keep nuts in holes without blocking the threads?

I'd do what Chris Hill suggested.. Make it undersized. Then I'd pull in the nut with a screw. There should be enough friction that the nut will stay without glue. 

Posted : 12/05/2024 10:09 pm
languer
(@languer)
Estimable Member
RE: How do you keep nuts in holes without blocking the threads?

Heat inserts are certainly the most preferred. You could also look at other swage (self-clinching) nuts for brittle material (such as the ones used for PCBs); but you need a special tool (or a user-made-tool) to press them into place. Another option would be to embed them into the print as some suggested (some suitable information can be found at https://markforged.com/es/resources/blog/embedding-nuts-3d-printing ; https://help.prusa3d.com/article/insert-pause-or-custom-g-code-at-layer_120490.  

Posted : 13/05/2024 2:01 am
_KaszpiR_
(@_kaszpir_)
Honorable Member
RE:

Silicone glue or hot glue? It's elastic so it would keep the nut in place and allow it to move. 

For more stiff solution two part epoxy?

CyanoAcryl glues are a bit tricky ( catch too fast and are leaky) and I noticed they tend to break after some time.

See my GitHub and printables.com for some 3d stuff that you may like.

Posted : 13/05/2024 7:18 am
Neophyl liked
Tango
(@tango)
Estimable Member
Topic starter answered:
RE: How do you keep nuts in holes without blocking the threads?

 

Posted by: @_kaszpir_

Silicone glue or hot glue? It's elastic so it would keep the nut in place and allow it to move. 

For more stiff solution two part epoxy?

CyanoAcryl glues are a bit tricky ( catch too fast and are leaky) and I noticed they tend to break after some time.

Isn't silicone glue kind of thick? I'm wondering if it might ooze from around the nut and the recess.

CA - yes, it can be tricky and once it's on a spot, it can't really be cleaned off.

Posted : 14/05/2024 3:05 am
Zappes
(@zappes)
Reputable Member
RE: How do you keep nuts in holes without blocking the threads?

Just as fuchsr suggested, I'd recommend CA glue. I recently printed all the plastic parts for my MK4 in PC Blend CF, and as the dimensions with that material are hyper-accurate, none of the square nuts would stay in their holes, making assembly a really tricky thing. I solved this by picking each nut up with tweezers and wiping the outside of the nut across the glue bottle's tip before dropping the nut into the hole. After a few seconds, you have just enough adhesion to keep the nut in place while you screw in your bolt.

My models on Printables
Posted : 14/05/2024 12:42 pm
Share: