Mechanical problem -- Joining 2 metal strips with some sort of hinge

[AbbyBaby]

Hello mech Engineers. To begin with, let me admit, I am not a mech engineer. But I am doing a project at home where I am stuck (I thought I will get through easily). To keep things simple, I will not deep dive into what the project was but the core problem.

Consider that I have two rigid metal strips. Lets call them Strip 1 and Strip 2. The two strips are perpendicular to each other with one end of 1st overlapping the other. At this point of overlap, there is a hold to put in a screw and nut and tighten the joint. I want to do something that the overlapping point remains connected (does not separate at all, what so ever) but still there can be free movement of the strips on the connection point.

I know I cannot achieve this using ordinary screw and washers as the overlap point will become very rigid as the screw is tightened. What can I do to handle this? If I cannot address this problem myself, then the solution is to buy this set up as is from the market (factory connected overlapping strips with a special sort of screw that is threadless and thick at one end and thin with threads at the other). I think they call it shoulder screw but it is actually not shoulder screw.

Will a shoulder screw allow me to achieve my goal? If not, I have to shell out a good chunk of money for this readymade thing from the market and on top of it, wait till it gets delivered to me.

 

[Baluncore]

Welcome to PF.

I know I cannot achieve this using ordinary screw and washers as the overlap point will become very rigid as the screw is tightened. What can I do to handle this?

You can use one or more Belleville washers. You can stack them to change the spring constant, as is explained on this wiki page.
https://en.wikipedia.org/wiki/Belleville_washer

 

[jrmichler]

It sounds like a shoulder screw will do what you want. Shoulder screws are readily available in the US from McMaster-Carr: https://www.mcmaster.com/products/screws/shoulder-screws~/.

Another possibility is a bushing. Drill larger holes in the metal strips, insert bushing, a bolt through the bushing with washers on each end of the bushing, then tighten the nut. McMaster-Carr again: https://www.mcmaster.com/products/spacers/spacers~/.

And another possibility is a bolt with washers and a self locking nut. Tighten the nut to get the right amount of free movement without wobbling. McMaster-Carr: https://www.mcmaster.com/products/nuts/locknuts~/.

If you are looking for ideas of small mechanical things to do something, it's worth your while to browse the McMaster-Carr catalog. That catalog is one of the favorite resources of design engineers.

 

[Rive]

using ordinary screw and washers

If one nut is not enough, use two. A jamnut (or just simply a second one for cheap) to prevent tightening up and keep things at place?

Ps.: the function of a shoulder screw is not only to stop the nut at the right place, but also to add material where the wear will be the worst. Using a standard screw with locked nuts will not be able to provide that. So you need to consider things properly.

 

[jack action]

Wouldn't a clevis pin [and maybe washers] better suit your application?

 

[Baluncore]

I want to do something that the overlapping point remains connected (does not separate at all, what so ever) but still there can be free movement of the strips on the connection point.

A bolt of any style, with a Nylock nut, will position the strips. Belleville washer(s) are needed to press the strips together, so they do not separate.