How to mechanically attach a compression spring to a flat surface 4

[RyanDehmoubed]

Hi all,


I am working on a project right now and I was wondering if anyone had any ideas on how to keep a spring fixed and connected to this plastic piece [image shown below].

Our goal is to keep the spring erect and allow for an upright, linear compression.

I was wondering if there was a mechanical method of attaching/fixing these two pieces together without using glue, epoxy, or other such products.

The best solution that we have been able to come up with so far is to add a custom threading into the plastic such that the spring can just screw into it, but we are afraid that this wouldn’t be too robust. Another downside is that the spring is winded in a counterclockwise manner so I am not sure how it would even be able to “screw” it in.

If anyone has a clever solution to this problem, I would really appreciate it.

Thanks,
Ryan

 

[BrianE22]

For compression you have to look at buckling. A rod with an OD a bit less than the spring ID inserted through the spring and screwed into the plastic would give you the guide you need. But then you would have an unmovable rod that would require a through hole in the mating piece.

 

[The Obturator]

You should have some 75% of the end of the spring made flat against the main component. Then consider a circular plate similar to the spring outside diameter, with grooves on the outer to match the spring wire diameter. This plate would have a centre hole to be able to screw sown onto the component. You would need to access this screw with a long driver through the centre of the spring - I can't see how long the spring is.

Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[hydtools]

Use a washer shaped like a + with a hole in the center. Insert it through the bottom coil and hold it in place with a screw.

Ted

 

[SnTMan]

Press fit the spring over a short(ish) boss protruding from the thing.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r13]

Can counterclockwise thread be made? Just curious.

 

[mfgenggear]

was is it compressing?

 

[Metalfixer]

Is there enough material for a counterbore, and longer spring?

 

[FACS]

I'm with Metalfixer.

C-bore and press fit.

 

[Tmoose]

How far is the spring from "coil bind" at full compression?

Is the concern just retaining the spring at assembly, or forever ?

 

[moon161]

The plastic part looks to be 3D printed, so an left hand thread is absolutely possible. If machined left hand is possible many different ways.

 

[goutam_freelance]

This should be robust.

 

[GregLocock]

No, that's terrible detail design where the washer pins the end coil. It'll bend the wire locally, and that is where it'll break. This is a solved problem if the spring is always in compression, a slight interference fit in a hole.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[goutam_freelance]

"Slight interference fit in a hole" . But the hole is likely to get bigger due to reciprocation motion of hard spring ( as usually is the case).
Also usually spring end coils are slightly deformed to provide a plane landing.

 

[IFRs]

Drill and tap the plastic part

 

[GregLocock]

As I said it's a solved problem. Just about every production car uses coil spring seats.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[mfgenggear]

I agree with Greg. there needs to be shaft or bolt to prevent the spring from failing. and yet allow the spring to compress freely
with out interference. it's been around in many industries. look at old school automotive valve springs and the method used to apply pressure
yet not to interfere with the spring. simple is better.

 

[hydtools]

Ted

 

[hydtools]

Ted