Design - Need to attach a cap to end of metal tube 2

[CPosner]

Hello,

I am looking for a way to attach a cap to the end of a tube and looking for some suggestions. The tube is Appx. 3" OD tube with .06" wall. The cap also has an OD of 3". Threading the cap on with internal threads into the tube is not an option. I'm looking for some more unique ways to attach the cap. Also, the cap cannot have any fasteners exposed. The cap should be removable so adhesives might be out as well. A simple twist-lock or maybe bayonet style connector would be neat, but looking for some off shelf components to make this happen. Maybe some type of push-lock connection?

Thanks in advance.

 

[rb1957]

any appreciable load applied ?

maybe a piece of spring steel, bent into a curve, ? to attach the cap you have to squeeze the spring to get it into the 3" tube ??

maybe two pieces shaped like an "S" (to balance the loads a little) ??

 

[MintJulep]

thread404-319220

Could also be formed to create a 1/4 turn or less catch.

Or

Just need to form two "bumps" on one or the other part to engage.

There is always "friction" as well.

 

[btrueblood]

Along the same lines as rb, a lip with an o-ring groove on the cap, and/or groove in the tube i.d. Size the grooves so the ring "snaps" into both to hold the cap in place axially. If an o-ring doesn't give enough fixity, then a spiral retaining ring engaging a slight groove in the tube i.d. (caution, without a taper on the outboard wall of the groove, this can become a near permanent fit) - see the Smalley website for details.

 

[CoryPad]

An o-ring can provide good low-force attachment. Retaining rings would be a step up.

 

[SnTMan]

CPosner, it doesn't get more off-the-shelf than duct tape

No? What are you trying to do?

Regards,

Mike

 

[racookpe1978]

Come on! Give us "some" info! Please?

Seriously.
What are you holding in the container? Sand? Dust? Gasoline? Food-critical liquids? Something "stiff" like Glue? Putty? Liquid helium? Thumbtacks? Screws? Thin wire? Semiconductors?
What pressure?
What temperature?
What "shape" and geometry will your users (the builder, the packers and shippers, the user, the "loader" who puts stuff in the container (man, machine, automated assembly robot, astronaut or diver working under pressure or vacuum, who unloads it? How often is it unscrewed or reloaded?
How many are you making?
What are the risks - the penalties of the container is turned upside down or sideways or is jammed or leaks or explodes (or doesn't open all).
How many are you making?
Who makes it and what will be the tolerances for that fabrication?
Will it have to work in a hot or critical environment where the user needs to wear gloves or be in protective clothing?
Who will open it? (Hot outdoors condition in Saudi Arabia may require something that can be different to open than a frozen-shut gadget underneath a ice-filled pipe in a blizzard at night?)

 

[1gibson]

Use a rubber cap.

 

[MiketheEngineer]

Weld, solder, glue??

 

[CPosner]

It's a consumer product and it's a housing for electrical components. No extreme temperatures. 0F-100F. It shouldn't be too easy to open either. It would only open for major service and of course assembly. Tube is metal(steel or alum extrusion(I'm leaning towards extrusion as I can design internal features to hold components in place). The cap should be "splash proof" as well. I can fasten the cap into the tube from the inside with small screws, but it's not the most elegant solution, but seemingly most practical given design criteria.

here's a quick snap of what we're looking at:

 

[MiketheEngineer]

Force fit??

 

[1gibson]

In light of recently available information:

Use a rubber plug sealing to pipe ID, with a grey metal outer shell.

 

[MintJulep]

How is your picture different from the Scooby Doo can - other than of course you don't have Scooby Doo on yours?

 

[DRWeig]

Mint, you're hilarious but always poignant and thought-provoking. Nice one.

The pic made me think of the key fob for clicking the car doors open and closed (and remote start, which is handy). The plastic clamshell is very well designed and I think it matches the OP's needs.

To change the battery is a challenging adventure with a thin-blade screwdriver or pocket knife, so it's not easy to open. There is no special cutout for an easy place to pry it open. It's gasketed against rain. I've had it apart and back together again at least four times, and it's still a booger to open.

There is also the interference fit on the back of my watch. Changing the battery in it is often accompanied by foul language and a craving for scotch and cheeseburgers. It's watertight to 100m. Also matches the OP's needs and is made of stainless steel.

Maybe you could look at how those are done?

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[Cockroach]

Use a condom....quick, easy, inexpensive and plentiful.

Regards,
Cockroach

 

[chicopee]

Instead of a metal cap, I would use rubber stoppers which are used frequently in laboratories. That should simplify things and they provide splash proofing.

 

[chicopee]

Better yet, glue rubber stoppers (somewhat truncated)into the inside of metal caps. You then have the best of two worlds

 

[1gibson]

I might have accidentally set my font to invisible, let me check my post settings.

In any event, chicopee I like the way you think!

 

[chicopee]

Sorry 1gibson, I did not read your reply until you mentioned my name, then I got curious and searched for you name and found your reply "Use a rubber plug sealing to pipe ID, with a grey metal outer shell." My reply was purely independent of your thought. Well, hopefully we'll find out CPosner final disposition.

 

[racookpe1978]

Buy a $2.00 wine bottle plug from your supermaket.

See how it works: The wine bottle cap has a expandable rubber band under a plastic lid, with a simple cam-and-lever on the lid. You insert the plug into the top of the bottle - rather than trying to re-use the cork - and flip the cam sideways. The cam lifts the plug up into the rubber band, which expands and seals the bottle tightly.