Connecting Parallel Plates Without Bolts, Welding, or Epoxy

[vc66]

All-

I have a somewhat odd situation. I need to connect two disk-shaped parallel plates. They need to be removable from one another (fairly often, this will happen); however, There can be no screw heads protruding on either parallel face. I'm thinking that I need to connect them around the border somehow, but I can't think of an elegant way to do it. I have a couple of crazy thoughts as to how to do it, but I would like to know if there's anyone who has ever run across anything like this before, and may know an easy way to solve my problem.

Thanks for the help.

V

 

[MadMango]

What material are the plates, how strong must the bond be? Permanent magnets, snap-fits, hook-n-loop?

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[dvd]

Use fasteners that don't protrude above the surface. It really depends on how thick the plates are.

 

[vc66]

Wow, yea sorry about that.

Both plates are 304 SS, and they have to be RIGID with respect to one another when attached. Both Plates are about .150" thick.

MM,

There is a 150 lb force trying to separate the two plates when they're attached, so magnets and snap fits are a no go. Hook and Loop might work, but as I said, they have to be rigid with no play, when they're attached.

dvd,

When I said can't protrude above, I meant there can't be any screw heads on the face, period, not that they couldn't be flush or below the surface. Sorry about the lack of a clear description.

Thanks for the help so far.

V

 

[KENAT]

Can you use sex bolts? I believe you can get these countersunk on both sides (tolerance nightmare of course;-)).

Oops just read the last line of your second post, that wont work.

How about some kind of double ended pit (pip?) pin. Something with some kind of snap fit that you actually have to press a small lever/collar or something you have to move to to 'un snatch'

If you use a bunch of them I would think you'd get the required force. You might need additional features for alignment though.

KENAT, probably the least qualified checker you'll ever meet...

 

[MadMango]

Well, now I'm thinking some sort of clamp around the diameter of the two plates. Have a look at McMaster.com for "vacuum tube clamps" for the idea.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[amorrison]

Solder or brazing.
Heat with torch to disengage.

 

[vc66]

Hmmm... Both good ideas.

I like the vacuum tube clamp set up, but I can only use about 75% of the border, as there needs to be an opening in about 25% of it. I may be able to design a variant, though, that I can use.

Has anyone had any experience with over-sized (~8 inch) specialty threads? I'd only need about 1.5 threads to lock the top piece in place, as the orientation doesn't matter. Would this be hard to create (manufacture)?

Thanks again for all the suggestions, and keep 'em comin'.

V

 

[MintJulep]

Take a look at the pin and cam gizmos that are used to assemble "build-it-yourself" furniture.

 

[dgowans]

You say you can't have any screws on the parallel faces - can you have them on the cylindrical faces, such that the axis of the fastener would intersect the axis of the disc? Your comment about 8" threads got me to thinking about one disc fitting inside the other one, which led me to this.

Just a thought that may not work for your application (or be very practical, for that matter).

 

[hydtools]

If you can make blind, flat-bottomed holes on the mating faces of the disks, use barrel nuts, screws and a wedge sort of clamp on the edges of the disks. Use as many as you need around the periphery of the disks.

Ted

 

[hydtools]

Here is what I mean as a barrel nut:

http://www.shur-lok.com/solutions/barrel/index.html

Ted

 

[vc66]

dgowans-

That's a great idea, and I think it will work for my application. I'm going to try that and see how it pans out. I'll keep you guys updated. Maybe I can incorporated your concept with MintJulep's idea of the furniture cams...

Hmmm...

Also, anymore Ideas are greatly appreciated.

V

 

[macmet]

What about just a set screw. They don't extend beyond the surface.

 

[btrueblood]

"Has anyone had any experience with over-sized (~8 inch) specialty threads? I'd only need about 1.5 threads to lock the top piece in place, as the orientation doesn't matter. Would this be hard to create (manufacture)?"

Mmm. No, not that big. But to manufacture threads on thin components, we clamped a stack of them on a lathe, and turned the thread across the whole stack at once. Getting the durn things started without cross-threading was a real female dog, solved finally by using an alignment/handling tool that kept the part from bending as it was being turned into mating threads.

 

[dvd]

If the inner surfaces of the disks do not need to be in contact then a pair of piano hinge sections attached to the inner surfaces would allow separation by pulling the hinge pins to allow separation. You could accomplish this in a more elegant fashion that allows the inner surfaces to contact each other, but the concept is the same.

The main issue in this game is that you are the only one who knows the rules and we are playing twenty questions.

 

[vc66]

Very true, dvd. So far, however, I don't believe anyone has been very far off of a potentially good idea. I appreciate all the ideas, and if there are any other constraints, I will be sure to mention them. But as I said, so far, these ideas are really giving me a good place to start.

Thanks all. Keep it comin'.

V

 

[jimkinney]

Do they have to be the same diameter? Could one screw into the other? You still have the problems of threading and starting, but your part count goes down.

Jim Kinney
Kennedy Space Center, FL

 

[vc66]

They don't have to be the same diameter, and I was thinking that they could screw together. That's why I had asked about over-sized threads. They are both about Ø8-10".

V

 

[MadMango]

You don't need full/actual threads, how about a pin and cam arrangement on the outside diameter to allow for an over-sized 1/4-turn fastener?

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?