[WOTDesigns]

I have a part that I am working on that has me stumped. There are lots of solutions offered by the 9 different suppliers I spoke with this week (rivet manufacturers, Fastenal, local fastener warehouses) For the life of me I can not find a good looking way to permanently fasten a new part.


It has 2 pieces of aluminum, one like a fork with a slot, and the other goes inside and pivots on (?????????). The "fork" walls are only .05 thick. Over all part is .25". Appearance is important so standard binding posts are out (all I have seen this thin have through holes and slots... ugly), as are tubular rivets, nut/bolt, and the walls are too thin to tap and just use a shoulder bolt.

The part will be subject to large amounts of vibrations, and any axial loading on the hole will prevent movement.

I like the idea of 2 part press fit rivets but I am afraid they will flare out when pressed together, and more than one rivet manufacturer told me they will not reliably stop at a given size without crushing my part.

I am looking at first run of only 100 parts so I don't mind a little manual labor.

I've done parts with the knurled-ended rods where the part in the middle of the assy has a slightly larger OD and is pressed into the outer holes creating a hinge... but with limited success. They tend to work out.

I need another set of braincells on this one... i'm stumped.

1. 3/16 - 1/4" hole size (prefer smaller)
2. Doesn't squeeze part
3. Permanent
4. ATTRACTIVE

I appreciate your input. Unfortunately I can not post pictures of drawings of the part.

Hopefully I provided enough info.

[txcncman]

I do not know why people refuse to upload pictures, sketches, or prints.

Spot weld.

[fizzissist]

No, you're not providing enough info.

From what I'm reading, you need a new part design.

[underthetire]

Laser weld.

[WOTDesigns]

I refused to post pics because I didn't have any and wasn't planning on being able to make it in today. I was wrong... here are some pics of a first article.

Not sure I would be able to weld as the part will be powder coated.

These binding posts work great but look like crap. So does the part in these pics since I opened up the home with a hand drill for the post.

http://www.imgur.com/kAISU.jpeg
http://www.imgur.com/4o628.jpeg
http://www.imgur.com/gYWTX.jpeg
http://www.imgur.com/mzldS.jpeg

Sorry for attempting to ask without having pics. didn't think of asking here till this morning.

[txcncman]

Where on the part does the connection take place? What does it attach to?

You definitely will have to use mechanical fasteners if the parts will be finished with powder coat. #0-56 thread will give 3 threads of engagement in a 0.050 thick part.

[WOTDesigns]

Its a screw clamp with minimal load. It pivots on this end and clamps down on to a round bar on the other end.

I'll take a look at 0-56 shoulder bolts and give that a try. So far the next best option I've come up with is cutting down longer flat head binding post that doesn't have the through hole. Lots of labor :-/

[fizzissist]

Could you consider a one piece design? Where the larger sections come together and you need a hinged movement, instead of a joint as shown, a thin section of material connects the two part and is corrugated. That will provide rigidity resisting twist, but also allow flexure.
Think bellows.

[WOTDesigns]

hmmmm... perhaps I "could". That was my original intent when this started (not corrugated though). The deign is to have 2" of movement 5" from the pivot and my initial tries snapped if they were too thin or wouldn't prove much grip. I changed the design to incorporate a hinge and pivoting nut captured in one half. The result is EXCELLENT.

Since the part will come on and off over and over I fear stress cracks over time.

[dodger889]

You could sleeve a bolt and nut t hold tem together.

[Dylwad]

Have you looked at knife making supplies? Lots of custom,attractive, strong bits out there for the purpose. Might have to slightly re-design though.

[WOTDesigns]

I looked at several 2 part connectors called "knife rivets" but never thought to pursue it further for options that don't flare when compressed. I LIKE THAT. google time

[fizzissist]

If you cut out a female notch in the end of each mating part, ... think turbine fan "tree".., then made a spring steel piece that had a corresponding male on each end, with the flat spring part in the middle.... It would serve the same purpose and function of the corrugated part, but because it's spring steel it could flex till the cows come home, and be made as thick as necessary for the application.
You could stack the steel plates and nest the pattern to EDM the parts, then heat treat the batch. Press fitting the steel into the alum would be easy.

Another hinging method would be to mill a round female pocket in one side that was cut down to half thickness, and mill a round male feature in the opposite half side of the mating part. The two pieces are put together, then a keeper flat spring holds them together.

If none of these ideas work, try heliarc.

[TechGuy5002]

What about a press fit dowel pin? Need to cool the pin and heat up the other parts. Then insert the pin into the parts. You would need to ream the holes so they are the exact size of the dowel pin, and slightly oversize the inner part hole so it doesn't bind.