Help re-creating a robot claw

[rea5245]

I want to make a non-working model of this robot claw. I'm puzzled by the fasteners. Can anyone tell me what they are, or are they just figments of the artist's imagination?

[Gyro]

They look like high tech (the shape imparted by the press tool) solid brass rivets.

Edit: The shape wouldn't be hard to replicate, on one end anyway,  with a small lathe. Actually you could do the complete fastener if you turn two half length pieces, center drill and tap the inner ends and join with some threaded rod. This would make the parts easy to assemble.

[coppercone2]

that looks like AI confused grommets with rivets. It does not really make sense because why would you make the rivet thinner in that location


The only 'design feature' of such a thng would be that if you beat on it hard with a punch, you can shear the 'brim' off the rivet and push it out. You have less metal to go through. Kind of like a cotter pin/rivet hybrid thing, inspired by perforated paper. Maybe that is how you make power armor rugged and battlefield repairable for battle with arachnids, so the combat engineers run around with hammers and punches instead of grinders.

[rea5245]

that looks like AI confused grommets with rivets. It does not really make sense because why would you make the rivet thinner in that location

It's not AI. This is from the cover of BYTE Magazine, April 1985. It was painted by the great Robert Tinney.

I don't know if he was painting from a real model.

[xrunner]

I want to make a non-working model of this robot claw. ...

In my opinion I think any model of that would be non-working. Of course I'm using my mind's eye to say this because I don't have a "real" model of it, but I do not think it would function (open and close) at all. I think the two different arms or links on each side he painted would not function together in any usable manner.

What I think it is, is a cool looking claw that the artist dreamed up with little regard to whether it would actually work in any fashion that a real mechanical engineer would design.

[rea5245]

In my opinion I think any model of that would be non-working.

I agree.

This is from a cover of BYTE magazine. I have a personal art project of re-creating the covers as photographs of real-world objects.

So I just need it to look pretty. I don't care if it never works.

[xrunner]

So I just need it to look pretty. I don't care if it never works.

I see.

Well then Gyro's suggestion would work if all you want to do is make it look like the artwork. Brass rivets or tubular rivets or hollow rivets just google those terms.

[coppercone2]

actually it can be one more thing like a rivet that goes into a oversized counterbore and gets smushed in there

I don't know why but you could theoretically do that


or it can also be like a threaded insert  that goes into a counterbore and has a end threaded thing that goes in there. maybe that is what it is, so the depression is just a bolt that is a tiny bit shorter then the insert and the thread is not drawn

it makes more sense then a rivet for precise robots holding pencil. rivet is what you would use for a robot arm to tear something apart, maybe like a junkyard arm, I think it would be for situations where the load drastically and erratically changes

[jpanhalt]

What's pictured is probably artistic license.  That said, you probably want a low profile fastener.  Countersunk sex bolts allow that (attachment).  You can also achieve that with other fastener types. With a barrel nut (as shown) you can easily achieve a tight fastener without clamping what it's fastened too tightly (like a joint).  Another option is self-locking nuts.

[Kean]

Rather than using single use rivets, you might be able to use bookbinding screws, aka Chicago Screws.

With regular motion they would probably come loose without threadlocker, but for your recreation they might be suitable and readily available in brass and different sizes.

I've not seen them quite as depicted in the artwork, but they are available with slotted, cross, knurled, and blank faces - and possibly other styles as well.

[Gyro]

I was trying to remember what those were called. Yes, they would save some effort, they could be touched up with a lathe to get the exact effect (maybe with some thread protection of the male one).

[jpanhalt]

They are apparently the same as sex/barrel screws -- just used for a different purpose.

[Kean]

They are apparently the same as sex/barrel screws -- just used for a different purpose.

Oh, yes.  Now the picture you included makes more sense.

I've never heard of them called that, but they indeed seem to be the same or at least within the same classification.
https://en.wikipedia.org/wiki/Sex_bolt

[Doctorandus_P]

You can buy a robot gripper like that for around EUR 15 from Aliexpress, but they do need an extra (hobby) servo, and they are made quite sloppily. I've thought about drilling up the holes, pressing in brass bushings and using precision axles to make them a bit better.

But overall, there are different mechanisms in these grippers. The cheapest aliexpress version works with two gears to make the sections move synchronously, other versions have two wormwheels with a worm in the center. There are also pneumatic actuated versions.

A generic search shows a bunch of the possible options quickly:

https://duckduckgo.com/?q=paralellogram+gripper+robot&ia=images&iax=images

On a sidenote: In the early 1980's there was a magazine called "Robotics Age". You may find it interesting.

[Andy Watson]

... you might be able to use bookbinding screws, aka Chicago Screws.

Also known as "furniture screws/bolts" or "furniture joint bolts".