Animated Assembly – Lazy Tong Riveter

[SillyOldDufferModerator @sillyoldduffer]

In another thread we got to discuss what constitutes an Assembly in 3D-CAD. One form consists of parts positioned statically in space. Another allows parts to be jointed as well, so they can move dynamically, realistically modelling entire mechanisms.

This type of Assembly often allows parts to be developed from other parts already in an assembly, making it easy to see interferences. Moving joints can be animated, making it easy to detect collisions between parts as they alter position when the mechanism is working.

This is my go at a lazy tong riveter: it has more joints than parts! A real example:

In developing my version the only measurement is of my fingers to determine the handle size. All the others are derived from the model, and maybe rounded to the nearest millimetre.

First step:

Then refined to this:

Same model, except the joints have been operated:

Nothing is ever easy! The crank-arm geometry doesn't move the pull-rod as far as I want, the cam action should operate along a curve, shape not known, and something is wrong with the head, where the blue crank has popped away from the head and it's driving tong arm:

This is a symptom that a joint or part isn't quite right. Another is that although the tong model works, the movement is sticky.

A possible cause is jointing 'this' to 'that' instead of 'that to this' : makes a difference, and I've not found an easy way of finding where I went wrong! No joy from Solid Edge's diagnostic tools, but I may not be using them properly.

Equally likely is Solid Edge dislikes my cam puller design. It's certainly flawed because the round arms pinch together as the cranks rotate, when a straight pull is needed. I don't know how a real one pulls the rod and guessed.

Any suggestions.

Also, how easy is it to develop a lazy tong riveter with your software?

Dave

[SillyOldDufferModerator @sillyoldduffer]

[JasonBModerator @jasonb]

Posted by SillyOldDuffer on 22/05/2023 16:12:20:

Also, how easy is it to develop a lazy tong riveter with your software?

Dave

Very

I can even set an amount of "play" in the fit of the pivots which would cure your sticky action.

[SillyOldDufferModerator @sillyoldduffer]

Alas the model isn't sticky because my pivots don't fit! Only one joint has an actual pin, the others are all axial aligns with rotation allowed. More likely the problem is in the head.

To answer my own question, FreeCAD doesn't have this type of Assembly. Fusion does, and I found it easier to learn than SE.

Been waiting in for a package, just got a message it's coming tomorrow when I'm out, sigh…

Dave

Edited By SillyOldDuffer on 22/05/2023 17:57:55

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