What is Reddit's opinion of Fundamentals of applied kinematics?

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This

https://www.amazon.com/Fundamentals-applied-kinematics-Deh-Chang/dp/B0006BOWN4

Gotta repost this where it might be seen.... Kinematics is one my passions.

[–]crosleyxj 5 points 12 hours ago*

This

https://www.amazon.com/Fundamentals-applied-kinematics-Deh-Chang/dp/B0006BOWN4

Or this, includes straight line synthesis

https://www.semanticscholar.org/paper/A-Four-Bar-Linkage-Adjustable-for-Variable-Straight-Tao-Amos/bde1698078686f569d4a98733f9602df6a47e83e

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[–]erythro 3 points 6 hours ago

I there's something conceptual I think I and some others are missing about this post, explained by this comment, that it looks like you have understood.

Could you explain what it is, or are you literally saying I need to buy and read this book from Amazon to understand this post?

I read the Wikipedia article on the watt linkage, couldn't you constrain a bar in a tube or something? I don't get what the advantage is of linkages and why they are special

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[–]crosleyxj 1 point 4 minutes ago

I there's something conceptual I think I and some others are missing....

YEAH - you're missing something! Imagine that you live in a world where you CAN'T BUY nice straight strips of steel because steel making itself is still somewhat of an artform. You can't grind or turn your own parts straight because precision lathes and grinders and machine tools haven't been invented yet - because they DON'T YET HAVE STRAIGHT SURFACES! You're missing that anyone can draw a "straight" line, but 200-300 years ago you couldn't hand-file a 1-meter long surface to be flat within 0.05mm! (which was pretty wavy even 100 years ago)

HOWEVER, drafting concepts and geometry to produce straight lines don't depend on physical objects, just mathematical concepts. People were at least as smart then as now and envisioned machines that could derive straight lines from somewhat precise mechanisms.

I read the Wikipedia article on the watt linkage, couldn't you constrain a bar in a tube or something

200 years ago neither was readily available in any precise form and "precision tubing" is laughable.

SO, a crude lathe or drill press could produce a tight rotary joint. It might not be to any exact dimension but it could be made precise. And a craftsman (or clockmaker) could probably produce two nearly identical links with rotary joints at the ends. They couldn't mass produce 50 parts. So with careful construction they could build a machine that could cut a very straight edge on a metal object. And THEN one starts thinking about how this technology could build steam engines and good machine tools.

These books are grad school mechanical engineering level with a heavy dose of geometry - they're pretty tuff reading - sorry.