"For big sizes and masses arthropod legs are a bad option" is what many people say, but nevertheless, this always looks cool and scary.

So based on the first solution for an Anatomically correct Arachne, we're going to assume a weight of 120 kg with 15 kg distributed for each leg (with variations), but even this solution the general consensus was that the biomechanics of the matter would not allow support that weight.

Add the fact of arthropod chitinous legs, because, yes, this probably can be solved using normal bones that just look like spider legs, but would be contradictory with the Arachne solutions.

Searching solutions for this, the best thing that I could found were these spider trucks:

Obviously, biomechanics are very different to technology mechanics (you can see those hydraulic pistons and motors), nevertheless, this gave me some hope to think that the design is viable.

Also, the most representations that can be found shows very long and thin legs, something that looks completely implausible and unrealistic

Are a few which shows shorter, stronger and thicker legs, like the showed by the first answer to the Arachne or this

So, maybe we will lose some of the height and for this some of the imposing posture as it rises, but if but the disturbing movements and form that terrify people so much remain enough will be enough.

What changes and implements should get the legs for resist the weight and walk?

How thick and short should be the legs for make physically viable?

Is the chitin enough for resist the weight?

Or it's completly impossible biological very segmented legs able to carry and move those sizes and masses?

Remember all the previous, some based on the arachne answer.

I thought were enough questions, other things like are very hard to think and more like magic, so is unnecessary

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    $\begingroup$ I'm afraid I don't understand what you understand by "arthropod legs". In particular, the legs of the "spider trucks" in the first two pictures are much more similar to human linbs (= articulated rods) than to arthropod legs (= articulated tubes). (Fun factoid: human limbs have the same number of joints as insect legs. The difference is that insect legs are articulated tubes, while human limbs are articulated rods; that is, exo- vs. endo-skeleton.) Human-made machines rarely use the articulated tube approach, mainly because we have no way of making strong flexible joints between two tubes. $\endgroup$ – AlexP Dec 7 '20 at 19:43
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    $\begingroup$ @AlexP: Why do you think there's no way of making flexible joints between tubes? At the simplest level, close the ends of the tube and use the same joints as for rods (or I-beams). Then there are for instance the joints in space suits, and a couple of minutes with Google will give you many more instances. $\endgroup$ – jamesqf Dec 8 '20 at 2:49
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    $\begingroup$ @Drakio-X: creature size limits can be discussed. Some argue that even large athropods (1m and larger) of the carboniferous were too large to support their weight, meaning there may be solutions to keep ventilation intact that we're currently not aware of or can speculate about. I am not self-confident enough to judge exact sizes and limits, but sure you can find work an the matter. In worldbuilding, some handwaving won't harm :-) $\endgroup$ – a_donda Dec 8 '20 at 9:42
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    $\begingroup$ Another thing that comes to my mind: creating a vertebrate / arthropod chimera combines two completely different "blueprints" with mutually exclusive functionality not just concerning breathing system, but all of metabolism and life cycle. E.g. how can it build a calcium skeleton and at the same time molt it's exoskeleton, or blood and hemoglobin and open ventilation, or digestion outside and inside of body, and all that. Body functions would be really ... messy. One would need a lot of hand (or whatever applies :-)) waving ... $\endgroup$ – a_donda Dec 8 '20 at 9:58
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    $\begingroup$ @AlexP: I don't see how tubular segments are "cheating". You might consider the hollow tubular booms used for pumping concrete, though. $\endgroup$ – jamesqf Dec 9 '20 at 3:21

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