So then, my questions is on the origin of a Techmarine. Is an astates created in the standard ways of the chapter then sent to the school of Mars for training? Or does the Macanicum send recruits to the various chapters to be made into space marines?

-Perhaps a better way to ask would be: Whats created comes first? the Astartes or the Techmarine.

Where would the techmarines loyalties, usually lie?

The Astartes is made first. When they have been raised to full Battle Brother they are sent to the forges of Mars.

Kage

If an astartes recruit shows technical prowess, he is seconded to Mars for a given period of time to learn the ways of machines and whatnot. They're just as loyal to their chapter as any other marine, but in return, the chapters offer protection to the mechanicum.

Chapter first, then the Mechanicus. There will, of course, be rare exceptions.

-=Brother Praetus=-

Thank you for the responses. Question answered.

Though you might want to go and read the entries on Techmarines, though. While their loyalties are to the Chapter, their personal loyalty leans more towards the machines.

Kage