Do techmarines know enough to train other techmarines?

Question

Imagine a space marine chapter which has lost contact with most of the Imperium (in particular, with Mars and other forge worlds) for centuries or even millenia, or a chapter which has fallen out with the Adeptus Mechanicus and can no longer send techmarines to it for training.

Assuming such a chapter had a well-staffed, knowledgeable Armoury to start with, is it possible for its techmarines to train new techmarines? Simply take the battle brothers who would normally be sent to Adeptus Mechanicus for training, and train them fully within the Armoury itself.

Assume the techmarines and the entire chapter are pragmatic enough to not care about the formal/ritualistic aspect of things, as long as the end result functions fully equivalently to a "standard" techmarine.

I've seen the related question on obscure chapters obtaining techmarines, but that (and its answer) are geared towards "how to get to the Adeptus Mechanicus when you normally can't", while I'm more interested in "what do you do when you really can't."

Answer 1

What happens on Mars stays on Mars

I've never read about any Techmarine teaching a novice to become a full Techmarine. He would probably pass on small pieces of information to his brothers if necessary but not everything. They spend decades training, 40 or 50 years I believe, day-in, day-out.

I know they flat out refuse to talk about their time on Mars (or whatever forge world they train on, they can't all make it to Mars). Obviously whatever happens on Mars is serious business and they would not duplicate the process somewhere else, without the Mechanicus's permission.

For the sake of argument though:

Could they? Probably.

Would they? No.

Answer 2

I am catching up with the War for Badab and also the Carcharodons Astra and I remembered your question.

From the Fandom article of above mentioned chapter:

The Nomad-Predation pattern evolved in use by Space Marine Chapters and certain Rogue Trader fleets operating beyond the Imperium's boundaries for extended periods of time. It refers to an entirely self-contained force that can sustain itself without any Imperial support whatsoever.

So, if they don't have any support by the Imperium, that would also imply that they don't have support (in that case training) by the Adeptus Mechanicus for their Techmarines and existing Techmarines train the new ones in the proper rituals.

So, it certainly may not be a standard procedure for a Space Marine Chapter but it would seem that at the boundary of the Imperium, some rules might be ignored by Space Marines if needed.