Continuing an old thread, I'm making some small progress on my Mechanicus army, and I thought I'd make a thread to record it all; There's pics and a bit of fluff to go with them (I like writing fluff, I like modeling (imaginary) military forces better than just painting playing pieces):
Explorator Expedition 11206
An Explorator ground survey expedition usually fields a base vehicle and as many support all-terrain vehicles as the mission requires.
The Base Vehicle carries a small but powerful reactor, providing energy to recharge the auxiliary vehicles. In addition, it usually carries a broad-spectrum voxcaster, allowing tech-magi on an orbiting cruiser to command several ground teams through full noospheric links. The drive trains are adaptations of the Land Raider template design, which are in plentiful supply on the Forge world.
The auxiliary vehicles are, unless special needs dictate, standard-issue Rhino armoured personnel carriers. They, too, are manufactured in bulk on Stenberg, and are thus cheap and plentiful. They are easily adapted to carry tech-adepts' or servitors living quarters, labs, or supplies.
The five Rhinos seen here is the minimum complement usually seen on a ground survey; There is one Geo-lab, on supply carrier, two people-carriers with four explorator techno-magi, and one carrier with ten servitors for menial work. A command crew of three magi and five servitors operates (and live aboard) the base vehicle.
Even on peacetime missions, all Explorator vehicles are armed with boltguns, and a base vehicle usually fields some sort of medium-range beam weapon as well; The weaponry is standard issue, and it is generally considered more trouble than it is worth to mount and dismount the weaponry depending on the mission - if there are no hostile natives, there is often enough nasty local fauna that needs to be dealt with.
Weaponized Servitors
When the war started, Forge servitors were quickly retasked for combat duty, by recalibrating arc welders, hardmounting heavy bolters and uploading combat and targeting routines to the servitor brains.
Forge Knights
The Stenberg Forge makes extensive use of large anthropomorphic mechanicals for heavy lifting and large-scale work; Only when a particular manufacturing process has been codified and entered into the Book of Standards will fixed installations like cranes and conveyor belts be built.
The mechanicals are typically crewed by one, a highly trained, skilled and respected Tech Adept. Since the machines look much like an ancient suit of armour, both the machines and their operators have, over time, acquired the name "Forge Knights".
In times of war, the Forge Knights are easily adapted to combat; Their hull is built to withstand accidental spillage of molten metal, and their list of standard configuration tools include arc welders and forest-clearing implements. The welders, re-calibrated for firing intense bursts over as long a range as their optics allow, make excellent mid-range beam weapons, and the chainswords works just as well on enemy armour as it does on timber (though the teeth needs replacement more frequently).
Class Gothic Cruiser 'Leibniz'
The Gothic class Cruiser
Leibniz is part of the Stenberg Forge defense fleet; It is nevertheless frequently away from its home port, serving as military protection for Explorator fleets both small (where it would be the only capital ship) and large (where it would form part of a cruiser squadron, possibly escorting an Ark Mechanicus flagship).
At the time of the Heresy war, it saw action during the fighting for Stenberg Forge; It provided ground support for the beleaguered defenders during the initial surprise assault, but was ultimately driven away once the attacking Guard had secured the orbital defence lasers; It subsequently took up station in the system, harrying Imperial reinforcement convoys until it was able to form up with the returning main fleet.
Stenberg Skitarii, 1st Demi-Century Hypaspists
The Stenberg Forge was not without regular military forces at the time of the outbreak of hostilities; In addition to the defending Imperial forces, the Forge maintained its own Skitarii militia.
When Imperial PDF attack came, the Skitarii Hypaspists currently on duty in the forge commandeered a shipment of Rhino APCs and went out in the face of overwhelming odds to protect the forge and the sanctity of the Machine Cult.
Macaroni Heavy Tank Cataphract
In addition to the Hypaspists, the Forge standing military force consisted only of a small squadron of venerable Macaroni heavy tanks; They were mobilized along with the Hypaspists and faced the Guard onslaught on the first day of the war.

The usual main weapon for a Macaroni command tank is a twin-mounted Vanquisher cannon, useful in stand-off tank battles. However, a small number of Macaronii were fitted with Vulcan Mega-bolters, for use in a close support anti-personnel role.
EDIT: Added obfuscation.
EDIT again: Removed possible IP infractions