Turbines and prongs

So the Shadowsword cannon base fit together with minimal headache, and I started on the front end of the gun. Using another Shadowsword cannon part for the front end, I managed to snugly fit the motor inside and glue it in so it was centered.

Now, some of you may wonder why there's a turbine on the front - after all, the videos above pretty much demonstrate that I have a SAG spinny front bit.

However, after a bit of eyeballing, I've come to the conclusion that the SAG spinny front bit has three problems that prohibit me from using it on this project. First off, it's too small. Since I'm making a very large Shokk Attack Gun, it seems only proper that the front spinny gubbin be much larger than the standard bit.

The second problem with the bit was that it was (surprisingly enough! ) never designed to actually spin, meaning that it spins horribly off-balance due to the 'prongs' not being angled out equally.

The third, and last problem with the bit was that it was heavy. While the Thunderfire Cannon chassis is more than weighty enough to hold the gun down and in place, the weight puts more of a strain on the motor, and I need the motor to survive a good, long time.

Thus, I started on what you see above by making the 'axis' for the new SAG spinny bit. The turbine on the front is one of the bits from the underside of a beakie drop pod, with styrene tubing behind it to help bulk it out a bit. There's a smaller styrene tube in the middle of the turbine that goes back through the front of the gun casing to the motor, which spins the part wonderfully. All assembled, we have the following:

 

You can see the stock SAG bit for scale here.

So, if I'm making my own SAG bit, how would I possibly make one that spins better than the existing Mega-SAG? Surely anything I make would inherently be offbalanced, due to it's hand-crafted natureWhat's worse, it could be fragile in the long run - how well does Superglue hold up to repeatedly being spun over and over and over again? I could picture one of the arms of the gun just falling off after a few years! Well, this is where the magic of casting comes in.

Here's the general idea: Make one prong out of styrene. Cast the prong three times. The resulting prongs will be extremely lightweight due to the fact that they're made out of resin, which means there's a lot less strain on the motor. They're also going to be all one solid piece, meaning that there's much less chance of any parts like rivets going flying off after years of use. Lastly, they're all exactly identical, which means that they are all the same weight, and will balance the front SAG bit perfectly as they spin!

With this in mind, I set about making the 'prong' for the SAG and came up with the following:

 

You may wonder what the heck's going on at the right side of the prong - it looks like two cylinders are just pointing out to nowhere. The answer to that is actually quite simple - there's going to be ribbed cabling between the two, from the base of the bit up to the spherical 'head', between the ends of the two cylinders. However, ribbed cable texture is a pain in the ass to cast, and is prone to defects that can be monstrously annoying to clean up. What I'm going to do instead is basically cast the bit as it is, and then get some very short, evenly-measured lengths of guitar wire to put in each end of the cylinders between the head and base of the prong.

So now, we cast the prong three times over!

Shokking development

A while back I put together Big Mek Booma, the grand architect of the warmachines in my Waaagh! When I did, I gave him a Kustom Force Field generator-type backpack in the expectation that I'd be using him for that more than anything else. However, times have changed, and I have come to see the error of my ways. You see, I tend to run big squads of Lootas. Lootas have an absolutely terrific range and high strength, but have a bit of a shoddy leadership, and if they take a couple casualties they have a tendency to up and run. Since they're pretty costly in terms of points, I've been experimenting recently with sticking a Big Mek with a bosspole in with them to try and prevent any early retreats.

From what I have been able to figure, giving that Big Mek a Shokk Attack Gun makes a ton of sense. The random 2d6 for strength averages around S7, which happens to be the same as the lootas, so it makes sense to turn the SAG on whatever the lootas are firing as well. Additionally, both the SAG and the deffguns share the same range, meaning it makes sense to keep them in a squad together. It's a beautiful squad for taking down those high-save units like Terminators, because the SAG will simply penetrate the armor if it hits, while the deffguns will just force piles and piles of saves.

The problem, then, is figuring out how to get Booma a Shokk Attack Gun. After a bit of head-scratching, I had what I thought was a rather clever idea: Make it the orky equivalent of the thunderfire cannon.

The thunderfire cannon, for those of you who may not be familiar, is the giant artillery piece that rolls along with Techmarines.

The way I figured it, if I'm going to be making a separate Shokk Attack Gun model, I may as well make it huge so that I can run it as the Shokk Attack Battery formation in Apocalypse. The idea's pretty simple: In regular games, I park the Shokk Attack Gun somewhere near Booma on the board to display what armament he actually has (which, of course, would be a SAG). In apocalypse games, I'd make a larger base (Maybe 3.5-4" diameter) that I could magnetize both my Big Mek and the gun to, which would have the same profile as 3 Big Meks (meaning, 6 wounds) and 'count as' the entire Shokk Attack Gun battery, by itself.

So, with the concept firmly in mind, my first problem was collecting the parts I'd need. I've been stewing this whole concept over for the past six months or so, and I think it was a foregone conclusion from the start that I would have to motorize the thing. The problem therein was motorizing it at an appropriate speed.

First, I started looking for motors small enough to fit in what I wanted.

The video above shows a stock SAG bit stuck to the front of a small helicopter motor. Now, this motor had two particular complications. First, it spun incredibly fast once it got going, which is impractical from a hobby standpoint because I don't need my models trying to get airborne from the table. Second, it didn't really have the torque to start spinning without help, even when voltage was applied; you had to give it a bit of assistance by spinning the bit first with your finger. I could have tried higher voltages, but the motor wasn't really rated for it, and would have burned out in a hurry.

The second motor I tried was from a lego kit. It was substantially slower, and a hell of a lot noisier, but due to it's 'lego' casing, it was a bit too large to be practical.

It was actually a bit slower than I wanted - I was aiming for a 'sweet spot' of sorts of about one to two revolutions per second.

I tried a whole host of other motors...

But I wasn't particularly happy with any of them. It seemed that with the low-voltage DC motors, your choices were either a small motor that spun at 30,000 RPM and didn't have enough torque to really get the SAG bit spinning, or larger, chunkier motors that had the torque but needed a hefty amount of voltage and space. I had been looking for a long time for a decent gear-motor mechanism that would take one of the speedy little motors and step it down enough to approximate 120 rpm or so, but the problem there was that most gearing mechanisms that could do that take up a relatively large amount of space. While I'm making a big SAG, I didn't want it to be too big as to not fit on a Thunderfire chassis!

Finally, I stumbled upon the 'holy grail' of Shokk Attack Gun motors: The 150:1 Mini Metal Gear Motor.

This little bugger had the ideal RPM for my project, ran on anywhere between 3 and 6 volts, had a hefty amount of torque, and a very small size (only 33.1mm long to the tip of the shaft!). The only downside to the motor was the price, but consider this: By making this Mega-SAG, I'm basically obviating the need to buy 2-3 more SAG Mek models, which more than recoups the cost.

I also decided pretty early on that I was not going to be using the actual body of the Thunderfire cannon, due mostly to how incredibly bad GW's casts are and how much repairing the body of the gun would have required. Instead, I'm only going to use the tread sections and the crosspiece that serves as the base of the gun.

So, what would serve as the body of the gun, then? I could scratchbuild something, and I figured I'd have to, but then the answer arrived all on its own: The Shadowsword Cannon. Specifically, the base of its gigantic barrel!

Once assembled, the base of the shadowsword cannon serves as a giant frame for the SAG to build upon, and it fills the space left vacant on the treads by the Thunderfire Cannon perfectly.

With these parts all in hand, I've set about building.