The success of this kit lies at it's foundation. So, instead of having all that fun with the top/cosmetic section first, I've decided potential walker builders must slog through the tedious mechanical bits first.
First and foremost: There are a lot of parts, and keeping them in the right orientation can be challenging to builder's not familiar with the AT-RT's geometry. This is an excellent rendition used for the Battlefront II AT-RT as well as the version that this kit was based. The pictures are excellent, and will help you keep track of things. https://www.artstation.com/artwork/lknEY
First up is the feet. They are cast from an open faced mold and are very easy to finish up. Simply sand as you would any flat bottomed part on a flat surface, but instead of using the usual 220 grit sandpaper or so, I recommend starting at something around 100. Then do a light scuff-up of all the other surfaces with 400 or wetsand 220.
Since we're already here, we might as well sand the toes. Clean up the seam lines with an exacto knife, then scuff all of the surfaces. Insert one into the foot and see how it fits. There might be a bubble or two at the base of the toe, but if it is not seen when installed, don't bother cleaning it up. Your prepped parts should look like this:
Once prepped, we can glue the toes. The left toe (left from the AT-RT's perspective, not the builders) is marked with an L and corresponds with the foot pictured below. The toes are a little different, so make sure you glue it in the correct foot or it will be a little off center.
Scuff the mating surfaces of the toe and inside the hole with some sandpaper. Then, but a few drops of super glue to glue it together. Make sure the foot is on a flat surface, and make sure the toe is also touching the "ground" at the tip, and centered. This will make the foot as stable as possible.
Moving on to the ankle joint and lower calf. Open up your parts kit, and grab these guys. Note that the caps for these bolts are stainless steel, vs the aluminum caps that came with the longer bolts. DO NOT mix those up. You need the strongest materials at this joint. This is the most important joint on the whole kit, so follow these steps carefully.
It seems a little strange, but we need to sand the both sides of the rubber spacers. Make sure they are completely sanded on both sides so there is no "shine" left on them. This will help it grip the resin.
You're going to need to scuff up the bolt posts themselves, too. The best way is to use a rotary tool with a cut off wheel attachment to scuff up the metal. I like to put shallow gashes in the metal and rough it up a little with the edge of the disk. Ideally, the underside of the cap and the first quarter inch of the post need some texture added to them. If you don't have a rotary tool, some manual sanding will have to do.
After that, put a single drop of glue on the area you just sanded, and insert it through the hole in the ankle in the direction pictured. Its ok to go light on the glue here, we're going to put more on from the other side. try and get the post as centered as possible relative to the plastic, NOT the hole drilled. The holes are sometimes a tiny bit off and are a tad larger than the post diameter.
Once the glue has dried, sand the post a little as well as the small rectangular nubs used for friction. (220) Then, glue one of those washers you sanded into place firmly against the friction plate.
Now we can simply bolt up the lower calf to test the fit. The metal post you just installed can vary in length just a tad, so a washer is included just in case. Install the calf without a washer first if you can. Then tighten it up to a moderate amount, move it around a bit. eventually the rubber will compress and you will probably need the washer to keep the tension. After break in, I recommend tightening down the ankle fairly firmly in the position you will most often use, and use the joint sparingly. When you do pose it, it will help longevity to loosen the screw, position, then re-tighten.
Give the lower calf the prep work and scuff to the level you desire.
Then, take a piece of 220 sandpaper and fold it in half, twice. The edge is firm, yet flexible, enough to get down into the circular grooves. We need to scuff those up and remove any imperfections on the surface. (and if you painted before assembly, it is probably better to get rid of any paint that made it into these grooves.)
Grab the upper calves and do the same thing. (Prep the parts, sand the circular grooves) With the upper calves prepped, we're going to install the lower fender. Look for these two little guys and flip them over to the bottoms. Then sand the bottom as pictured before vs after. Keep in mind that the area being sanded angles back a tad to fit the geometry of the leg. It is not a perfectly flat surface.
Then glue them into place on the upper calves. They go on the side with the rectangular panel. Having the fender on there before gluing the joint/pins will help easily determine which side of the calf is "up" for assembly.
With all the resin prepped and ready to go, go into your parts kit and grab these guys. Make sure to wipe down the O-rings with a towel, as they might have some residual oil/lubricant from the factory.
Rough up the metal screw posts just like you did at the ankles. Only this time, we're going to rough up the top 1/2" of the post instead of just the top 1/4". Install the O-rings into the grooves of the lower calf and press them in firmly. They will stay in place. Then carefully slide the assembly into the bottom of the mid calf. Make sure the leg is "bent" forward, and the fender you just installed is facing up!
Carefully put the joint together and put the post through as a test fit. Check the orientation of your parts. The fender faces upward when the leg is bent. Then check. Then check again. Once you glue the post, you cant go back easily at all.
Just like before, put 2-3 drops of glue at the end of the post, then push it all the way in. We don't need tons of glue here, we're just trying to stop the post from rotating during tightening, we aren't gluing the leg together directly. Get the cap for the other side, and tighten it up just a little while it dries. wait about 20 seconds, then try and bend the leg a little. If all is well, the bolt will stay in place, but the leg will still move.
We'll move on to the magnets and hips before we do the thigh joints. Get out these parts:
It is recommended to rough up all the magnets with some 220 sandpaper. I find that keeping them in a row makes it easier to sand the round edges all at once. (in progress, pictured below) Then, individually take them off (can be a challenge) and scuff up the flat side the same way you would a resin part.
Get one of the pistons, and sand the little nook at the tip of the ball joint, then glue a magnet in. There is enough clearance that after the magnet is placed, you can still drip a tiny bit of super glue along the edges to cement it even more.
Get out the other three piston parts, and do the same. Make sure the magnetic polarity is facing the identical direction on all parts. it will make your life a LOT easier.
The thigh parts have obvious mounting locations for these pistons/magnets. Rough up the cavity, check the magnetic polarity several times, then glue the magnet in. Make sure the magnet sits flush with the bottom of the cavity. (push it in with something non-magnetic) If it is too high, the ball joint won't rotate as smoothly and will be a weaker bond. The piston part with the smaller spherical end is the one that goes here. (Pictured)
Enjoy the fruits of your labor. Wiggle it around, make it extend, etc. It isn't your first time.
Home stretch. The Hip parts are last. Make sure you grab the last two stainless steel screws for the posts. (They should have came attached to the hip joints when they shipped to you) The are shiny, and magnetic. The aluminum ones are not. Rough up the track in the hips, the thighs, and a little bit of the surface of the 0-ring. (This process is the same as the lower calf joints, so no pictures required. )
Do a test fit with each of the thighs. If the aluminum post is really close to the surface, you may need to sand/grind down the edge of the aluminum about a MM or so. It is very difficult to suspend hardware in molds while they are being rotocast, so a slight variance is always possible. The one pictures below checks out, just barely but may be shortened in the future as the 0-ring compresses over time.
You can go ahead and screw it in. These joints, along with the ankle joints can be removed at any time. Here's a picture in the correct orientation for reference. As you can see, the large fender points up, and the mounts for the magnetic joints face inward. ( I don't recommend gluing the large fenders until after painting as it is easier to paint, but it is your call. )
The joints/process between the upper calf and thighs are identical as the other joint you did earlier that utilizes two O-rings. I recommend removing the calf from the hip as you assemble/glue that joint if you haven't installed it already, but the order isn't important aside from ease of assembly.
With those last two joints done, you're ready to start messing with the poses and get ready for the top half!
before you tackle the top half though, I recommend breaking in the bottom by posing it, and re-tightening the joints periodically.
Welcome to the first resin kit tutorial! Although the kit used in this tutorial is slight departure from our usual space gun/ship kit, this kit has a TON of parts, three different types of resin, and covers a lot of techniques that should help you through other kit builds and more if you have never touched a resin kit. So, let's get right to it. This tutorial will serve as a general resin kit tutorial, as well as a specific tutorial for the 1/6 scale Star Wars AT-RT Walker resin kit we produce. Although I don't recommend this specific kit as a first kit, it is certainly do-able for the motivated maker.
We'll start off with what you'll need for build and prep. At a bare minimum, you'll need 220 and 400 grit sandpaper, a hobby ("Exacto") knife, cyanoacrylate ("Super Glue"), and on this kit specifically, some way to drill a 1/16th inch hole. Things like scissors, a model saw ("exacto saw") and a rotary tool ("Dremel") are highly recommended in general for kit building.
Trimming Raw Parts
This is where some good old fashioned scissors can help. We usually remove most of the flashing from our parts, but in cased we missed some, you want a closer cut, or got a kit from a 3rd party with some heavy flashing, this step can save time. Simply do your thing and cut the flashing off. Be careful not to cut too close or at an angle.
Sanding Open-Faced Parts
The easiest parts to prep are cast from "open faced molds". These are parts that are relatively simple in geometry and have been made in a such a way that one surface doesn't show, has no detail and can be sanded flat, or is simply glued to the face of another part. That means no seam line, and usually one simple surface to take care of. For this, we use 220 grit sandpaper and a flat surface (a machined, flat surface is ideal. However, at this small a scale a piece of wood etc. will do fine)
Simply take the part, and sand it back and forth on the 220. Try and apply pressure evenly with your fingers, or the part may come out a little crooked. Slow, precise, and firm sanding is ideal as opposed to quick, vigorous sanding. we don't want to create a rounded surface on the bottom.
Check your work as you go. This particular part has a fairly simple thickness/ geometry and is easy to see if one side is higher or lower. Don't always follow the line/ridge at the edge of the face you're sanding, it can be misleading if the mold was trimmed after production. I like to clean up that small edge with a light pass of 400, just to round it out a tad. Can you tell the right side is a tad thicker, even after sanding? It won't matter for this application, but is something to be aware of.
Some open faced parts are made to be glued together. This is designed to reduce production time/costs, or simply to orient the casting process in a way to minimize or eliminate bubbles. This exhaust muffler assembly needs to be surfaced and glued. You can also see the original state of the back of the part we just sanded.
You know what to do! (Hopefully)
Gluing Open Faced Parts and Assemblies
Now the scary part. Glue. If you are using "super glue", you only get a +/-3 shot at this. on surfaces that have been sanded with 220, the bond is instant. You only need 2-3 tiny drops on something this small. The bond is incredibly strong. If you wish, you can also mix up some 5 minute epoxy instead. It is much more forgiving in the sense that you have way more time to position your parts before they set. On the downside, they often need to be clamped, and on parts this small, it is near impossible, and the parts can "float" around a bit before they settle. Epoxy is also thick and oozes from cracks. I also like to scrape the edges with an exacto knife before I glue them down to ensure no "lip" remains. More on exacto-based cleanup in a bit.
On larger, or multi-part assemblies, injecting super glue (Not the gel type super glue, which is awful for everything) into the cracks and crevices after holding the parts in their ideal position can work, as long as the glue has room to seep into the area. This doesn't work with perfectly matched up parts, so you'll need to intentionally leave a gap or simply use it on an application where fitment isn't near perfect. This AT-RT assembly is a good example, as finding alignment here can be tricky, and once the glue is laid down and the parts touch, that is it. This method works backwards from that, and while can result in some runny glue marks, will ensure your alignment is exactly where you left it. Just be sure to sand the mating surfaces with 220 grit.
Cleaning up Bubbles
We're going to go back to that rectangular part to cover the bane of resin kit building: Dealing with bubbles. There are two types of bubbles. Positive, and negative. Positive bubbles are a result of bubbles from the silicone process and therefore all subsequent casts will have these. Negative bubbles are from the casting process and vary part to part. Positive bubbles, as the name implies, are typically easy to deal with and can usually be removed by simply scraping them away with a hobby/exacto knife of the like. Be careful if you are using a brand new blade, the tip can easily break off and hit you in the eye. Here's an example of some pesky little bumps we have to deal with. At least there's medicine for these...
As you can see below, simply dragging the exacto parallel to the surfaces in question made quick work of the positive bubbles. We're going to remove all of them in this inside area, as well as on the top surface inside those two parallel grooves.
Sadly, we aren't done yet. This part has two, tiny negative bubbles we should probably address. Counter to what you might think, we're actually going to make those holes larger by digging them out slightly with an exacto knife. This will make them easier to fill.
Now we fill it. This is a point of contention for makers. Do we use body filler (Bondo)? Spot putty? Apoxie sculpt? Super glue and baking soda? That all depends on the scale of the imperfection, as well as which method you prefer. Personally, we loathe body filler (Bondo) on anything that isn't a large, smooth surface. For most things, especially things this small, we prefer the super glue method as it is by far the fastest and the materials are already in front of us. We start by sanding the surrounding area of the hole with 400 grit until some resin dust fills the hole. (or you can use some from your sanding excursion earlier, or use baking soda) Then, we add a tiny drop of super glue.
Here, we can wait for the glue to dry completely before sanding. Personally, we like to remove a little of the excess, and when it is about half way cured, start sanding it with 220 or so. This will immediate pack the hole with dust and cure the glue, at the expense of gunking up your sandpaper, so we use scraps for this. It should look something like this when done. You can repeat the process as many times as needed to fill the hole, and on the plus side, since it uses the same filler that the part is made from, it is very close in color. This is good for kits that encourage the builder to use the resin color of the kit as the base color, such as our Arwing kit and black M96 Mattock kit.
For general seam lines and larger bubbles, we like to use a combination of the above super glue/fill method, as well as some careful exacto handling. Here's a large bubbled area on the front shroud of this kit that required about three passes of the super glue method and some 220:
Hopefully, whatever part you are working on has some shallow seam lines and can be partially (If not mostly) addressed with an exacto blade simply by scraping it. Use as new a blade as possible for this, and ONLY scrape away from you. Do not scrape back and forth, as it causes vibrations and a wavy finish, and more importantly can lead the user cutting themselves. This method is extremely quick and the results are hard to argue with. Provided the kit is of highest quality, and not from an older mold) Pictured here is a partial seam line on the exhaust muffler we glued together earlier. Any imperfections leftover after scraping should be treated with the super glue method. (Or your filler method of choice)
Transparent Resin parts
Resin parts can sometimes be printed vs cast. For small parts like this, printing in clear resin is much faster and more economical than casting resin. However, prepping the part is the same. Since clear parts are typically for illumination, we need to diffuse the light. We can do this many ways, but the most simple step is to sand all of the surfaces of the part with 400 grit sandpaper. This is a tiny leadlight lens, and luckily it is flat and quick to sand.
You can fold a small piece of sandpaper in half one or two times to create a firm, thin "file" of sorts. This helps get in nooks and crannies without the need for specialized files. However, the thin edge will wear down fast, so you'll have to periodically re-fold the sandpaper and use a different location on the sandpaper. In this case, we need to kit this tiny crack with 400 grit.
In cases like this where a clear part needs to be installed it will need to be glued after painting, but for this kit/example we are going to glue it in early. If you are lucky, the part will simply press into place firmly. Ours didn't though, so a few TINY drops of super glue were used. They make special glues for this sort of thing (Model aircraft canopy glue) if you want to try that, but because we have access to the front and back of the lens the excess glue can simply be sanded off with more 400 grit. Super glue is typically runny/watery and gets into little cracks to help bonding, but on the downside can leak into places you don't want. One of my drops leaked into the back here, but sanding made short work of it.
Sprue Clean up/sawing
Our kits ship out with the sprues already cut, but in case we missed a bit, or you got one from another vendor, there are two options. The Dremel/rotary tool is probably the most common method out there and for good reason. You can do most operations on one tool and have tons of options for bits. A lesser used method is the exacto saw. This is a far less dusty, and often more precise for the bigger. One slip up with the dremel and you can create a lot more work for yourself. The exacto saw is a slower and safertool for this sort of thing. Pictured here is the removal of two casting vents from a resin part.
Lastly, and possibly most importantly, give all of your parts a sand with 400 grit sandpaper, ideally a wetsand. (Wetsanding, as the name implies is sanding while the surface of the part is wet. Some sandpaper adhesive will deteriorate in water though, so try and get sandpaper made for wetsanding if you plan to do it a lot) The reason for this is during the casting process, any maker worth their salt sprays the mold with a release agent which by design makes it hard for things to stick together. The molds are then brushed with powder to soak the resin into the nooks and crannies, resulting in less bubbles. The downside is the powder and resin adsorbs most of the mold release and gets embedded into the surface of the part. This means that paint won't stick well to a resin surface that hasn't been prepped. Sometimes it seems like it does, and then chips off later. Be VERY sure to prep any/all surfaces before paint! Below is a picture of 3 different resin materials, all wet-sanded with 400 and ready for paint.
Part 2 soon!