Gunpla Mod Build: 1/144 XXXG-01H Heavyarms Part 2 – Elbows

Now that I have upgraded the hands. Next, I’ll modify the elbow joints.ha_104

The old poly cap joint only allows 90 degrees bend on the elbow. Although it’s enough for certain poses, it won’t do in case I decide to put the Heavyarms in a more dynamic pose.ha_201

In this mod work, I’ll be using the following tools:

tools_01Knife cutter, plamo side cutter and super thin cement.

tools_02Sanding paper (180 & 400 grit), mini saw, pin vice drill (2mm bit), and needle files.

tools_03Eraser, pencil and steel ruler.

item_01Pla plates with varying thickness (1.0mm, 0.5mm & 0.3mm)

item_02An old ABS leftover runner. If you’ve been building Gunpla for quite some time now, you are bound to have a few of these laying around. This is a good way of repurposing them.

ha_202Now, let’s get on with the mod build!

Where to start? First, we must have an idea of what we want to do and then figure out a way to do it! Confusing? I know… Well, since this is my first try in completely modifying an elbow joint of an old kit, I need to be careful so that I won’t end up like what this modeler did.


YIKES! Is it just me, or does it look like the Altron has freakishly long arms?

If I’m going to do this, I got to do this right! So, I had to get some inspiration from the company that design Gunplas, Bandai. Although the Heavyarms didn’t get a modern HG treatment, it did have a sort of upgrade in the form of the Robot Damashii release. And this version has an interesting elbow design.


Cool, sharp details and a neat elbow joint!

Now, that we got our inspiration we’ll now start with some cutting and bashing of parts.

ha_203First, I glued each half of the arm together, hollowed it out and then cut it just below the shoulder poly cap joint. I closed the bottom of the shoulder joint with a 0.5mm pla plate and then glued a 2mm peg on it, as seen in the photo above. I also carved out a wide opening near the elbow to accommodate the new joint same as in the Damashii Heavyarms.

ha_204I made a double joint elbow based on the Damashii elbow design. I carefully measured the length of the new joint so that it won’t end up being too long, or too short. I used a 2mm bit to drill the holes and I made 2mm pegs cut from the ABS runner.

ha_205The newly installed elbow joint. Side by side comparison of the modified arm with the unmodified one.

ha_206Bend test is a success! The elbow can now bend nearly 180 degrees.

ha_207bHere’s a before and after photo.

Below are more photos of the new and improved Heavyarms elbows! Just look at him all manly holding up his fist and machine gun hand. Not to mention that the elbow looks cool too!

Next phase are the hip joints and knee joints, heck even the ankle joints! Stick around for the next post!

Image sources: A modeller’s Innovation;

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