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HOWTO: Assemble thighs (butt join with cover strips)

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I figure a detailed "How to" would be helpful for those assembling thigh armor. If anyone has additional expertise / feedback, post it up so that I can edit this so we can all use it for reference. I hope you find it useful!


A butt join is where two halves of armor are glued end to end, and a cover strip is glued on the outside. Butt joins are a more "screen accurate" method of assembling limbs on TK armor. Some troopers will also glue a shim on the underside of the seam for more strength. Though not always required, it will make the armor more durable.


Most armor kits are assembled this way. Kits like RT / AM / FX were designed to have the halves overlap, however - it is possible to build those kits with butt joins if you are crafty.


Example of a butt join with cover strip glued on top



Most troopers try to keep the front of their thighs closer to screen accurate, and cut material or shim extra material in the back of the thigh to widen it, depending on their size. If a troopers actual thigh is bigger than the armor, then wider shims are needed on the front and back.


*Measure twice and cut once! It's always easier to remove more material than to add it. Make cut and leave room for error, and re-trim if required.*


Trim your armor of extra material at the tops and bottoms, and sand the sharp edges. This can be done later after assembly too.


1.Test fit the thigh armor on your leg, see how much material you need to remove / add. If you can have a screen accurate front, proceed. If not, you will need to accommodate for wider cover strips on the front and back of the thigh.


2. Measure 10mm (assuming this will fit you) in from the outside "ridge" line on the front outside piece of a thigh, draw a straight line parallel to the ridge. *You will measure 10mm on the inner and outer thigh, equalling 20mm (the 20mm cover strips will cover the seam).


Example of a 10mm strip, used to draw a line on the front of the thigh. The material to the left of the strip will be cut / removed



3. Cut the excess material off using scissors, score and snap method or Dremel. Sand smooth


4. Take your inner thigh piece. Measure 10mm (assuming this will fit you) in from the inner "ridge" line, draw a straight line parallel to the ridge. Cut away the excess material as decribed above, sand smooth.


5. Take the outer thigh and butt up against the the inner thigh, tape them together and test fit. If there is enough material for a butt join in the back, you can move onto the next step. if there isn't, you will need to add extra material (shims) to take up the space.


Example of a thigh with trimmed front, leaving 10mm on each side equaling a 20mm butt join, with tape on the inside. Test fit it to make sure it fits you



Gluing the front butt join

You want to glue the fronts of the 2 halves together at this stage.


6. Some troopers will apply Plastic weld and glue to the front of the two halves together (tape the 2 halves together and run Plastic Weld cement down the seam - it bonds by melting the plastic slightly, but when it cured they are bonded), and glue the cover strip on top.

Others will glue the 2 halves, and then glue in an inner strip inside, before doing a cover strip. I used E6000 to glue the inner strips and cover strips, but there are many choices of adhesives. Choose the right one for your armor / intended use.




Another method is to glue the inner shim to one side, and after it has cured glue the other side thereby joining the halves, and apply a cover strip later. All of these methods work, it's up to you to choose what works for you.


If you're using E6000 to glue an inner shim, make sure to sand the inside of the seam and the underside of the inner strip / shim and clean them off. Then squeeze out some E6000 on each surface, and spread it with a popsicle stick, etc. Let the surface tack up, then join and clamp the parts.


If you are gluing an inner shim (or cover strip) in place, something that can help with assembly is using clamps at the ends of the shim / strip, and using rare earth magnets on both sides to clamp the strip down. It's sometimes hard to find clamps that will reach the deepest sections inside the armor, so magnets can be a huge asset.


Example of inner shim glued in place joining 2 thigh halves, using clamps and magnets



7. Once the glue on the front of the thigh is cured, test fit the back of the thigh.


*A note on sizing. I see a lot of troopers with thighs that have a lot of extra space especially around the knees. It's up to you / comfort, but I find that if I can get the thigh closer to the circumference of my actual thigh, and be able to slip 3 fingers under the gap on either side of my thigh, this is more than enough room. Granted, the images from the film show that most of the armor was very "fitted" to slim troopers. There is a balance you must decide on in terms of screen accuracy vs. comfort. Look at the screen reference images, and decide what works for you.


Example of test fitting my first build. I found the thighs too big for me, and on subsequent build have made them more fitted.



Wrap the armor around your thigh, and see where the back overlaps. In a perfect world, if the backs of your thigh armor have ridges on either side of the seam, and you can accommodate a 20mm cover strip to hide it, this would be perfect! In my experience, I found that I could maintain the outer thigh ridge, but not the inner one (I cut the ridge and the extra material off). You need to size the armor to fit YOU! You should be able to slip your feet through the thigh piece. *Note: see below for gluing the back vs velcro closure.


Take a pencil and make a mark at the top and bottom of the thigh. This mark should be roughly in the middle of the overlap (split the difference). This is where you will have a butt join / cover strip. Again, if you can maintain the ridges - great. If you have bigger thighs, you can maintain the ridges and have material in between (a wider shim and cover strip. If you are slimmer, try and maintain the outer ridge.


Example of marks on the back of the thigh indicating where the parts overlap and where the rear butt join will be



Example of outer ridge being maintained



8. Draw a straight line on the outer connecting the 2 marks on one side. Cut off the extra material, then test fit again. If it fits and the marks are still correct, draw a line on the inner thigh that matches the outer thigh. Cut off the extra material.


Example of material trimmed from back of thighs



9. You should now be able to tape the back side of the thigh butted together and test fit it. Adjust the cuts / trim more if required.


Example of back of thigh taped for test fitting



Gluing the back or velcroing?

Some people like to permanently glue the backs of their thighs, some like to close them with velcro (using the cover strip to hide it). It depends on how you put your armor on, comfort, etc. My thigh backs are glued shut, so I put my thigh armor on first, held up with a belt / garters, then put my boots on, then put the shins on. Some people do it differently. The choice is up to you.


10. Gluing the back of the thigh shut.

Butt join the back and glue the halves together like you did in the front, using the methods described above.


To demonstrate, this example shows the inner shim being glued to one side first, then after it has cured - it's glued to the other side.

Example of shim being glued to one side



11. Once the thigh assembly is complete (inner shims have been glued / cured), you can apply the outer cover strips. The cover strips for thighs are usually 20mm (approx 5/8") in the front and back of the thigh. These may need to be wider depending on your size. Again, most people try to make the front screen accurate and the back wider if necessary.


Example of cover strip on a finished thigh



Simply use a metal ruler and an Exacto to score parallel lines 20mm apart on your flat styrene / ABS plastic. Score and snap these strips, and sand the underside (where they will cover the thigh seam). Measure the length required to cover the butt join. Sand the corresponding areas on the thigh (make some pencil guide lines if necessary) as well before gluing.


Somethings that adds a nice finish is rounding the corners on the finishing strips. You only need to remove the sharp corner, do not take off too much material. Apply your glue to the strip, and tape it in position before clamping to prevent the strip from moving while it cures.


Example of placement of cover strips



Example of cover strip being glued / clamped in place




Sometimes the back of the outer thigh won't line up with the inner. Or the bottoms have a one side overhanging slightly. You can trim these areas and even add a return edge if you want to. Here, I have fixed an alignment using a heat sealing iron and some sanding.


Stukatroopers tutorial on how to make a return edge

Return Edge


The back of this thigh needed some trimming at the top and a return edge, so I used a heat sealing iron and smoothed it out. A little sanding, and it blends in nicely



After heating



After sanding



TO BE CONTINUED: adding Battery packs.

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The "battery packs" are the series of small blocks that surround the lower edge of the right knee on the thigh armor. A detail that many troopers recreate is the "rounded corners" on the lower edge of the battery packs. This was seen in throughout many scenes in the films, including the famous "Move along" sandtrooper scene.




The most common method for attaching the battery packs is heating the strip with a heat gun, and bending it to a curved shape. Once you have obtained the correct bend, you can drill a 1/8" hole on each end, and drill a corresponding hole on the lower thigh armor. Make sure to bend or clamp the battery packs in place, so that the tension of them stays "tight" to the lower thigh.




Because the battery pack is held in place with rivets, it may pivot loose on the thigh. Some builders may choose to apply some glue or velcro to the underside of the battery pack where it contacts the front of the thigh to prevent it from slipping down. Others simply use the tension of the battery pack to keep it in place.





You can use 1/8" diameter rivets, but you may need them to be 1/4" long. You want to put a rivet washer on the inside of the thigh armor to prevent the rivet from pulling out. The thickness of the battery pack, thigh armor and rivet backing washer may necessitate a 1/4" long rivet. The rivet can be painted white after installation to match the color of the armor.


Here's a tip you can use for bending the battery pack


Getting a good heat bend on thigh / belt armor

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Great tutorial, I bought a assembled set of AM armor of a friend that built it using your guidelines. He's shorter than me so I have to make new thigh pieces. He bought a spare set luckily. After reading this I'm going to jump into assembling the thighs.

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