Cy Girl Ankle Cup Replacement

When you want to change the clothes of a Cy/Cool Girl you often need to remove the feet, with the v1 bodies this means popping the ankle balls out of the ankle cups, if you do so repeatedly the ankle cups may widen or break.
To remove the feet of newer CG bodies you have a choice of popping the ankle balls out or pulling the ankle cups out of the lower legs, but the latter puts quite some strain on the knee joints.
Takara does not offer replacement ankle cups and BBI no longer carries the regular Cy/Cool Girls series (only Perfect Bodies that have fixed ankle cups), so I decided to try and make my own replacement ankle cups.

The method described here works for CG v1.5 and v2 bodies.
For Perfect Bodies and CG v1.0 bodies with fixed ankle cups, Paul and Laura at offer an excellent tutorial on how to replace broken ankle cups.

This page contains the following sections:

Tools and materials needed:

v1.5 ankle cup
overview of tools
Overview of tools and materials for making an ankle cup.
I prefer using a sleeve around the stem of the large (6mm) cutter head to limit the cutting depth (a 5mm diameter sleeve with a 6mm head means that when you cut inside a tube the cut can go at most 0.5mm deep before the sleeve hits the inside of the tube, provided you keep the motor tool axis perpendicular to the tube). The sleeve consists of sections of brass tubing, simply slid over each other.
I put a pencil mark on the sleeve at 1mm from the edge as a guide for determining how far into the tube I wanted to cut the groove.
The ball cutter head is 6mm so if you align the mark with the edge of the tube, then the center of the groove ends up at 4mm from the edge. With original CG ankle cups this distance is 3.5mm.

Use a bootfoot without sleeve and make sure the sole is firmly screwed against the feet. The other bootfoot can remain on the leg, but it is better to remove the bootsleeve and any clothing that covers the ankle cup.
cut a groove inside the tube using the round cutter head
Start by cutting a groove on the inside of the Plastruct TB12 tube using a 6mm round cutter head fitted to a motor tool.
Before cutting, decide how far up the tube the groove should be:
If the groove is closer to the edge of the tube the ankle ball will fit more loose but the range of motion of the ankle joint will be greater, if the groove is further away from the edge the ball will fit more tightly (and the cup will hold its shape better so it will remain tight for longer !) but the ankle joint can not bend as much.

Cut the groove by gently rolling the rotating head along the inside of the tube, two or three complete turns should be enough.

After cutting the inside groove use the cutter head to chamfer the inner edge of the tube.
make a U-shaped cut-out in one side of the cup
Next make a U-shaped cut-out in one side of the cup. This cut-out serves two purposes:
  • to relieve the strain when inserting the oversized ankle ball and
  • as a guide for popping out the ankle stem in a tilting motion.
The cut-out in the original cups is 6mm wide and 6mm deep, but 5mm wide and 4.5mm deep will do. The cut-out should end where the groove on the inside begins.
You can use either the small (2.3mm) cutter head or a small round file to make the cut-out, make sure the cut-out has a smooth round shape without sharp angles.
testfit bootfoot
Take a CG bootfoot and test if the ball fits snugly in the newly made cup.
If the ball won't go in, use the large cutter head to chamfer the edge of the cup a little more and test fit again.
If the ball fits too tight or doesn't 'pop' into the groove, slightly widen the inside groove and test fit again.
If the ball fits loose, cut the edge of the tube just beyond the inside groove and start over.
measure length of foot plus ankle cup and mark length on new ankle
If the new ankle cup is to be combined with an original ankle cup, measure the distance between the top of the original ankle cup (where the cup joins the leg) and the sole of the foot (please note that there is no need to remove the cup from the leg, it was just easier to make a picture that way).
This distance determines the length of the newly made cup, so measure from the sole of the foot on the new cup and mark the right distance on the tube.
If you are making a pair of ankle cups, mark the first one 13mm from the edge and determine the height of the second one as described above.

Remove the bootfoot from the tube and cut the cup off the tube at the mark.

Use either a saw, a tube cutter or a knife to cut the tube. If you use a knife do not try to force the knife straight through, but make the tube roll by moving the knife back and forth along the marked line whilst applying moderate pressure. This way of cutting is both more accurate and much more safe.
cut a recess in end of peg
Use the 6mm cutter head to cut a recess in the center of the lower end of the peg, this allows the peg to fit deeper into the cup before it touches the ankle ball inside.
insert peg into top of ankle cup
measure and mark length of peg
Pop the bootfoot back into the new ankle cup.

Insert the peg into the top of the ankle cup and make two pencil marks, one at the edge of the cup and one 12mm above the edge of the cup.

After marking the peg, pull the peg out of the ankle cup again.
Cut the peg from the rod at the upper mark.
sanding down the peg to 4.0mm
Wrap a piece of masking tape around the (lower) part of the peg that should fit inside the ankle cup.
The tape should protect this part of the peg from getting sanded down.

Measure the width of the peg, it should be about 4.8mm wide. The width should be sanded down to 4.0mm. Sand the first side down until the total width is 4.4mm, then sand the opposite side down until the total width is 4.0mm. Sand each side right up to the masking tape, but try to create a slight taper: a total width of about 4.2mm near the masking tape helps to fit the ankle firmly to the leg.

Repeat the above for the remaining sides.

Apply water to the file and the surface while sanding to avoid airborne plastic dust.
mark and cut a locking groove in the peg
Remove the masking tape and mark the locking groove, it should start at 6mm from the edge of the cup and end at 8mm from the edge of the cup.

Use a thin square file to file the locking groove in each side.

Using a sharp knife, cut the tip to a pointy taper: 3.0mm wide at the tip to 4.0mm wide at 4.0mm from the tip.
Save the snips of plastic cut from the tip, these are useful for filling the gaps between the square rod and the inside of the tube later on.

Use the nail file to clean up any sharp edges, etc.
final assembly
Carefully test-fit the new peg in the leg, it should snap into position.
If inserting the peg into the leg takes too much force, then it needs some more sanding, look closely at the gaps between the peg and the hole in the leg to see which side is too wide. Sand this side some more and test fit again.

Remove the peg from the leg and fit it to the newly made cup (which still has the bootfoot fitted), the lower edge of the locking groove in the peg should be exactly 6mm above the top of the cup.
Pop the bootfoot out of the new ankle cup.

Use the snips of plastic that resulted from cutting the pointy tip to fill the gaps between the peg and the curved inside of the tube. This adds more surface for the glue and increases capilary action to draw the glue into the gaps.

Glue the mounting peg into the cup using Plastruct Plastic Weld glue or a similar type of glue that melts plastic. Note that most types of Superglue (Cyanoacrylate) are not suitable because these types of glue can not withstand shear stresses.
Apply the glue sparingly and from the top of the ankle cup only to avoid damaging the inside of the cup.
Let the glue cure for at least a day, after that the ankle cup is ready for use.
comparison pics of original v1.5 ankle cup and my version
comparison of new and original v1.5 ankle cup
v1.5 ankle cup dimensions
CG v1.5 ankle cup dimensions.
CG v1.5 ankle cup dimensions:
White tube (Plastruct TB12 Butyrate): 13mm tall (9.5mm diameter) centerline inner groove at about 3.5mm from the lower edge.
Gray peg (Plastruct ST06 ABS): 18mm tall (6mm inside the white tube, 12mm outside; 4.0mm wide, 4.0mm deep) 2.0mm wide locking groove at 6.0mm from the edge of the tube, top 3.0mm chamfered. The locking groove is cut in all four sides of the peg.

The new cup is slightly smaller (0.5mm) in diameter than the original cup, this allows for fitting some thin styrene tubing around it which is useful for painting as most types of paint won't adhere well to this type of plastic.
If you do want to paint the cup itself, model enamel paints work best.

v2 ankle cup
homemade v2 ankle cup
The v2 ankle cups differ from the v1.5 cups I made before: the v2 legs and ankles have a slightly larger diameter and have an egg-like shaped cross section due to the way the shin is modelled. To make sure the ankle cup can not be inserted sideways, the v2 ankle cup peg is slightly rectangular.
I haven't found a way to include all of these changes into my homemade cup: I am already using the largest diameter ABS tube I can find and adding any kind of putty to build up the shape of the shin won't last due to the flexing of the cup when the ball is inserted or removed.
So for now this v2 cup is useful for girls wearing boots, but with bare ankles it won't look nice.
The method for making a v2 cup is similar to that for making a v1.5 cup, only the dimensions are different.
v2 ankle cup dimensions
CG v2 ankle cup dimensions:
White tube (Plastruct TB12 Butyrate): 15mm tall (9.5mm diameter) centerline inner groove at 3.5mm from the lower edge.
Gray peg (Plastruct ST06 ABS): 22mm tall (9mm inside the white tube, 13mm outside; 4.0mm wide, 4.15mm deep) 2.0mm wide locking groove at 7.0mm from the edge of the tube, top 1.0mm chamfered. The locking groove is only cut in the sides of the peg.

v2 ankle cup from ZC ankle cup
zc ankle cup converted to v2
Another way to get some CG v2 replacement ankle cups is by modifying a pair of ZC ankle cups. ZC includes a pair of spare ankle cups with their 'nude' Eve bodies, the ones on the Eve body are 15mm tall, the spare ones are 20mm tall, which may be too tall but there is a way to shorten these ankle cups.

The only thing you need to do to get a ZC ankle cup to fit a CG v2 leg is to file down the sides of the peg and cut a locking groove in each side.
The ZC peg is 5.0mm wide and should be filed down to a width of 4.15mm.
The locking groove should be 2.0mm wide and starting at 7.0mm from the edge of the cup.
The grade of plastic these cups are made of is pretty dense, I wore out a (cheap) sapphire nail file just filing down a single pair of these pegs !
I think you're more likely to break the ball off of a bootfoot than to break one of these cups !
Do use plenty of water when filing down these pegs to avoid any airborne dust (avoid breathing in the dust and avoid getting dust on your skin).

Note: When using a cutout as a fulcrum for removing the bootfoot, always use the small cutout, the large one is too large and might cause the ankle peg to break !

The end result: another Cool Girl back on her feet !

trying out the new ankle cup
trying out the new ankle...

yup, it really works !
yup, it really works !


For testing the longevity of these DIY ankle cups I fitted LM v2 bodied Angela with a pair of ankle cups to see if the cups retain their shape and grip.

broken DIY ankle cup I also made a separate ankle cup that I used for reference when making ankle cups and for test-fitting ankle balls.

10 years on, the ankle cups fitted to Angela still retain their shape and grip well, but after 10.5 years and many times of inserting and popping out ankle balls the separate ankle cup suddenly failed. There were no signs that the cup was about to fail (no cracks and no stress-marks), yet it suddenly broke.

The failed cup was rarely exposed to direct sunlight but was often exposed to scattered daylight, i.e. moderate UV light exposure, which might have contributed to the material aging.
Given the time it took to fail and the number of times ankle balls were popped in and out of the failed cup (averaging about one 'out-in cycle' every two weeks over a 10 year period), I consider this an acceptable life span.
A single length of TB12 tubing should yield about 10 pairs of ankle cups, making it excellent value for money.

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