I designed this for my 20 month old daughter who has severe hypotonia. The problem was that as she got older and bigger it was harder and harder for her to fight gravity and hold her head up. I built this to take some of the weight off of her head and still allow her freedom of movement. This allows her to still use her core muscles and build them up slowly while still interacting with her environment.
NOTE: I have a public github repo that has the original Alibre Design files and STEP extracts. It can be found here: http://github.com/wantmys2000/Head_Balanceinator
If you print this out please note that I designed it for my 20 month old daughter. I can not guarantee that it will support your child's head without breaking. I offer this design to be used as a starting point for your research and testing with your child, but I can not warranty or vouch for its safety in your situation. Never allow a child to be alone with this device.
I am going to break the build up into 3 parts; the head piece, the head piece support and the brace arm, and the bases.
On my RepRapPro Mendel it takes about 32 hours to print all the pieces and it takes about another 2 hours to clean up the prints and assemble the pieces.
You will need a roll of Flex EcoPLA from FormFutura for the head piece. It is super flexible and its tensile strength is much stronger then PLA or ABS.
I use LOCTITE PLASTICS BONDING SYSTEM 2 part glue to attach all plastic pieces. It seems to bond stronger then the 3d printed layers.
The head piece is print using the FormFutura Flex EcoPLA. You will also need about 5" of Velcro with sticky backing.
Print one of each of the following pieces:
- Slide the end of Front_Strap_hole_2.stl into the slot on Front_Strap_hole.stl. Make sure this slides freely.
- Once the two pieces are together and sliding freely, glue the Front_Strap_Nub.stl onto the end of Front_Strap_hole_2.stl. This gives you something to pull against while attempting to tighten the strap onto your childs head.
- Take one of the pieces from SideBracket_2.stl and push the round boss through the hold in one of the front straps. The small extrusion in the hole on the strap should fit into the small hole on the boss and keep things aligned.
- Repeat this with the remaining SideBracket and Front Strap.
- Take the Back_Strap.stl and hook it onto the hooks on both SideBracket's.
- Cut about 1" of the fuzzy side of the velcro and stick it on the end of Front_Strap_hole_2.stl, right under the nub you glued on.
- Cut about 4.5" of the scratchy side of the velcro and stick it on the front of Front_Strap_hole.stl between the big hole and the slot.
You should now have a complete loop that can be placed around your childs head, with the side brackets above the ears, the Back_Strap looping below the occiput on the back of the head, and the Boss's on the SideBrackets positioned about 1cm in front of the middle of the ears.
You will use the Attachment_Strap.stl later after you print up the rest.
You should be able to determine what I am describing from the pictures, but let me know if it is not clear.
Head Piece Support
This is the hard loop that attaches to the head piece and the Bar it will attach to.
Print each of the following pieces in PLA in the quantity indicated.
- Hard_Head_2.stl (1)
- SideBracket-Bool.stl (2)
- SideBracket-cap-Bool (2)
- Bar.stl (1)
- Take 1 SideBracket-Bool.stl and 1 SideBracket-cap-Bool.stl and test fit them on the end of Hard_Head_2.stl. I found that that the holes in SideBracket-cap-Bool needed to be drilled out to 2.5mm to fit over the posts without breaking. I also realized that the fit with hard_head_2 was very tight and required some heat to fit right. I used a hot air rework station to put some 200C air on the shaped cutouts in the SideBrackets and the ends of the hard_head_2 and pushed them together. That made a super tight fit.
- Once you get a nice tight fit glue the SideBrackets together and to the hard head. Make sure the SideBrackets are oriented correctly before the glue dries. Use the pictures as a reference for the orientation.
- Do this again with the remaining SideBracket.
- Insert the boss's from the SideBracket_2's from the previous section into the big holes in the SideBracket_bool's. You should be able to pull and "click" them into place. This will be the support structure that the Attachment_Strap holds onto.
- Take the "T" end of the Attachment_Strap and insert it into the last hole on the strap around the Hard_Head_2. This will make a loop that should have the second to the last hole wrap around the little clip in the middle of the hard_head_2. NOTE: this clip is just to keep the strap centered, it should not be used to support the weight. The strap should be looped tightly around the hard_head_2 supporting the weight.
You should now have what looks like in the above pictures. You will see I used a little piece of neoprene to reduce the pressure on the forehead.
You will use the Bar.stl in the later steps.
Print one of each of the following:
- extension.stl (optional, required if the bar is too close to the head)
Base_1 is a simple slip on base that can be used on solid backed kitchen chairs, etc. I have had to use zip ties to help hold it in place on most chairs.
Extension.stl can be used to raise the height of bar.stl if it is too close to your child's head. Be careful though as this puts extra stress on the joints of the base's. Make sure it can support the weight of your child's head without breaking. You might want to consider making this out of something more substantial then printed plastic.
Base2.stl is a more versatile base that uses velcro to secure it to things like head supports on standers and wheel chairs. It does require some assembly and a few additional parts to build.
- M5x70mm Cap Head Screw x 2
- Velcro One-Wrap x 3ft
- Insert one M5 cap screw through each set of holes. The screw is used as a strong bar that the velcro will wrap around.
- Cut the Velcro One-Wrap into 2 1.5ft pieces.
- Fold over the last inch back onto itself mating the ruff sides together on both ends.
- Hot glue the mating ruff sides together. This should give you a length of velcro that can be folded around each screw and attach back onto itself.
- Loop the ends of the velcro around the screws, starting from the back and looping over the screw.
You should be able to get the idea for the velcro from the pictures, but let me know if it is not clear.
You should now have all the pieces to use the Head Balanceinator. Put one of the bases on a chair, insert the Bar into the hole on the base. Put the Head Piece on your child's head and put them in the chair. Loop one of the holes from the Attachment Strap over the Bar to hold your child's head up. The head piece does not need to be too tight on your child's head, the back_strap should do a good job of holding it on. Also don't use too low of a hole on the attachment strap, you are just trying to remove most of the weight, not pull up on the neck.