High Bar Acrobat on a String

Some days ago a customer brought a DIY toy acrobat to our repair workshop. It was in parts because, obviously, her grandchildren had played with it a bit too resolutely.

For repairing it, several strings had to be re-attached, but unfortunately we didn't manage to make it work again - because, you guessed it, there is a trick behind it.

In order to understand its function, I tried a web search. As soon as I had worked out how this toy is called, I also was able to find it. There are several web sites describing it, some of them even provide plans for DIY-ing it.

I thought it a nice idea to try it myself, for better understanding its working principle, and perhaps as a gift for my granddoughters - and, who knows, I might be able to make such a toy together with them.

Materials

1. Some poplar plywood, thickness 4 to 6 mm (a piece of about 20 × 30 cm is sufficient for four acrobats)
2. Some square beechwood strip. I had some with a cross section of 10 × 17 mm in my junk box. Required length for one acrobat about 70 cm
3. Some plywood; I had a piece of about 5 × 10 cm, thickness 18 mm, in my junk box - it may as well be a little larger
4. 6 pcs. 3 × 30 mm countersunk head SPAX screws (or nails, 2× 30 mm - but screws will be much better)
5. Some sturdy wire of about 1 mm dia.
6. 8 glass beads with a bore a little larger than the wire
7. Some sturdy hemp string of about 1.5 mm dia.

Tools

1. Jigsaw (or electric scroll saw, if available)
2. Rip saw (or band saw, if available)
3. Sandpaper (or disc-type sander, if available)
4. Awl
5. Hand drill (or cordless power drill, if available), drill bits of 1.5, 2.5 and 3 mm dia.
6. 90° countersink bit
7. Phillips screwdriver
8. Wire cutter
9. Small round-nosed pliers
10. Small hammer (if using nails instead of screws - not recommended)

Cutting the parts

I found a plan for both a girl and a boy acrobat online, see PDF file attached below. I printed the plan on plain paper, taking care that the size was set to 100% (full size) in the print menu. Then I roughly cut the five pieces per acrobat - body with head, two arms, two legs) and taped them on the plywood piece. The adhesive tape needs to cover the respective piece completely, so that the piece can be cut with the jigsaw with the paper piece remaining upon the plywood until the end. You might as well copy (trace) the contour of the five pieces on the plywood directly. Lightly sand the edges of the cut-out pieces.

Mark the holes in the body, arms, and legs using the awl (so that the drill bit knows where to start); drill the holes afterwards. A diameter of about 1.5 mm for the joints is ok, the two holes in each hand need to be somewhat larger, 2 or 2.5 mm will be ok.

If desired, you can paint/decorate the body parts.

Assembling the parts

Cut a length of about 3 cm from the wire and bend one end to a loop using the round-nosed pliers. Thread one of the beads on the wire, then one arm (or leg), a bead again, the body, a bead, the second arm or leg, and the last bead. Bend the other end of the wire to a loop. Check whether the joints can move freely.

BTW, the joints of the acrobat in our workshop didn't use wire for the joints but string knotted on both ends instead - but I could persuade our customer that using wire is easier and works somewhat better...

Cut two pieces of about 32 cm and one of 5 cm from the beechwood strip. Sand the ends so that they are nicely square. Lightly sand all the edges, too (it is then more comfortable for kid's hands). Drill 2.5 mm holes in the longer pieces - two each about 5 mm from the top, two each about 18 cm from the top, and in one of these pieces two holes about 9 mm from the bottom.

Drill matching holes in the front and rear side of the short 5 cm piece. You might want to drill these holes in one go with the ones in the long strips by carefully positioning the parts and clamping them together so that, later, the mounting screws will find their way easily. After that, increase the holes in the long pieces to 3 mm so that the screws can pass through them. Use the 90° countersink bit to provide recesses for the screw heads. Screw the high bar together; you might want to use a little wood glue at the ends of the 5 cm piece before tightening the screws.

If using nails (not recommended), drill holes of about 1.5 mm dia. in the long pieces, and don't forget to tap the nail's tips lightly with a hammer before using them to connect the two long pieces with the short one. In this case, a little wood glue at the ends of the 5 cm piece is recommended.

Cut two slots in the plywood piece as shown in the detail pictures. The side with the short slot will be used for fixing (screwing on) the long beechwood strip piece with the two holes at the bottom. The longer slot must be a bit wider than the beechwood strip, so that the strip can move freely to and fro when squeezed. This plywood piece can also serve as a foot when the high bar is placed upright.

From the outside, thread a piece of string through the two top holes of one of the beechwood strip pieces. Now comes the trick: Take the string end from the rear hole and thread it through the front holes of both hands, then back to the rear hole of the second strip piece. Take the string end from the front hole and thread it through the rear holes of both hands, then back to the front hole of the second strip piece. This way the string is crossed at both sides of the hands. Knot the two string ends together so that there is a little tension in the string.

Provided that the string is crossed correctly (this is what I didn't know when trying to repair the acrobat mentioned in the introduction), a little manual squeeze of the lower ends of the high bar is sufficient to let it make the craziest acrobatic movements, as shown in the video clip of my prototype that can be downloaded below. And all - the lady in our repair shop as well as my granddoughters - really had a lot of fun with it.