A rocking horse for Sophie

October 18th, 2009

Hmmm, almost Christmas again. Being someone who ‘makes stuff’ my sister asked if I was making something for Sophie for Christmas this year. I suggested a rocking horse. This is my attempt to do so. I don’t have much experience with horses. Probably the closest I have been is gluing two bits of paper together. Don’t blame me if it looks more like a sheep/dog/cow than a horse. It’s for a 2 year old, she won’t know the difference!

I decided to make the base rocker from wood and build a horse approximating shape on top of that for Sophie to sit on. The horse is made from polystyrene with pool noodle legs which is then covered in fibreglass to form a tough but light shell. The shell will be covered in foam then given a horse skin coat (that makes me think of ‘It rubs the lotion on its skin…’).

First I needed some polystyrene blocks to carve up into the basic shape. A sensible person would get some solid blocks from some sort of specialist polystyrene shop or something. I decided instead to glue together a few sheets of underfloor insulation foam since that was easy for me to get from Bunnings (where I seem to end up several times a month for some reason). I glued the sheets together using Ados F2 spray contact adhesive. The legs are made from sections of pool noodle.

blocks Foam blocks and pool noodle legs.

Once I had the foam blocks I needed a way to cut them so I threw together a hot wire cutter. This is simply a wooden frame with a handle, kind of like a hacksaw frame. Stretched across the opening of the frame is a piece of nichrome wire. I use small screw eyes to attach it and at one end have a spring to keep the wire under tension. If you try to attach the wire to the screws eyes directly when it heats up it will expand and go slightly slack. The spring ensures it is always taut. A wire runs from either end of the nichrome and attaches to my car battery charger. At 12 volts the wire draws about 1 and 3/4 amps of current.

hotwire Hot wire cutter.

Next I drew something vaguely horse shaped on some cardboard then cut that out and transferred the shape onto the blocks.

horseshape outline Template and shape draw on foam.

Once I had a basic outline I used the hot wire cutter to remove anything that didn’t belong on a horse. Then after the basic shape was cut out I used a long knife to cut holes in the base of the body to push the legs into. I then used a 40 grit sanding disc on an angle grinder to sand the basic shape smooth. You need a gentle touch doing this as the disc will eat into the foam rapidly.

cutting roughed sanded

Basic shape cut and sanded.

Since the horse was taking shape I decided he needed a name. The horse is named in honour of an awesome ex-workmate of mine, Awesome Paul (so called because he is so awesome). The horse is of therefore known as Horseome Paul. Not many people can say they have a rocking horse named after them. Not sure many people would want to…

Once the shape was done I cut and pushed wooden dowels down the hole in the middle of the pool noodle legs. These extend right into the body to make the legs nice and strong. I drilled the ends of the dowels and inserted in some long 8mm bolts with the heads removed to turn them into threaded studs. These studs will attach Horseome Paul to the base. They are held in with extra strength Araldite epoxy.

legdowels legbolts 8mm bolts glued into wooded dowels in the legs.

Next I started work on the base. First I drew a rocker shape onto some 6mm thick MDF to make a template. I used some scrap cardboard and a steel rule curved against a large steel block to form half of a smooth curve in the rocker. Once that curve was drawn on the cardboard I cut that out and transferred the first half of the curve to the MDF. I then turned the template over to draw the same curve on the other side of the rocker. The MDF template serves two purposes. First it gave me something to trace around onto two pieces of wood to give me a line to cut out with the jigsaw to form the rockers. Then I was able to screw it to the roughly cut wood and use the MDF as a guide on a ball race router bit to make the rocker edges square and identical. When tracing around the template I use a wide Sharpie marker to give a nice thick line. I then cut around the outside of the line meaning the rough rocker is about 1mm over-sized all around.

curves template jigsaw

Template for the rockers.

The routing takes some explaining. What I do, and this is probably dodgy as hell, is bolt my router to a flat piece of MDF to serve as a base. I then screwed that to my temporary work bench I was using (a bit of chipboard sitting on a panelbeaters frame). This holds the router nice and firmly upside down with the bit facing upwards (Note to self :  I really must make a proper router table someday). I then screw the MDF rocker template firmly to the roughly cut rocker making sure it is lined up so the 1mm extra is even all around. Then I run rocker against the router bit (making sure as you push the shape around that the tool cuts INTO the wood) with the bearing on the tip of the bit running against the edge of the MDF template. Because the bearing is following the edge of the template the wood will be cut to the exact shape of it too.

routing1 routing2 Routing around the edge of the template.

Once routed out the two rockers are almost identical. Just to be absolutely certain I screwed the two pieces together then sanded the edges together to make them smooth.

sanding rockers Random orbit sanding the two rockers together.

With the two rockers made I then cut two small supports that are screwed to the inside of the rockers. The tops of these supports were cut with a curve on the top face to match the curve on the rockers. Two wooden dowels attach each end of the rockers together. These are screwed in place then small wooden plugs were glued over the screw holes. Wooden slats were then screwed across the rockers, the outer two being slightly thicker than the middle ones so the legs can bolt down onto them.

supports slats onrockers

Base completed.

While Horseome Paul is off his rocker(!) a temporary MDF board drilled to match the holes in the rocker base keep the legs fixed in the correct position so the bolts will line up once he is fibreglassed. Without this the legs might shift position during the glassing process then not fit through the holes in the base.

legsupport Temporary leg support.

One final detail was making a handle to go right through the head. The handle is just a piece of dowel. It does need to be removable though so later on I can fit the horse suit over the body. I found a piece of PVC pipe the dowel slides nicely into. I pushed the pipe through the head and made sure it was flush on each side. When the body is done the dowel will slide into this and be glued into place (or perhaps wrapped in tape and just held by a friction fit).

handle

Handle and PVC pipe being inserted. Went right through! Didn’t hit the brain!

Finally before fibreglassing I needed to cover the polystyrene foam to protect it from being eaten by the polyester resin I was going to use. To do this I glued tin foil all over the body to form a barrier to the resin. By the way the polystyrene ears  are just there to remind me that I am making a horse and not a sheep/dog/cow. The proper ears will be sewn on at the end along with a mane, tail, bridle and saddle.

tinfoil Ooohhhh, shiny…

Finally fibreglassing could begin. To be continued soon.

Part two is now available here:

http://www.asciimation.co.nz/bb/2009/12/25/finishing-sophies-rocking-horse-before-christmas-just

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One Response to “A rocking horse for Sophie”

  1. Asciimation » Blog Archives » Finishing Sophie’s rocking horse (before christmas – just) Says:

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