Thursday, 18 June 2015

Eyes and Tail

It's been over nine months since I last updated this blog, so I must apologise for keeping you all waiting so long; but now, the story continues...

Before moving on to finishing, I next drilled the holes necessary for the horse's eyes and tail. The kit comes supplied with two glass eyes attached to either end of a short length of wire - snip the wire to separate the two eyes. They're about 18mm (3/4") in diameter and the instructions suggest drilling holes to mount them, using wood filler as glue, without providing much detail. I pondered this for a while, but here's how I did it...

The location for the eyes is easy to find, as it's where a dowel comes right through the head to hold the two halves together. At this stage the ends of the dowel should have been cut off and sanded down flush with the rest of the head, but they're still easy to see:
 
The end of the dowel marks the eye location

I started by drilling a small pilot hole, maybe 4mm or so, right into the centre of the dowel, with the drill perpendicular to the surface of the wood. I then followed that up with a 22mm spade bit; the spade bit should stay centred on the pilot hole, and you can just carefully allow the bit to scrape away 2 or 3mm of wood until you have a shallow recess for the eye to sit in, as shown here:

Eye socket recess created with a 22mm spade bit

I'm sure there are many ways to do this, and something like a Forstner bit would probably do a cleaner, easier job, but they're expensive to buy just for a single job.

The hole for the tail is just a little trickier. The horse's tail will be formed from a short piece of horse hide rolled into a tube and wedged into place in a hole in the horse's rump. There is a leather strap thing (I'm sure there is a technical term for it that I don't know) that runs from the back of the saddle to go around the tail, so to find the right place to drill the hole, you'll need to saddle up your horse and mark where the leather strap thing falls. I then just drilled straight through with the same 22mm spade bit to create the hole where the tail would eventually be fitted. In hindsight there are probably better ways to have done this, and creating a tapered hole might have made things easier when fitting the tail. But, the tail went in ok anyway so this wasn't a big problem. The tail hole looks like this:

Tail hole drilled, and some filler applied


As a final step before applying any dye or paint, check over the body of the horse for any voids. It's normal for the edges of plywood to have occasional voids where a small piece of one ply has chipped out, or possibly where two pieces of a single ply never quite met properly when the plywood sheet was manufactured. I had maybe six or seven of these that were quite noticeable, so I filled them with some dark wood filler, let it dry and then sanded smooth. You can see a few of these on the horse's rump above, and there were a few gaps round the leg joints as well, which I filled in the same way:

Filler applied to leg joint; another void to be filled at top left

The horse and stand are now ready for finishing!

Friday, 12 September 2014

Sanding and Shaping

In previous posts, I completed the assembly of the stand and the rocking horse itself, so all the major parts are now complete; the next stage of construction will come pretty much at the end of the project - mounting the horse on the stand.  Before that though, there's a whole lot of sanding to be done!

Sanding the stand is straightforward; the wood is already very smooth as delivered and it consists mainly of large flat surfaces.  You should ideally have sanded each piece down to around 220 grit sandpaper before assembly, so the main tasks now are to ensure that there are no rough spots or glue residue left anywhere and to ensure that the wedged tenon joints are sanded flush.  You can use an electric sander for most of this, but the posts are a little trickier and you'll need to do those by hand, and take your time. If you'll be dying your horse, like I did, it's important to get a consistent smoothness across each piece, because the dye will be absorbed differently by the rougher areas and leave a slightly blotchy appearance (I discovered this the hard way, as I'll discuss in the next post!).

Sanding the horse is a different proposition altogether.  It's not difficult, but it will take much longer than the stand and you'll be removing a lot more material from around the areas where the legs join the body.

A raw front muscle block and leg
Most of the sanding is just smoothing out the 'steps' that were left in the main parts by the machining process - this is straightforward and you just need to take your time. I used a random-orbit disk sander which really speeds things up, but you could use any other method, no problem. Just keep going until all the surfaces of the horse's flanks, legs, rump, neck etc are smooth to the touch.

The (slightly) trickier part of this job is dealing with the joints between the horse's body and its legs. These areas, particularly after the addition of the muscle blocks, were quite uneven, with significant steps between the different pieces - body, leg and muscle block. To blend these areas out and create nice smooth contours, I used an 80-grit flap sander mounted in a corded electric drill. This allowed me to remove material quite fast whilst also allowing fine control over where I was removing it from. Here's how it should look after sanding, shaping, dying and varnishing:


A finished back leg
For each leg, I started by smoothing out the surface of the muscle block to:
1 - bring the top edge of the muscle block down to be flush with the body;
2 - taper the muscle block into the leg down near the horse's 'knees' (do horses have knees?) and around the sides;
3 - achieve a smooth contour all the way from the body to the leg.

Because all the parts of the horse are made from plywood, achieving a smooth contour is much easier than it sounds - as you taper the muscle block down, the boundary between each layer (or ply) of the plywood reveals the overall shape of the muscle block very clearly; if the boundaries run in nice smooth evenly-spaced curves, then the muscle block is a nice smooth shape, but if the boundaries are uneven with lots of zig-zagging then the surface has got some hills and valleys in it and you need to smooth it out some more.
Smooth contours mean a smooth leg!

You'll have to remove a surprising amount of the muscle block during this process - the bit that's left on the horse will be a very thin sliver compared to what you started with - but you should get a nice clean result with the body and legs appearing as a single unit.

The final stage is to blend in the front, back and sides of the leg where it meets the body - all the areas that aren't now covered by the muscle block.  I needed to remove quite a lot of material here too, but the flap wheel sander made easy work of it. The flap wheel naturally produces a gently concave shape when worked into the joins, so just work slowly and remove a millimeter at a time until you're happy with the shape you've achieved. The leg pieces are supplied a little oversized compared to the body, so the back legs, for example, protruded about seven or eight millimeters from the body beneath; this overhang needs to be sanded back until the leg and body are flush to each other. The same work is required for each leg.

This whole sanding process took me two whole weekends, so far as I remember - longer than any other part of the build - but it's important to take the time to get it right.


Right leg/flank join - shaped to blend the leg into the body.

The inside of the right front leg.


The inside of the left front leg.


After all this, you should have a perfectly smooth and shapely horse - congratulations! The next step will be to dye (or paint) your horse - that will be the subject of my next post.

Wednesday, 7 May 2014

On to the Rails

At this stage, with the stand and the horse's body completely assembled, I decided to make a small modification to the two rails.  These are the lengths of wood to which the horse's feet get bolted, and which receive the ends of the hangers.  As supplied, these were shaped to a point at each end, and were pre-drilled for the hangers, but they had sharp square edges. As all the stand's parts had nicely chamfered edges, I decided to add a chamfer to the rails as well.

Rails as supplied - note the sharp edges

The only slightly tricky thing here was to NOT chamfer the two areas on each rail where the horse's feet would go; I didn't want to be left with a gap where the chamfered edge ran under the feet. With the stand and the horse's body and legs assembled, I dry-fitted everything together so that I could lower the horse on the rails, drill holes for the horse's mounting bolts, and mark the outline of where each foot overlapped onto the rail.

With this done, I used a chamfering bit in my router table to chamfer all round each edge of the rails, except for where the feet would eventually be, as shown in the photo below. I have a relatively cheap router table from Rutlands which made life easier, but you could use a hand-held router just as well for this job (or even do it by hand with a plane and a file, if you have the skills and patience for that). Approaching the marked foot areas, I backed the work piece away from the bit to leave what I have found is rather wonderfully called a 'lark's tongue'.

A chamfer added all round each edge, except for where the horse's foot will eventually be attached.

With a bit of sanding, the rails were then ready for finishing. 

Friday, 2 May 2014

Attaching the Legs

The horse's legs are supplied as simple shapes cut from a single sheet of plywood (not laminations like the body) with some milling on the outside of each leg to give it a more horse-leggy shape. Importantly, the inside face of each leg is bevelled where it joins the body - this is what makes the legs splay out slightly from the body when it's all assembled. As with the body, this is done very accurately so it all fits together perfectly without any adjustment or fettling required.

Each leg has two dowels to locate it into place on the body; both the leg and the body have pre-drilled dowel holes which makes fitting the legs very easy. Two screws per leg are also supplied, but there are no pre-drilled holes for the screws, so I just selected a spot for each screw that looked reasonable - not too close to the dowels, and also ensuring that the screw would bite into a solid bit of the body behind. Drill a 4mm hole through the leg for each screw, and countersink each hole to make sure that the head of the screw will be well below the surface of the leg - you'll be gluing a muscle block over the screws so you don't want a screw head sticking up and preventing it from sitting flat on the leg.

Dowel holes (and holes to ignore) for a front leg
As when joining the body halves, clean up all the areas to be joined by sanding them lightly, making sure that there are no loose fibres or wood chips left that might stop the two parts coming together properly.

Glue the dowels into the dowel holes in the body and tap them down as far as they will go, then spread a good layer of glue over the entire mating surface of the body and the dowels. Locate the leg's dowel holes over the tops of the dowels and carefully tap the leg down over the dowels until it's sitting flat against the body. Be careful to support the foot end of the leg so that it can slide evenly down on the dowels without getting stuck. The dowels will stick through the leg - that's fine, you can cut them back flush later.

The dowels hold the leg quite firmly in the right place, but the screws will ensure it stays put. Working through the 4mm holes you drilled earlier, drill a smaller 2mm pilot hole in the body for each screw and then drive the screws home to pull the leg tight up against the body. Wipe off any glue that's squeezed out of the joint, and that leg's done!  Now repeat the above for the other three legs.

The right front leg fitted
Both right legs fitted

After the glue has had some time to dry, trim off the ends of the dowels with your flush trim saw and sand the whole area to make sure it's good and flat.

The final job for each leg is to glue the muscle block in place. This is a small shaped piece of plywood that covers the screws and dowels so that the finished horse won't have any visible fixings. The muscle blocks are quite oversized and will need a lot of sanding down later, but for now just make sure that the top edge of each block, where it butts up against the body, is a good fit - a couple of mine needed a little shaping to get the curves to match and minimise any remaining gap.

When you're happy with the fit, simply spread a layer of glue on the back of the muscle block and clamp it in place to dry. Be certain that you have glue over the entire surface with no dry spots, because when you later shape the block down to blend smoothly into the leg, you'll be exposing parts of the glue joint that are initially nearer the middle of the muscle block, and you don't want that newly-exposed edge to come unstuck from the leg.
The back muscle blocks clamped in place
Left front muscle block, out of the clamps. Lots of shaping/sanding to come!

You should now have a horse that can stand on its own four feet, looking something like this (I took this before fitting the back muscle blocks):
Legs and front muscle blocks fitted.


Tuesday, 18 March 2014

Assembling the Body

With the assembled stand put safely to one side, I started on assembling the body of the horse.  Using some coarse 80-grit sandpaper, I quickly cleaned up all the edges of the mating surfaces to remove all the loose fibres and bits of tear-out that were left from the milling process - I didn't want anything to stop the two halves from coming together as closely as possible.

Working on a soft surface, I laid one body half on top of the other to check the fit; I was pleasantly surprised to find that this was very good.  The mating surfaces were very flat, so they went together well with only a hairline gap visible in a couple of places - nothing that couldn't easily be clamped out during glueing.

The body halves are located together using dowels - two at the bottom, front and rear, and a thinner dowel through the horse's eye holes.  Each of the dowel holes goes right through the body, so I marked the centre of each dowel before applying some PVA glue and tapping them into place - knocking each one through until the centre mark was flush with the surface of the body. I let the glue dry for 10-15 minutes so that the dowels wouldn't move when bringing the two body halves together - I wanted to be reasonably sure that the dowels would be centred between the body halves when it was all assembled.


Next, it's time to bring the two body halves together. I checked again for any loose fibres or anything else that might stop the two halves from joining properly, then spread a good amount of PVA over the entire mating surfaces of both halves, including the exposed ends of the dowels. Then drop one body half on top of the other, ensure that the dowels are aligned with the dowel holes, and tap them together, being careful not to mark the wood surface. When they're together, the body will stand upright, and can be clamped up while the glue dries.

Clamping the body needed a little planning. It's easy to get two clamps across the leg recesses on the bottom edge; another clamp or three will go across the horse's neck, cheeks and nose to hold the head and neck together, though these need a bit of care to avoid damaging something.

I found that I still needed some clamping around the middle of the body to get it all to come tightly together; you could make some fancy custom clamping jig for this, or maybe lie the horse on its side and pile some weight on top, but I decided to just use some rope - it was simple, safe and got the job done.



As you can see in the photo, I tied some rope loosely round the horse's middle and then used the handle of my mallet to twist the rope tight; when it was tight enough (I could see some glue being squeezed out of the joint), I used a loose end of the rope to hold the mallet handle in place.

After letting the glue dry overnight, I unclamped it all to find this:


You can actually see where the jaws of my clamps left some dirty marks on the cheeks and nose - fortunately these sanded away easily and didn't affect the finish.

Next post, I'll talk about attaching the legs and the muscle blocks.

Monday, 10 March 2014

Building the Stand


Building the rocking horse's stand is quite straightforward. There are only eight parts and everything is pre-drilled so there's no measuring or laying out required.

Before going further, I must apologise for the small number of photos in this post - I didn't take enough of this stage of the build, but it's all fairly self-explanatory so I don't think too much is lost.

The parts are: the top rail, the bottom rail, the two turned vertical posts, two large feet and two small feet. The top and bottom rails, and the two large feet, all have large-diameter mortice holes pre-drilled to accept the cylindrical tenons on either end of the turned posts.

I dived straight in and glued and screwed the four feet to the bottom rail, using the pre-drilled pilot holes for alignment; unfortunately I then found that the mortice holes in the large feet didn't quite line up with the holes in the bottom rail, so that the posts' tenons wouldn't fit. I spent 20-30 minutes filing away the inside of the holes to get the tenons to fit, but alternatively you could fit the bottom rail and the feet onto the tenon and drill new pilot holes - you'd have to check which method gave the most accurate final result in terms of having the feet and posts centered left-to-right on the bottom rail.

With the posts dry-fitted to the bottom rail assembly, you should find that the top rail drops neatly onto the top tenons.

When you're happy with the fit, it's time to glue everything together. The posts are secured using 'wedged tenons' - the tenons have a 3-4mm saw cut across their diameter, so that when you tap the supplied wedge into the cut, the two sides of the tenon are forced apart and will grip tightly into the mortice holes. The wedges exert a lot of force so it's very important to ensure that you have them aligned across the rails, pressing forward and back along the length of the rail. If you have them the other way, aligned with the grain of the rail, the pressure of the wedge might split the rail.

The tenons are intentionally a little longer than necessary, so that they can be cut back flush with the rails when the glue is dry. The extra length means that if you try to seat the posts into place while the feet are sitting on a flat surface, they won't go all the way through (yes, I learned this the hard way!). Prop the bottom rail on a couple of pieces of scrap wood to give the tenon space to come through.

Put a thin coat of PVA glue around the outside of the tenons and the inside of the bottom rail's mortice holes, then drive the posts in with a mallet. When they're fully home, you can turn the assembly over, spread some glue into the wedge slots, and drive in the wedges. You may need to trim the wedges with a Stanley knife to get them to fit nicely across the width of the tenon. Make sure that the wedge goes far enough into the tenon that the bottom edge of the wedge is well below the surface of the rail - you want at least some of the wedge to be left after you trim the end of the tenon off. You can then repeat the process with the top rail - this is much easier as the whole assembly will now sit nicely on your work surface.

When the glue is dry, you're left with a lump of tenon sticking out of the rails, with a lump of wedge sticking out above that, the whole thing looking rather like a wafer in a tub of ice cream.  To finish the joints, take your flush trim saw and carefully cut the protruding ends of the tenons off, flush with the surrounding surface. The technique (for right-handers) is to use your left finger tips to hold the saw blade down flat against the surface as you work the blade across sideways - that should ensure that the tenon is cut off flush without any risk of the saw teeth marking the surface.


The stand is now assembled and ready for final sanding and finishing. It's a good idea to give all the parts an initial sanding before assembly, because it becomes much harder to get into all the nooks and crannies once it's all together; however, it's not too bad either way.  I'll talk more about the final sanding when I get to the dyeing stage.


Next, we'll start on assembling the horse itself.

Tuesday, 28 January 2014

What's in the Box

The Rivelin rocking horse kit was delivered in three parts: one large cardboard box, strapped to a pallet, contained all the wooden parts, the hardware, the leather parts (saddle and tack) and the grooming kit. Around the same time, a shoe-box-sized delivery arrived containing the horse hair, some wood dye, some varnish and some sandpaper (Harry had included the sandpaper, very coarse 40-grit, to get me started on the substantial amount of sanding required... but more on that later). Finally, a Jiffy bag containing our custom-engraved brass plaque arrived about a week later - this is sent directly from the engraver, though it was ordered via Harry/Ringinglow - we never dealt with the engraver directly.

Here's how the large box was packed:

And here are the components for the stand laid out:

There are actually two small foot blocks as well - I forgot to pose them in this photo. The next post in this series will show the assembly of the stand; it goes together very easily. The only thing to be careful of is to get the wedged tenons in the correct orientation.

Here are the components of the rocking horse itself:

Two body halves, four legs, and four 'muscle blocks'. A muscle block is glued at the top of each leg to cover the dowels and screws holding the leg to the body.

Assembly of the horse takes a bit more 'finessing' before gluing and a LOT of sanding once you have it assembled. I'll go into a lot more detail on the whole process in future posts. For now, let's see why so much sanding is needed.  Take a look at this close-up:



You can see that the horse's body and legs are made from sheets of plywood glued together and then milled down by a computer-controlled milling machine. The milling process leaves the parts with hundreds of tiny steps, with each step following a contour line around the body.  The legs are milled in the same way.

Although this milling process leaves a very accurately-shaped part, all those steps need to be sanded away to leave a nice smooth surface before you can get on with dying, staining or painting the horse.

Tools

Very few tools are required to fully assemble and finish this rocking horse. Access to some power tools will make things easier, of course, but they're not essential.

For the assembly, you'll need:
  1. a sanding block with coarse sandpaper (80 grit)
  2. a power drill
  3. a 5mm wood bit and a countersink
  4. screwdrivers, or a power screw driver
  5. standard PVA wood glue
  6. a soft-faced mallet (or you could use a hammer so long as you protect the surface you're hitting with some scrap wood)
  7. some clamps
  8. a file or rasp
  9. some chisels (12mm or 18mm wide)
  10. a flush trim saw

These are all pretty standard except for the last.  A flush trim saw is a small hand saw whose teeth have no 'set'; it's used for jobs like cutting off the ends of dowels, where you want to run the blade of the saw right up against another piece of your project. There are other ways of doing this, but the flush trim saw makes it very easy.

On a normal saw, the teeth are 'set' - bent outwards so that the kerf (the saw cut) is slightly wider than the blade, which helps with getting the sawdust out of the cut and stops the blade jamming. If you tried to flush-cut a dowel with a normal saw, the teeth would scratch the adjoining piece of wood. A flush trim saw, having no set, doesn't scratch the adjoining piece.

The good news is that a flush trim saw isn't expensive - I got one from Amazon for about £6 all-in.  See this Google search for more information.

For the sanding and finishing of the horse body, a variety of tools will be useful. First and foremost, an electric sander, preferably a random orbit one, will make life much easier. You can use this with 80, 120 and 240 grit sanding discs (I think I got through four or five discs of each grade in all) to do almost all the sanding on the stand and the body of the horse.

However, the areas where the legs join the body need a bit of shaping and sculpting before you get into final sanding (don't be alarmed at this, I didn't find it difficult despite having no artistic capabilities whatsoever). For this, I used a 60-grit flap wheel like this:

These are available quite cheaply, a pound or two. Fitted to a mains-powered electric drill, I found this gave a good balance between removing material quickly whilst allowing finer control than the random orbit sander.


I also used files, planes and spokeshaves with varying amounts of success for this shaping/sculpting, but in hindsight I don't think they added much to the two sanders.

Safety

Besides general common sense when working with cutting tools etc, the main safety issue with this project is all the dust from the sanding process. Remember, you're not just sanding wood, you're also sanding the glue/resin used in producing the plywood. You MUST wear eye protection AND a dust mask of some kind. You can get cheap paper dust filters from any DIY shop, but I invested in a proper respirator like this:

This will cost you about £25 but your lungs will thank you for the investment. I found it very comfortable to wear and a much better fit than the disposable paper masks, which always seem to leak around the sides of my nose.

If you have deeper pockets than me, a proper workshop dust extractor would be very handy, but I managed without.

Workshop

Finally, a quick word on my 'workshop'. You don't need anything fancy here, I just used my standard double garage, but given all the other junk in my garage I'm sure you could easily use an uncluttered single garage or shed. All you really need is power and a decent amount of light, whether natural or artificial. The sanding process will make a LOT of mess so building this horse in your kitchen will probably not go down well with the rest of your family. Some carpet, lino or thick cardboard will be needed to keep the wooden parts away from the concrete floor.