Tuesday, 3 August 2021

Gnarly back scratcher

I quite often get an itchy back and have thought for ages that I must sort myself out with a decent back scratcher.

And so, at last, I made one!

This project was a particularly satisfying way to spend a weekend. It was good to use raw logs that I had scavanged, for all the wood used. It also involved lots of enjoyable carving using power tools. 

The wood came from:

  • A cast-off pruning from a tree surgeon's waste chip pile (cherry fork)
  • The edge of a log from the woods (spalted beech). This was an off-cut from cutting planks for a table-building project about four years previously.

The finished back scratcher

Here it is. I like its organic bony look. It looks like some found limb, that has somehow become detached from a strange mythical woodland creature and decayed somewhat.

In this early evening low light, it looks a bit creepy... 

Same light, rear view

The scratchy bit had to be a hand. The fingernails are just like real nails - hard enough to give a good scratch and not so sharp they scratch your skin off. It is just like being able to get you hand round your back and scratch it properly.

The lovely grain is from a forked cherry branch log. This was a pruning from tree surgery.
Cherry has a natural orangey red colour in its heartwood. The pinky finger and the fingertips are sapwood, which is lighter and more yellowy.

I collected it last winter and it has been seasoning in my wood pile for about 10 months.
It smells really good. Almost like a conifer, but sweeter and really earthy.

While the hand is cherry, the bony appendage that serves as a handle is spalted beech. This is beech that has had a fungal colony growing in it that has added lovely dark veins of character to the otherwise quite neutral beech grain.

The gnarly elbow shows the spalting in the wood surrounding a knot where a branch emerged from the trunk of the tree.

You can see the joint between the orange and yellow cherry hand and the pinky grey-brown beech handle.

From another angle. You can see the far end of the beech handle is actually quite yellowy too. This was from some light staining using canary yellow artist's ink to blend the colour across the two different woods.

Build part 1 - making a hand...

To build the hand I chose this forked cherry log. It just looked like a hand
(albeit with a very branch-shaped mitten on it!)

It looked a bit dull, so I sawed off the end.

You can see the lovely orange heartwood inside.

On this flat end, I screwed on a base lug, so I could hold it easily in the vice. I marked a danger zone, so that I didn't accidentally cut into the screws with the carving tools later. 

Here it is with the lug attached.

The first thing to do was get rid of all the bark, so I could see just the wood.
You can really see the natural hand shape here.

For this, I used the trusty Arbortech.

Basically a spinning disc accessory for a standard angle grinder, with a weighted rim (to give it flywheel-like momentum) and three conical tungsten carbide gouge cutters.

This is the stripped log showing the underlying shape.

Closer up, you can see the grain patterns and the rough edges of these from the cutters.

Next, I started the roughing out stage - this is where you cut the log into its roughly final BLOCK shape. It is very important to do this before getting fixated on carving fine details like fingers. If you don't do this, you may end up with excellent fingers, but not in the right place.

The blank lump needed a few patches drawn on it, so I could see where to hack off waste material when blocking out with the Arbortech. It is important to be bold and hack it off early.

Another area that needed removing...

And what it looked like afterwards.
This is the hollow between the palm of the hand (centre) and the curled fingers (top left block).

The convex curve of the back of the fingers.

More cut from the palm side. The darker heartwood is starting to show through.

ONLY when the blocking out is done, should one start on the next level of detail.

Here, I have made saw cuts to create the basic finger blocks within the overall finger block.
(from a mitten to a glove, so to speak)

From the front, after widening the cuts with a fine rotary burr in a Dremel rotary tool.

Here you can see the finger shapes emerging. The pencil lines on the back of the flat of the hand mark where the tendons lie. These were used as guidelines. By hollowing out between them, the raised tendons could be formed. 

This is one of the burrs I use. This one is quite coarsely-toothed and removes quite a lot of wood at a time, but as a result, does not leave a superfine finish. This is held in a die grinder, which is a rotary tool, like a Dremel, but much bigger and stronger. It is similar to an angle grinder, but without the angle - it has a colleted head to lock bits into.

The finger blocks from the front, before forming the knuckles.  

After hollowing out the fingers between, the knuckles and tendons of the back of the hand emerge. 

The front of the hand again, after forming the knuckles. The fingernails are just formed. This was done with a much finer burr, in a Dremel

This is the same view after a LOT of sanding to smooth out the ridges from the initial forming with the burrs in the die grinder.

Still not finished, but getting there.
Note the little finger (left) showing some grooves that need smoothing out.

Looking good...

Sanding between fingers with strips of paper.

The sanding started with 60 grit (but it was quite worn), but only for really big smoothing. It quickly moved to 120 grit, then 180 grit, then 300 grit.

Almost finished. 
Sanding this took several hours.

Build part 2 - making a handle

Having got a hand, it needed a handle. I had started off with the idea of a separate handle connected by a plain rod, so was looking at various blocks from which to render that.

This curved-grained cherry log was appealing for a hooked handle.

I also considered using this Elm log, because it has irridescent grain, if cut in a certain direction.
This is an elm log, left over from my old dead elm tree in the garden.

The long piece here is an oak table leg that I was originally contemplating using to create a connector rod between hand and handle.

But then I found this twisty bit of spalted beech, left over from a previous project that involved converting logs into planks of timber.

I had to use this piece, not just because of the beautiful lines from the spalting (most obvious on the bottom face), but also because the knot in the middle had twisted the grain nicely in different directions.

Discovering this piece of wood also made me decide to make the handle as an arm-like extension of the hand, not just a plain old handle.

As before, the first step was to remove the bark.
This showed me how much wood there really was to play with.

The alternate light and dark of the fungal colonies that cause spalting are really obvious in this picture.

I then proceeded to block out the main twisty shape of the bony arm. 
The most important task here was to remove the sense of a flat face from the original block of wood and carve in some all-round sweeping curves in 3-d.

Here, the elbow is emerging from the knotty central part. I didn't bother drawing on the wood for this piece and just carved it freehand from the rough image in my mind. 

This method is riskier for carving very specific shapes (like hands), but is really good for allowing vague shapes to form naturally as you carve, when the exact shape is not defined in advance. It is more about creating a feeling and adjusting as it emerges.

Once the rough blocking out was done, I smoothed the sweeping curves of the bony bits using the filing sander. When using this tool, you have to be a bit careful not to go too close to the final shape.
It creates cross-lines in the wood from sanding across the grain, that need to be removed later and that is hard work and tedious.

Finally, I did dome further smoothing using a belt sander fixed in a vice while holding the wood. This allows greater control for making smooth curves.

I also carved out some of the final bone shapes on the very end using the sander.

Build part 3 - putting it all together

Now I had a scratchy hand and a bony appendage, the next job was to join the two together.

For this, I created a tenon on the end of the appendage-shaped handle. Here it is, roughed out

I then used a die to cut a thread on the end of the tenon (the die handle is not shown here).

This created an OK thread, but it was pretty rough 

I then drilled a corresponding hole in the hand to receive the tendon. 

I then used a tap to cut the internal thread to match the thread on the tenon.

This thread was actually a bit better than the one on the tenon of the handle.

Here is a test fit of the threaded tenon screwed into the threaded hole in the hand.

In the end, although I was gluing it in, I wasn't convinced the thread would be sufficiently strong.
The thread was quite loose, so I added in a second metal pin to secure it to stop it rotating.
You can't see it in these shots. 

I glued them together and let it set for 24 hours.

Build part 4 - Final carving 

Now the two parts were joined, I was able to carve them down into a single continuous shape. This was the same process as before - blocking out first, then smoothing gradualy down to the final shape.

The handle is wrapped in a cloth to stop it getting damaged by the jaws of the vice.

Headphones, eye protection and a trusty leather apron are all advisable when doing this. 

I haven't show all the rest of the smoothing steps. They were the same as above, but simpler as they were really just taking off the waste wood from the hand block and blending the shapes into one.

Build part 5 - strengthening the joint

Here you can see the finished piece after all carving was complete.

The joint had a slight gap between the edges of the two pieces. This needed sorting. I didn't want to leave it, not just because it looked unsightly. You could also feel it with your fingers and most importantly it left the joint vulnerable to become weakened by long term use. 

To rectify this, I used a filler made from epoxy resin and padded with fine sawdust from the sanding of the wood so far.

This is quick setting Araldite. It is extremely strong and also very adhesive. It really sticks to the wood on each face of the joint.

Here is the paste being mixed from the two parts of the epoxy resing and sawdust.

I squidged this in so it packed the void between the two pieces. This forms a very strong joint, that complements the tenon joint by stopping any twisting or movement in the joint. 

By using sawdust, the joint was stronger than epoxy resign alone too. It forms a composite material that is equivalent to GRP (glass-reinforced plastic aka fibreglass) or papier mache. 

Here it is after drying and sanding back.

Another angle. The sanding is not quite finished.

Build part 6 - blending the colour of the two woods using ink

Because beech is naturally less yellow than the orangey cherry, I used some artists ink to apply a light stain to the appendage end, to ever-so-slightly raise the yellow hue to match the hand end.

It's subtle, but it did help blend one piece into the other, so the eye focuses more on the continuity of the shape, and less on the previous discontinuity of the colour when left unstained. 

I did also apply a very faint stain to the hand too, to merge the colout more gradually. In both cases, I sanded back after letting the stain dry and applied more or less ink to local areas, depending on their colour.

The final scratcher shows a much more balanced colour range across both pieces.


This was a great build. I did it over three days and it took about 16-20 hours in total, not including drying time etc.

It was good to combine carving something representative (the hand end) and something more expressionistic (appendage end) and largely the shapes followed the natural shapes of the source woods.

It's also really good for scratching your back!