Cat Scratching Post

My cat being a cat, she chose my sofa, at the center of my main room, as the best area to scratch. Before having to sit on a pile of shred, I looked on internet for a scratching post and... this was a disappointment. I found lots of dull posts, and a few nice but (some ridiculously) expensive. So I tried to make my own, mainly made from cardboard and mortar, keeping the cost low while having an aesthetic result, and allowing for an easy replacement of the cardboard.
The good thing is that my cat likes it so much that she forgot about my sofa!

The size, shapes and finishes shown in this instructable are examples. The size can vary depending your needs (although I would not recommend to make it smaller than 60cm), the foot and cardboard pieces shapes can be anything you want, and the white finish I choose can replaced by any concrete style or color you prefer. You can even use wood instead of mortar for the foot and top, so be creative! Just keep in mind to not use materials with strong smell, as it could deter your cat from using it.

Size : The whole post is 60cm tall, and about 16x16cm wide (about 24x24cm for the foot).
Difficulty: Easy.
Tool Requirements: Basic .
Time: about 3 hours, plus several days for the mortar to set.
Cost: about 10 euros (7 for mortar, 1 for threaded rod, 2 for a plastic basin)

One last thing; this instructable is an entry of the 'Pets challenge', so if you like it, do not forget to vote!

They scratch mainly to mark their territory, visually and olfactory. Visually because of the shreds (as a side note, this is why cats prefer scratching an area with vertical stripes : they see the stripes as pre-made marks), olfactory because the cat paws have glands that excrete pheromones.
Scratching is also a way for cats to stretch their muscles.
Finally, scratching removes the cat's claws outer husk, freeing the newer claw beneath (which is often misinterpreted as a sharpening).

Of course, they tend to choose areas visible to others, near the places where they feel good. They will also choose a material on which they can dig their claws, and leave marks. Like a sofa.

On the other hand, some says cats scratch as a part of their scheme of world destruction. You choose.

The fact is no one can stop them from scratching, so you must redirect them on the thing you are willing to sacrifice, like some cardboard.

There is not advanced materials or tools needed, with maybe one exception (see at the end of the tools list) :

Tools :

• A drill (a manual one is sufficient, as we will drill cardboard and plastic...),
• A sanding block with (about) 200 grit sandpaper,
• A wrench,
• A pen and a ruler,
• A knife,
• A metal cutting saw (a manual one is sufficient)
• A trowel or a big spoon to mix the mortar,
• Something to vibrate the mold (I used a sanding machine),
• rubber gloves, dust mask and eye protections for you safety,
• A 3D printer if you wish to put the cat figurine at the top of the post,

Materials :

• About 5kg (or more, depending your cat size) of mortar. I chose a white mortar, only for its look,
• A basin to use as mold for the post foot (a cheap, plastic one is better, as you are going to drill a hole in it),
• A box and some paper to mold the top of the post,
• Some wall putty to enhance the molded mortar aspect,
• A 8mm threaded rod (of a minimal length of 600mm),
• One 8mm washer,
• Four 8mm nuts (one being needed for the work in progress only),
• Four protection pads for the post foot (to protect your floor),
• ... and of course lots of cardboard boxes

Your cat will not like the scratching post if it is not stable, so we will use mortar to make an heavy post foot. I used 4kg of mortar, which is enough for my 3.5kg cat; if yours is heavier, you might want to use more.

Your can get a lot of information in this concrete class; it gives some hints to give a custom finish to the molded parts, in case you do not like the white aspect of this DIY. We will use mortar instead of concrete, because it is easier to obtain a smooth surface using mortar (concrete contains gravels).

You will need a big bowl of about 24 cm side length (or diameter) as a mold (its size and shape may vary depending your taste and supplies). As you are going to pierce a hole in it (for the threaded rod), the best choice is a cheap plastic basin. I found a square one with rounded edges, which gave a nice shape to my scratching post foot.

The foot must contain a captive nut on which the threaded rod will be screwed on. This threaded rod is the backbone of the post, and gives its sturdiness to the cardboard tower. So once you have found the proper basin, you will have to drill a 8mm hole in its center.

Pouring the mortar in the basin with the whole rod inserted is not going to be convenient, so you will have to cut a small part of the rod (about 4cm long) as temporary guide.

It is better to lube this rod to help extracting it once the mortar is set (I did not lubricate it, but was nevertheless able to extract it). Screw a first nut at one of its extremity, then another one 1 cm farther. Insert this rod into the hole, so that the nuts are inside the basin, then fix the rod by adding a washer and a third nut on the other side. Make sure there is enough space to add a fourth nut on top of this last one, as these two nuts will be necessary to extract this temporary guide. It is also important for the guide to stay straight, so ensure you have some supports on which to place the basin so that the guide is not pushed away.

It is now time to mix the concrete with water. You could do this directly in the basin (like I did), just take care to not disturb the guide; using another dedicated bucket may be easier. Before manipulating mortar, keep in mind that the powder is very thin and alkaline, so it is best to protect yourself from inhaling it or covering your hands with it. Use rubber gloves, dust mask and eye protections for your safety.

Pour the water slowly, step by step, and mix thoroughly before adding more water. Again, the concrete class gives a good visual reference of what a good concrete should look like.

Once satisfied with the look, you will have to remove the bubbles that got trapped in the mix. This is done by vibrating the basin, the best way being the use of a sanding machine : remove the sanding paper, place the machine against the basin and move it on all sides. Do not forget the corners, they are sturdier than the walls, so as a result the bubbles are more difficult to remove.
If you do not have a sanding machine, you can tap on the basin using anything somewhat heavy, like a small hammer, a screwdriver handle, etc...
You should see bubbles popping on the top of the mortar. Keep in mind that, if you choose the same white look as my post, the last bubbles holes will be filled with wall putty, so do not worry!

You can now let it set. It is important to cover the basin with some plastic wrap, so that the mortar keeps its humidity, and to refrain the need to unmold the foot before about one week : mortar must set for a long time in moist conditions to be strong.

I initially thought to use some wood to cover the post, but I actually tried something else to get the same style as for the foot. So I molded a kind of 'broken brick' with mortar; here is how to do the same.

You will need a square box about 10cm wider than the cardboard pieces, and some paper.

The following instructions are hard to explain, so dot hesitate to refer at the picture! Crumple the paper and put it in the box so that there is a space in the center, to act as the mold for the mortar. The paper folds will give the 'broken' look to the mortar brick. Once satisfied with the look, use some glue to fix the paper, and cover it by a plastic wrap to make it waterproof. Make sure the plastic wrap follows the folds.

As you did for the foot, add a piece of threaded rod in the center of the box.

Then prepare some more mortar, and pour it into the mold. Use a small stick to ensure the mortar goes everywhere in the folds, but take care to not piercing the plastic layer. Remove the bubbles like we you did for the foot. Again, wrap the mold with plastic to contain the moisture, and let it set for one day only, because we are going to work on it while it is still not to hard.

The next day, unmold the brick, and extract the threaded rod. Use the drill to enlarge the hole, so that the brick can slide along the rod. Do this gently to avoid breaking the mortar. There is little chance the brick looks right at this step. The mortar not being fully set, it is still easy to grate and file it to trim it, and enhance its 'broken brick' look.

Once done, wrap it again and let it set for one week.

Now that you have to wait for the mortar to set, lets gather cardboard. I used 4mm cardboard, as it was the thicker I could easily find. You can of course use any thickness, just remember you will have to build a 60cm tall stack of it : the thicker the quicker!

There is no need to buy this cardboard, as there is many in any store, waiting for being trashed. You can either ask to your local stores, or wait for the hour/day of collect of your town and gather them in the streets.

I cut them in 16x16cm squares, but here again, you could cut pentagons, circles, etc, in different sizes. It is up to your taste (and time actually), and I would be happy to see your creations! Some advice : use a sharp knife to get nice cuts, and prepare a pattern to quickly cut the cardboard. Having to measure and draw each shape would be a waste of time.

Once having a 50cm tall stack, you will have to drill a hole in the center of the cardboard pieces for the threaded rod. Note that it is quicker to drill several stacked pieces than to drill them one by one...

After a week, you can unmold the foot. I did not use any release agent, as plastic basins are flexible enough to remove the cast without problem. Check its surface is flat, and glue some protection pads on it.

I preferred a smooth white finish, so I used some wall putty to cover the few bubbles left. Of course, you can leave the foot as is, if you prefer! If you choose to apply putty, do it step by step (do not try to fill the bubbles in one time), and sand it after each layer. It is important to use a sanding block if you want to get a clean finish.

You now have to extract the guide from the foot: screw one nut on the rod, and lock it in place using a second nut. These nuts should allow you to unscrew the guide from the foot. I had to gently tap mine with a hammer, but again I did not lube it. Once done, you can screw the final threaded rod, cut at 60cm long.

I treated the top 'broken brick' as the foot : wall putty and sanding, to give the brick a smooth white finish.

You now should have a foot with a threaded rod, lots of cardboard pieces and a top brick. Slide the cardboard pieces through the rod, then cover them with the brick. Add a nut on the top, but do not screw it too much yet.

My initial thought was to let all the cardboard pieces aligned, but it appeared that any slight cutting error was visible. So I chose to twist the cardboard tower, to hide my mistakes. Luckily, I actually prefer the tower this way... Here is again your choice, straight or twisted tower! When satisfied with the result, screw the top nut a little more, so that the cardboard do not rotate to easily.

There is still one thing to settle : the top nut is not pretty. I personally have access to a 3D printer, so I choose to print a low poly cat, designed by xavab29, slightly modified to contain a nut. With sanding and white paint, it completes the tower. Of course, not everyone has access to a 3D printer, but there are some other options : you could cast in mortar, or carve in wood, a form you like.

Having a scratching post does not means your cat is going to use it. There are two problems to solve : the first one is to to get your cat to like the post, the second one is to get your cat to stop scratching the previous scratching area.

In order to maximise the chances your cat uses the post, you will have to place it near the place he likes to be. Furthermore, the post must not be hidden; remember the cat is scratching to mark its territory, so the post must be seen by anyone passing by! As noted in the introduction, you should not have used materials with strong smell, as it could deter the cat from using the post. Let him take some time to get accustomed to this new thing in its living space, and do not force him to use it. It could be useful to show him the post and pet him near it. Try not to grab his pawn in order to mimic a scratching, because this will likely get him stressed, thus make him look at the post with suspicion. I read somewhere that thyme is liked by cats and tends to excite them, so I added some between the cardboards. My cat used the scratching post pretty quickly, but I can not be sure the reason was the thyme!

The second problem is to disaccustom your cat from his previous scratching area. Luckily, once the cat starts scratching the post, there are chances he will stop scratching nearby objects. There are some solutions if your cat continues :

• Apply some perfume on the scratching area, preferably vanilla or lavander, to cover the pheromones it left before. Do not use a too strong perfume (like citrus), as it seems cats could urinate on it to cover the smell! Of course, cat repellents work as well, but do not put to much of it!
• Cover the area with something that the cat will dislike; a plastic cover, a space blanket or some

  double adhesive tape if the area is localized, for example.

Never ever punish your cat, he will not understand. At the contrary, this could stress him and push him to scratch even more to relax...

I hope you have found this instructable interesting, and in the case you have made your own scratching post, do not hesitate to submit a picture of your creation!