The final product

Adventures in cat-scratching –or– how a laser project became a regular project

When you first start out with the laser cut­ter (for me, not in-person but via a ser­vice like Ponoko), it seems that everyone’s “hello, world” project is a set of coast­ers.  I have done a cou­ple of projects since then, but have had one in par­tic­u­lar in my eye that is actu­ally not that much more com­plex than the coast­ers.  As a raw mate­r­ial, cor­ru­gated card­board is extremely cheap, and we have a cou­ple of old card­board cat scratch­ers that I had to throw into the recy­cling, so I thought I would com­bine these to make my own cat scratcher.

The cat scratcher design I had in my head was noth­ing new.  I have seen many designs that are, effec­tively, lots of lay­ers of card­board sand­wiched between two boards, all held together with bolts.  I wanted to make some­thing like this tri­an­gu­lar design that I saw on ModernCat, but with a more wavy style, like this other one.

I did up my design, first on paper, then in Illustrator.  I cal­cu­lated how many lay­ers of “filler” are nec­es­sary with the thick­est card­board to make a nice big cor­ru­gated sand­wich.  In the end, I had designs that looked good at the time, but now that I see them side-by-side with the above wavy ver­sion might have been a bit too wavy.

Cardboard Filler

Wooden Ends

As I recall, I needed three copies of the filler laser-cut in thick card­board.  This par­tic­u­lar wooden-end design included one wavy pair with the cats’ names engraved, one plain wavy pair, and one square pair — this was mainly because I had a lot of excess space in the wood.  At the very least, I fig­ured I could use the extra pair of square ends to man­u­ally make a scratcher by maul­ing some card­board boxes with a box-cutter.

As usual, it took a few rounds of revi­sions to get Ponoko to rec­og­nize the design.  Their uploader, under­stand­ably, is quite picky about your files.  Etch lines must be the cor­rect color and thick­ness.  Etch areas must be the cor­rect color.  Cut lines must be cor­rect, and so on.  I finally refined the design to a for­mat that passes the upload gate­keeper and clicked through to get an esti­mate.  Given the cut­ting and etch­ing on the wooden ends, I expected them to be a lit­tle spendy, but they are reusable.  The really dis­heart­en­ing part was that the card­board filler was $1.95 in mate­r­ial and $49.30 in cut­ting.  The whole cat-scratcher would cost just over $90.  Ouch.

As Microsoft BASIC used to say: “Redo from start.”  Back to the draw­ing board.  I decided I would cut the card­board myself.  Between ship­ments I occa­sion­ally get and Kim’s busi­ness, we have a ton of card­board boxes lying around and I could spend some time and elbow grease with a box cut­ter.  This meant a rec­tan­gu­lar design because I was not going to sit around cut­ting wavy lines by hand.  I would have to buy the hard­ware (wingnuts and bolts) regard­less of how I man­u­fac­tured it, so went out to seek those from Home Depot.  While there, I got inspired by some ornate mould­ing.  I decided to base the design around nicely stained mould­ing and not laser-cut pieces.  This also allowed me to make my design a lit­tle longer than the orig­i­nal and, at just over $2/ft, was way more eco­nom­i­cal.  Laser cut­ters, you are cool, but you are not for this project.

Hardware

I looked around at the selec­tion of bolts of a usable length and could not find one I liked.  At that size, you are mainly look­ing at hex bolts and car­riage bolts.  I didn’t like the aes­thetic of the hex bolts.  The car­riage bolts looked a lit­tle bet­ter, but I didn’t like the way you have to make an extra cutout for the extra thick square part of the shaft near the head.  I decided to just go with a threaded rod.  I could cut that down to any size with my favorite Dremel attach­ment: the car­bon rotary cut­ter.  It had the added bonus of look­ing more sym­met­ric.

Required hard­ware: ¼” threaded rod, four wingnuts, four wash­ers

Cut And Finish The Moulding

I started with the afore-linked mould­ing and sliced it down to an arbi­trary length based less on mea­sure­ment and more on hav­ing four com­plete pat­terns on each piece.  I threw away a few cen­time­ters at one end as scrap because the board started mid-pattern.  I also used this time to visu­al­ize where the holes (and con­se­quently, the wash­ers and wingnuts) would sit within the pat­tern.

Careful square cuts in a mitre box

Two uni­form pieces plus some scrap

The edges were rough and needed some sand­ing.  As I recall, I started with some 80-grid sand­pa­per and grad­u­ated up to 220-grit.

These rough cuts need sand­ing

Although nobody would ever see the back, I thought I would sand out the stip­ples that, pre­sum­ably, were left by the man­u­fac­tur­ing process.  It would make the back look a lot bet­ter, espe­cially after stain­ing.

Before (left) and after (right) sand­ing out the stip­ples

I found it ter­ri­bly use­ful to do this with a disc sander ver­sus sand­ing by hand.  I also found out, the hard way, that hav­ing a piece of butcher paper between the wood and my work sur­face would pre­vent the wood from pick­ing up dirt and old paint from the table.  While sand­ing the back, the face picked up a bit of old green paint that I had to care­fully sand out.

Working on a sheet of paper

I then drilled and filed out the holes.  The drill bit was just a size up from ¼” to allow the threaded rods to eas­ily slip in.  This is one step where I may have to do a bit more research on the best way to per­form this next time — if there is a next time.  Quite often, when I drill a hole and do not want to leave splin­ters around it, I will put a piece of mask­ing tape on each side of the wood.  This method did not work so well in this instance.  I am not sure if it is because of the shape of the face, the den­sity of the wood, the speed of the drill (I tried a cou­ple dif­fer­ent speeds), or the sharp­ness of the bit.  At any rate, I got a few more splin­ters than I would have liked.  I both cleaned up the holes and per­formed a bit of surgery on the splin­ters with a small file.  At any rate, any splinter-induced imper­fec­tions would later get cov­ered over by a washer.

I then put a few coats of stain on them.  This took a lot longer than expected because of the freez­ing tem­per­a­tures we had that week.

First coat, dry­ing

The Cardboard

The next step was to cut the card­board.  I basi­cally just took a cut­ting mat and a box cut­ter and attacked the card­board.  By this time, the wooden ends were dry, so I used them directly as tem­plates.  Since the boxes had slots in them for the top/bottom flaps, I had to work around that.  I used mask­ing tape, on both sides, being sure to keep it a few mil­lime­ters from the edge so it was not stick­ing out or vis­i­ble when the card­board gets sand­wiched.  I also pushed the cut flaps close together when tap­ing so that there was no gap between pieces.  I also made sure to pull off any left­over pack­ing tape because I wanted to guar­an­tee the exposed cut ends were just card­board — no mask­ing tape, no plas­tic pack­ing tape, no ship­ping labels.

Keep the tape away from the cut lines

Push together any gaps

This left me with a lot of card­board (this is three small-to-mid sized boxes worth), cut to the right size.  If I were to do it again, I prob­a­bly would have cut the holes for the threaded rods as I went instead of wait­ing to drill them at the end.  I could have just marked through the wooden piece’s hole with a pen­cil, then used the box cut­ter to make an over­sized square or dia­mond hole.  The hole does not need to be all that accu­rate or even round  because it gets sand­wiched together and held by com­pres­sion.

I rearranged the card­board strips so that I did not have too many masking-tape-gap ones or ones with folds next to each other — for bet­ter looks and struc­tural integrity.  Finally, I held every­thing (loosely!) with clamps and drilled some holes for the rods to get through.  This took sev­eral tries because my drill bit was not long enough to go from one end to the other.  I had to drill in one hole, then go around to the match­ing hole on the other side.  Since I was doing this by hand, the holes were not per­fectly straight and did not quite match up.  It took a few attempts to get a com­plete hole from one board to the other.

Finishing Touches

I was then down to assem­bling and trim­ming the hard­ware.  I put the threaded rod through one end, attached wingnuts and wash­ers, trimmed it, and then did the same for the other end.  I also made sure to deburr any rough cuts in the metal.

One rod cut

The fin­ished prod­uct

Cat Approval

Leave out for the cats, throw on a lit­tle cat­nip if you like, and observe the results.

Cat approval: suc­cess!

Posted in: Projects

2 thoughts on “Adventures in cat-scratching –or– how a laser project became a regular project

  1. Cool idea, Sir.

    As for the square part of the shaft on the car­riage bolts, you don’t actu­ally have to cut any­thing for them. When you tighten the nut on the other end, these tend to sink them­selves into the wood. Cutting a square notch for them actu­ally defeats the pur­pose of the square piece; it’s there to pre­vent rota­tion of the bolt itself. Cutting the square notch would allow the bolts to rotate if there was some sort of twist­ing force being applied to the ornate wood pieces.

    That said, car­riage bolts would have been overkill for a cat scratcher. I can’t imag­ine the cats are going to put that much torque on the ornate pieces when what they’re really after is the card­board. :)

    1. Yeah — I only looked at the car­riage bolts because they were some of the few “pre­made” bolts that were long enough (at least 6 inches). I’m glad I ended up going with the threaded rod, instead. That just feels like an over­all bet­ter solu­tion, espe­cially con­sid­er­ing it’s easy to hack down to a spe­cific length.

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