Introduction: Cat Exercise Wheel Device
First Prize in the
Spectacular Failures Contest
So I have this cat. he is very old and not wanting to let go of life just yet. In fact he was with me on my journey into the California lifestyle(15 years ago). patiently he was there purring all the way. As a matter of fact... when he is fast asleep. poke him and the purring begins.
I fear that he is almost done. Himalayan cat, 21 years... His fur is thin, he needs constant supervision and he will not leave my laundry room, snuggles up to the heater, refuses to move.
When it was warm I would have him with me outside all day. This works amazing on his back legs. Now the snow is here and he seems to be fading. Like me he needs to work out.
This simple project has turned into a massive 2 week time sucker. I'm finally done and have learned a lot in the process.
Initially I tried to run him on a treadmill but that just didn't work. I saw the hamster wheel type of device a few years back but the cost was way too much.
So I thought I could build one for less than the shipping of a commercially available product. Plus all the ads show that the cat loves it and will use it endlessly. What could go wrong?
The original brown base design was a spectacular failure based on ego, assumptions and arrogance. Do not even attempt a support base of this type. it will frustrate and destroy your willingness to live.STEP 4 is EVIL!
so far the cost is about $75 and it is remarkably quiet with the MAJOR redesign Now I play with it, the cat, well, we will see!
Step 1: What You Will Need
The big Orange store has a bundle of 48 inch lath which contains 50 pieces.
When I made my wooden prop sword and shotgun from this material, it was only $12 for 50 sticks, now it is $21. Calgary prices are not ideal!!! I chose to cut the sections into 14 inch pieces. I felt that this would allow for my ancient cat to walk freely without having to maintain a straight course. He is beginning to stagger as his back legs atrophy.
I took the entire stack of 50 lath and turned it into 150 by making 14 inch cuts. The remainder is in my bin for future use.
looking back on this, I cut way too many pieces. simple math and measuring assumptions had me needing 113 1 inch wide pieces. Turned out that the lath I used is wider than 1 inch. measure twice. I should have not cut the entire stack. the lath is the width of a standard 2X4.
I ended up using 77 and a tiny bit. Math was way off, have to stop drinking at 10AM, but at least the circle was complete, at least it looks like a circle...
Step 2: Make the Form
Since this is meant to rotate, you will need two circle forms of correct diameter to create a 3d device.
I wanted a 36 inch ID so I fastened the Dremel circle cutter to a piece of scrap wood that would give me a 18 inch radius. this was then used on the Dremel with a spiral cutter to create a large circle of 36 inch diameter.
This was done twice. Orbital sanding was necessary since the Dremel was gouging rather than cutting smooth. Directions for Dremel cutting? Left really fast and rough while right slow and smooth. I'm impatient so you can guess my direction...
The resulting circles were then fastened together with 3 10 inch scrap pieces of 2X2 from another project.
The resulting 3D circle was rolled across the floor to check the parallel round. I was satisfied with the linear round and then was able to begin the circle tread of the the wheel. Boy was this not the way to go. While it did work, the rusulting cylinder was, well, not as expected.
OK so my Dremel died and would not turn on after the end of the second wheel, lots of sparks, plastic burning, uncomfortably hot and such. NOT KIDDING! No blue smoke just burned plastic smell. I know what this is.
Step 3: Place the Slats
Using clamping force and friction, glue the cut lath (slats) together. I started with just 15. Use one edge of the 3D circle and glue sections together to form a ring around the outside using the plywood edge as a guide. The goal here is to have both sides as parallel as possible.
I held mine in place with a cargo strap. clamp as you glue. the foaming nature of this type of adhesive should correct your mistakes.
I also used some clamps to correct for any odd slat warping. this was done at 15 sections at once.
Continue until the circle is complete. Make sure that the 2 36 inch disks are not attached to the lath. The glue has this unfortunate side effect. just hit it from the side to break any glued points. Turns out that foaming poly style adhesive has very low shear strength, flat pieces together will never come apart but angular attachments do not hold.
As I write this it is 1:53 in the morning. Glue does take time to dry
and I just finished section 53. anyone who knows me will take sick pride in the significance of this number. I have made use of clamps and duct tape to make sure the the outer surface of the wheel is true.
Fast forward, there may be an odd size section as the last. I cut about a quarter of an inch off of the side of the remaining piece and fastened it into place with a large quantity of foaming adhesive.
You may have noticed a location change. the later pictures are in my basement due to sub zero temperatures in the workshop.
Added bonus... This will destroy your cargo strap. there will be little lines of adhesive on the strap that will prevent you from being able to properly use it again. Thin lines of hardened razor sharp glue do not work well with the soft pink hands.
Just patiently continue until the circle is complete. So far I am at 5 days and the circle is now complete!
Full assembly is now done so let this bit dry for a couple of days and meanwhile...
Honestly, now we wait...
Step 4: It's All About the Base
This step is a bad bad horrible design idea. Assuming that your outer circle is perfect, the chances of getting the rollers to work without rumbling or wobble is a matter of needing computer precision. It cannot be done using hand tools and rudimentary measuring tools. Scrap this part and move on to a more traditional solution. I will show you mine in a bit.
Once you are done basking in the magnificence of your circular creation. you will need to make it stable and connect it to a surface that allows for proper perpetual rotation.
The off cuts from the large circles would really come in handy about now... Check the bin, make sure the trash guy hasn't taken them away yet. Still have them? good! If not make a couple more but fix the Dremel first if needed.
The roller base is a piece that is 14.25 inches wide and has a rollerblade wheel at each corner. The wheels are oriented so that there are 2 per side. They roll but keep the big wheel in line.
The base needs to be insulated from the floor as well. use some sort of rubber mat or foam. Mine is foam rubber, see what I did there? As the big wheel turns it will amplify any bump or imperfection. Rolling this at 2 AM this will sound like a truck coming through your house. quiet is the goal.
I chose to hide the wheels from view but this has a secondary purpose. The small rollers are a pinch point. Hiding them is also a protection of the tiny furry paws.the contact space is kept to a minimum.
The wheels I use are 80mm from a local CT and the bearings for this are from VXB. I have no affiliation with either but I may have financed their kids through college.
The wheels are fastened from the inside to the frame as shown. Use just enough spacing to create a stable base but still allow for a tiny friction contact so that the big wheel rolls free and true.
The small wheel hub bolts used are 1/4 inch to fit the bearings. Make sure the hub bolts are square, otherwise there will be binding which will create friction and wear out the wheels really fast.
If you have time, finish the exposed wood. It will look extra shabby in a couple of months if you don't.I used a Varathane finish on the exposed wood. More on this at the end.
Step 5: Reinforcements
OK so the Dremel is toast. seriously, even I can't repair it. Major brush melt. nothing left.The change of plans now includes smoothing the entire outer surface with an orbital sander. This thing is my new best friend...
Wait at least 24 hours from the last adhesive application. Ignore the
centers and sand the sides smooth with an orbital sander and 40 grit paper. pay special attention to the outer edges of the big wheel. The support wheels will roll here.
Now we are 4 hours and 6 40 grit disks later good thing for dust masks otherwise I would have succumbed to the consumption... My shop is now covered in a thick layer of fine dust.
The big wheel is finally smooth but for some reason the combination of thin materials and extremely dry environment has perfected a fragile foundation. Did I mention that Calgary weather does not work well with human life!
Again my calculations were wrong and the big wheel needs a reinforcing layer of material. I chose to make this from the original plywood wheel forms. I got out another Dremel, OMG this one is a 4000, Thank you Instructables u... and made a cut in the big form to allow a big wheel that was 1.5 inches smaller than the first. These disks are then glued to the outer big wheel at the edge.
OK so it would appear that my forms were way off. The wheel is not round or true. The slats have created a distinct rumbling effect and it wobbles about a half of an inch. More sanding more 40 grit disks after about 6 hours I realize that there is no way for me to correct this as an open wheel.
SOLUTION:Ironically, I just cut the side open, now I need to make it solid again. I will need to close one side and make this a center rotation device. Looks like it will be placed against a wall in the future. My magnificent creation is just plain awful in the world of precision.
Step 6: Close One Side
Initially I thought to have a rear side wheel support cross built from 2X4 to be able to leave the back side mostly open. I liked the open nature of the wheel. Upon thinking about it, open rotating supports coupled with a stationary support structure... well that is exactly how scissors work. This idea was killed for obvious reasons. A protective solid back was now needed.
I had some 5/8 plywood which needed a 37.5 inch circle cut from it.
Learning from my earlier mistake, I chose to make several 1/16 inch cut passes with my Dremel circle cutter. CLOCKWISE.
This made for a smoother outer cut.
The construction grade piece was extremely rough on both sides so I chose to sand it with 60 grit orbital. Now it looks much better.
The added bonus is by using the circle cutter I now know the exact center.
Since my wheel was out of round I will be needing to make sure that this new circle is as close to flat as possible.
I accomplished this By identifying a flat section in my storage room.
The floor was protected with brown craft paper.
The best looking side of my new circle was placed upwards and weighed down with quite a bit of free weight.
I then identified which side was the furthest from true by alternating laying it down on the weighed circle.
There was a thick layer of foaming adhesive placed about a half an inch from the outer diameter of the circle.
The worst side was then placed face down on this line of glue and aligned with the edges.
Much weight was placed at the points of closest contact and a little was placed at the worst.
I had about 3/8 of an inch at the worst point.
Wait for the glue to dry., at least 4-5 hours, it will no longer be sticky.
Smooth all exposed surfaces.
Flip the enclosed wheel on its face.
Using tape on the inside of the gaps, create a dam to prevent adhesive from seeping through.
Put a bead of glue in the gap. Do not fill it since the glue will expand and then wait for it to set.
Repeat this for any big gaps. Wait for the glue to set. Now sand the edges smooth.
Step 7: Fill the Gaps and Reinforce the Back
Since I don't trust the structural integrity of any plywood, and I like to overbuild things, I chose to reinforce the shaft contact area of the big wheel.
From a failed attempt at making a power feed mechanism, I had a cool piece of cut plywood in the shape of a gear. This should give a great visual element and it was placed on the rear face as a reinforcing piece, the back side also had a section of plywood added as well but it was a mundane square.
I like to use spade type and hole saw bits for anything larger than a half an inch. I find that my boring tools create a kind of weird triangular hole with larger spiral bit sizes.
I drilled holes for the shaft in the big wheel back using the circle cutter point as a reference, Oh yes and the square piece. Oddly enough the gear that I made a year ago had the right size hole. for cutting holes, drill about half the way through or until the point of your drill comes out the backside, and then flip the piece over and use the place where the drill point came through to drill back towards the center. This way you will not have an ugly torn out hole on one side of your piece.
I applied liberal amounts of white wood glue to the facing surfaces of the gear and square then used a short three quarter inch bolt to clamp all the pieces together through the center hole of the assembly. Again more drying time is needed.
Curious! I found that white glue if left to dry in sub 10 degree C temperatures while taking longer to dry, will still form a tight bond but will remain white. Further, it even stays white when brought into a comfortable warm environment. It will dry and stay clear above 10 degrees C.
Step 8: Make the NEW Base.
The base needs to be a stable platform and strong enough to support the load of the wheel plus the cat. and if the specs are right on the bearings and bolt then I have nothing to worry about.
I chose to make this from 2X4 studs. The local Orange store has lots of these so you can choose the straightest.
I chose to use 2 6204 RS bearings and a 10 inch 3/4 bolt as an axle shaft. This is serious overbuild but that's the way I like to roll.
All of the dimensions were chosen to accommodate what I assumed would be needed. I started with 2 sections of 2X8 which were cut wide enough to allow for a shaft to pass through the center supported by bearings. the top is about 4 inches wide and it is cut at 22.5 degrees.
The 2X4 supports for the bearings are 24 inches long and the ends were cut at 22.5 degrees as well.
The width of the base was chosen on the width of the bottom of the bearing support 2X4's
The base square was made to displace the rotational force. It needs both gluing and clamping force
All cut pieces were clamped together then drilled for exact fit.
all cut sections were sanded to get rid of splits and imperfections and then glued and clamped together.
The upper A frame is then attached to the base square. I used clamps to determine the best location then drilled though the base, glued the contact surfaces and fastened it using 6 flat face 3 inch cabinet mounting screws.
the bearings were chosen to support a 3/4 inch shaft. this is a bolt 10 inches long. Shear strength about 150000PSI Take that QA inspectors!
The upper green sections are milled with a Dremel and circle cutter to accept the outer race of a standard bearing with a 3/4 inch id shaft.
The bearing milled holes need to be just large enough to support the outer race of the bearing. too much friction fit will cause the wood to split, not enough the shaft will wobble.
I used magnets to make sure the shaft is level and square, then fastened the rear bearing support piece to the frame using 6 deck screws.
Hopefully the bearings will allow for the wheel to turn freely and smoothly for many years to come.
Step 9: Get a Grip
The inside is a no brainer. Just adhesive cover a back of a section of carpet and stick it to the inside of the big wheel, that will work as both a insulator and a grip surface.
An old hallway runner works great for this. Try Ikea, again no affiliation but I seem to live in one of their show-suites.
I had to cut mine down in width then also fit the remainder to the inner circle since I didn't have enough length. the grip runner was cut into 13 inch wide pieces, my material was thoroughly rubber backed. I randomly chose the width of the wheel and for some unknown reason the Ikea runner was 26 inches wide.Seriously why would a carpet be 26 inches wide? I'm not complaining since it worked out for me.
Do not use foaming adhesive to fasten the carpet down. it will make a big ugly mess, I am great at creating one of those. standard white glue diluted to 50% will work, it just takes several days to dry fully. Not the way to go!
The carpet layer needs to be flat and smooth to prevent a tripping hazard.
Carpet tape works great on this and allows for material rehabilitation. I found that the tape is definitely the preferred way to go.
use extra carpet tape at the seams.
Step 10: Finishing!
Seal the wood. it will take on an odour if not.
By now it should look good and run smooth.
2 weeks later it is done and perfect.
I chose to finish the wheel wood with clear Varathane. I think that it looks great.
The original base was done in Mahogany finish. Kind of looked wrong. This was scrapped and the center spin device was used.
What about the cat. Let me just say that internet cats are the best. they do what you want, when you want. no questions asked. mine, well, they are typical cats! F You and such...
I first tried with the old guy and he just sits on it rubbing his face on the edge. he does move a little but there is definitely no running. No amount of food and coaxing or forcing would get him to run on it.
All of the three of my cats seem know what it is but hate it. Two of them won't even go near it. Now I have to make coats for them to go outside in... Yes I'm sure that will go over well!!!
Further... I have a 3 and a half foot AMAZING conversation piece in my house...
We have a be nice policy.
Please be positive and constructive.