building a dog exercise wheel

Our sweet little McNab dog, Willie, is 6 months old now.  What a great dog -- but she is a handful!  Never-ending need for action.  So we thought we'd try building one of these dog exercise wheels.  Basically, a giant hamster wheel.  There are lots of videos on youtube, showing different hand-built and storebought wheels.  Some dogs take to them, others don't.  The cost of manufactured wheels is ridiculous, like most pet stuff, and our requirements are quite specific, so it seemed like building from scratch was the best option.  However, this meant that we wouldn't really know if the wheel was a success, or a big waste of time and materials, until the whole thing was built and functional.  No way to incrementally test as we go.

I wanted to make the wheel just about as big as possible, while still fitting vertically in our basement with fairly low ceilings.  So I went for approximately a 6-foot diameter.  The wheel rides in a support frame, a few inches off the ground, so the total height is slightly over 6 feet.

The overall structure is based on 1x2 lumber, along with some pieces made from 1/2" plywood.  I used two 2x4-foot sheets of plywood, and 16 8-foot 1x2 boards.  Not all the material was used, but close, and having a bit of extra material was useful at several points in the build process as I changed aspects of the design, etc.  Lumber is generally quite expensive these days, but at Lowe's I found a type of 1x2 lumber known as "furring strips", basically very low-grade 1x2s, which cost under $2 each.  Of course, considerable selection was necessary to find boards which were straight enough and not full of knots and defects.

The wheel consists of two 6-foot circles.  The curved outer rims are made from 1/2" plywood (six 1.5 inch wide curved segments each).  The outer rims are joined to central plywood hubs with six 1x2 spokes each.  The hubs are drilled with 3/4" center holes, which ride on the axle which is a piece of steel electrical conduit.  The axle is stationary (screwed to the support frame), so that the "bait cup" arm can be affixed to it, such that it stays in position at a given angle as the wheel turns (see photos).

The 6-foot circles are connected together by six 1x2 crossbars, 13 inches long each, so that the inner edges of the plywood rims end up spaced by 14 inches.  This matches the width of the 14" aluminum roof flashing which I used to create the "floor" inside the wheel.  The circumference is approximately 18 feet; a 25-foot roll of flashing would have sufficed, but it was only available in 50-foot lengths, which is OK because I use this material in many projects.  This was the most expensive individual material component, however, and if one were only interested in building a wheel like this, it would be worth searching around to get a 25-foot roll.  The aluminum flashing is then covered by strips of carpet, which we found at Good Will.

Details of the support frame and the construction of the "bearings" which hold the electrical conduit axle and keep the wheel centered so it doesn't scrape against either side, are probably easiest to see by looking at the construction photos.

We originally tried to use construction adhesive to hold the carpet to the aluminum, but it didn't stick adequately, and so I ended up holding the carpet down with screws and washers along the edges.  The adhesive maybe still helps a little in holding down the middle of the carpet.

As mentioned, there is a "bait cup", which is a plastic cup we can put treats in, which rides on an arm coming out from the axle.  This can be set to any desired angle, so that it is always just out of reach and encourages Willie to try to get to it.  Shades of the myth of Tantalus.

Everything was screwed together with 1+5/8" coarse-thread, and 1+1/4" fine-thread, sheetrock screws.  Crucial joints were also glued with Titebond wood glue: the rims of the wheel, and the flat portion of the support frame.  The vertical members of the support frame and the spokes of the wheel are held with screws, but no glue, so that the unit can be taken apart; otherwise, it would not fit through normal 30-inch doorways.

At first, Willie was scared of the wheel, both from its imposing size, and due to the way it moves when she is inside it.  But after a few sessions gradually getting her used to it, involving treats of course, she is now not scared of it and willingly walks inside of it.  I think she is starting to realize that it is fun!  She hasn't yet started really running inside it, which would be the ultimate aim of course.