Figure 1: Initial frame design for Noa's wheel
Building a wheel involves using tools which can potentially cause injuries. Please be careful, and follow safety instructions.
There are two major issues with hedgehog wheels: a) they must be large enough for a hedgie, and b) they must be safe for hedgehogs to use. There are a number of design points which help make the wheel safe, and we have tried to incorporate them into our design:
The original frame design, for Noa's wheel, was an A-shaped one as portrayed inFigure 1. The frame was made from scrap wood from our tabletop. The wood was cut into stripes about 3x4cm using a circular saw. The length of the posts depends on the size of the actual wheel you are planning to use. K-rauta, Etola * and possibly other stores, sell 65-liter plastic buckets (around 13-15Euro) which both Noa's and Alfred's wheels utilize. These are just over 40cm in diameter, giving the posts length of about 30cm.
An improved frame was made by Jari, and is portrayed in Figure 2. The vertical piece allows for easy modification of both the angle of the wheel with respect to the vertical axis, as well as the mounting height, in case the wheel is replaced.
The wheel use two rollerblade bearings, available from either hardware supply or sports stores. You can also use used rollerblade bearings, however please make sure you clean them well. The bearings allow for quiet operation without squeeks which is essential for being able to sleep at night. The bearings are usually 22mm in diameter and accept an 8mm axel. You can use either a threaded rod, or M8 bolts. To take the slack, purchase also a few washers in various sizes. Bearings are about 4 Euro a piece, while the bolt, butterfly nuts and washers should be under 2 euro altogether.
To do the hole for the axel follow these steps:
Refer to Figure 3 on how to mount the axel. The key to note is that inbetween the the bearings, you must either place nuts, or washers to precisely compensate for the space. If you tighten the bearings against the wood, the wheel will not turn freely. If you tighten it loosely enough to allow the wheel to turn, the nuts are likely to come off when the hedgehog is running. This was discovered when Noa was using his first wheel. Initially the problem was fixed with a piece of copper piping, however it was difficult to make and totally unadjustable. Alfred's wheel bearings use a number of small washers to fill the space, and it works great. Vilhelmiina's wheel uses two nuts inside the axel (Figure 3). These work equally well, and its mainly a matter of choise which one you choose.
Although we initially used glue to hold the frame together, we found out soon enough that it wasn't up to holding the frame with our sporty hedgies. Use wood screws instead.
You can add some filc padding under the frame to make it sit better on hard, uneven surface. It is not necessary though.
Here is a short review of the steps when I was building Noa's wheel (click on thumbnails to get a bigger image):
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The 4 strips of wood which make up Noa's and Alfred's wheel frame. Similar bits were also used to make a wheel for Nuusku. |
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The posts with the join cut out. Also notice the sanded edges of the bits, eliminating any sharp edges. |
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Matching up the bits |
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Initially, I tried gluing the bits together. Before actually commiting the pieces together, make sure the fit is snug. If not, then sand it down until it is. Don't overdo it. If you take off to much, you will need to make new parts. |
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I quickly decided glue was not going to hold this together, and put two bolths through. Also notice the centerline helping to aim where the hole should be. |
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Matching the "legs" |
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Both legs attached. Again, initially with glue. After one of them came off after a nightly marathon, I took it the frame down to the workshop again, and put two good screws in each leg. That ought to hold it. |
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The frame ready, and hole drilled. Sorry about picture quality, must have pressed something wrong on the camera. |
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Frame with bearing visible. |
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Zoom on the bearing |
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The early prototype utilized only one bearing. This was VERY quickly discovered not to work well, and a second bearing was added into the design. If you are stubborn, you can use a 1-bearing version, but it makes a job out of attaching it to the frame in a solid fashion. |
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Trying the "wheel" on |
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Frontal view of the ready wheel. Notice that the inside surface of the wheel itself has been sanded with harsh sandpaper (grade 50-80) providing the hedgie with a bit of a grip surface. |
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Rear profile. Nowadays, Alfred's wheel also includes a support board which goes on the back of the wheel part helping to keep it straight. Although it is the size of the wheel, smaller support plates have been successfully used on Jalmari's and Elvira's wheels. Much will depend on how hard and how suspectable to deformation the plastic is. |
Some pages from USA suggest sizes of about 11-12" (27,5-30cm) which we consider well too small for a normal hedgie. All of the wheels we have built have been around 42cm in diameter (almost 17") giving the hedgie a fairly flat surface to run on. Smaller hedgies could probably do with a bit less, but we would think around 35cm (14") is the absolute minimum.
Although the bucket we used was blue, we have also found the same model available in gray and green. Some stores also carry similar models, but which have a thick rim around the bottom. These are better because are less suspectable to deformation, however its more difficult to find them. The last word had it that RTV or Rautia might have some. Avoid plastic that is soft, even if the whole bucket feels rigid. After you cut the bottom off, the chances are its going to go yoyo on you, and be pretty useless.
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The basic 65 liter bucket used for the construction of the wheel. Notice some tape around the lower end. It was used to mark where the cut should be. |
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Another picture, this time in color. If you squint very much, you can just about make the markings on the measuring tape. |
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Cutting off the base. Its about 15-16cm, giving hedies plenty of room. I used a dremel with normal cut-off wheels to do this, but you can use a saw, or some other cutting tool. The dremel provided fairly clean cut with little distortion... |
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...but was well messy. Next time I did this, I asked Minna to hold a vacuum cleaner right next to where I was cutting. And I hope I don't need to remind anyone about using a dust must when doing this kind of stuff. |
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Voila! The rough wheel before further processing. Make sure you drill the hole for the axel well in the middle, otherwise you hedgie might get dizzy. Also, sand down the edges of the cut to prevent any sharp corners or thorns. Don't forget to make the inside surface a bit less slippery, although this depends on the plastic. Some buckets are rough enough and don't require sanding. |
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The downside of the wheel making from a bucket is that the rest of the bucket is left over after you use the bottom. If someone has any ideas on how to utilize this, please tell me. |
* All names of stores or places refer to Finland