Anyone help design me a...

[sloth]

... small animal wheel?

Another odd request!

I currently have in my house 4 running wheels, for lots of degus. They are noisy, and last a couple of months before starting to wear out and break completely by 4-6 months. And at £20 each I'm fed up with them!

You can get 'better' ones for £30, £90ish for solid ones which run on bearings.

I am wondering if I can retrofit an axle using a bearing to the existing plastic wheel.

The wheel (a large Savic) is 28cm diameter and about 9-10cm deep. It already has a moulded 'sleeve' in the centre with 20-25mm ish diameter hole. It needs to bolt through a 12mm thick cage wall, or through a mesh side.

Any suggestions how or if this may be possible cheaply using off the shelf items? I have a good bearing supplier near me, or Internet delivery.

I was thinking maybe a suitable sized needle bearing to sleeve the bolt which slides through the centre of the wheel. Any issues with this or better suggests most appreciated!

Cheers...

[agg221]

You can retro-fit, but you might find by the time you have made all the bits it would have been cheaper and a lot less grief just to buy one!

 

A starter for 10:

 

Assuming you do not have access to machine tools, I would start by accurately measuring the diameter of the centre sleeve in the wheel and buy some rod to fit - it doesn't matter what as it will not be running on this surface so probably aluminium would be the best option. I would then take the rod to your local bearing supplier and get two sealed unit bearings which are a good sliding fit.

 

I would make two blocks of wood or plastic, one for each side. They would be square, and about 2cm bigger across than the outer diameter of the bearing, and thick enough to embed it in. I would find the centre (draw diagonals) and then drill a hole the outer diameter of the bearing so that it can be pushed in, using either a flat bit or a holesaw depending on the size (either can be had cheaply on ebay if you don't have them).

 

I would want to fix the blocks with four fittings, one in each corner of each block. Fixing method for the blocks would depend on available tools, the internal clearance between the wheel and the case and how much hassle I could be bothered to go to. Simplest would be to use plain bolts, pushed through from the inside (you really don't want to try to get the nuts in there!) and then tightened up from the outside. Neatest would be socket head cap screws rebated into the blocks, running into tapped holes in the case.

 

Having figured out which fixing, I would drill clearance holes in the blocks, in each corner (8off in total), sized as required.

 

I would cut the axle to the length across the outside of the cage, plus the thickness of the two blocks, plus 2mm.

 

I would also buy some threadlock.

 

I would then work out the hole locations on the case by pushing the axle through, pushing the bearings onto the blocks and sliding these on and marking the case hole positions through the holes in the blocks. Holes would be sized depending on whether they are to be clearance or tapped.

 

The final assembly sequence would be to insert the bolts from the inside first (if using that method) then the wheel and insert the axle through it. I would push the bearings into the blocks, having first applied some threadlock, leaving them just back from the mating surface of the block to allow them to run clear - let the threadlock set before going any further. I would then slide the blocks/bearings onto the axle and temporarily bolt up to check all runs smoothly. Finally, I would slide the blocks back off, apply some threadlock to the axle and bolt back on, setting the position up to allow free running.

 

There are probably more elegant solutions to dealing with end float than threadlock, but they are a lot more complex and probably require machining capability.

 

Any advances?

 

Alec

 

p.s. can you tell that part of my background is design engineering.....

[sloth]

p.s. can you tell that part of my background is design engineering...

 

... Yes! I'm having trouble visualising this to be honest. But thank you for trying nonetheless.

If I get a chance later I'll have a measure up and post a pic of one in pieces, in case it helps. I really don't want to be spending a total of almost £400 to get four almost silent running wheels with bearings that may last a good while, or a total of almost £150 for 'heavy duty' non bearing ones which may well wear out quickly anyway. So spending £15/20 a wheel making what I have quiet and long lasting might be worthwhile. The noise is driving me mad! Once they start to wear and rattle you can barely have a conversation in the same room...

[agg221]

p.s. can you tell that part of my background is design engineering...

 

... Yes! I'm having trouble visualising this to be honest. But thank you for trying nonetheless.

If I get a chance later I'll have a measure up and post a pic of one in pieces, in case it helps. I really don't want to be spending a total of almost £400 to get four almost silent running wheels with bearings that may last a good while, or a total of almost £150 for 'heavy duty' non bearing ones which may well wear out quickly anyway. So spending £15/20 a wheel making what I have quiet and long lasting might be worthwhile. The noise is driving me mad! Once they start to wear and rattle you can barely have a conversation in the same room...

 

What I described should be able to be made for the cost of the bearings and threadlock, maybe the rod (if you can't scrounge some from the scrap bin of a local engineering works) and the large sized drills if you don't have them and the same for the bolts.

 

If I had CAD here I would just draw what I am talking about - once you've put up a picture I'll have a go at sketching something.

 

Alec

[kinderscout]

Would two clutches of a chainsaw make suitable bearing.

cut the wall off and use the back plate and needle bearings.

[sloth]

Sorry for the delay, but hope this helps and makes sense...

 

I didn't measure anything yet, but I think the bolt is 8mm, and the hole in the centre of the wheel is about 15mm (guesstimated, will obviously be sure when it matters)

There is a shoulder on the yellow back plate to give clearance between the wheel and the wall, and the white sleeve is slightly shorter than the yellow 'spindle' it slides over, so the bolt doesn't just tighten against the wheel.

 

Edit: not sure why I have doubles of the images? Sorry...

 

Edited April 17, 2017 by sloth

[sloth]

The best I could think of was to replace the white sleeve for a suitably sized needle bearing, or something like the drawing below.

 

Glue/epoxy a tight fitting tube into the centre hole of the wheel; get bearings (are they called taper bearings, and would they even work?) to fit snug in each end of the tube; use a wooden back plate 'spacer' to give the wheel clearance from the wall; use nut/bolt/washers to hold it all tight.

No idea really if this would work though!

 

Edit: bloody doubled up again!

[agg221]

What is the cage wall made of?

 

Alec

[sloth]

9mm ply in most places, could easily make a bit double that though...

[matelot]

why not get an old pram. take the wheels and axles off, then fix the running wheels to the pram wheels?

 

just make a basic wooden stand so that the wheels stand clear of the ground?

 

I'd imagine there will be cheap second hand prams on ebay/ gumtree.