Introduction: Mower Wheel Repair

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I destroyed the wheel center of my mower wheel on the weekend by turning the mower while the wheel was in a small rut next to a concrete edge resulting in the majority of the of the inner part of the hub being torn away.
As you can imagine a replacement wheel for an aging mower is expensive & hard to find. So using some pipe, nuts & bolts I repaired the hub in no time & very cheaply!

Parts Required:

  • Small piece of pipe with an i/d to suit wheel bearings
  • 5x 3/16 bolts
  • 5x washers
  • 5x spring washers
  • 5x nuts

Note: Attached is the DWG model file of the repair design.

Formlabs Competition: If I had one of your 3D Printers I'd draw & Print a replacement wheel! :)

Attachments

Step 1: Mesuring Up

  1. Measure the location of the existing outer bearing relative to a fixed point. In my case I laid a small rule across the center of the hub.
  2. Measure the location of the inner bearing relative to the same fixed point.
  3. Set out both bearings on the bench relative to each other the same as they are in the existing hub.
  4. Now measure the distance between the flanges on each bearing, this is the length of pipe required to fabricate the new housing.

Step 2: Pipe Cutting

  • Find some pipe the bearings will slip into (pipe may need some filing) & has a wall thickness strong enough for the application (at least 1.2mm I'd say). In my case the pipe was 32mm o/d mild steel galvanized CHS (may have once been a TV antenna bracket).
  • Cut your pipe to length making sure cut is dead square. Check with a square & adjust with a file if required.
  • De-burr all edges.

Step 3: Drilling New Hub

If you don't have a hole saw the right size to suit the outside diameter of your pipe, you could also use a rotary burr or round file to ream the hole, but be sure to keep the hole even & straight.
Then tap the pipe into position.

Step 4: Testing

Lightly place your bearings into your pipe & slip onto the stub axle to check length & check if anything fouls.

Step 5: Drilling

  1. With the pipe in position mark the center of your bolt holes at each wheel spoke location.
  2. Maintaining a decent edge distance of plastic. (my case was 7mm)
  3. Make sure the bolt heads won't foul on the bearing on the inside of the pipe.(see image above)
  4. Use a bradawl to start the holes.
  5. Drill a pilot holes through the plastic until the drill bit marks the pipe.
  6. Remove the pipe from the wheel.
  7. Drill the holes in the pipe using the a drill press for best results.

Step 6: Assembly

I used 5x 3/16 bolts but M3 or equivalent would be fine. It is important to either use spring washers, nylock nuts, or loctite on the threads as the nuts will be prone to coming loose from the vibration.

  1. Tap the pipe into position.
  2. Install bolts.
  3. Apply never seize or equivalent copper rich grease on each thread.
  4. Smear some never seize where the bearings contact the pipe.
  5. Tap the bearings into each end of the pipe.
  6. Smear some never seize on the stub axle & axle thread.
  7. Install wheel, washer & nut, be sure not to over tighten nut.

I suggest painting the pipe with a zinc rich paint especially if you live close to the coast as the salt air settles on the grass & will make it's way to the raw steel during mowing & cause the pipe to rust in no time.

Thanks for your time & happy mowing =)