If you had a LEGO train set in the 80s or 90s, chances are that some of the wheels have come off by now, and they just won’t attach to any of the common LEGO axles.
These are the wheels I mean. They have small metal axles and attach to a thick 4×2 block. In my wheels, all the little axles are long since missing, and all that is left is a wheel with a small hole through it.
What I did to fix mine is drill the holes out to fit standard LEGO wheel axles, like in the image below (see ‘the plan’).
- A drill press*
- A 3.2mm drill bit (optional**)
- A 3.5mm drill bit
- A 4.5mm drill bit
* You could try this without a drill press, but you won’t get consistent results, and you may get some tight wheels and some loose.
** The 3.2mm drill bit is used to set the depth stop to the perfect depth without trial and error. You can do this with a ruler or something else if you need to.
The steps are:
- Enlarge the hole all the way through the wheel with the 3.5mm drill bit
- Insert the 4.5mm drill bit and set the depth stop using the 3.2mm drill bit
- Drill the hole larger part way through the wheel until the depth stop is reached
The wheels should now snap perfectly onto the axle and spin smoothly without being too tight or too loose.
1. Enlarge hole to 3.5mm
Insert the 3.5mm drill bit in the drill press. Place a block of wood on the platform to ensure you don’t drill into the platform itself. Carefully but tightly hold the LEGO train wheel in place with one hand, and very slowly drill through the centre of the wheel all the way through. Because there is already a hole, the drill centres itself and ensures the hole is perfectly vertical.
- Although I wouldn’t normally recommend just holding the work piece between fingers, if you hold it steady and drill slowly you shouldn’t have a problem. The plastic is soft and shouldn’t snag.
2. Set up 4.5mm drill bit depth
Insert the 4.5mm drill bit in the drill press. Now lay the 3.2mm drill bit on the block of wood directly under the inserted bit and lower the drill press until the inserted bit sits on the 3.2mm drill bit. Now set the depth stop so that the drill press will not drill any deeper than that.
- A depth of 3.2mm gives the perfect depth for the lego axles to click in place and allow the LEGO train wheel to freely spin. 3.5mm results in a tight wheel and 3mm allows the train wheel to move (too much slop).
- If you don’t have a 3.2mm drill bit, use the 3.5mm drill bit from the previous step, and then carefully lower the drill press a tiny bit more before setting the depth stop. It is best to drill the hole too shallow than too deep. You can always drill it a tad deeper later if the wheel is too tight.
3. Drill the 4.5mm hole
Finally, drill the 4.5mm hole in each wheel, lowering the drill press until the depth stop is reached. Remember to drill from the front of the train wheel towards the back!
- Make sure you drill from the front of the LEGO train wheel to the back, like in the photo.
- Hold the LEGO train wheel securely, and drill slowly. You do NOT want the plastic shavings to snag and pull the train wheel upwards, or you’ll get a hole all the way through the wheel and it will be ruined.
- Drill down to the depth stop, not all the way through the wheel!
Hopefully your wheels now snap onto the axles and spin nice and freely! Have fun.