3D-printed gears for 1" pegboard
Any gear you add to a pegboard has to mesh with the ones already there and land on a 1" hole. Here is the arithmetic, the Spur Gear add-in settings, and a motion link to prove it.
Standard pegboard has ¼" holes on 1" centres. If you want gears that pin into those holes and turn each other, the tooth size and the gear diameters have to agree with that grid. The existing set here is a 25-tooth gear meshing with a 5-tooth gear at 5:1. We need a bigger one that joins in.
The arithmetic
The 25-tooth gear has a pitch diameter of 5", so its mesh point is 2.5" from its centre. Gears mesh where their pitch circles touch, so centre-to-centre distance is half the sum of the two pitch diameters. For that to land on a whole number of inches with an existing gear on a hole, every pitch diameter has to be an odd number of inches.
Tooth size is set by diametral pitch: teeth per inch of pitch diameter. 25 teeth over 5" is 5. 5 teeth over 1" is 5. Every gear in the set is diametral pitch 5, so the acceptable gears are:
| Diametral pitch | Pitch diameter | Teeth |
|---|---|---|
| 5 | 1" | 5 |
| 5 | 3" | 15 |
| 5 | 5" | 25 |
| 5 | 7" | 35 |
| 5 | 9" | 45 |
| 5 | 11" | 55 |
Make the gear
Utilities → Add-ins → Scripts and Add-ins → Spur Gear. Use the English standard, because the pegboard is imperial.
- Pressure angle 20°
- Diametral pitch 5
- Number of teeth 45 (pitch diameter shows 9")
- Backlash 0.1 mm. This is for printing: 0.1 mm of clearance on each tooth face so the gears turn instead of binding. In a real machine that space is for lubricant or play.
Put it on the board
Move the new gear as a component (including its origin) somewhere clear. Then J for Joint: bottom centre of the gear to a pegboard hole. Which hole? 9"/2 + 5"/2 = 7" from the 25-tooth gear’s centre, so count seven holes. Look from the top, orthographic, and rotate the gear until the teeth clear. Capture Position.
Spin it: it turns, but the other gear does not follow. Add a Motion Link between the two revolute joints. The ratio is the tooth counts, 45 to 25, and tick Reverse, because two meshed gears turn opposite ways. Now one turn of the small gear gives you the right fraction of a turn on the big one, and the teeth stay clear all the way round.