2" Flywheel with 5 Straight Spokes: Fit and Mounting Guide
By Products for bench top machinists | LittleMachineShop.com | Published: 2026-11-03
Category: Guide all'acquisto
Learn what the 2" five-spoke flywheel fits, how to check bore and hub dimensions, and the decision rules for mounting it on a model steam engine.
Quick answer
Choose this 2" five-spoke flywheel when you need a small, straight-spoke flywheel for a model steam engine or similar project and can machine the bore to match your shaft. Check the hub dimensions against your frame before you buy, because the bore is not pre-finished.
Why the oversize casting changes your buying decision
The flywheel arrives as an oversize casting, so the final diameter and bore are determined by your machining. That is an advantage for hobby work: you can true the rim and fit the bore to your crankshaft rather than accepting a fixed, off-the-shelf bore. The trade-off is that you need a lathe and the ability to hold the casting securely while you machine it.
If you do not have a lathe or do not want to machine a bore, this flywheel is not a drop-in part. In that case, look for a pre-bored flywheel or a matched engine kit instead.
Straight spokes versus curved spokes: a visual and practical choice
Five straight spokes give a clean, mechanical look that suits many model steam engines and hit-and-miss engines. Straight spokes are also easier to set up for machining because the spoke pattern is simple and symmetrical. Curved-spoke flywheels can look more ornate, but they add no functional advantage at this size and can complicate workholding.
This is a hobby flywheel buying guide, so treat the spoke style as a personal and period-correct choice first, then confirm the dimensions fit your model.
When a 2-inch flywheel is the right size
A 2-inch flywheel suits small model steam engines, small hit-and-miss engines, and compact workshop projects where a larger flywheel would overwhelm the frame or exceed the available space. It is not intended for full-size machinery or for engines that need substantial rotating mass to smooth out power strokes.
If your model calls for a flywheel of roughly 2 inches in diameter, this casting gives you room to finish it to the specified size. If the plans call for a larger flywheel, do not try to stretch this one; choose a larger casting instead.
Decision rules for buying and mounting this flywheel
- Check the bore requirement: Measure your crankshaft diameter. Because the flywheel is supplied as an oversize casting, you will need to bore and ream the hub to match. If your shaft is larger than the hub can safely accommodate after machining, choose a larger flywheel. Confirm you have enough hub material for your finished bore before buying.
- Verify hub clearance: Compare the 0.910" overall hub length and 0.532" hub diameter against your engine frame. The hub must not rub the frame or any adjacent parts, and you need enough exposed hub to grip in the lathe when machining. Mock up the hub dimensions on your model before committing.
- Plan your workholding: The oversize rim gives you material to hold in a chuck or on a mandrel. Decide whether you will machine the bore first and hold on a mandrel, or hold on the rim and machine the bore. A four-jaw chuck or a purpose-made fixture is often needed for a casting of this size. If you cannot hold the casting safely, do not buy it.
- Decide on finish and fit: After boring, you can press or Loctite the flywheel onto the shaft, or add a set screw through the hub. The straight-spoke design leaves room to drill and tap the hub for a set screw if you prefer a removable fit. Choose your retention method before you finish the bore.
Product facts
- Flywheel, 2" Diameter, 5 Straight Spokes: The flywheel casting is oversize so you can finish it to the specified 2-inch diameter. You can true the rim and final diameter on your lathe, which helps if your model requires a precise fit.
Flywheel, 2" Diameter, 5 Straight Spokes - Flywheel, 2" Diameter, 5 Straight Spokes: It has a rim width of 0.537", a rim thickness of 0.245", a hub diameter of 0.532", and an overall hub length of 0.910". These hub dimensions determine whether the flywheel clears your engine frame and whether you have enough material to bore for your shaft.
Is this flywheel right for you?
Best for
- Model steam engine builders who need a small, machinable flywheel
- Hobbyists with a lathe who want to fit the bore to their own crankshaft
- Projects where a 2-inch straight-spoke flywheel matches the plans
Not for
- Anyone without a lathe or machining experience
- Engines that require a pre-bored, drop-in flywheel
- Applications needing a flywheel larger than 2 inches
