Spindle Cap Retainer vs 3 mm Spindle Spacer: Fit and Function
By Products for bench top machinists | LittleMachineShop.com | Published: 2026-11-03
Category: Produktbewertungen
Compare the spindle cap retainer for HiTorque and SX3 mills with the 3 mm spindle spacer for X3 mills. See which bench mill spindle part your machine actually needs.
Quick answer
Buy the spindle cap retainer if you are working on a HiTorque Bench Mill (SX2.7) or an SX3 mill and need the cap fastener. Buy the 3 mm spindle spacer only if you have an X3 mill and need the spacer that sits below the spindle bearing. They are different parts for different machines, not interchangeable upgrades.
Why the machine model decides the part
These two parts sit in different places on different mills. The spindle cap retainer is listed for the HiTorque Bench Mill (SX2.7) as part A49 on parts diagram A, and the same retainer is also found on SX3 mills as part 54. The 3 mm spindle spacer is listed for the X3 mill spindle, below the bearing.
That means the model number on your mill, not the price or the size of the part, is the first thing to check. A retainer that fits an SX2.7 or SX3 does not become an X3 spacer, and an X3 spacer does not retain a spindle cap.
The trade-off: low-cost parts versus a wrong-order return
Both parts are inexpensive, so the cost of trying one is low. The real cost is time: a wrong part means the mill stays apart while you reorder. The retainer is the more broadly listed part, appearing on both SX2.7 and SX3 documentation, while the spacer is tied specifically to the X3 spindle below the bearing.
Neither listing supplies dimensions beyond the spacer's 3 mm size, so do not assume a fit from appearance alone. Use the parts diagram and model number as your evidence.
Trade-offs at a glance
- Spindle cap retainer: broader model coverage: Fits the HiTorque Bench Mill (SX2.7) as A49 and the SX3 as part 54, so one part number covers two mill families. The trade-off is that you must still match the diagram position on your machine. Check your parts diagram letter and number before ordering.
- 3 mm spindle spacer: X3-specific placement: Listed only for the X3 mill spindle below the bearing. The trade-off is narrower coverage: it is not listed for SX2.7 or SX3 use, so do not order it as a cap retainer substitute. Confirm X3 spindle and below-bearing location first.
- Price versus downtime: Both parts are low-cost, so the deciding factor is fit, not budget. A wrong part costs more in reassembly time than the part itself. Order by model and diagram position, not by price.
Product facts
- Retainer, Spindle Cap: Spindle cap retainer listed as part #49 on SX2.7 parts diagram A (A49) and as part #54 on SX3 mills. You can confirm the retainer against your own diagram before ordering, which reduces the chance of a wrong fit.
Retainer, Spindle Cap - Spacer, Spindle 3 mm: 3 mm spindle spacer intended for use below the bearing on the spindle of an X3 mill. It suits X3 spindle work specifically, so it is not a substitute for a cap retainer on an SX2.7 or SX3.
Spacer, Spindle 3 mm
Which part fits your mill
Best for
- HiTorque Bench Mill (SX2.7) owners replacing the spindle cap retainer at diagram position A49
- SX3 mill owners replacing the retainer at part 54
- X3 mill owners who need the 3 mm spacer below the spindle bearing
Not for
- Anyone treating the retainer and spacer as interchangeable
- X3 owners looking for a cap retainer, or SX2.7/SX3 owners looking for an X3 bearing spacer
- Buyers who have not checked their mill model and parts diagram
