Guide · Router and spindle mounts
Spindle mount adapter rings, shims and adapter plates
What a reducing ring or shim can and cannot do, how an adapter plate differs, and the mount-to-body pairs PwnCNC documents.
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Short answer
An adapter ring or shim only steps a larger mount bore down to a smaller body, never the other way. An adapter plate is a different part: it bolts the mount to the machine. Use only the pairs a maker documents, and if a router or spindle is not held evenly, do not run it.
Rings and shims: one direction only
A ring sits inside a larger bore and gives a smaller body something to clamp. It cannot make a bore larger, so a 65 mm mount can never hold an 80 mm spindle.
PwnCNC sells reducing shims in these mount-to-body pairs, in several heights:[1]
| Mount bore | Body it reduces to |
|---|---|
| 69 mm | 65 mm |
| 80 mm | 65 mm |
| 86 mm | 80 mm |
| 89 mm | 80 mm |
| 108 mm | 80 mm |
PwnCNC says its shims were designed primarily around PwnCNC spindle mounts, and that a shim should sit evenly without overlapping a split, bolt or internal obstruction.[1] So a PwnCNC shim in another brand's mount is outside what PwnCNC describes. Ask both makers before you try it.
No ring fits every mount. A pair the maker does not list is not a pair you can assume.
Adapter plates bolt the mount on
An adapter plate changes how the mount attaches to the machine, not what the mount holds. PwnCNC's Spindle Mount includes four M6 mounting bolts, and machines other than Dominator CNCs need a separately sold, machine-specific adapter plate.[2] PwnCNC's 65 mm and 80 mm mounts share the same external dimensions, so the plate question is the same for both bores.[2]
SainSmart's earlier Genmitsu water-cooled kit included an 80 mm spindle holder plus adapter plates for PROVerXL machines and for the 3030-PROVer MAX and 4040-PRO MAX.[3] That applies to those earlier kit SKUs only.
Machine-specific holders instead
Often the cleaner answer is a holder made for your machine in the body size you have:
- Genmitsu's 65/69 mm aluminum holder is listed for the 4040-PRO, 4040-PRO MAX, 4040 Reno, 3020-PRO Ultra and 3030-PROVer MAX.[4]
- Genmitsu sells a 4030 V2 holder in 69 mm and 65 mm for the PROVerXL 4030 V2, also listed for the PROVerXL 4x4 Z axis.[5]
Some stock mounts carry their own sleeve. Genmitsu lists 42 mm and 52 mm spindle mounts for the 4040-PRO.[6] SainSmart's setup article says the 52 mm mount has an internal sleeve for 44 mm motors such as standard 775 motors.[7] The two pages disagree, so check the sleeve in your own mount.
Which part changes what
| Part | What it changes | Documented examples |
|---|---|---|
| Reducing ring or shim | Bore down to a smaller body | PwnCNC 69-65, 80-65, 86-80, 89-80, 108-80 mm |
| Adapter plate | How the mount bolts to the machine | PwnCNC plates for non-Dominator machines; SainSmart's earlier kit plates |
| Machine-specific holder | The whole holder, in one bore | Genmitsu 65 and 69 mm holders |
Holders that replace a ring
No reducing ring or adapter plate is approved in our catalog yet. If your machine is on Genmitsu's list, a holder in your body size avoids a ring altogether:
Picks that fit2 products
Choose the bore that matches your body: 65 mm (101-63-ZC65) or 69 mm (101-63-ZC69). Genmitsu lists both for the 4040-PRO, 4040-PRO MAX, 4040 Reno, 3020-PRO Ultra and 3030-PROVer MAX.
65 mm holder for the Genmitsu 4040-PRO family
Genmitsu 65 mm aluminum spindle holder (101‑63‑ZC65) for the 4040‑PRO family
69 mm holder for the Genmitsu 4040-PRO family
Genmitsu 69 mm aluminum spindle holder (101‑63‑ZC69) for the 4040‑PRO family
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Questions
Can I put a 65 mm router in an 80 mm mount?
Only with a reducing ring or shim made for that pair, seated evenly. PwnCNC sells an 80 to 65 mm shim, designed primarily around its own mounts.[1]
Can I put an 80 mm spindle in a 65 mm mount?
No. A ring only steps a larger bore down; nothing makes a bore grip a larger body. You need an 80 mm mount made for your machine.
What is the difference between an adapter ring and an adapter plate?
A ring changes what the mount holds; a plate changes how the mount bolts to the machine. PwnCNC's mount needs a machine-specific plate on machines other than its Dominator CNCs.[2]
Will a PwnCNC shim fit another brand's mount?
PwnCNC says its shims were designed primarily around PwnCNC mounts and must sit evenly without overlapping a split, bolt or internal obstruction. For another brand's mount, ask both makers first.[1]