The CEM120 is a large mount, and in a permanent installation the pier underneath it becomes part of the system. If you are building your own steel or concrete pier, the important part is having a known interface between the CEM120 base and whatever you build below it.
The iOptron #8036-120 provides that interface. It is a 210mm square, 14mm-thick machined aluminum adapter plate with the mounting pattern for the CEM120, CEM120EC, and CEM120EC2 on top and additional counterbored mounting patterns underneath. Instead of designing your pier around measurements taken from the mount itself, you can work from iOptron's published CAD drawing and build the pier top to a known set of dimensions.
The #8036-120 can also be used to put a CEM120 on iOptron's standard Tri-Pier #8034, but there is an important limitation: iOptron specifically says that combination is intended only for lighter CEM120 payloads. If you are building a heavily loaded CEM120 system, use a substantial permanent pier or iOptron's heavy-duty Tri-Pier 360A rather than treating the standard Tri-Pier as a full-capacity CEM120 support.
Key Features
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Made for the CEM120 family. Fits the CEM120, CEM120EC, and CEM120EC2, which share the same mounting base.
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210mm × 210mm adapter plate. Matches the basic footprint of the CEM120 mounting interface.
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14mm thick. A substantial machined plate designed to provide a solid transition between the mount and the support below it.
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Four M8 threaded holes for the CEM120. The mount-side holes are arranged on 180mm centers to match the CEM120 base.
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Multiple lower mounting patterns. Separate counterbored hole patterns accommodate M8- and M10-size fasteners for attaching the adapter to a compatible pier or support.
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Published CAD drawing. iOptron provides a fully dimensioned drawing so a fabricator can design and drill a custom pier before installation.
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Standard Tri-Pier compatibility. Allows a CEM120 to be installed on the standard iOptron Tri-Pier #8034 for lighter-payload applications.
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Useful for custom piers. iOptron specifically notes that the adapter can be modified or incorporated into a custom CEM120 pier installation.
For a Custom Observatory Pier
This is where the #8036-120 makes the most sense.
A custom observatory pier might be fabricated from steel tube, built around a concrete column, or incorporated into an existing structure. The dimensions of the pier itself can vary considerably, but the CEM120 still needs the same mounting surface at the top.
The #8036-120 gives the pier builder a finished mount interface instead of asking them to reproduce the CEM120 base directly.
iOptron's CAD drawing specifies the plate at 210mm × 210mm and 14mm thick. Four M8 threaded holes on 180mm centers accept the CEM120 mounting pattern. The underside provides separate counterbored mounting holes that can be incorporated into the pier-top design.
That means your machinist or fabricator can work from the published drawing before the telescope mount ever reaches the observatory.
When designing the pier, establish the CEM120's north-facing orientation before drilling or welding the final top assembly. The mount itself provides ±5° of azimuth adjustment for fine polar alignment, but the permanent structure should be oriented reasonably close to true north or true south so that adjustment range is available for its intended purpose.
Using It with the Standard Tri-Pier
The #8036-120 can also adapt a CEM120 to iOptron's standard Tri-Pier #8034.
That does not turn the standard Tri-Pier into a full-capacity CEM120 support.
iOptron specifically warns that because of the payload limitation of the Tri-Pier, the #8036-120 and standard Tri-Pier combination is not designed for a CEM120 carrying a heavy payload. iOptron describes the adapter as an option for lighter CEM120 payloads.
That can still make the combination useful for testing a mount, temporarily setting up a lighter telescope, or operating a CEM120 before a permanent observatory pier is finished.
If the goal is a heavily loaded CEM120 with a large SCT, RC, CDK, substantial refractor, or a complex dual-telescope imaging system, move to a support intended for that scale of installation.
Tri-Pier vs. Tri-Pier 360A
There are two different products here that are easy to confuse.
Standard Tri-Pier #8034: the #8036-120 adapter allows a CEM120 to be installed on it, but iOptron limits that combination to lighter payloads.
Tri-Pier 360A #8037A: this is iOptron's heavy-duty support. The CEM120 mounts directly to the Tri-Pier 360A, so the #8036-120 is not required simply to put a CEM120 on a current Tri-Pier 360A.
The same distinction matters when shopping for an observatory support. Do not choose the lighter standard Tri-Pier simply because an adapter makes the bolt pattern fit. The support itself still has to be appropriate for the complete mount, counterweights, telescope, and imaging equipment.
Mounting Hardware
The adapter is the interface plate; mounting hardware is not supplied as a universal hardware kit.
The four threaded holes on the mount side are M8 and match the CEM120 base. The underside includes counterbored mounting holes sized for M8- and M10-class fasteners.
For a custom pier, the correct fastener type, length, grade, and method of attachment depend on the thickness and construction of the pier top. Use the iOptron CAD drawing when specifying the pier rather than selecting bolt lengths from a generic recommendation.
What's Included
- 1x iOptron #8036-120 CEM120 pier adapter plate
Not included: CEM120 mount, pier, Tri-Pier, or universal mounting hardware.
Frequently Asked Questions
Does the #8036-120 fit all three CEM120 models?
Yes. It is made for the CEM120, CEM120EC, and CEM120EC2, which share the same basic mounting interface.
Can I use it on a pier I build myself?
Yes. That is one of its most useful applications. iOptron publishes a fully dimensioned CAD drawing so your machinist or fabricator can incorporate the adapter into a custom steel, aluminum, or concrete pier design.
What size is the plate?
The plate is 210mm × 210mm and 14mm thick.
What mounting pattern does the CEM120 use?
The mount side of the adapter has four M8 threaded holes spaced 180mm center-to-center in both directions to match the CEM120 base.
Can I put a CEM120 on the standard iOptron Tri-Pier?
Yes, with the #8036-120, but iOptron specifically limits that combination to lighter CEM120 payloads. It is not intended as a full-load support for a heavily equipped CEM120.
Do I need this adapter for the Tri-Pier 360A?
Not simply to mount a CEM120. The current heavy-duty Tri-Pier 360A is designed to accept the CEM120 directly.
What should I use for a heavily loaded CEM120?
A properly designed permanent pier is the natural choice for most observatory installations. iOptron's heavy-duty Tri-Pier 360A is another purpose-built option when a portable or semi-portable support is required.
Are the mounting bolts included?
Do not assume a universal set of pier fasteners is included. The correct lower fasteners depend on the support or custom pier underneath the adapter. Use the CAD drawing when specifying the installation.
Can I drill my pier before the adapter arrives?
Yes, provided your fabricator works from iOptron's current #8036-120 CAD drawing rather than measurements copied from a photograph or third-party drawing.
Final Thoughts
The #8036-120 is a simple part, but it solves an important problem when a CEM120 becomes part of an observatory: it gives the mount and the pier a known interface.
For a custom pier, the published dimensions let your fabricator build around the actual CEM120 mounting pattern instead of guessing at it. For the standard Tri-Pier #8034, the same adapter provides a temporary or lighter-duty way to support a CEM120, with iOptron's payload limitation kept clearly in mind.
If you are building around a heavily loaded CEM120, CEM120EC, or CEM120EC2, use the #8036-120 as the interface to a properly designed permanent pier, or choose a support such as the heavy-duty Tri-Pier 360A that was built for the weight involved.
