Description

The AM7 includes a non-standard 25mm counterweight shaft in the box, but ZWO presents no great option for a counterweight to use with this shaft. We have adapted an iOptron counterweight for use with the AM7's smaller shaft. The counterweight natively has a bore diameter of 28mm, but we have stopped it down to the necessary 25mm using a 3D printed sleeve. This sleeve is made from a very robust thermoplastic polyurethane (TPU) that will stand up to high heat, moisture, and heavy loads. It is also flexible, to increase friction on the counterweight shaft when the locking screw is engaged. It is safe to say that your counterweight is not going anywhere with the sleeve installed.

The sleeve only weighs in at 8 grams, so the added counterweight mass is negligible. A single 5kg counterweight will bring your expected payload capacity up to about 25kg. ZWO recommends a 10kg counterweight to bring the AM7's payload capacity up to the 30kg maximum, so 2 of these weights will work perfectly.

Two smaller weights also have other benefits when compared to a single 10kg weight. It makes achieving proper balance more precise, and allows for operation with smaller systems that don't need all 10kg of counterweight. Not to mention moving around 5kg is much easier than 10kg.

Of course, this counterweight can be used with 28mm shafts by simply removing the sleeve.