Seestar S50 EQ Mode Mount Version 1.0

Please Note: Come back here often and be sure to download the latest build instructions before printing and building your mount as I am fixing errors and omissions regularly.  Please give me your feedback so I can make this project better for everyone. 

Warning! Please read all the instructions first and if any of this seems like it is confusing please seek help from a member of your local astronomical club or society or seek help on any of the Seestar forums online. Incorrect assembly could result in damage to your expensive telescope! 

This document is a work in progress, please provide feedback on errors, omissions

Corrections and suggestions to @HandyHandcrafts on Printables.com, thanks!

Coffee contributions are much appreciated.

The real power in the Seestar S50 is resized by using it in Equatorial or EQ mode. You can have longer exposures and have less dropped frames. It tracks objects naturally as they move across the sky. The default Alt-Az mode is very simple to setup, I comes with costs to your images. That is why there have been efforts from very early in Seestar’s history to use this amazing telescope in EQ mode.

Now with this project you too can realize the advantages of EQ mode. With some modest hardware and less that 1kg of filament you to can have you own EQ observatory. 
 

I began designing this project after admiring Kia Young’s version on the Facebook group Smart Telescope Underworld. His design is innovative, ingenious, and user-friendly. I appreciate how he incorporates easily accessible parts and provides a clear understanding of the configuration. This design alleviates the stress on the S50’s bearings, resulting in a smooth and stable operation. You can purchase his version on Etsy. 

While I could have simply copied his design and stopped there, my specific requirements necessitated a unique implementation. I sought a comprehensive setup that could be placed on a level platform. Consequently, I developed this design, which you can see here. I have designed all the original parts, except for the 3030 angle brackets and the 3030 end caps.

As mentioned earlier, you must place this stand on a level surface to enable micro-adjustments for polar alignment. I utilized a piece of 19mm plywood that I had lying around, along with wooden blocks and wedges, to create a platform that is as close to level as possible, within 0.1°. Subsequently, you perform the fine leveling using the leveling feet and move the stand left and right to achieve the correct azimuth. With this setup, I can achieve an accuracy of 0.004° in both Altitude and Azimuth (Using seestar_alp polar alignment tool).

This stand should work with either Seestar_alp or. the Seestar S50 app supplied by ZWO as both have EQ mode available

If you use PLA as a printing material, only use this mount at night as it can be deformed by the heat of the sun.
 

Supplies list

1. 1x - 1 meter Extruded 3030 

2. 14x -  M4x8 or M4x10 bolts and t-nuts

3. 1x - M4x20 Bolt and nut

4. 1x - 1 meter x 16mm dowel
   Or
   1 - 36" x 5/8“ dowel

5. 1x - 3/8-16” Bolt and nut or 1.5”-38mm long 3/8” knob

6. 1x - 1/4” or 6.35mm steel rod 130mm long for hinge and 1/4” drill bit
   You may be able to use a 7mm rod and drill bit, but I don’t have availability for those so test it to see if it’ll work for you.

7. 1x - PLA or PETG

8. 1x - PTU or other Flex 

Optional but highly suggested

1 - level or electronic level  (Highly recommended) 

This is just an example others will suffice.

1 - Compass
1 - Battery
https://www.amazon.com/dp/B07FDXDB3W
1 - Short USB-C to USB-A cable
1 - Hex key to match your M4 bolts
 

3D Printed Parts List

1. 1x - S50-Platform with henge

2. 1x - 3030-platform with henge

3. 1x - S50 Spacer for hinge platform ( This raises the S50 up to clear the platform)

4. 3x - 3030 End Caps

5. 2x - 3030 Right Angle Bracket

6. 1x - Polar axis support plate

7. 1x - Polar axis support mount
   These are printed separately for and can optionally be glued together 

8. 1x - Polar axis support pivot ( 2 sizes Choose just one for 16mm or 5/8” dowel)

9. 1x - Polar axis support - bearing holder  ( 2 sizes Choose just one for 16mm or 5/8” dowel)

10. 1x - Polar axis pivot spindle

11. 3x - Adjustable Foot - 3030 Mount

12. 3x - Adjustable Foot - Foot and Post ( Print-in-place combo)

13. 3x - Adjustable Foot - Pad
    https://www.printables.com/model/1219803-adjustable-leveling-foot-for-3030-extrusion-with-f/files

14. 1x - Seestar Power Bank Holder

15. 1x - Battery Pack Wedge

Tools

1. 3mm hex key

2. Hack saw

3. Small Hammer

4. Sand paper 80 or 100 grit

5. File

Assembly

3030 Extrusion

1. Cut the 1 meter long extrusion into 2 parts a 330mm (13 inches) section and a 480mm (19 inches) section (You may want to leave it long and not cut it to lenght until you set your latitude if you are using the wooden dowel as you polar axis support). Also, make sure the angle between the S50 and the polar support are greater than 90°. This will ensure the polar support will stay connected to the S50. Try to cut the 3030 extrusions as close to 90 degrees as possible.  You can use blue tape and wrap it around the 3030 and mark with a sharpie at the cutline to use a hand hack saw. Sand or file the extrusion ends to make sure they are smooth and not ragged. 

2. Mark the short 330mm section at the midpoint and add the two right angle 3030 connectors with long ends facing each other loosely with two t-nuts and bolts on each side of the center mark where you can adjust them.

3. Start the t-nuts for the right angle side and slide the long 480mm section into them. Make sure everything is tight together and you have a good 90 degree connection between the two sections of 3030. Tighten all the bolts, on the long 3030 section first and then the ones connecting the short section.

Hinge

1. Drill out the 2 hinge parts with a 1/4” drill bit to ensure the proper fit for the steel hinge rod. 
   If you cut the rod with a hack saw make sure the file the ends to ensure it is smooth.
   Connect the two hinge parts together with the 1/4” rod and make sure the hinge moves freely, it may be stiff, but that is not a problem. You may need to move it back and forth a few times to loosen it up a bit.

2. Now mount the hinge on the short section of 3030 aligning the S50 mount hole with the grove on the long section and tighten the t-nut bolts.

Polar Axis Support

1. Assemble the polar axis support and plate and attach to the long 640mm 3030 about 200mm from the far end, and don’t tighten it completely.

2. You will want to get help to measure the rough length of the wooden dowel as this needs to be pretty accurate (longer is better as it can be trimmed more accurately later). Mount the S50 with the 3D printed washer as a spacer to get enough clearance between the telescope and the mounting plate. Have an assistant hold the S50 at your current Latitude.  (use online resources to get your local Latitude if you do not know it) so you can measure between the bearing holder and the pivot, Add and extra 10mm (3/8”) to the length. You want it to be slightly longer than you need. You will be tuning it later to get the precise angle of your Latitude. 

3. Now attach the polar support pivot to your wooden dowel. Please note if the rod is to big you may have to sand it a bit or if it is to small you may have to use a gap filling wood epoxy to secure it. You can always drill a small hole and put a wood screw to secure it as well, bit it needs to be a secure fit. Insert the spherical bearing into the polar axis bearing support holder. It should be a tight fit and you may have to use a block of wood and a hammer to tap it into place. Do not use excessive force as it may damage the bearing. 

4. Now do the same with the polar axis Trunion Bearing Set. 

5. Position the Polar axis base-plate at the opposite end from the hinge of the long 3030 leaving 5mm clearance for the endcap.

6. Secure the polar axis support to the mounting plate with a M4 12 bolt and nut.

7. Put the endcap on all 3 ends.

Adjustable Feet

1. Attach the 3030-Mount with screw to the underside of all 3 ends of the extrusion with M4 bolts and t-nuts and tighten

2. Screw on the Foot and Post. You will probably need to work these parts together a few times to get them wot work smoothly. If they are too tight you may have to reprint the 3030-Mount at 99% to get it to work. They are designed with tight tolerances and it needs to be a really smooth action on the screw to work as intended.

3. Attach the PTU pads to the feet using rubber cement or even double-sided tape

Usage

Calibration

1. With the platform on a level surface, level both the short and the long 3030 extrusions with the adjustable feet. Make sure to get them to 0.00º. This will ensure the next step is as accurate as possible. 

2. Install your Seestar S50 on the stand and make sure the power button is facing up. 

3. Set your latitude angle by adjusting the polar support mount forward or backward and once you have the correct angle tighten both the bolts. For example, If your latitude is 45.41º, ensure your electronic angle finder reads 45.41º, with the bottom of the angle finder on a flat side with the power button.

4. Make sure to tighten all the screws to fix everything in place.

Platform Setup

1. This stand works best while sitting on a level platform. Place the S50 installed on the stand on the platform.

2. Use either Seestar_alp or the Seestar App to polar align your telescope. Fine adjustments in azimuth can be made by moving the north pointing end East or West in small motions. You can adjust altitude by adjusting the east and west pointing adjustable feet. Hold the fool stationary and slowly turn the feet to move up or down. Only adjust one foot at a time. Remember small adjustments are your friend. 

3. If you use a dew shield please monitor the telescope while slewing to new objects to make sure it doesn’t get caught on the polar axis support.

4.  

After you get everything setup, Enjoy!

Resources

Seestar_alp - Community created application for Seestar S50

Facebook - Smart Telescope Underworld
Github
FAQ
Discord

Seestar App - Official Seestar Application for Seestar S50

Zwo Seestar Website
Seestar S50 Sales Website
Manual 
Support
ZWO Seestar Facebook Group 
Official ZWO Seestar user forum
 

https://youtu.be/2hy1_b2iQ-c

Change Log:

2025-04-13

• Added warning to use PLA constructed mount only at night.

2025-04-10

• Added note to make sure angle between polar support and S50 is greater than 90° 

2025-04-03  

• Updated the length of the long extrusion from 460mm to 480mm to allow for the adjustment of the polar axis support if using the fixed length dowel 

• Added washer for hinge platform to elevate the S50 to clear the platform. 

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