Home > Uncategorized > How to install a ZWO EAF on the William Optics Star71

How to install a ZWO EAF on the William Optics Star71

I bought an EAF and found that that installing it on my WO Star71 was less than straightforward, so I’m posting this tutorial to help others in this situation. It’s quite doable, and a quick trip to the hardware store can make it even better.

  1. Removing the course focuser knob (the one with the thermometer) is tricky because the screws to loosen it are actually under another screw.  Remove the grub screw (it’s just to cover the hole) closest to the knob.  Here, I’ve set it next to the hole so you can see it, but you’ll want to put it away in a little bag somewhere in case you ever take the EAF off.  Look through the hole and turn the knob until you see one of the two screws that holds it on.  For both these tasks, the provided 2.5 mm Allen wrench is fine.Step1
  2. Here you can see the knob removed, showing the two screws that hold it on.  They are about 90 degrees apart.  Step2
  3. Get one of the provided grub screws.Step3
  4. Screw it into the flexible coupling.  For the Star71, you need the second largest of the four couplings provided.Step4
  5. It needs to be almost flush in order to fit it into the hole where the knob was.Step5
  6. This is where the coupler is going.  The grub screw will need to tighten on the flat part.Step6
  7. Turn the focuser so the grub screw is aligned with the hole and put the Allen wrench through the hole to tighten it.Step7
  8. Get another grub screw and use it to attach the EAF to the coupling.  It’s not shown here, but you can’t put the coupling all the way into the EAF because the shaft is not flattened across its whole length.  The point shown here is about right.Step8
  9. Attach the bracket using one of the provided M4 screws to the second from left screw hole on the focuser.  You’ll need to take off the focus lock screw, but since it’s a little longer, you can actually use it on the far right side.  Use two more of the provided M4 screws to attach the bracket to the EAF.  Here is my initial setup, using only parts from the kit.  Step9
  10. I put two washers under the left side so the bracket wasn’t at so much of an angle.  I would have used three washers, but the screw provided isn’t long enough.  It’s not perfect, but it works.  You can see why the bracket won’t sit flush with this WO focuser.Step10
  11. MINOR IMPROVEMENT:  I didn’t love the slight angle of the bracket, so I went to the hardware store and bought an M4 screw that is 10 mm long (the ones provided are 8 mm) and a 1/4″ nylon spacer.  For a total cost of $1.18, this really improved things.  Much better.Final improved setup

So there you have it.  It is possible to install the EAF on a William Optics Star71 using the provided parts, though a little less than ideal.  With a very cheap addition of a longer screw and spacer, it can be improved.

Categories: Uncategorized
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: