Mounting ZWO EAF to SW 72ED

[Mr Thingy]

SOLUTION BELOW, FOR REFERENCE.

I'm trying to attach a ZWO EAF to my SkyWatcher 72ED but I can't figure out which holes the mounting screws should use.

Perhaps someone with this setup could advise? On the plate of the focuser housing there are 6 hex screws, which I assume hold the focuser in place - see pic below. Then there are 2 grub screws (with a weird size that none of my hex kits fit). Lastly is the focusing lock (which I assume needs to be removed). 

Also what size screws did you use? SW seem to use some weird sizes...

TIA

-Thingy-

Edited January 24, 2021 by Mr Thingy

[Geordie mc]

I don’t have this scope, but I believe the top left/right and bottom l/r are the screws that fix the the focuser of the scope, so I’d use the bottom l/r and remove the focus lock knob that’s center right. The screws are M3 and I think 8mm so you’d need M3 screws that are long enough to go through the ZWO’s plate and still have enough reach to thread firmly down. I can’t remember what length the ones in the kit are. Pop one of the originals out at a time and put in the ZWO screw before removing the second one just to keep everything lined up although it shouldn’t move. There are some pictures on the ZWO compatibility chart that show the 72ED but they aren’t very clear what’s being used. If the ZWO are too long you can just add a washer or 2. If too short then it’s easy to get longer ones online. Good luck. The EAF has worked really well for me. I’m thinking a of getting second one when funds allow.

[Mr Thingy]

9 hours ago, Geordie mc said:

I don’t have this scope, but I believe the top left/right and bottom l/r are the screws that fix the the focuser of the scope, so I’d use the bottom l/r and remove the focus lock knob that’s center right. The screws are M3 and I think 8mm so you’d need M3 screws that are long enough to go through the ZWO’s plate and still have enough reach to thread firmly down. I can’t remember what length the ones in the kit are. Pop one of the originals out at a time and put in the ZWO screw before removing the second one just to keep everything lined up although it shouldn’t move. There are some pictures on the ZWO compatibility chart that show the 72ED but they aren’t very clear what’s being used. If the ZWO are too long you can just add a washer or 2. If too short then it’s easy to get longer ones online. Good luck. The EAF has worked really well for me. I’m thinking a of getting second one when funds allow.

Thanks. I think you're probably right. I'll start there and see if that works.

I was contemplating drilling some new threads into it, but I'll hold that in reserve in case other options don't work. 

I'll post whatever solution I find for future reference (unless I bodge it, in which case I'll pretend this never happened 😳).

[Mr Thingy]

I took a screw out and they seem to be M2. I've ordered a pack of various lengths so hopefully one size will fit.

[Mr Thingy]

On 15/01/2021 at 22:14, Geordie mc said:

The screws are M3 and I think 8mm so you’d need M3 screws that are long enough to go through the ZWO’s plate and still have enough reach to thread firmly down. I can’t remember what length the ones in the kit are. 

You are correct; they are M3.

I bought a selection of lengths and will figure out which ones work best. 

(I also bought some M2, which clearly don't fit, but at least I now have some replacement screws for the 2 I lost recently when doing a RAM upgrade on my lappy 😁)

[Geordie mc]

Sounds promising. Sure you’ll be enjoying using the EAF soon presuming the weather improves. 

[Mr Thingy]

On 21/01/2021 at 22:49, Geordie mc said:

Sounds promising. Sure you’ll be enjoying using the EAF soon presuming the weather improves. 

All sorted. Thanks for your help.

Some detail below for future reference.

I attached via the 4 screws that hold the focuser in place. M3 screws, 14mm long.

I needed to drill 2 extra holes in the mounting plate to access all 4 screw holes.

All set up and working nicely. Now I just need a srarry night so I can set up the focusing routine.

[gaz81]

Nice kit 🙂