Sky Scan 2001/EQ3-2 AstroEQ conversion teaser

[JamesF]

I shall write this up properly when I have time to sit down and think through everything, but as I've just finished assembling it all I thought I'd post a teaser shot of the AstroEQ conversion I've done for my aging Sky Scan 2001 mount.  Previously I had the standard EQ3-2 motor kit fitted, but the handsets for these don't have the greatest reputation for reliability and I wanted some degree of protection from mine dying on me.  Obviously the AstroEQ unit also gives me GOTO which the standard handset doesn't have.  Because I've never really been happy with the hideous amount of backlash in the gearboxes on the standard Skywatcher motor units either, I also went for a set of replacement motors with belt drive.  I know this mount will carry my 127 Mak or the PST quite happily and those are the scopes I tend to take on holiday, so hopefully this will make an acceptable holiday rig.

I could have sold this mount and bought an EQ3-2 Pro GOTO, but I reckon that would probably have balanced out at costing me about half as much again, there would still be gears in the drive to the worm and I don't think I'd get control from a PC without having to have the handset in the way.  And I just fancied doing it this way anyhow

Anyway, here's how it looks now it's all assembled:

Now I just have to get the software installed and test it

James

[igorb]

Hello James!

First of all, congrats on your nice work! I'm trying to upgrade my EQ3-2 mount pretty much the same way as you did. But I have a problem with RA axis where I'm using pulley with 60 teeth. If I mount the pulleys and the motor as you did, at some point large pulley is clashing with the clutch handle. When I turn the mount around RA axis without pulley, I notice that there is very little space so I don't think smaller pulley would suit either. Did you encounter the same problem?

Thanks in advance,

Igor

[Horwig]

Nice one James, I've been looking at the same setup for my old eq-5. Can I ask about arc seconds per step on the motors, I assume you are using micro stepping to give fine enough control.

 

Ta

 

Huw

[igorb]

Maybe I can answer your question. AstroEQ mod can use two stepper driver models A4988 with max 1/16 microstepping or DRV8825 with 1/32 microstepping. EQ3 mount has 1:130 RA worm ratio and by using 200 step/rev motors you get 3.12 arcsec/step (16 microsteps) or double the precision with 32 microsteps. Final resolution depends on belt drive ratio which is in my case 1:4. Hope that helps.

[Horwig]

Thanks Igor, just the info I was after.

 

Huw

[JamesF]

I don't recall that I had problems with the pulley fouling the clutch lever, but that may just have been good fortune because I assembled it a particular way or something like that.  I'll try to dig the mount out (I've not used it for a while) and have a look, but that may be a little while I'm afraid.  I'm struggling with an exceptionally nasty cold virus at the moment.

James

[igorb]

No hurry! Get better first.