Fettled motor focus for steeltrack

[Nigella Bryant]

Hi all, I've just added a baader steeltrack focuser for my C11 and fettled on an electronic focuser based on a spare skywatcher electric focus motor. Works a treat for the cost of a few parts (£20). Similar off the shelf items are around £200. Not bad for an hours fettling, lol. Very similar to the TS off the shelf item.

The slow motion is slow but course focus is done via the main C11 focus knob and fine focus now via the computer. 

[Dr_Ju_ju]

It's good to make use of parts you already have....   

One thing I found with my similar mods, is that hooking the motor up to the 'slo-mo' wheel meant that it took ages to reach focus, and if using some of the auto-focus tools meant failure as it wasn't able to reach/go-through focus quickly enough....

[Nigella Bryant]

44 minutes ago, Dr_Ju_ju said:

It's good to make use of parts you already have....   

One thing I found with my similar mods, is that hooking the motor up to the 'slo-mo' wheel meant that it took ages to reach focus, and if using some of the auto-focus tools meant failure as it wasn't able to reach/go-through focus quickly enough....

I was wondering whether to put a large cog on the motor which I already have to get a bigger ratio. 

[Dr_Ju_ju]

As an initial test, and if possible, just reverse the motor, to hook up with the other end, but you may then have an issue with the belt properly mating with the wheel.  Just have a play & see what works !!

I did what you suggest, in replacing the single 'Knob', with a pulley wheel, on an old ST80, I use for Astro e.g.

 

 

 

Edited July 10, 2023 by Dr_Ju_ju

[Nigella Bryant]

2 hours ago, Dr_Ju_ju said:

As an initial test, and if possible, just reverse the motor, to hook up with the other end, but you may then have an issue with the belt properly mating with the wheel.  Just have a play & see what works !!

I did what you suggest, in replacing the single 'Knob', with a pulley wheel, on an old ST80, I use for Astro e.g.

 

 

 

Yeah, I'll try the larger wheel on the other side to see if that works better and the course focus. 

[Nigella Bryant]

Second iteration, working better on the course adjustment. 

[windjammer]

I used an old servo and a direct gear coupling - probably not more than 1.25:1 ratio.  No problem with getting bored while focussing - even though the servo will only manage a couple of turns per second.

Simon

 

 

[runoffshed]

Looks excellent, Nigella.

Can you tell me please if you had to sleeve / adjust the pulleys or rods or were they a good fit to start with?

( I want to do exactly this on a newly acquired OVL and wondered if a lot of these focuser rods were a standard diameter)

Many thanks

John

[Nigella Bryant]

3 hours ago, runoffshed said:

Looks excellent, Nigella.

Can you tell me please if you had to sleeve / adjust the pulleys or rods or were they a good fit to start with?

( I want to do exactly this on a newly acquired OVL and wondered if a lot of these focuser rods were a standard diameter)

Many thanks

John

Hiya John, I had to drill a larger hole in one of the pullies as the steeltrack has quite a large rod. I've a drill press so easy for me to do. Not sure if you can buy pullies with larger or smaller bore diameter.  It's the only thing I had to do plus making the bracket.  My experience is that each focuser is different bore/rod size.

I've fettled a number of focuser's using the skywatcher motor focuser. Some with direct coupling. Just did one for my TS 70ed focuser too. 

Hope that helps. 

[CedricTheBrave]

I 3d printed some dovetail clamps to fit onto the steeltrack and a box to house the motor and controller