Focusser I do NOT want a permanent mod to my scope

[Ukastronomer]

I am getting there

I do NOT want a permanent mod to my scope for remote focus therefore I am adding the old focusser from Skywatcher, see attached images, what I need now is a NON stretch solution to join the motor to the focusser.

Just to check it works I have made and tried a belt and it is fine, now I need to add either cogs or a non slip belt, any ideas,

Thanks

[xelasnave]

I reached a similar point and thought to use a wet suit type material...which is about an eighth of an inch thick and you can but and glue ends with contact cement...I dont know if it will work but that was the solution I had in mind. The glue holds ...that much I have tested by making a couple of belts but I have not found a suitable method to attach the motor which is the same as yours...I am trying to place a motor on my espirt 80mm.
Alex

[Ukastronomer]

Thanks that gave me the idea A Mouse Mat :)

[xelasnave]

Yes its just like that in fact I made a mouse mat from it...it is also good to make small dew covers for camera lens.
Alex

[JA]

Hello J,

You could try one or two wide elastic rubber bands or a silicone wrist band (of the type often used for advertising or to represent various causes) ....

Best
JA

[xelasnave]

Hi Jeremy
Please let us know how it goes.
Also maybe run the belt to the large focuser knob as it should have more purchase.
I am thinking there may be slippage and ways to overcome such an issue..glueing wet and dry paper around the knobs is all I can think of...
But it would be so good to know how it goes for you.
I cant work out a satisfactory way to attact the motor yet so I like your approach.
Alex

[Sunfish]

If it is a no-stretch belt you require, a urethane belt reiniforced with wire is available for a few dollars down to a length of 110mm from cnc / 3d printer suppliers on line in various widths and lengths. Many good suppliers in the UK.

Some have shallow teeth to engage with a toothed pulley which you can also buy for a few dollars but I think they would also work on a smoothish surface.

[Imme]

I was looking at pulley/belt driven in the one I set up but found too many issues with slop, slip and backlash to allow it to be useful. Direct drive is the way to go. Simply take the focuser knob off and install directly to focuser spindle via a flex coupling (cheap on ebay).
Will solve all your issues and also solve some issues you don't even know you're going to experience yet if you go down the belt driven road.

[Imme]

.....actually looks like you may already have a flex coupling on that motor????

Just modify that bolt on motor mount to suit fixing it to the spindle and you're good to go

[xelasnave]

Well I had a go at installing the motor and with belt drive as a starter but could change to gears somehow which will probable be necessary.
I attached one scope ring from an old 80mm scope around the mount similar to the op approach and at this stage just rapped the mount with cheap yoga mat which may or may not be enough.
The belts have been made and glued but I am giving them a bit of time for the glue to settle in...I am working on the assumption the focuser is only going to move a couple of millimeters once focused manually...the motor only have to adjust between filter changes ..not running the focuser all the way in or out approach.
Here it is so far. Photos coming soon.

Alex

[Ukastronomer]

I will look at them thanks, I mean that

[Ukastronomer]

I have tried (and run out, more ordered) believe it or not Bicycle tyre repair, large, it is VERY not tacky but you know what I mean on the side that meets the tyre, will do the other side when the repair patch comes Tuesday

I always keep things I think may be useful and this laminate of expanded foam is very strong and hard, the black knob on the motor is a spare from a scope focusser


https://www.amazon.co.uk/gp/product/B0063HIOFM/ref=ppx_yo_dt_b_asin_title_o00_s00? ie=UTF8&psc=1

[raymo]

Being as there is no inbuilt clutch system on the SW motor focuser, so that the focuser can't be operated manually, you need to remove the single speed
focuser knob/wheel, and connect the motor directly to the shaft via the
flexible connector shown in your pic [ as posted by Imme], and modify the bracket to support the motor.[ The original kit comes with the necessary bracket]. You need the motor on the single speed side because if you
connect to the geared down side, even on max speed the focuser will move
glacially. On the single speed side the motor on its slowest speed will allow
little taps on the button to give miniscule movement for fine focusing purposes.
Its not a permanent mod because you can convert it back to its original set up in 5 minutes.
raymo

[Ukastronomer]

Thanks for the advice, appreciated, but as I will only be using it for Ha, and will have pre focused I am happy with slow, and as the skywatcher has fast/slow it is more than adequate, thanks again for your help.

[xelasnave]

The belt works by the eye but I added "tracks" or strips of material ...but strange a hair tie works made in a figure 8.
I dont know how these will work in the field but at least its turning☺
Got contact cement everywhere.
Alex

[xelasnave]

Thinking of making a large primary wheel to slow the gearing.
Alex

[xelasnave]

No one noticed ..you need to make the primary smaller and the secondary larger to slow it down.
Anyways field test was great...I open the focuser to a set spot which is close then added the belt put on the mask and it was only a few revolutions to get great focus..the rubber has an effect of dragging it back a little which really helped..all good but had other issues and got nothing tonight except a test on some stars choosen because they were above me.
Alex

[Ukastronomer]

Thank you ALL

A combo of advice led to this

When you correctly align the two parts there is no belt movement it stays level and comes off in a second, the unit can stay on the scope

https://youtu.be/T3loXMvInGI

[Ukastronomer]

Nothing I can do about the blasted neighbours though

[Merlin66]

Sounds like you may have found your solution....

I use the SW motors on all my solar imaging scopes..
Fitted with a toothed pinion and timing belt which just runs on the 10:1 focus knob. Very precise control, no issues, no drama.

[ChrisV]

Isn't it dangerous driving the 10:1 focuser knob rather than the main one. I've read that you can damage the gears - at least with stepper motors?

[Merlin66]

Chris,
Don't know where you heard that....I've never come across any evidence.

I've been using the belt drive on all my gear for ten years.....
Nothing has gone wrong with the 10:1 gear drive.
As I said, no issues no drama.

[xelasnave]

You are lucky in Sydney I am in one of those nice treed suburbs and get maybe 20 minutes to capture.

Nice movie I left a comment...when will youtube send you a cheque☺
I am going to pull down a remote vacuum cleaner that is a pain cause you spend si much time cleaning it and see what belts and gears it gives up.
I ran my set up and the fact is you dont need to move things much at all.
And thanks for starting this thread as you got me motivated and now I have an electric focuser on my80mm.
Alex

[xelasnave]

No worries if it breaks they meed to up their game☺
I cant see why there would be a problem do you have anything that offers a reason why there could be a problem.
Alex

[JimsShed]

Jeremy, what Ken said. I’ve done the same and for me it’s a perfect solution on my Esprit. When I want to manually focus at the scope I can easily slip the belt off. Search for GT2 Closed Loop belts on eBay.

[Ukastronomer]

Again many thanks and much appreciation to all of you

[Ukastronomer]

I am NOT good at describing things so I have attached images, the FINAL belt used to drive the focusser from the Skywatcher unit

http://www.opticalvision.co.uk/astronomical_accessories-focusers/skywatcher_auto-focuser.html

attached to the actuall scope focusser via home made (as I couldn't find one the right size) belt, from a cut down vacuum cleaner belt

https://www.amazon.co.uk/gp/product/B006O02ZTO/ref=oh_aui_search_asin_title?ie=UTF 8&psc=1

and shaped cycle inner tube repair kit

[Ukastronomer]

https://youtu.be/o7VXcG6hmFA

Again thanks to everyone for their help, the wristbands gave me the final idea JA but all were MOST helpful

[Ukastronomer]

I am making a modification to the 120Esprit brackets to take the Skywatcher focusser (electric)

https://www.rothervalleyoptics.co.uk/skywatcher-auto-focuser.html

What I forgot to say was a warning.

I can't remember what forum he was on but a chap complained most annoyed that Vixen were a bad company" because they did not say that the screw holes in their tube rings went "all the way through" ????

Personally I have not found any that do not ?, so that people can mod/add components if needed, but no matter what people told him, he was adamant that because his scope was damaged due to using long bolts that he just kept screwing until tight, it was Vixens fault.

REMEMBER to measure depths of anything that relates to work being done where damage can happen.