Nema 17 stepper on EQ1

[Armand Popa]

Hello

I have an eq1 mount unused, so I want to motorize the RA axis, to use a small refractor on sidewalks, to show people the Moon

I need some ideas how to adapt the nema 17 stepper motor to the mounnt. I will use two cogwheels and arduino. The problem is how to attach the motor

Thank you

 

 

[Cornelius Varley]

The RA drive for the Skywatcher EQ1 is attached to the side of the mount with a simple metal bracket.

https://www.firstlightoptics.com/sky-watcher-mount-accessories/ra-single-speed-motor-drive-for-eq-2.html

[JamesF]

Off the top of my head I can't recall what the area around the motor mounting looks like on an EQ1.  The aftermarket motors for my EQ3-2 only fit with a single screw to hold them in place, but there is a flat section on the side of the RA housing where the mounting bracket goes so when I wanted to fit a stepper instead I could use the shape of the housing to stop my new mounting bracket from moving about:

(Clearance over the RA clutch lever was fearsomely tight though.)

I wonder if you might have to make something that fits all the way around the RA housing for the EQ1?

James

[vlaiv]

I'd say you need shaft coupler:

Nema 17 bracket

And visit to your local hardware store that sells hinges, L brackets and all those accessories for doors, windows and such (sorry, don't know exact term in English):

in any case, I think that you'll find something suitable to mount nema bracket to mount there - or at least something that you can easily modify yourself.

 

[JamesF]

Apologies for the poor focus.  My phone clearly decided the background was more interesting than the EQ1.  This is how the aftermarket motor looks on my EQ1:

I don't really like that the motor mount is held in place by the alt axis bolt.  I suspect what I'd be tempted to do here is to get a couple of clamps (munsen rings, perhaps?) to fit around the RA body, above and below the bit that goes on the alt axis and fit a plate to them to hold the stepper motor, driving the RA worm using a belt.

Alternatively you could perhaps get away with using the alt axis bolt to hold a motor mounting plate by also using the mounting for the RA pointer to fix the plate and prevent it from rotating.

James

[Armand Popa]

thank you for the answers. I will make a combination between the options Vlaiv and James gave to me. I will come back with pictures when I will find a good way  

 

[Armand Popa]

i solved the problem like this. I will test it tomorrow 

[JamesF]

I suspect in that configuration you will find that you can't turn the RA axis sufficiently slowly and smoothly.  The EQ3-2 I pictured above has a 4:1 (if I recall correctly) step down in the belt gears to allow a reasonable stepping rate with the motor.  The EQ1 has far fewer teeth on the worm wheel, so needs to be turned more slowly.

James

Edited November 17, 2020 by JamesF

[Armand Popa]

20 hours ago, JamesF said:

you can't turn the RA axis sufficiently slowly and smoothly

I don't know yet. As the nema 17 stepper motor is controlled with Arduino, i can make it to move slow enough( hopefully) , what i am not sure is how smooth the movement will be... It must be just usable, for visual observations only at sidewalks. It has to keep the moon in the middle. Hope will do it

 

[JamesF]

That's a good point.  For visual it may well be good enough to keep the target roughly central with a small amount of drift between steps.

James