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Converting a Celestron CGE mount #CGE #CELESTRON #CGE Mount #cge #celestron


Frederic Cuccarolo
 

I don't know where to start. I am not an expert at electronics and only a computer technician but I could be a quick learner for DIY conversion. I would appreciate if someone that has successfully converted their Celestron CGE mount make a detailed list of all the electronic components, motors and parts needed for the conversion. Furthermore, if there is any programming involved and where I could find sources with links. Moreover, if possible tell me what to look for and the pitfalls during and after the conversion that could happen and how to find a solution. I know it's a lot to ask but it would save me lot of time trying to find the appropriate components and possibly avoid making mistakes. Also, I would focus more on putting it all together and enjoy doing the conversion. Thanks.


Dennis Hurlbut
 

Start here, there are a few CGEs on the page and you can see what others have done.: 

https://onstep.groups.io/g/main/wiki/Showcase%3A-What-Users-Built-With-OnStep

Also, read through the construction section of the wiki, thoroughly. I got bit by having a long interruption in my work, and wiki items had changed that I missed, so stay up-to-date with what's been going on. There are 5 pre-designed versions in the wiki, some of which are being sold by community members as kits.

Buy good quality components. If the wiki says somewhere that x brand and model will work the best, it's always right. If you aren't sure on an item you're going to purchase, ask here first.

I'm a learner on this as well and don't have a successful build yet, but feel I am close. It's definitely a challenging project.


fetoma
 

Not that easy. Machining would usually be involved. You need a big pulley to fit on the worm shaft to get the gear ratio to about 3:1 minimum. The only way around that is to use a planetary gearbox like this→ https://www.omc-stepperonline.com/precision-planetary-gearbox/nema-17-stepper-motor-l39mm-gear-raio-51-high-precision-planetary-gearbox-17hs15-1684s-hg5.html

You'll need to do some searching and reading here and there are kits you can buy and assemble.


Khalid Baheyeldin
 

On Sat, Mar 28, 2020 at 10:52 PM, fetoma wrote:
Not that easy. Machining would usually be involved. You need a big pulley to fit on the worm shaft to get the gear ratio to about 3:1 minimum. The only way around that is to use a planetary gearbox

Machining is not inevitable.

There is Marko H's conversion using geared motors, and 1:1 pulleys.
The results are just stunning.

See the thread I linked to, and the videos linked from there.

Ask whatever questions you have, but read the Wiki first (yes, it is like drinking from a firehose).


Jay Murphy
 

All I bought was the bluepill kit from (now) George Cushing. Two 400 step nema17 motors. Pulleys. Belts. And two s109 stepper drivers. You'll need to do a bunch of homework first. Like Khalid mentioned, you can use a stepper motor with a gearbox on it so you don't have to machine near the worm for a bigger pully. You'll want at least a 3:1 reduction between the motor and worm. So if you could find a stepper with a high precision 5:1 box on it you could go 1:1 between that and the worm and still even use your home position switches. You may want to look into a different board than the bluepill because I feel it's a bit limited, feature wise. But it's cheap. It's also a great idea to tear it the rest of the way down and clean/lubricate everything and replace the bearings in the worm block with high performance bearings because the stock bearings are terrible. You can email me directly if you want to pester me with questions. I've got a lot of thoughts on the CGE conversion and some things I should've done differently.


Khalid Baheyeldin
 

On Mon, Mar 30, 2020 at 05:19 PM, Aisling Lightworks wrote:
All I bought was the bluepill kit from (now) George Cushing. Two 400 step nema17 motors. Pulleys. Belts. And two s109 stepper drivers. You'll need to do a bunch of homework first. Like Khalid mentioned, you can use a stepper motor with a gearbox on it so you don't have to machine near the worm for a bigger pully. You'll want at least a 3:1 reduction between the motor and worm. So if you could find a stepper with a high precision 5:1 box on it
I would go with a 15:1 motor for finer stepping that is not too high yet to impact slewing speed.

For example, this motor, which should have enough torque, and low resistance.

Your spreadsheet (link on the Construction page) will look like this:

200 steps per rotation, 1/16 microstep, 15:1 gearbox, 180:1 wormwheel = 24,000 steps per degree.
Slewing speeds of 3 deg/sec should not be a problem.

You need to check the length of the motor to make sure it would fit inside the housing.

On the same page, there are also link to sites that will tell you how long of a belt you need.

you could go 1:1 between that and the worm
Yes. Hopefully that should fit the housing without machining.

and still even use your home position switches. You may want to look into a different board than the bluepill because I feel it's a bit limited, feature wise. But it's cheap.
The Blue Pill does not have built-in heaters, or a second focuser. But that did not prove to be much of an obstacle for the vast majority of users.


Frederic Cuccarolo
 

Thanks for all the replies. It will give me a starting point for when I will convert my mount.