stepper motor controller suggestion

[iwols]

hi just thinking about making a focus controller for my c8 edge but dont know where to start,can anyone suggest a motor /controller that maybe usb controlled

Edited June 23, 2018 by iwols

[Dr_Ju_ju]

Search for TechyDave's build here or there are a few on Sourceforge e.g. https://sourceforge.net/projects/arduinoascomfocuserpro2diy/?source=directory

I usually find the most difficult part is making brackets to attach the motors to the focuser, the electronics, for me, are the easy part.

[Gina]

Yes indeed.  I have made several remote controlled focusers with both Arduino Nano and Raspberry Pi and stepper motors.  I use 3D printed brackets designed to suit.

[iwols]

4 hours ago, Gina said:

Yes indeed.  I have made several remote controlled focusers with both Arduino Nano and Raspberry Pi and stepper motors.  I use 3D printed brackets designed to suit.

Thanks do you recomend Any inparticlar as Thérè seems to be loads especially on ebay cheers

[Gina]

Do you mean stepper motors?

[iwols]

Yes gina and ide need something to contrôle it with as Well thanks

[Davey-T]

As mentioned by Julian have a look at Tekky Daves thread, it tells you all you need to know.

https://stargazerslounge.com/topic/218975-arduino-ascom-focuser-mark2/

Dave

[Gina]

Yes, Dave's is a good one.  Has the advantage of working with the most popular software.

[Dr_Ju_ju]

I know Gina likes these https://www.ebay.co.uk/itm/5V-Stepper-Motor-with-ULN2003-Driver-Motor-Driver-Controller-Board-UK-Seller-New/191457771129?hash=item2c93c5be79:g:xnYAAOxy4eJTMYiA

but I prefer Nema 17's e.g. https://www.ebay.co.uk/itm/Nema-17-Stepper-Geared-Motor-27-1-Planetary-Gearbox-0-4A-CNC-Robot-3D-Printer/122598500009?epid=1044827377&hash=item1c8b70a6a9:g:WD8AAOSwf~9ZaIoa

 

[sloz1664]

You could also try Robert Brown's DIY focus controllers:-

https://sourceforge.net/projects/arduinoascomfocuserpro2diy/

Steve

 

[Gina]

The 28BYJ-48 gearbox stepper motors are small and very cheap but suited to light duty only.  Generally speaking focusers don't need much power.  However, my newer focuser drivers have used Nema type steppers plus A4988 driver modules and Raspberry Pi as I now use these for remote controlled astro imaging so everything in one unit saving a PC in the observatory.  But they use the Linux INDI drivers (RPi uses Linux) and my indoor computer uses KStars/Ekos on a Linux Mint machine and many are unwilling to go the Linux route.

[stash_old]

1. Another Robert Brown Focuser supporter - but if you want to use std bits use either the A4988 or drv8825 (same as A4988). or lot bigger footprint but will handle ANY current/voltage use a single axis TB6600 driver board - used one for 3 yrs without a blink and using any Nema 8 - 42 even with high torque geabox. As I say the size is the problem with the TB6600 but needs no soldering or fiddling current/voltage measurements as per A4988/DVR8825.

  Roberts support is brilliant !

2. If you do your own via Arduino IDE please use Accel library - makes thing easy and supports every driver there is. A professional bit of software with many key features not found in Roberts or Dave's projects (IMHO).

3. Nano is stuck with USB/Serial connection without add ons - look at ESP32 which has Wifi therefore no need for any addons or USB/Serial. Best for accuracy is Teensy as its MHZ rate is far greater than Nano but are more expensive !

4. Steer clear of 5v or 12v 28byj - they are useless and cannot be counted on for accuracy especially with high torque micro stepping.

5. As someone else has pointed out OMC-Online (use there own site it is sometimes cheaper than Ebay) have great Stepper motors and a vast range. Just have to hit the site/ebay when they are trying to get rid of a range/stock. Excellent delivery - for me anyway.

6. Ascom supplied driver(Dave and Robert provide this) is probably the best but I have found a lot of problems mainly with the Camera software provider side

To be honest if you can use a RPI for something else as well as a focuser then go RPI as you can one of the 4 ports(1 on RPI zero W) and it works great - look up SER2NET and HWCONFIG virtual com if you want Windows support and still use RPI. I have run SW Mount and Focuser thru RPI from Windows Vista - 10 with no problems and you dont get driver problems on Linux (well nearly never with USB/Serial HW)

Have a great build !

 

[Dave_D]

haven't had any issues using a 28BYJ-48 12v but my camera isn't that heavy being a modified dSLR, my focuser easily lifts the camera vertically, and yeah daves focuser code works perfectly over bluetooth

 

[fozzybear]

3 hours ago, stash_old said:

1. Another Robert Brown Focuser supporter - but if you want to use std bits use either the A4988 or drv8825 (same as A4988). or lot bigger footprint but will handle ANY current/voltage use a single axis TB6600 driver board - used one for 3 yrs without a blink and using any Nema 8 - 42 even with high torque geabox. As I say the size is the problem with the TB6600 but needs no soldering or fiddling current/voltage measurements as per A4988/DVR8825.

  Roberts support is brilliant !

2. If you do your own via Arduino IDE please use Accel library - makes thing easy and supports every driver there is. A professional bit of software with many key features not found in Roberts or Dave's projects (IMHO).

3. Nano is stuck with USB/Serial connection without add ons - look at ESP32 which has Wifi therefore no need for any addons or USB/Serial. Best for accuracy is Teensy as its MHZ rate is far greater than Nano but are more expensive !

4. Steer clear of 5v or 12v 28byj - they are useless and cannot be counted on for accuracy especially with high torque micro stepping.

5. As someone else has pointed out OMC-Online (use there own site it is sometimes cheaper than Ebay) have great Stepper motors and a vast range. Just have to hit the site/ebay when they are trying to get rid of a range/stock. Excellent delivery - for me anyway.

6. Ascom supplied driver(Dave and Robert provide this) is probably the best but I have found a lot of problems mainly with the Camera software provider side

To be honest if you can use a RPI for something else as well as a focuser then go RPI as you can one of the 4 ports(1 on RPI zero W) and it works great - look up SER2NET and HWCONFIG virtual com if you want Windows support and still use RPI. I have run SW Mount and Focuser thru RPI from Windows Vista - 10 with no problems and you dont get driver problems on Linux (well nearly never with USB/Serial HW)

Have a great build !

 

+1 for Roberts design any problems and he is on the ball to help out.

[wimvb]

14 hours ago, Dr_Ju_ju said:

I usually find the most difficult part is making brackets to attach the motors to the focuser, the electronics, for me, are the easy part.

Same here. I used a sw dc motor focuser for my electronic focuser sollution. I had to write a piece of arduino to make it compatible to the Moonlite protocol. The electronics and software may be the easier parts if you don't have a metal workshop.

The dc motor sollution has a lot of backlash, and I want to redo it with a stepper motor. Getting the motor in place is the biggest challenge.

[sloz1664]

Here are the three Robert Brown Focusers I have built. Each having their own Ascom driver. FocuserAscom1, FocuserAscom2 & FocuserAscomPro.

Steve

[stash_old]

IMHO -  I also suggest direct drive - no belts . Using a coupler like this https://www.ebay.co.uk/itm/Aluminum-Alloy-Drive-Flexible-Shaft-Coupler-Motor-Connector-3-5mm-Red-/122630560672?clk_rvr to replace the "wheel" if it comes off easily. Limits backlash and gives you a simple 1:1 ratio plus simpler bracket.

1 hour ago, Dave_D said:

28BYJ-48 12v

Probably get away with it on a focuser but where you need repetitive accurate positioning,e.g. Filer Wheel, they are very poor and do a skip every now and then in my experience no matter what driver/step count/voltage/current is being used. Plus they get very hot when pushed to the limit and switching off,via software, the coils is a must. As Gina says "light duty" only.

But if it works for you then great !

Edited June 24, 2018 by stash_old

[Horwig]

4 hours ago, stash_old said:

5. As someone else has pointed out OMC-Online (use there own site it is sometimes cheaper than Ebay) have great Stepper motors and a vast range. Just have to hit the site/ebay when they are trying to get rid of a range/stock. Excellent delivery - for me anyway.

Another vote for OMC (https://www.omc-stepperonline.com). have used them many times, really good firm to deal with. they hold stock in Europe as well, so long delivery times are not  a problem.

Huw

[stash_old]

Just now, Horwig said:

so long delivery times are not  a problem

Well not always true but they do mark if the stock is held in the UK which is great - so check first even if the stock level looks ok - Once "ran out" of UK stock even though it reported 10+ they answer very promptly.

[sloz1664]

Purchased all my Nema steppers from OMC. Great company to deal with.

Steve

[Horwig]

21 minutes ago, stash_old said:

Well not always true but they do mark if the stock is held in the UK which is great

I got a motor from Germany next working day, what's not to like?

[saac]

Must be a British supplier surely?

Jim 

[stash_old]

3 hours ago, saac said:

Must be a British supplier surely?

Jim 

Sorry Chinese as far as i am aware

[iwols]

wow do these units come prebuilt (pcb wise)

Edited June 25, 2018 by iwols

[NickK]

15 hours ago, stash_old said:

 drv8825 (same as A4988)

 

Careful - the drv8825 will take more voltage, less current. I use a 3.8V 650mA stepper with 100:1 gearbox but use a 12V supply. Set correctly the 8825 chops the current automatically so you get no heat in the stepper and the 12V step overcomes back EMF.