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StepperBee based focuser


james_screech

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Focusing manually can be a problem when imaging as the location of my laptop is not always close enough to reach the focuser while looking at the screen. Also touching the telescope can make the image jump all over the place. A stepper motor seemed like the best idea but how to control it and how to mount it?

 There were three options for control, a standalone box of electronics, a computer (USB) interface or both. As my electronics skills are a bit limited I settled on a computer controller. An internet  search came up with the StepperBee controller and this was available with a suitable stepper motor as a kit.

(https://www.pc-control.co.uk/ocart/index.php?route=product/product&path=59&product_id=134)

This was a geared motor with 2048 steps per revolution.

As for mounting the motor on a C8 SCT that was a bit more of a problem. The telescope has three small screws around the base of the focuser control that could be used to hold a bracket. To connect the output shaft of the motor to the focuser I decided on a friction drive as the focuser was too big for a belt drive pulley.

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A few quick calculations showed that this configuration would move the main mirror about 1 micron per step of the motor, as the mirror if F2 it’s critical focus range is about 12 microns. So the system was more than accurate enough for the perpose.

The StepperBee board itself I put in a box that is attached to the side of the telescope with Velcro.

The stepper motor is rated at 5v, I decided to run it from a 7.4v rechargeable lithium ion battery I had (extracted from a crashed remote control helicopter). This is also located in the same box as the StepperBee board.

post-12132-0-17159200-1410701353.jpg

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The StepperBee board came with a driver and .dll so that users can write their own control software. As a professional software engineer I found creating an ASCOM driver using this a relative simple task. When it was all complete it was a matter of waiting for a clear night to test it, when this eventually arrived the Moon made an ideal target. And everything worked amazingly well as can be seen by the first image taken.

post-12132-0-69721600-1410701363_thumb.j

If anyone else uses the StepperBee to control a focuser I will gladly let them have a copy of the ASCOM driver.

James

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James,

Nice and simple, and it works judging from your excellent photo, sometimes wish I wouldn't make my stuff so complicated!

You mention that you may have a 'copy' of your ascom driver for Stepperbee that you would be willing to share.

I use Stepperbee driver boards myself and a copy of your driver would be very useful.

I also have a Motorbee VII which I use occasionally, nicely made boards and simple to use, just wish that the 'screen/display was a little less obtrusive.

Perhaps you could PM me and discuss.

Regards

Boyd

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James,

Nice and simple, and it works judging from your excellent photo, sometimes wish I wouldn't make my stuff so complicated!

You mention that you may have a 'copy' of your ascom driver for Stepperbee that you would be willing to share.

I use Stepperbee driver boards myself and a copy of your driver would be very useful.

I also have a Motorbee VII which I use occasionally, nicely made boards and simple to use, just wish that the 'screen/display was a little less obtrusive.

Perhaps you could PM me and discuss.

Regards

Boyd

If you PM me with your email address I'll send you the software.

James

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James,

many thanks for documenting this...helps me greaty.  Is almost like you took my idea form other thread and made it happen.... I likey.

Few quick questions...

1.  Take it the light blue wire from -ve to terminal 2 is the one mentioned in the documentation for transient suppression?

2.  Do you have any issue with using the 7.2V battery pack as opposed to the rated 5V one?

3.  How long do you get between charges on the batteries? (this shoulld be fairly long as the motor is not being run that much...am guessing)

4.  What software are you using to control the focuser then?

5.  What address should I send the beers to? :grin:  :grin:  :grin:

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James,

many thanks for documenting this...helps me greaty.  Is almost like you took my idea form other thread and made it happen.... I likey.

Few quick questions...

1.  Take it the light blue wire from -ve to terminal 2 is the one mentioned in the documentation for transient suppression?

2.  Do you have any issue with using the 7.2V battery pack as opposed to the rated 5V one?

3.  How long do you get between charges on the batteries? (this shoulld be fairly long as the motor is not being run that much...am guessing)

4.  What software are you using to control the focuser then?

5.  What address should I send the beers to? :grin:  :grin:  :grin:

1) Yes, don't know if it's needed, it works fine without it.

2) During testing if I ran the motor a lot it was rather warm, but in actual use there was no problem.

3) Don't know, I think self discharge is probably going to be the biggest drain! I planned on re-charging every 2-3 months.

4) I tried Nebulosity but it does not work properly (in fact I have a lot of issues with it for DSLR image capture as well), APT works fine, but mainly I'm using a test application I created myself.

5) I'll be waiting for them to arrive.

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Great news there James.

Not used APT so will have a look at that.  Although I use Nebulosity for my stacking, do not use it for image capture as I use a Nikon D7100 so use Backyard Nikon for that.  Not sure if that has the ability to control a focuser on that on......does BYE have that function?

Will drop you a PM with my email address in later for the driver if that is OK?  You can also let me know what beer you would like then too :cool:

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Great news there James.

Not used APT so will have a look at that.  Although I use Nebulosity for my stacking, do not use it for image capture as I use a Nikon D7100 so use Backyard Nikon for that.  Not sure if that has the ability to control a focuser on that on......does BYE have that function?

Looking at the specs for BYE the Premium edition claims ASCOM focuser support, but I've never used it myself.

James

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Hi James I seem to have hit a comparability problem trying to use the driver when selecting it from the ascom chooser it says its registered correctly as 32bit but won't work in a 64bit system!

Trying it on my XP laptop it installs but doesn't move the motor!

Any ideas to help a non programming engineer/photographer!

Sent from my Nexus 7 using Tapatalk

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The driver should work on a 64bit system as I developed it using my Windows 7 64bit laptop, though I haven't run the installer on 64bit hardware.

It works on my XP netbook, which version of ASCOM are you using? Does the motor work when controlled by the software supplied with the StepperBee?

James

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I was trying to select it in ascom diagnostics / select device type/ focuser/ choose/ stepperbee focuser/ then get a warning box which says

incompatible Driver (Ascom.StepperBee.Focuser)

This 32bit only driver won't work in a 64bit application even though it is correctly registered as a 32bit COM driver.

Please contact the driver author and request an updated driver.

I can't get further than that!

Sorry to be a pest

Mike

Sent from my Nexus 7 using Tapatalk

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I think I can see what the problem is with 64bit systems. I'm compiling as a x86 application instead of one for any processor.

I'm currently working on an update that will allow long moves (over the 16000 step limit imposed by StepperBee), I'll ensure I change the compiler options before I release the next version.

James

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I was trying to select it in ascom diagnostics / select device type/ focuser/ choose/ stepperbee focuser/ then get a warning box which says

incompatible Driver (Ascom.StepperBee.Focuser)

This 32bit only driver won't work in a 64bit application even though it is correctly registered as a 32bit COM driver.

Please contact the driver author and request an updated driver.

I can't get further than that!

Sorry to be a pest

Mike

Sent from my Nexus 7 using Tapatalk

I think I was wrong about the issue here. The StepperBee ASCOM driver must be 32bit as the interface .dll is a 32bit dll. Unless I can get a 64bit dll from the StepperBee supplier I wont be able to do anything about this. 64bit applications cannot call 32bit dlls

James 

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I was trying to select it in ascom diagnostics / select device type/ focuser/ choose/ stepperbee focuser/ then get a warning box which says

incompatible Driver (Ascom.StepperBee.Focuser)

This 32bit only driver won't work in a 64bit application even though it is correctly registered as a 32bit COM driver.

Please contact the driver author and request an updated driver.

I can't get further than that!

Sorry to be a pest

Mike

Sent from my Nexus 7 using Tapatalk

Mike,

Unfortunately there is no 64bit interface for the StepperBee. I'll look to see if I can find another solution but it just may not be possible.

There will be a delay in the next version of the priver while I look into this and try to overcome some multi-threading issues I'm have with long moves.

James

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  • 11 months later...

Funnily enough I have just bought a StepperBee with the same idea in mind!  I only found this post when searching for 'StepperBee Transient Suppressor', so I will take the opportuniny of asking, what type/spec of suppressor are you using?  StepperBee folks are not comfortable with the longevity of their boards if it is omitted.  You also answered another question - I could not get the .dll to work in my VB 2010 environment. Until I reset it to compile as 32 bit!  Thanks for that.  Bob.

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