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Old 15-05-2016, 07:01 PM
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Modding my Schaefer AT Mount with a Losmandy DDS 492 *Help Needed*

G'day all, from South Australia.

I was perusing the forums/internet looking for an answer to my modification challenge of a Schaefer AT EQ Mount. Here is the link for my post on my mount:

http://www.iceinspace.com.au/forum/s...d.php?t=122706

This mount has had the 115vac 60hz Synchro Motors removed sometime ago. It now has two different stepper motors on it. The mount still has a tangent arm as I haven't got around to modifying the Dec Axis to a gear and worm (and probably won't for sometime).

Basically the setup is a 9" or 10" (not exactly sure) 359 tooth Byers gear. It's the Porter type mount, which means there is a bit of friction to overcome as the clutch is always engaged. There is a 2:1 reduction gear between the motor and worm on the RA. It currently uses the Bartels electronics, and a switch-mode PC for the steppers and electronics. The stepper on the RA is a 200 step TEC (3v 350 ohm). It also now has Argo Navis with encoders installed.

I don't have a permanent obs and to set everything up is a bit of a chore due to needing to not only setup the mount, but also the switch-mode PC and laptop to run everything. So I wanted to look at an alternative to that (especially when in the field), that is where the Losmandy DDS 492 comes in.

I am not too familiar or understanding of the ratios for the gear control, I am also concerned of burning out my stepper motors as using the Bartels software via PC it states the laptop must be on first and running before switching on the power to the motors. Otherwise it states you can damage/burnout the motors.

So my big questions are - Am I able to just plug my existing stepper motors in the Losmandy DDS board? Will this system potentially burnout or damage my motors? Will it keep the correct tracking rate? Or will have have to modify the gear train/electronics/speed?

Any assistance you are able to give would be greatly appreciated.

Cheers

Gav

Last edited by GC - South Aus; 15-05-2016 at 07:29 PM.
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Old 16-05-2016, 03:24 PM
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RE: 2:1 Gear Reduction Modification

G'day All

Further to my last post, to assist anyone who may be able to in turn help me with this.

The following images are of the modified gear train 2:1 (belt drive) modification between the motor and the worm drive.

The other shows the mount before it had modification installed and the previous 60hz Synchro Motor use to just attach directly to the drive.

The new stepper motors already have the RJ12 connectors so should be able to just plug into the Losmandy DDS.

Cheers

Gav
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Old 16-05-2016, 03:29 PM
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Before Modification

Image of mount before 2:1 belt modification.

This is when the 60hz Synchro motors use to be installed directly to the worm drive.

This image was taken before I owned the mount, and the stepper mod was already in place when I bought it. I have never previously used it with the 60hz Synchro Motors.

Cheers

Gav
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Last edited by GC - South Aus; 16-05-2016 at 03:41 PM.
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Old 16-05-2016, 11:45 PM
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Hi Gav,

First.....I know very little about steppers and drivers.

The 2" pillow block mount I'm still building has a Byers 359 tooth 10" gear. I ordered it with a stepper motor. I sent details of gear and stepper (which is a Hurst and the same as the Losmandy G 11) to AWR Tech in the UK.

Alan Buckman from AWR built the controller to work with the stepper I had.

The hand control is a stand alone box that has RA and Dec leads. The Dec works with a G 11 Hurst Stepper, same as the RA motor.

Alan has been around for a long time and has vast amounts of know how about telescope drives. The AWR controller I bought does what it's meant to do, and cost 190 UK Pounds. Send an email with details of what you have and want to do. I rang Alan too....very helpful gentleman

The Losmandy drives are for 360 teeth gears and are a 1:1...direct coupling thing.

Here is the AWR tech link http://www.awrtech.co.uk/

Hope this is of some help to you...It was my solution to much the same problem you have. Electronics is another world to me


Matt
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Old 17-05-2016, 07:23 AM
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Thanks Matt

Quote:
Originally Posted by MattT View Post
Hi Gav,

First.....I know very little about steppers and drivers.

The 2" pillow block mount I'm still building has a Byers 359 tooth 10" gear. I ordered it with a stepper motor. I sent details of gear and stepper (which is a Hurst and the same as the Losmandy G 11) to AWR Tech in the UK.

Alan Buckman from AWR built the controller to work with the stepper I had.

The hand control is a stand alone box that has RA and Dec leads. The Dec works with a G 11 Hurst Stepper, same as the RA motor.

Alan has been around for a long time and has vast amounts of know how about telescope drives. The AWR controller I bought does what it's meant to do, and cost 190 UK Pounds. Send an email with details of what you have and want to do. I rang Alan too....very helpful gentleman

The Losmandy drives are for 360 teeth gears and are a 1:1...direct coupling thing.

Here is the AWR tech link http://www.awrtech.co.uk/

Hope this is of some help to you...It was my solution to much the same problem you have. Electronics is another world to me


Matt
G'day Matt

Thanks mate

Will contact AWR see if they have any advice.

Yeah, I know what you mean by another world!

I guess for me, the system works fine when using the Mel Bartels 'Scope' solution (shown in the image below) from what I can see. It's just a lot to setup and take down when working outside, especially if you want to image as I have to set up another computer because the old laptop has to be running to DOS with no other applications to control the mount. Also the Scope program by Mel Bartels will take some getting use to!

My ultimate aim would be to have the mount setup in a obs (when I can get one made) for use with Mel Bartels software, and the Losmandy DDS 492 to use with field tripod away from the obs (a lot less to transport, power, setup and simplier to use).

I am starting to lean towards just plugging the stepper motors in and just see what happens. I am just scared of burning them out or damaging them someway.

I have been very impressed with your mount build, and have been keeping track on it.

Cheers

Gav
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Old 17-05-2016, 07:44 AM
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Try plugging them (one) in and see. I did that with a few steppers I have around, Synta ones from an HEQ5 mount, and they sat and vibrated away (there is a term for it) but didn't burn out at all.
One youtube I found a what wire is what in stepper motors and bought a multimeter from Jaycar to work out which wire did what on the Byers/Hurst stepper I have. That is the extent of my electrical knowledge thus far. The Losmandy drives have 6 wire steppers, your photo looks like 4 wire...is that right?

The AWR driver and hand control box is a single unit a bit smaller than an Argo Navis. It runs on 12V DC and has a variable tracking rate knob...another tech term
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