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  Rowan Astronomy EQ6 Belt Drive Modification

And my new method of adjusting the worm mesh

The first time I did belt modification to my EQ6 mount, the Rowan's belt kit wasn't existed yet. And when I saw it for the first time, I knew I want it. So I planned to install it next time I was going to disassemble my mount.

This kit is very well made and of high quality. The installation is straight forward and comes with very well described step by step manual.


One of the beauty of this kit, is that it doesn't require to modify your mount in any way. It is also does not affect the performance of Synscan hand controller either, goto's and everything esle will work as if no belt modification performed at all. 

Very important and don't get me wrong !!!

What I did to my mount in next steps NOT required to perform the belt modification with this kit !!! You don't have to drill, cut or saw anything to perform the installation.

Here I just want to share with my readers what I did to my mount, taking the installation a step further.

What I was going to do, is to ease the installation process and later maintenance of my mount by making two openings in the mount's body. 


That will get me an easy access to the belts and motors from both sides.


I don't have access to any serious tools, so I've used what I had by the hand. First thing I did is to drill many small holes in a shape of a window that I wanted to make.  

The moun't body have very thick alluminium alloy and It took me some time to cut all of the the sides left connected between the holes. Small cutters and metal saw did the job done.


After removing that big chunk of the body, the window had left with very rugged edges and awful looking.

Next I used file tool to file down all of the edges giving to it a nice looking shape.

The most important step was the cleaning afterwards. It was a real mess, small debris were everywhere, outside and inside of the mount's body and I was afraid that some of very small debris could get on to the worm or drum wheel and sabotage the performance of the mount.

So cleaning was very important and I didn't stopped to clean until I made my self really thorough.  

To cover the windows I used clear perspex of 5mm thickness. Drilled and tapped three small holes and used screws to attach the perspex.

You can see on this image how easy it is now to access the motors and belts from both sides. Installation of the idler plates and motors was really piece of cake.

Here how it looks after everything put back together.


I can't express my self enough, how convenient it was to see the motor and belt from this side. Adjusting the belt tension and see how it all actually runs. Well, that was the reason in the first place to make those windows.

And just for the fun of it and make it looking cool in the darkness, I put two red leds inside, each for it's own window. 

Adjusting the worm mesh using my new method

    I think I'm finally have found a best way to adjust the worm mesh. The method I use (and belt mod) gave me Periodic Error as shown on the image below  and it is 5 arcsec from peak to peak , with RMS PE of 1 arcsec !!! This is crazy, If I remember right, Losmandy G11 is what, 11 arcseconds out of the box and if done precision worm upgrade doing 5 arcseconds? 

    Anyway, this is EQ6 which comes with 20-30 arcsec of PE out of the box. I can't be happier to tweak my mount this way and get such a great performance.

    Ok, let me describe the method.

1. First of all, you'll need to power your mount  through the Ammeter, so you can watch for an instant power draw changes.

2. Adjust the worm mesh using two small set screws on worm carrier leaving good amount of backlash.

3. Set your mount to a fastest slewing speed (hand controller -9, eqmod - 4) and run the motor for about 10 seconds in both directions. Watch your ammeter. Since we left large amount of backlash, the motor would turn the head (clutch engaged) by running without any considerable load. Your ammeter should show a power draw of about 1 ampere.

4. Start adjusting small set screws to reduce the backlash, tightening one and loosening the other by small amount. Run the motor again and watch the load.

5. Continue to adjust the set screws and runing the motor each time until you start to see rising in power draw on your ammeter. 

The moment you'll start to see rising in power draw, for example from 1 amp to 1.15 amps, this means that the worm gear engaged the drum gear enough to show some load. At this point you should feel no play in axis at all. You can try and back up a little, say to 1.10 Amps, to be more precise and make a worm just to touch the drum gear. While doing so and watching the ammeter, you'll get the feel of it, you'll see the changes from your adjustments and you'll know what to do.

    Run the motor and turn the axis for full 360 degree, watch for hot spots. The worm may not be binding yet, but if engagement too much, you'll see very high spikes of power draw on your ammeter, say 1.4-1.5 amps or so. Make further adjustments accordingly.


    Well, that's about it and I hope you'll find it useful ! 

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