CGEM dec motor free play

[Paul and Chrissy]

Hi everyone.

I have noticed in this warm weather that there is quite a lot of free movement in the dec motor gears on my CGEM. If l remember rightly it was almost non existent during the cold evenings a few months ago. Does the free play increase during warm weather. Can this be adjusted out. Has anyone come across this.

cheers Paul and Chrissy

[x6gas]

Hi Paul and Chrissy.

I've noticed a little extra backlash in my DEC too... Are you sure it is the motor? If the aluminium casing is expanding in the heat then it could be that the worm is moving away from the ring gear a little bit. This is easily sorted with a couple of allen keys - it's basically the same procedure as for the EQ6/Orion Atlas and is explained by Astro-Baby here.

[Paul and Chrissy]

Hi. That sounds very possible. I will play with it tonight. The pictures in the adjustment procedure do look the same as the CGEM. I presume that when the weather cools down l need to make sure it doesn't bind.

cheers for that. Paul and Chrissy

[x6gas]

Hi. That sounds very possible. I will play with it tonight. The pictures in the adjustment procedure do look the same as the CGEM. I presume that when the weather cools down l need to make sure it doesn't bind.

cheers for that. Paul and Chrissy

That thought also occured to me!

If it tightens up, though, it just means that the motor will stall - nothing more drastic than that AFAIK. It's a bit of a job to understand which of the allen bolts are for the Dec and which for the RA. Basically the very top of the Dec housing - where the saddle is - can slide forward and backwards parallel to the saddle. You need to slacken the larger allen bolts to allow that part to move. The smaller allen bolts push against brass blocks so you need to slacken one, and then nip up the other. It's a two minute job once you've done it a few times but I reckon it took me an hour first time! IIRC you need to slacken off the bolt nearest the worm gear (the one by the index mark, I think?) and tighten up the one on the other side of the top part of the Dec housing. A quarter turn might be too much so take it steady! I then slew the mount around it's full range to ensure there is no binding.

HTH!