maybe just add a shim to tilt a motor in the right direction.....
Might be a good idea. I have just spent an hour trying to adjust out the problem, just on the RA drive. Tightening the lock bolts tilts the motor back, the wedge is mainly serving as a belt tensioned and was backed right off on my drive. With the motor tilting, the sprocket tilts. So shimming the motor carrier might work. I did manage to move the sprocket further out on the shaft slightly, which decreased the overhang of the belt when slewing, what can j hse as shim material, it has to be pretty thin?
coke can makes good shim. of course, if you tilt the motor back, you will first need to back the belt tension right off and then carefully adjust it up with the shim in place.
Thanks guys. I am making some progress. Working on just the RA for now, I cut and tried a variety of shim material, including aluminium flashing material, and some thin galvanised steel strapping used in building. Backed off everything, and inserted the thin gal steel strip in between the motor carrier and the main drive casting. Once adjusted and locked down, effectively pushing the motor drive outward, it improved the situation a fair bit, with the belt now staying on the motor sprocket with no overhang. It will need some more refinement in coming days, to tune the angles and belt tension abit more, but i have had enough for now. At least its on a pier and easy to work on.
Edit: I am considering inserting a support block under the motor in the area indicated in orange, as the entire weight of the cantelivered engine and transmission is supported by the arm and secured with the lock down screws. Small movements in the shim area affect the angle of the rear of the motor (in red) and thus the running angle of the sprocket.
In more tuning today, the RA drive is now performing pretty well. The belt is staying on the motor sprocket, through all sorts of slews. The final shims are aluminium flashing material. I made a template out of plastic so that I could do a production run of shims, 8 in all, 4 for the RA and 4 for the DEC. I would still like to get a hold of a couple of new motor sprockets with edge flanges, with some offset build in (I might be able to ditch the shims then). The sprockets I need, have 14 teeth, a 22mm outside dia from edge of tooth to edge of tooth, 5mm axle shaft, tooth width seems to be about 2mm at the base, and to work with the T5x165 belt. Something like this.
I have finished off the belt tuning, thinking that it is the best I can do without a new motor pulley. I gave up on the thin aluminium flashing shims, and just went with a piece of 1mm plate under each motor carrier. Can't push it up too far as the belt starts to rub on the motor carrier. I also extended the motor pulley on the shaft as far as I could (this provided about 1mm of extension as well). Photos are attached of DEC and RA. Did a bunch of slewing to check on how the belt was behaving and it looks good, no wobbling and tension is about right. The photos are post the slewing. If yours needs tuning, be aware that the adjustments are very touchy, and you don't want belt tension to get too stiff or loose - the belt is not spring loaded, that's for the worm only.
Of course Celestron should have paid more attention to this aspect of QA, IMHO.
I have finished off the belt tuning, thinking that it is the best I can do without a new motor pulley. I gave up on the thin aluminium flashing shims, and just went with a piece of 1mm plate under each motor carrier. Can't push it up too far as the belt starts to rub on the motor carrier. I also extended the motor pulley on the shaft as far as I could (this provided about 1mm of extension as well). Photos are attached of DEC and RA. Did a bunch of slewing to check on how the belt was behaving and it looks good, no wobbling and tension is about right. The photos are post the slewing. If yours needs tuning, be aware that the adjustments are very touchy, and you don't want belt tension to get too stiff or loose - the belt is not spring loaded, that's for the worm only.
Of course Celestron should have paid more attention to this aspect of QA, IMHO.
Glad you got the solution sorted Glen. This sort of engineering oversight is not what you should expect for a new mount. Let's hope it will be addressed in Mk 2.
Bo
Celestron should pay you for solving their problem.
A friend of mine in Brisbane solved a graphics card issue with the Apple II when it was first released. He got a free trip to the USA and a cheque for $50,000.
While I was working on my belt alignment I had a look at the spring loading on the worms. The CGX is supposed to have spring loaded worms right? I couldn't find any evidence at all, I could not get the worm carrier to move, I thought I was doing it wrong. So I returned to it today to work out why there was no movement possible in the worms. I tried the recommended pull back technique (put your index fingers on either side of the worm carrier below the bearings and pull back away from the ring, and you should see and feel some movement - not a lot, just enough). In my case, both worms were screwed down tight against the ring gear, no movement. If you check page 25 of the CGX Manual, it sets out the method to check the recoil and adjust the spring loading tension. I have backed off the Distance Adjustment screw so that there is now a small amount of recoil. You don't want the recoil to exceed 1mm and can use the Range Limit screw to control that. I have mine set at about 0.25 - 0.50mm at the moment, just enough to feel it move back. Obviously you need to pay attention to any backlash on the axis your working on, and I still can't detect any.
I am looking forward to some imaging weather to test the new settings and see if there is any change to the PE. Sadly, we cannot assume that they are setup correctly by the factory.
I have finally received a response from Celestron Tech Support concerning the drive belt misalignment problem which I reported early last week, this is from Christopher in Customer Support:
"I am sorry to hear about the experience that you are having with your mount. I am working with our product development team to get some instructions on how to make the adjustments to the belt send out to our distributor. I am going to be working with our distributor in Australia to get the issue resolved with your mount. I apologize for the delay and want to thank you for your patience in this matter. I will have an update tomorrow with more information."
So my take on that is that Bintel will be expected to adjust the drives to correct the problem. I await the instructions (assuming I am allowed to see them). I don't know how Bintel will be able to solve the problem without a hardware solution such as a shim and/or a sprocket change. We'll see.
I don't want to send the mount head back to Bintel until I know what the procedure involves, and am convinced that they are equipped to solve the problem permanently.
Tim, did you ever hear back from Tech Support on your wobbly drive sprocket?
I have finally received a response from Celestron Tech Support concerning the drive belt misalignment problem which I reported early last week, this is from Christopher in Customer Support:
"I am sorry to hear about the experience that you are having with your mount. I am working with our product development team to get some instructions on how to make the adjustments to the belt send out to our distributor. I am going to be working with our distributor in Australia to get the issue resolved with your mount. I apologize for the delay and want to thank you for your patience in this matter. I will have an update tomorrow with more information."
So my take on that is that Bintel will be expected to adjust the drives to correct the problem. I await the instructions (assuming I am allowed to see them). I don't know how Bintel will be able to solve the problem without a hardware solution such as a shim and/or a sprocket change. We'll see.
I don't want to send the mount head back to Bintel until I know what the procedure involves, and am convinced that they are equipped to solve the problem permanently.
Tim, did you ever hear back from Tech Support on your wobbly drive sprocket?
I have finally heard back from Celestron. They don't see any issues with the movement. They basically are saying that the gear is fine, It's just that the belt is moving back and forth across the gear. I have already seen th wobbling occur without a belt attached, so that will be the next expose
