JohnTN

The Nuts tried above did not work out so well. The one on the azimuth loosened as before and the one on the altitude actually tightened to the point the altitude would barely move! So I tried another type I had on hand, these from Lowe's and plated instead of Stainless. They look a lot like the two already tried so I have little hope... While I was disassembling (I'm getting pretty fast at it!), I decided to take the blue base off to see what the other end of the axis looks like. It appears to be only a screw head, driven in tightly. I did not go any further, as it appears this has nothing to do with the adjustment in which I am interested.

I have had better success improving this mount since my last writing. In summary, the adjustments for play and tightness on this Sparta mount are accessed by removing the dovetail saddle (4 bolts) for the altitude axis and by lifting the rubber cover exposing two bolts which can be removed to access the azimuth axis. I adjusted both axes a couple of times but they loosened up after a short time. I removed the factory M8 locking nuts and replaced them with the ones shown, which came from Home Depot. I had to order them but they do not charge shipping. The nut with the black insert is the original and with the white insert is the Home Depot replacement. I adjusted them a little too tight at first but went back in and loosened them 1/16 to 1/8 turn. This still left the altitude axis a little tight and I went back in and loosened it a bit. At the same time I noticed the azimuth axis had a little wobble so I tightened it a bit. The new lock nuts are better but still maybe not good enough!

Thank you for the exploded photo of the assembly. It helps my understanding. It looks like there is a lock nut and washer on each end of a shaft. Possibly many of these similar mounts have the same design.

Good to know. Thanks for the additional information. I saw one copperhead here, many years ago. I don't like to see them around!

I do not have a scroll saw. That looks like a great way to make the washers. Thanks for the extra details. I went to Home Depot yesterday and bought the last two M8 nylocs they had, with two different nylon colors. They were zinc coated, not my favorite. We shall see... It must have been Lowes where the Hillman nuts were. I was going to go there after a Physical Therapy session but my girlfriend texted me saying there was a snake in the kitchen and I needed to come right home! You would have thought it was an anaconda from the way she talked! Of course it had disappeared by the time I got there. Later it surfaced again in the same place. It had to be the smallest snake I had ever seen! I swept it into a large storage tub and took it outside. She was greatly relieved.

The worm shafts turn easily, but there is a little lash. Probably acceptable for now, at least until I get the wobble problem ironed out.

Concerning addition of your bearing sandwich under the steel washer, I have some questions. When I adjusted the nut last time, I noticed that the washer does move sometimes when the axis is rotated and even more so when I rotate using a side load. So possibly the more load is on the mount, the more tendency to unscrew. Now the question. Do you think adding your design bearing sandwich would eliminate entirely the tendency for the washer to move? Is it possible that this would increase the load carrying ability of the mount? Would there be room for it without removing other parts of the "stack?" Third question. I think you said you order the bearings, but how do you make the phosphor bronze washers? Thanks, John

The existing nut does appear to be the locking variety, but I will seek a better one as Alan64 suggested. We have no local hardware stores anymore, a dying breed unfortunately. Ace doesn't carry much metric. But I have spotted a Hillman brand at Home Depot that appears to have a longer Nylon portion. Next time I go out I will pick up a couple of those. I also ordered a bag of Nylocs at random on the hopes that they might be better. Thread lock is a possibility, I would think. I can't see the harm using the Blue Loctite very sparingly so it doesn't go everywhere. Maybe one drop on the inside threads of the nut and then reassemble. I had thought of a jam nut arrangement using two thin ordinary nuts, but there really isn't room for tools to implement this.

I understand. And is it true that all 4 set screws (two on the bolt side and two on the non-bolt side) have to be loosened to free the cam so it can be adjusted?

Upon closer inspection, perhaps what I'm seeing on the "non-bolt" side is a thin plate cover whose holes don't match up with the set screw location. I guess you have to pry off the plate to access the set screws. I can't be sure as I can't get enough light in there to see properly. So I guess there is no problem except a poorly made thin cover. Thanks, John

I can see set screws on the side that contains the adjustment bolt, but not on the opposite side. This is true for both axes. Is this normal? John

I plan on digging into both axes in a few hours. You pose a good question. I'm not sure I will know the answer even after digging in as the adjustment required last time was so small. I will make some marks on bolt and nut this time so I can tell next time. Something tells me this will be an ongoing problem. Thanks for your reply. John

Unfortunately, there has been a step backward. The wobble has come back in the altitude axis and in the azimuth axis as well, after only a little bit of use. I will go in search of a proper locking nut as you suggested as I suspect it has loosened. Another potential problem I noticed is that the set screws near the slow motion shafts are missing. I'm beginning to think my copy of this mount didn't receive a proper QC at the assembly line. Thanks, John

All very interesting, Alan. Perhaps I will "super modify" my mount someday, but, for now, I am just glad it works! I took it out last night, along with my "work in progress" Frankenstein telescope, for about an hour. First light, I think it's called! Mount and scope performed well viewing the moon! John

Thank you Alan64 for sharing this. I'm beginning to see what you will do with the bearings. Will the bearing and shim assemblies replace the wave washer, or do you still have a spring of some sort for tension? Very interesting how you have planned this all. John

Thank you both for your encouragement! The dovetail saddle is attached by 4 metric socket head cap screws with 6 mm allen size. The central nut (13mm) exposed when the saddle is removed makes and holds the adjustment for play or wobble. It is somewhat critical. You have to adjust it tight enough so there is virtually no play but not so tight that the mount has too much resistance to turning. The adjustment nut appears to be of the locking variety. If it starts going out of adjustment too often, I will get a tighter locking nut. Feedback on the Sparta would indicate that going out of adjustment is one of the problems of this very inexpensive mount. I think I can live with it now that I know how to adjust! John

Thank you Alan64 and RT65CB-SWL for you comments and suggestions. It is within return period, but I got such a good deal on it that it would cost a bit more to get a replacement. As it turns out, I don't have to remove that cap or logo just yet. I had posted this on Cloudy Nights almost a week before I posted here and had no reply until today. Antal on that forum came up with the solution to adjusting the play or wobble. The key was to remove the dovetail attachment plate and adjusting a nut exposed in the center. I removed the 4 bolts with 6mm hex key, and then adjusted (just slightly) the nut with a 13mm socket. All works well now! John

Hi and thanks for the welcome! I have been following that thread from Alan64 and it is very interesting, especially because of his detailed photos of the inner mechanisms. But I think the method of cover attachment was different on the Porta's vs the Sparta. The Porta's I have seen in various threads have a steel disc with a thin logo piece glued on (and the steel disc has to come off to gain access). The Sparta seems to have a plastic cap with the logo glued on. I may try getting the logo off, but I doubt it will give me any better access. I think I have to get the plastic cap off and the answer may be to just pry on it until it comes off! Thanks for your comments! John

I have a new Sparta WD006 mount with some play in the altitude axis. I'm wondering if someone has experience removing the plastic cover over the altitude axis. Note this is made differently than the Porta's that are similar. The cover interface is marked by the green paper clip in this photo. There is a gap if you pull on it, but it does not turn loose easily. Just trying not to destroy the cover if there is a trick. Thanks for any help you can give me.

I am following this thread with great interest. Keep up the good work! When finished, you will have a "better than new" mount. I can't wait to see how you implement the roller bearings. Your photos of the internal mechanisms are especially interesting to me as I have a Sparta WD006, which may or may not be a copy of your mount, but it is similar. When I received it new a week or so ago, it exhibited significant play in the altitude axis. Your photos will help if I decide to repair it myself. Thanks for posting this. John