Sparta WD006 disassembly help needed: Cover removal

[JohnTN]

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.

 

[RT65CB-SWL]

Hi @JohnTN and welcome to SGL. 

Maybe adding some gentle heat from a hair dryer may soften the adhesive, assuming the manufacturer has used a glue or self-adhesive pad, then gently pry with a butter knife or paint scraper.

That said, have a look here too… 

 

[JohnTN]

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

[Alan64]

Usually a medallion, badge, or other conceals nuts or screws that keep the plastic frame for the badge in place.  I would remove the badge, not the plastic frame ion addition.

1 hour ago, JohnTN said:

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.   

Yes, it differs, although not by much I would think.  The hardware, holding the plastic frame in place, is likely just under the decorative "Sparta" badge.  Remove only the badge.  I don't think that the entire disk will pop off, without some damage.

Edited August 17 by Alan64

[RT65CB-SWL]

@JohnTN Just a thought… if it is new and under guarantee/warranty, have you contacted the reseller or manufacturer direct?

[Alan64]

On the other hand, it could be one of those snap-fit affairs.

[JohnTN]

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

[RT65CB-SWL]

Well done @JohnTN 

[Alan64]

Very good John!  Way to go!

[RT65CB-SWL]

Just a thought @JohnTN - was the saddle secured by a ‘plain’ nut and bolt?

It maybe worth getting a lock-nut or ‘Nyloc’  nut as it may prevent it coming loose in the future… or apply some thread-lock to the bolt thread. 

[JohnTN]

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

 

[Alan64]

I'd get another lock-nut from your local hardware store, not Home Depot or Lowe's.  It might be better than the original, and worth the bother.

It appears that there's room enough to add extras under the steel washer...

You'd be amazed at how easy they are to make; well, not particularly easy, although not particularly difficult.  

Clean and re-grease throughout with Super-Lube, if you'd like.  It's not mandatory, or is it?

Then there are needle-thrust bearings, with mini-rollers integrated, splayed round, to place here and there perhaps...

My Porta I, so far, requires only one of those for each axis, and that happens to be at the same point as your own adjustment, not actually within the axes where light does not shine.

The bearings should be sandwiched within two phosphor-bronze washers, like this...

 

That one was for the DEC-axis of my Meade LX70 EQ5-class equatorial mount.  I will need to make two of those sets for the Porta I, one set for each axis.

Inside the axes, I will make those same washers, two for each axis, but without the bearing.  I could include bearings however, if the spacings and other will allow.  The increase would be negligible.

Such will eliminate any jerking, hesitations, stiffness, catching on this and that, during the motions.  Then, all aluminium surfaces having to do with the axes' motions should be smoothed and polished.

Iron-based metals, including stainless-steel, should not bear against aluminium surfaces, like this one...

Take from that what you might, and for an improved experience.

Edited August 19 by Alan64

[JohnTN]

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

[Alan64]

1 hour ago, JohnTN said:

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

No, I don't place springs or springy stuff among the axes.  Keep in mind for my own that the wave-washers could be re-installed, yet they should be enclosed, too.  The steel washers under the lock-nuts of the Sparta's axes would keep their position in the stack, and with the sandwiched bearings underneath those.  There might be enough length of the threaded shaft to allow that addition.  Earlier I hinted at eliminating the steel washer, but I edited that part of that post. 

[JohnTN]

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

 

[JohnTN]

On 18/08/2024 at 12:15, Alan64 said:

I'd get another lock-nut from your local hardware store, not Home Depot or Lowe's.  It might be better than the original, and worth the bother.

It appears that there's room enough to add extras under the steel washer...

You'd be amazed at how easy they are to make; well, not particularly easy, although not particularly difficult.  

Clean and re-grease throughout with Super-Lube, if you'd like.  It's not mandatory, or is it?

Then there are needle-thrust bearings, with mini-rollers integrated, splayed round, to place here and there perhaps...

My Porta I, so far, requires only one of those for each axis, and that happens to be at the same point as your own adjustment, not actually within the axes where light does not shine.

The bearings should be sandwiched within two phosphor-bronze washers, like this...

 

That one was for the DEC-axis of my Meade LX70 EQ5-class equatorial mount.  I will need to make two of those sets for the Porta I, one set for each axis.

Inside the axes, I will make those same washers, two for each axis, but without the bearing.  I could include bearings however, if the spacings and other will allow.  The increase would be negligible.

Such will eliminate any jerking, hesitations, stiffness, catching on this and that, during the motions.  Then, all aluminium surfaces having to do with the axes' motions should be smoothed and polished.

Iron-based metals, including stainless-steel, should not bear against aluminium surfaces, like this one...

Take from that what you might, and for an improved experience.

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

 

Edited August 26 by JohnTN
clerical error

[AstroKeith]

Is the nylock nut actually loosening, or is just that the bearings are settling in? These castings often are poorly machines and a bit of working in can help.

But also try a new nylock, but before fitting make sure the thread on the axis is grease free.

[JohnTN]

2 minutes ago, AstroKeith said:

Is the nylock nut actually loosening, or is just that the bearings are settling in? These castings often are poorly machines and a bit of working in can help.

But also try a new nylock, but before fitting make sure the thread on the axis is grease free.

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

[Alan64]

5 hours ago, JohnTN said:

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

 

The set-screws can be deep inside the holes, and difficult to see.  I wouldn't adjust or remove those however, unless you've other plans.

[JohnTN]

On 26/08/2024 at 11:59, Alan64 said:

The set-screws can be deep inside the holes, and difficult to see.  I wouldn't adjust or remove those however, unless you've other plans.

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

[JohnTN]

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

 

[Alan64]

I can see both set-screws now...

[Alan64]

2 hours ago, JohnTN said:

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

 

The Sparta mounts are known to have plastic parts.  The set-screws work in tandem with the cams to adjust and set the distance between the worm and gear, and for each axis.

[JohnTN]

12 hours ago, Alan64 said:

The Sparta mounts are known to have plastic parts.  The set-screws work in tandem with the cams to adjust and set the distance between the worm and gear, and for each axis.

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? 

[JohnTN]

On 18/08/2024 at 03:02, RT65CB-SWL said:

Just a thought @JohnTN - was the saddle secured by a ‘plain’ nut and bolt?

It maybe worth getting a lock-nut or ‘Nyloc’  nut as it may prevent it coming loose in the future… or apply some thread-lock to the bolt thread. 

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.