Friday Night Star Parties at TXMOST

For about the past four months I’ve been helping host Friday night star parties at the Texas Museum of Science and Technology (, weather permitting. They’ve become quite popular, with as many as 100 people showing up over the summer. We had a relatively slow night this time, so I was able to capture a few photos.

With the smaller crowd, we were able to see quite a number of objects, including Venus, Saturn, Mars, the Hercules Cluster (M13), the Swan Nebula (M17), the Lagoon Nebula (M8) & open cluster, the Ring Nebula (M57), and the Andromeda Galaxy (M31) & M110.

Update: This last Friday (September 30th) we moved to starting an hour earlier (8 PM instead of 9 PM) due to the shorter days as we move into Fall.  We had a much larger crowd this time (probably 50 people or more) and the cooler weather was wonderful after the hot nights we’ve had all summer.  The few light clouds blowing through weren’t a problem.

I arrived even earlier to set up my camera with a timer to catch the images to make this time lapse video.  This video covers two hours from setup to tear-down.

Note the clouds moving south all night and the stars rotating around Polaris in the upper right corner.  In the first part of the video you can also see Venus setting to the left of the street light and right down through the window of the SUV parked there. Be sure to view this full screen for the best result.

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Welcome to X10 Hosting!

Hi Everyone,

If you’re seeing this, hopefully you’re on our new web server and hopefully everything is going smoothly.  I’d actually posted this yesterday, but something still hadn’t refreshed in my browser and the post ended up on the old site!

After working through some initial headaches, primarily with WordPress and some missing functions in PHP, things now at least seem to be functional.  There are still a few problems with the gallery that I’m working on cleaning up.  These are really the fault of not being able to download the entire old site as a single zip/tarball from my old hosting provider.  In the process of doing a full FTP file transfer through Windows, various file naming conventions caused problems with some directory and file names getting changed, and the hidden thumbnails used for folders in Gallery getting corrupted.  I’m working through those and hope to have the rest resolved tonight.

I was generally happy with my previous service at Hostmonster, but their price had gone up in recent years. When I needed to add some additional services to be able to add an SSL certificate to my wife’s Orion Ranch Spa website, the added cost was absurd. I found X10Hosting who would do much of what I was getting on Hostmonster for free, and for a fraction of what I’ve been paying Hostmonster, I could get my own private IP address and professional SSL certificate. Despite the pain of migrating the sight, the cost difference is just too good to pass up. As long as the performance remains similar, I think we’ll be very happy here.

Please let me know if you encounter any missing files or anything else that doesn’t appear to be working as expected.



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Website Migrating to New Hosting Service

Hi All,

As some of you may have noticed last night, I’m in the process of migrating the website to a new hosting service, which always has its difficulties.  However, in order to test I need to point the orionranchobservatory domain name over to the new server in order to see what’s working and what’s broken.  I’ll be doing that in the evenings for the next day or two (or however long it takes).  Since the WordPress installation that handles this blog is giving me most of the problems at the moment, I’ll be adding a notice to the main page of the website that will let you know when you’re seeing the new host.  As if the other problems wouldn’t be enough to tell that.  The gallery does seem to be working pretty well although the thumbnails aren’t displaying properly.  I may diagnose that first this evening since that’s more important than the blog anyway!

Note that since it tends to take some time for the domain name server (DNS) information to propagate, you may experience period where your browser is attempting to source portions of the website from different locations.  Since I’m using sub domains here (,, all of those have to be refreshed in addition to the main domain name.  You can try refreshing the DNS list on your Windows PC by using “ipconfig /flushdns” from the command line.

Note that for the duration of the changeover, the weather conditions on this site will generally not be updated.  The hosting service I’m leaving isn’t flexible enough to allow me to set up the same FTP account on both sites.

Please bear with me as I attempt this move.



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3-D Printed Tripod Parts

I’m running behind on my posts relative to the pictures I’ve been uploading and sharing on Cloudy Nights, so I’m going to merge a number of different related posts into one here.  I’d posted on my new business cards for the observatory and the 3-D printed card holder I’d made, and that was more or less the start of a series of 3-D printing efforts that have culminated in quite a few changes.

The used Celestron 8SE I picked up off of Craig’s List (and finally sold after finishing this) was missing the leg spreader/eyepiece holder, so I finally decided to try designing and printing my own.  I didn’t have one handy as a reference (my other was out in the observatory) so I found a picture online and scaled from that to get suitable dimensions and then just kind of eyeballed everything else.  I wasn’t sure if I’d have a big enough footprint on my printer, but I knew there was a reason I bought the largest I could get for the price!  The design itself is pretty simple, so I was able to put it together pretty quickly.  The only problem was tolerance on the eyepiece holes, since the width of the print trace tends to shrink the holes a bit.

At any rate, it turned out pretty good and worked great, but was still just the same as the original Celestron spreader, which was pretty limited.  I’d also decided the center column was too short, requiring more turns than necessary to clamp down. I figured I could do better. Thus I designed my initial version of a delta shaped leg spreader that provided six 1.25″ and three 2″ eyepiece holders which were slotted to do double-duty and allow the legs of the tripod to close completely without having to remove the spreader from the tripod.

In the meantime I wanted to see how well the printed spreader would hold up, so I tested the strength of one of the first prototypes by screwing the nut to the bottom of the thread. It flexed, but there was no evidence of cracking or failure. Upon release, it went back very close to its original shape, and at this point I couldn’t tell you which of the two I’d printed was the one I tested.

I then tried out a new glow-in-the dark red filament, that actually tends to look closer to the Celestron orange of the 8SE OTA than does the orange filament. The material was a pain to print with as you have to run hotter and slower than typical PLA material, so a print like this took about 19 hours! This image is with the camera at auto-exposure just after charging, so is pretty close to what you’d see visually. After a few hours, you’ll have to be in really dark skies to see anything. Notice too the hand controller clip I designed based on the clip for the business card holder.

With a thirty second exposure it looks really cool!

Unfortunately, it just doesn’t last that long. I’ve come up with a solution for that as well, but that’s somewhat out of order!  As mentioned, the glow in the dark material doesn’t work all that well (at least in my printer) and I had a lot of failed attempts trying to get it to work.  Along the line I also discovered problems with the Y axis of the printer now that I was trying to use the full build volume.  The original Robo 3d design uses drawer slides that over time start to bind as the bearing moves out of center.  Normally in a drawer you just pull a little harder and re-seat them, but the stepper can’t overcome the additional friction.  On top of that, the range of motion is limited by the drive limits and cabling, so the only way to reset it is to partially disassemble the bed.  Before I figured all that out, I had a lot of disappointing if somewhat entertaining results.

The delta design eventually evolved into something a little nicer, with curved edges and a set of retention bumps to allow the legs to snap into place when closed.  That took a few attempts to get right.  I was also having problems with warping due to the large size.

I even developed a version for the larger 1.75″ legs of the Celestron CG-4 and equivalents.

Here’s a closeup of that leg retention mechanism.

I then set my sights on making a spreader version that had more 2″ eyepiece holders since that’s generally what I use exclusively.  In the “check it before you build it” category, I came up with a really cool looking design that just didn’t work!

I was afraid of this when I designed it, but didn’t take the time to model the whole tripod or even check using my existing delta design.  The problem is that you can’t put anything tall under the legs due to the angle.  Thus, even my smallest 2″ eyepiece won’t fit.

It’s not a total loss though.  I can still use it for caps.

As mentioned, the glow-in-the-dark material doesn’t last very long, but it also happens to be fluorescent.  Thus I bought a strip of UV LEDs and printed a holder that clamps to the top of the rod.  It turned out that the half meter of 30 LEDs was far too bright, so I cut it down to three that I still need to turn off when doing deep sky observing.  I still need to print a new holder that’s smaller for this simpler approach, so I’m not even highlighting that.

It still glows for a bit after turning off the UV light.

So my next iteration on the spreader was to try to exceed the limitations of my build volume by breaking it into pieces and moving away from the delta design to get more room out from under the legs.

Here’s one segment of the three-part 2″ eyepiece spreader.  Note the retention feature on the side of the rib.

I also printed the logo into the “top” as well, but that’s such a pain to clean out that I don’t think I’ll continue with that approach.

The three segments snap together with three clips that hold quite well.  I don’t really see any need to glue anything together, although that could be done if more strength is desired.

Here’s the finished spreader.

Fully loaded, the legs are still a problem.

Of course nothing can help the Holy Hand Grenade that is the 21 mm Ethos.  It needs a whole side to itself!

I finally made a model of the entire top of the tripod so I could address the leg clearance issues.  With the three wedge design, I still have room to expand in my build area, so I’m going for a larger design that will sit lower on the tripod.  This new spreader will accommodate multiple 21 mm Ethos, and six 1.25″ eyepieces as well.  There are 12 holes total, but the ones near the legs can only be used for caps or small eyepieces due to the same clearance issues as before.  I had the space though so I figured why not?!!  It doesn’t hurt to use a bit less plastic either.  With this larger design, I’ll also have to extend the tripod rod to attach it.

Here’s the finished over-sized spreader.  Again it’s a three wedge, three clip design and holds solidly without any glue, etc. although I might add some just as a hedge against catastrophe.

To install it on the tripod, I ordered a piece of threaded rod and a coupling nut to match the thread of the knob and extend the center shaft.

Here it is , loaded for bear with every 2″ eyepiece I had at home plus some adapters, and a case full of Meade 1.25″ eyepieces plus an extra Celestron for good measure!  I was actually thrilled that all the small eyepieces fit by the legs with no problem.  I wasn’t sure they’d actually go into the holes due to the legs.  That monster of a 21 mm Ethos in the middle doesn’t look so big anymore!

In the closed position there’s an added bonus to the coupling nut in that now the spreader is captured in both directions and doesn’t move to the top anymore.  That keeps it where I want it to keep the legs closed.

As mentioned above, I also developed a hand controller clip based on the business card holder leg clip.

I eventually enhanced this as well, just before going on to design the first sectional spreader.  In this case I added a slot for the power cords to capture the cord on the leg.  After a number of iterations where I had to tighten the clamping power due to the longer overall arm length, it works pretty well.  Also in continuing with my Orion Ranch Observatory branding, I managed to get the letters ORO and an Orion constellation into the part as well.  I was also having fun with different colors when I did this.

Here it is with cables routed.  I also developed a smaller clip for the lower portion of the leg.

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Celestron NexStar 8SE Azimuth Axis Adjustment

I finally sold the used 8SE that I’d picked up, so I pulled out my original 8SE to use at the TXMOST star parties we’ve been having every Friday.  Unfortunately when I got there and set everything up, I discovered that I probably should have kept the one I sold!  The mount had a tremendous amount of vibration from the slightest touch; something I recall now from when I used it before.  If I pushed on it at all, the azimuth axis would move back and forth noticeably (several degrees of play).   What I didn’t realize until just then was that this mount had always been defective and never performed as it should.  The used mount I had performed much better than the one I’d bought new.  So after years of working on other Celestron mounts that more often than not do not arrive from the factory in peak operating condition, I wasn’t afraid to tear into this mount and take care of it.

As I reassembled the mount, I took a picture log to give others an indication of how to disassemble/reassemble this mount.  I’ll post a few images here, but see the gallery for more detail.

Here’s the NexStar mount disassembled down to the base to gain access to the motor and drive spur gear for the azimuth axis. Note too the motor control board with the interface board on top. The design is very simple.

Here’s a close-up of the stack up of interface and motor control boards. These are the only PCBs in the entire mount.

There are two ferrite cores clamped on each of the motor and interface cables. One in the base and one in the arm.

Here’s a view of the arm and elevation drive system. I didn’t make any modifications or adjustments to it this time. The plastic cover is held with four screws.

Views of the base cover with battery compartment (just unplugs from the interface board) and the cover around the OTA clamp.

After re-installing the azimuth motor and pushing it tight to the spur gear to eliminate play in the azimuth axis, the drive is much tighter now.  There’s quite a bit of adjustment in the four screw holes.

Four socket head cap screws hold the arm to the base above the azimuth drive motor and behind the power switch plate.

Here’s a view of the assembled mount components and cables before re-installing the covers. Note the location of the ferrites.  Oops, that bottom ferrite should probably be clamping all four cables (don’t recall now if it did or not).  Doubt I’ll get in to change that though.

See the remaining images in the gallery.

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New Business Cards and 3-D Printed Business Card Holder

I’ve been doing a bit more outreach, helping to host star parties for TXMOST, so I finally got around to designing a business card to direct people to this website and getting them printed. I then decided I needed a good holder to make it convenient to pass them out. Rather than buying something and trying to figure out how to attach it to my tripod, I decided to print one on my 3-D printer. It turned out better than I might have hoped.

First off, here’s the front and back of the business card. Since the observatory is not currently open to the public and the goal of the card is to point people to the website (and to just look cool!), there’s no additional contact information.

Here are a few different views of the holder, with more on the gallery page.

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TEMP-est TEMPerature Equilibration System for Telescopes

Deep Space Products sells these neat looking vent replacement fans for the Celestron CPC series telescopes.  While they have a rather confusing selection of choices depending on whether you have a newer (e.g. EDGE HD) or older model, wedge mounted or separate OTA, etc., most of the difference between the different stock vent configurations are two fans vs. three.  For older scopes without vents there are options to drill your own holes and add theirs, but at that point, why not just add your own fan?  There are a variety of color choices, but even there the ordering process is a bit disturbing, since you’re asked for a backup color in case they’re out of stock on the color you want.  I went for the orange to complement my Celestron gear, and didn’t provide an alternate option.  Luckily I got what I wanted.

The vents look pretty nice, and fit was decent, although not perfect, as far as hole alignment is concerned.  I’m not sure whether to blame that on DSP or Celestron, although the Celestron covers don’t appear to have an interference problem with the screws.  As far as the electrical connections through the back of the OTA, I found that process a bit hokey, with the supplied “Y” jumper cable being too short to route the cable around the clutch pins and focuser shaft, so it sits on the central baffle tube behind the mirror.  That makes me rather nervous about the potential of pinching the wires.

When I plugged the first fan in to my nominal 12V supply (typically 13.8V car battery replacement supply) I was rather disturbed and disappointed at the amount of vibration each fan had.  Even installed, there’s a fair amount of vibration detectable when I rest my hand on the body of the OTA.  Since I bought these to improve my  imaging quality, I’m rather worried at the potential degradation due to the added vibration.  I also don’t want to have to add a circuit to switch this on and off, nor lose the continuous circulation these are supposed to provide.  Just to be sure it wasn’t the power supply, a created a regulated 12V cable specifically for these fans and while I could detect a minor drop in pitch, there was no net improvement in terms of the vibration.

I pulled the fans back out to send back and took a video of the vibration effects. By letting each fan just contact the surface of one of my tables, you can hear the whole assembly bouncing off the table top. Some of them rattle pretty good, and when you get them all going, the vibration at the far end of the table is impressive!

Here’s the greasy jumper wire Y cable that was riding up and down the center tube of the OTA. Now I need to re-grease the tube to put all that back!

Since I was already making the investment, I also sprang for their Fastar cooling fan that goes into the front of the SCT after removing the Fastar objective mirror.  I did so only after contacting DSP to confirm that this would work for my 11″ NexStar  GPS, since I don’t intend to be pulling the objective on the Edge CPC when I’m imaging remotely.  This unit turned out to be even a bigger disappointment.  Unlike other such solutions that come with a storage tray for the objective and are designed to actually ensure circulation through the OTA, this was just a pretty simple block of plastic with a fan attached to one side.  The design assumes that you’re using it on a vented OTA, so it’s really useless for my NexStar GPS unless I open up the eyepiece hole and leave it open for stuff to fly up into.  Without that, the fan would just sit there and cavitate without moving any air into the OTA.

So in all, I’m pretty disappointed in my purchase from Deep Space Products and in the lackluster response from Edward Thomas at DSP once he had my money.  I certainly wouldn’t have bought the Fastar fan had I realized its limitations.  The other components at least saved me the effort of printing my own parts, but I wouldn’t say I got my money’s worth.

As usual, there are more images in the gallery.

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Telescope Collection Menagerie

I have a Celestron 8se that I picked up used and in rather bad shape and after tuning it up I’m planning to resell it to a worthy home.  However, before I let it go I realized I needed to capture a picture of the huge menagerie of OTAs and mounts that I’ve collected in recent years.  Thus, I packed everything up and hauled it all out to the observatory for a photo-op.  I think the results are pretty impressive.  I even have the original culprit telescope framed in the background.  I just should have added all my binoculars and the SkyScout as well!

A trio of Celestron NexStar SCTs:

And a trio of Meade achromatic refractors:

Finally some aerial views:

As usual, there’re more shots in the gallery. Just follow the links.

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EdgeHD CPC Elevation/Declination Axis Rebuild

After completing the bearing upgrade on the azimuth/RA axis of my Celestron CPC Deluxe 1100 HD 11″ EdgeHD telescope, I followed up with a rebuild of the elevation/declination axis drive.  This effort was more about addressing issues with the drive mechanism itself rather than just working on the bearings.

The EdgeHD was still on the tripod in the warm room from the azimuth axis rebuild.

I started by removing the clutch knob by loosening the setscrew that captures it and unscrewing, just like the azimuth axis. In fact, several of the clutch parts are identical to the azimuth axis, and the procedure is the same.

Six screws, four short and two longer ones up near the OTA, hold the plastic outer cover from the inside.

Four larger screws hold the metal handle insert to the aluminum frame. All ten screws must be removed to take off the cover. Ideally, these four would be removed first. First two:

Oops, two more!

There’s the inside view of the plastic outer cover and bottom handle.

And a shot inside the drive fork assembly, showing the servo motor, gearbox, and worm gear.

Here’s a close-up of the worm gear and drive unit. The drive looks similar to the azimuth drive, but the main aluminum worm gear is obviously smaller than the brass one in the base.

After slipping the main worm gear off the clutch plate, you can see the rubber sheet on an aluminum assembly that appears identical to the azimuth axis clutch plate. Note the Allen wrench tool being used as a spacer to keep the spring loaded worm from hitting the clutch and getting grease on it.

The declination/elevation axis worm gear is just a simple aluminum part with no additional features. Not a great picture, but I’m not about to take things back apart to get a better one!

The declination/elevation axis has the same two flats and key for attaching the clutch plate.

Close-up of clutch plate showing set screws and center socket head cap screw. Looks a lot like the azimuth axis clutch plate, doesn’t it?

After removing the nut and washer, the same thrust bearing as the azimuth axis is visible.

After laying the scope on its side, declination axis pointing up to minimize stress, the bearing slips out easily.

The removed thrust bearing. Again, this appears to be the same thrust bearing as the azimuth axis.

After cleaning and re-greasing the bearing it’s re-installed.

And finally re-installing the pressure nut and washer on the bearing.

Now comes the fun part, working on the drive assembly itself. I start by loosening the gearbox. Two screws hold the gearbox to its mounting bracket. Removing them allows it to rotate around the worm gear axis.

Here it is tilted up to expose the two socket head cap screws that hold the whole assembly to the frame.

Removing the two socket head cap screws releases the drive assembly.

With the drive detached, we can inspect it from the sides. The “left” side of the drive shows the pivot set screw, worm bearing, encoder, and tension adjustment screw.

From the other side, the cover of the gearbox is held with three screws, and you can see the exposed pivot pin and bushing.

Removing the thee screws to expose the guts of the gearbox reveals five gears total.  There are three floating gears and spacers on pins in the cover and then the motor and output shaft gears.

After removing the set screw and sliding out the pin, the assembly comes apart.  The bushing inserts are both through-hole and nothing holds the pin in other than hydraulic pressure of the grease.  That’s why when I got this scope the DEC axis bounced all over the place.  The pin had slid out of the bushing on the set screw side and was allowing the worm to move back and forth about a centimeter or so.

The shaft coupling appears to be Loctited to the shafts and won’t come loose even with set screws removed.

After cleaning and oiling inaccessible bushings and re-greasing everything, the drive is re-assembled. Keeping the pin in is tricky when installing the set screw, since the grease and any air pressure wants to push the pin out. The set screw must be tightened enough to clamp the axis snugly enough to keep it from sliding back and forth on the axis pin.

Now I can install and align the main drive gear and drive assembly prior to re-greasing.


Here’s a side view of the worm gear teeth while they’re nice and clean. This is definitely a much lower-end gear compared to the azimuth axis gear. While it’s obviously not as critical as the RA axis, it’s still more cheaply made, with just a straight cut at an angle, instead of the curved cut on the brass RA axis gear.

Between this and the difference in the drive gearbox, it’s apparent why my RA gearbox has the 1:1 spur gear with no cover, instead of the similar gearbox as the DEC axis as shown in Gary’s guide.  If you go back and look at that guide, you’ll see that the older CPC used the same aluminum worm gear and five gear gearbox on both axes, while on the CPC Deluxe HD, the RA axis uses a bigger brass worm gear with a better overall tooth profile.  That would change the gearing ratio to the servo motor to get the same overall encoder feedback.

Here’re some views of the worm gear assembly re-greased and ready to go.

For a real hoot, check out this video of the drive in operation, after running it back and forth to run-in the grease. It’s amazing how much wobble the gearbox has on the coupler, which is why it’s mounted on a spring bracket.

While re-assembling the cover, take note. The upper two screws are of different length, with the longer one for the thicker side of the fork pylon. The two screws should extend through the same length.

Now on to the handle-side axis. Remove the aluminum handle first with the two large set screws that attach it to the aluminum frame. The remaining six screws that hold the plastic cover are the same as the other side.

Here’s the handle side cover, inside and out.

And the interior of the handle side fork pylon showing the simple lock nut and the GPS antenna. The antenna is well placed for Alt/Az mode, but not necessarily ideal for wedge mounting.

Here’s a closer view.

After removing the lock nut and washer.

There’s a simple flat roller bearing with another steel washer under the lock nut and several washers.

The roller bearing rides on a large flat washer held on with a thin layer of red Loctite. Mine was not properly centered (obviously slipped before the Loctite hardened) and was rubbing against the top of the shaft.

You can see the Loctite residue on the back side of the large roller bearing washer.

The thrust bearing is under a special lock ring behind the washer. This is where I stopped due to the special tool required for removal. I figure the grease is probably still fine and if I have to get back in it later, I’ll deal with it then!

Here’s what it looks like after centering the larger washer and re-installing the re-greased roller bearing and lock nut.

And finally, putting everything back together in reverse of the way it came apart, the scope is mounted back to the pier.

It’ll be a while before I have time to test everything well and come to any conclusions on the performance of the upgrade/repair/destruction I accomplished here! However, a few comments so far. First, while I was a bit worried that the azimuth bearing felt a bit gravelly when I swung it around manually in AZ mode, once I put it on the wedge, things changed drastically. The ride is extremely smooth under all that offset weight, which puts much more force than the vertical force in AZ mode. I do hear a small clatter every 360 degrees when I roll it around continuously, which almost makes me wonder if I dropped a ball in there. I think it’s just one ball rolling over the small gap in the balls in the outer bearing, but who knows. I can’t imagine how something loose would only clatter in a very narrow region. Beyond that, I do currently have a problem with the DEC axis slipping teeth when I try to pass a certain point. The setup is well balanced horizontally around the pivot, but not top to bottom, as you can see. Previously I had over-tightened the spring tensioner on the DEC axis so it couldn’t slip, but I think I’m going to try putting a piggyback on top again to better balance it and see if that works. I’d rather have the safety of being able to slip a tooth if something binds, but before I was getting quite a bit of hysteresis/backlash from the gear not meshing tightly, so we’ll see if I have to dig back in and adjust that later.

One other thing I’ve noticed is that I may have done too good of a job of cleaning the rubber pads on the clutch plate and the gear pressure plates.  They tend to stick when released and take a bit to break loose when released.

I did run some initial tests with PHD, and while I can’t say much about the RA performance, I did see a very regular sawtooth pattern on the DEC axis performance.  That may be that my polar alignment is off, since I haven’t re-tuned the wedge after remounting, and it does have some play.  From my initial alignment, the NexStar polar alignment indicates I’m off one degree in both axes.  Interestingly, however, after having it lose communication on me and re-aligning, it indicated I was almost dead-on with only seconds of error, so who knows?!!  This was also not a true 1:1 comparison against earlier results as I made one change to the PHD settings, going from the 0.15 pixel default to a 0.5 pixel setting for the minimum error setting.

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EdgeHD CPC Azimuth/RA Axis Rebuild

In a somewhat misguided attempt to improve the tracking on my Celestron CPC Deluxe 1100 HD 11″ EdgeHD telescope, I decided to perform the bearing upgrade described by Gary Bennett on the NexStar Resource Site.

I started by moving the EdgeHD to the tripod in the warm room in order to prepare for the azimuth axis rebuild.

I attempted to measure the force required to rotate the azimuth axis for a before/after test. I didn’t have a force gauge handy, so came up with a pretty simple scheme for using gravity to test for how much weight it took to overcome friction. By determining how much water weight was needed to get the axis to rotate, I could compare after the upgrade. Unfortunately, it turns out most of the friction was from the clutch assembly and not the bearings, so there’s really no way to use this information to determine if I improved anything.

After partially removing the set screw to clear the upper lip of the clutch base, the clutch knob unscrews completely revealing the Teflon pressure plate that lets the knob slip to loosen or tighten the clutch.

The spur gear servo motor drive turns the worm gear on the far side. You can see the black encoder on the back of the servo and the PEC reference sensor on the main worm gear shaft. The spur gears connecting the motor to the output shaft are typically covered with a shroud. Not sure why my unit doesn’t have it. Also not sure why they need a 1:1 gear vs. finding the space to direct drive the worm and eliminate that additional point of play.

The main board cover plate must be removed to get to the third screw on the front side cover panel. Turns out it’s not necessary to remove ALL the screws. The four screws on a rectangular grid hold the controller PCB to the panel, so removing the four screws along the edges allow removal of both the panel and board. See the re-assembly pictures for more info.

After removing the aluminum cover, I can access the third cover screw. I just left the board and cover hanging rather than having to label all the connections before disconnecting.

The main gear just slips off the bottom plate. There’s a bit of grease in the middle to let the brass gear slip when the clutch is disengaged. There’s a textured rubber pad on the plate to actually create the clutch grip.

Here’s a close-up of the clutch plate showing the rubber textured sheet, the grease on the hub, and one of the set-screw holes.

Here’s the brass main worm gear and clutch plate after wiping off most of the grease and contamination.

After removing the two set-screws and center screw, the clutch plate will slide off the center spindle of the AZ/RA axis. There are two flats for the setscrews and a key/keyway to keep the clutch plate solidly attached to the spindle, which is embedded in the non-moving aluminum base of the scope.

The nut came off the center spindle rather easily, although you can see the remnants of red lock-tite.

The tapered shaft bearing slipped out easily, freeing the upper assembly.

Here you can see the upper assembly after lifting off the base. The portion that rides on the outer bearing is just a flat surface with a taper to the middle. A lip around the edge minimizes dust infiltration.

It turns out that the CPC Deluxe HD mount uses a mix of metal and nylon bearings. The balls appeared to be greased in something the consistency of Vaseline. The nylon balls appear to be slightly larger than the metal, but that could be an optical illusion. This mix of metal and nylon appears to work much better than the old approach of using only plastic bearings and after removal of the clutch, the motion was quite smooth and easy. However, by the time I determined that, it made sense to investigate further. By this point, I’m already here so why not try the all-metal approach, saving the existing balls in case I need to put them back.

In the process of removing the bearing balls from the original installation, there were a number of machined metal chips in the bearing and grease that I removed when I cleaned everything up. It’s rather depressing just how dirty the mechanical components were left by Celestron’s manufacturing team.

After cleaning the base of both components to remove all old grease (and any metal bits), you can see the bearing channel and lip.

After removing all the grease with a vigorous dip in solvent (paint thinner) the center capture bearing is nice and clean.

I’m using AeroShell 64 Molybdenum grease, which is a high end aircraft grease with a broad range of operating temperatures and is suitable for high pressure applications. The 1/4″ bearings are stainless steel.

Here’s a picture with all of the 123 stainless steel balls installed with a coating of the moly grease.

Setting the upper body carefully on the base, everything rolls quite nicely, although the all-metal bearings are a bit noisier as the balls rattle against each other. The next step of re-inserting the thrust bearing to capture the unit ended up being the hardest part of the whole process. The tolerance to the center shaft was so tight that the bearing tended to bind with only a mm or so of engagement when not perfectly aligned. This resulted in having to remove the entire assembly multiple times to use the scope to pop of the bound bearing. In the process, the new bearings were upset at least once and had to be re-worked. ARGH! Eventually it went on correctly and I was able to complete assembly. Given the constantly greasy hands, and simple reverse process, it didn’t make a lot of sense to take a bunch of pictures going back.

Finishing up the re-assembly with a shot of the aluminum cover attached to the controller PCB, you can see the four screws that I shouldn’t have removed that attach the panel to the aluminum standoffs.

Here’s a shot of the re-greased main gear and worm assembly after running everything in.

And finally, all closed up, here’s the finished re-assembly of the AZ/RA axis base.

Next up, I still have to rebuild the DEC axis that’s given me more problems in the past. We’re currently in a full moon phase so there’s no point in remounting it anyway, so I haven’t tested it after the alteration (I hesitate to call it an upgrade at this point). More to follow when I get things tested.

As usual, there are more images in the gallery than I embedded here, so if you follow the link icon, you can browse any details you missed.

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