The IEXOS-100 Mount Problem Seemingly Solved

The problem with getting the ExploreStars app to reconnect to the mount seems to be solved. The app connects to the mount through TCP which is a connectful protocol unlike UDP. (Stuff i learned last century.)

It seems that leaving the app to do anything else or depowering the mount leaves the app in a state where it still has a connection open. Solution: stop the app. Force Stop (clumsy) or drag the app off the home screen which stops it.  Restart opens a new connection. The app has no stop or quit command. 

I was able to reconnect multiple times this way. I can do two star alignment after reconnecting.  I wish the Envision version which runs on Android cellphones would successfully connect.  A phone is more connection than a tablet for this. 

The Explore Scientific iEXOS 100-2 Mount I Bought

I bought this because I wanted a small easy to transport mount for public astronomy with my Televue-85. That it was a goto mount just made the.$300 price all the better.  It is very well made so I was very disappointed when it started behaving erratically a few days after it arrived  

The factory said it was fine. When it came back, i suspected the problem was that it needed more than 12V to operate; goto mounts demand a lot while slowing across the sky 

It now appears that the intermittent problems that I am seeing hs because the bundled ExploreStars app is, in the words of SuperGrok, "abandonware": software free but largely forgotten by its authors and supported like they no longer remember their child. It works but unreliable enough that few people use it.

What most owners of the mount use are ASCOM (a standard free Windows driver package) or INDI (the Linux equivalent). Planetarium programs such as Carte du Ciel and Stellarium can control the mount through the ASCOM drivers telling it where to go (ditto for KStars in Linux). So using a laptop, not a tablet or cellphone. This takes away much of the simplicity of a small tablet.

Kstars under Linux is pretty clumsy to control the mount. Setting these up under either Linux or Windows is clumsy because you are either on the Internet reading instructions or connected to the mounts server, not both. Lots of disconnecting and reconnecting. I ordered a USB WiFi adapter so that I can have both open at the same time. I have done this before in the 1980s where I set up a PC with two Ethernet cards to create a LAN analyzer, so i know it can be done.

In any case, if it turns out to be too clumsy to use for goto, it is still a nice compact mount for public astronomy. 

UPDATE: I spent some time with the manual for Explore Stars (which does not match the app), some time with SuperGrok, and some analyzing what it seems to want to do. I think i have ExploreStars app figured out. I will try this tonight.

UPDATE 2: Up too late gathering documents for the HELOC.

UPDATE 3: Low amperage.  The battery had been used to operate the Losmandy and the iExOS without recharging. 

Telescope Winch

The new house will need a telescope winch for lifting Big Bertha off the base and the 8" reflector off the Losmandy mount 

I have been thinking about all night.  I will four pulleys secured to studs in the garage ceiling. Ropes through pulleys. One end of each rope will need a hook that can grab a loop without scratching.  The far end of each rope will be tied to weight plates.  For lifting Big Bertha, two 25 pound weights on each will counterbalance most of the weight.  About 10 pounds of force pulling down to lift the telescope off its base. Then push the base out of the way and slowly lower the telescope to the ground.

For moving the 8" reflector, loosen the clamps holding it on the mount, and obe 15 pound weight on each rope to lift it off. This requires a stand under each rope end where the weights will sit when not actively lifting telescopes. 

I have done this before for moving a anowplow from my wife's Blazer.  I was younger and strong enough to put the pulleys and rope up myself. 

In case you are curious, this is part of how multitasking stones ended up at the top of cathedrals. Counterweights means you only need a few dozen peasants pulling on the rope 

Latitude Change

My 17.5" Dobsonian sits on an equatorial platforms. This is a clever, somewhat magical (to me) method of making an alt-azimuth mount track stars across the sky.

Unfortunately, equatorial platforms are latitude-specific. They are simulating having the telescope move across the sky as though they were turning in a circle around Polaris.  As I said, somewhat magical 

Besides the latitude-specific nature of the equatorial platforms, they have several other deficiencies. They typically only track for about an hour, at which point you unlock one clamp and rotate it back along its magical pseudo-polar axis. This is not a big deal for visual use, especially for public astronomy.

For astrophotography, there are two problems. That reset will make your 4 hour exposure of M51 completely useless. 

The obvious solution to latitude is to raise the south end of the platform by seven degrees to compensate.  In this case, 21.5" (distance between front and rear of the platform times sin (7 degrees). This gives a 2.62" lift. This does not sound so bad. It scares me thst it might be unstable to move the center of gravity that far to the side.

Alternative strategies:

1. Sell the existing platform (a lovely all-aluminum platform made by the late Gregg Blandin) to someone in my latitude and buy the more sophisticated platform made by Tom O.

2. Remove the OTA from its cradle, and attach it to a dovetail plate that goes on a high payload equatorial mount. This is very expensive, mostly because high-payload mounts are very expensive.  This is also slightly more uncertain as to how to make it work.

3. Rebuild the telescope in a carbon fiber tube which should get it below 50 pounds. High expense carbon fiber tubes 20" ID are not cheap), a lot of work, and uncertain results. 

Simpler, less obvious solution.  Shim the south end of platform 2.62". Bolt ground board to platform. Bolt platform to the board with casters. Even if center of gravity is a little off, it should not make it a leaning Tower of Pisa.

Public Astronomy

I assisted Boise Astronomical Society with a star party at Future Public School in Garden City. The name sounds like someone had a planning map for a subdivision and wrote Future Public School in a box and someone assumed that was the name not a projection.

This was in late afternoon so we were limited to the Sun and the Moon. The Sun has a pretty decent sunspot right now that is very big, many Earth diameters and a few freckles right at the limb.

Lots of polite kids very excited to look. There is a future for America. A couple adults curious to know about solar cycles and Earth climate.

I took my Televue-85 sitting on an EQ1 mount. This is really a bit more scope than this meant was meant to carry. It clearly was unhappy. I am inclined to buy a Vixen AP-SM mount. They are about 3x as expensive as the Chinese mounts of comparable capacity and features. The CFC mount project started because i thought the Vixens were no longer available in the U.S.

The Vixen mount is fairly light for its capacity, about 14 pounds plus counterweights.  Something i can pick up and carry seperate from the scope. (A Televue-85 is pricy enough that you do not want to trip while carrying it.)

I expect a substantial inheritance soon and I may buy it when that comes into my account. The EQ1 mount is appropriate for the 3" f/4.5 reflector i built some years ago.

My Wife Thought the Thumbscrews on the Wide Angle Finderscope Were Too Long

It looks much better now.

And you can see the packaging from Thumbscrew Depot (a US maker with a very narrow niche name).

It Is Still in Need of Some Editing and Paint Touch-Up, But It Works

That is a 25mm eyepiece in it, not what I will use in it for the wide angle, high brightness finder.  

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The tube needs to be shortened another inch to get more infocus distance for the helical focuser to go between extension tube and eyepiece. Then a little touch up paint on the PVC. I am pleased with the optical quality of what was a $15 objective lens. This has not received much of a test; chromatic aberration is more of an issue as magnification and brightness go up 

With the 25mm eyepiece, I get 6x, 7.5 degree field of view. The exit pupil is 10mm so roughly 75% of the light gathering capacity is lost going into a 5mm human pupil.  That is still more than three magnitude deeper into the sky than the naked eye.  I have no stars available for testing but used outdoors, the image is noticeably brighter than naked eye.

A couple possible choices of eyepiece for finder. The Svbony 25mm Plossl is cheap. It would give me 6x, but the Plossl design has a slightly wider apparent field of view, so i would get 8.2 degrees of sky. The Svbony 40mm Plossl would get me 3.8x and more than 10 degrees of sky. AstroMania 40mm is a bit wider so 12 degrees of sky. I am not sure that the extra field of view is really necessary and lower magnification means giving away light 

I Have Not Rolled the 5" Refractor Out in Some Time

It has the advantage that you do not a ladder to get to the eyepiece and it is a spectacular apochromat. But once I was outside, I discovered the focuser would not move.  Not even a little.

Cold weather froze grease? Cold tightened a close tolerance too much? Were the screws that hold the rear plate to the focuser axle too tight?

No, simpler than that but only after I brought in back inside, removed it from the mount and started disassembly. Thus is a rock and pinion focuser and the rack along the tube had gone beyond the pinion.  I needed to gently pull the focuser tube out far enough for rack and pinion to mate.  I think i will epoxy a piece of plastic at the last slot in the rack that will prevent him from going too far in again.

Blackening Aluminum

That lens cell needs to have no reflections.  Flat black paint is one solution but I wanted to not change the dimensions.  Hence using blackening compounds that promise they are non-dimensional.  In this case, Birchwood-Casey Aluminum Black. This is really for fixing scratches on your AR15  but dunking the cell in it and leaving it there for an hour seemed to be adequate. 

The label warns that it is corrosive.   I did not feel any effects but watching the aluminum bubble in it tells me that there is some acidic reaction under way.

The next step is going to a friend with a retaining ring wrench to put the ring at the back of the lens.

Adventures in Optics Part 2

This part with the threaded end holds the lens and a 2" ID pipe slides into the non-threaded end.

The threaded end was 1.91" ID, so it would have partially obstructed the 2" diameter (actually 52mm) of the lens.  I was going to amputate the threaded version but then I found this threaded end cap:

I now have a cool dust cap that will never wear our or get easily lost.

I still have a few holes to drill here and there.  This ring goes inside the threaded fitting part to both center the lens in the tube and allow me to put setscrews in that fitting to press that ring for collimation adjustment.  

This started out as something else and needed to go from .5" to .25" wide.  Cutting on the mill would require tightening it down more in the mill vise than would be advisable for a weak, brittle material like PVC.  The lathe was the obvious choice.  Cutting that much off using the standard lathe tool is not practical. I do not have a parting tool for the lathe.  Perhaps I should get one.  

Solution: put it on the three jaw on that rotary table.  Bring 1/8" endmill to the outside of the ring.  Cut down into the ring very slowly.  Rotate the table at 50 inches per minute 

This is a cheap, likely only so-so strategy for collimation, but this is a finderscope, not a high end refractor so good enough 

This is how it will look after I get the lens in place.  The big ring on the left is a union to hold the main tube and eyepiece draw tube together.

One more thought.  The drawtube is now very thin wall.  1.31" OD and 1 25" ID.  I doubt that a thumbscrew would hold in such think material.  I will cut a 1.5" OD, 1 31" ID x .5" piece of carbon fiber to glue on the end of the drawtube, then tap a hole for the thumbscrew.   The black of that part will go nicely with the black of the helical focuser as contrast to the rest.

I am still waiting on 52mm ID O-rings.  In the meantime, flat black paint on interior and bright white on exterior. 

Paint.   I should have thought this through before pulling out the paint cans. Tape all holes on the inside before spraying interiors.   Then tape all holes on the exterior, paint exterior and interior. Then remove all tape on interior and paint again.  Then remove retake interior holes and paint exterior again.  Otherwise you get spray through the holes.  I will then touch the ends with a brush.

Reducing Vibration in the EQ1 Mount

I previously mentioned that when I used the EQ1 mount last time, it was so sensitive to vibration thst adjustment of focus started it quivering for about ten seconds.   If you are patient,  this is okay.

A couple tricks for reducing vibration on this cheap mount are to collapse the legs to minimum length and the tiny screws that hold the legs to the base on the mount.

So I did so.   Big improvement.   Vibration is less than three seconds.  I also get to observe from a chair.   This is really useful for public astronomy where you have small children.  Also, I can pick up and carry the mount with the legs collapsed fairly easily and then put the Televue-85 on it. The CFC mount should be even easier. 

The next step of improvement is adding a hanging weight to damp vibration.   The mount tracks well.

Jupiter is a bit low and viewing conditions were less than ideal.  108x was no more detail than 90x--multiple cloud bands.  It is still amazing for such a tiny scope.  

Going Grab-and-Go

One of the new trends in amateur astronomy is the grab-and-go telescope.   Instead of a behemoth that takes an hour to set up, you settle on some nights for a scope on a lightweight mount that you can just pick up and carry out.  This is also attractive for public astronomy where you go somewhere to share the night with friends or the general public.   It simplifies transportation a lot.

My Televue-85 is almost in that category.   I use it on an Orion EQ1 mount, which causes laughter in some circles.   It is the equivalent of a Porsche on bias-ply tires.

I take the mount out separately from the Televue-85 because it is a hideously expensive piece of optics.  If I drop the mount,  it likely will experience no appreciable damage; it only cost about $200.

I am going to be doing some public astronomy in Nevada next month.  Tonight. I was verifying that the mount tracks the sky adequately with the Televue-85 and its weight on it.  It does.  Jupiter was my test subject.  At 30x, all four Galilean satellites were easily visible.  At first,  I was disappointed at Jupiter.   But there was just too much sky glow.  As it darkened, several cloud bands appeared. 

My left eye is noticeably inferior in resolution, even with corrective lens.  My ophthalmologist says it is a fundamental aspect of the retina and is not correctable.  I am reflexively used to observing with my left eye.  I have to consciously use my right eye.

The downside of this cheap mount is that even a little vibration starts and it takes a whole to calm down.  The mount that I am building will not have that problem. 

That Delrin Bracket

I made it out of Delrin, not carbon fiber composite (CFC) for three reasons.

1. because I thought I would need to make a bearing in which to rotate the spur gear.  I did not.

2. Because one part seemed to require me to mill a slot that would destroy a big piece of CFC, which is not cheap.

3. The easiest way to make this part involved attaching one part to another and I really do not like the threaded insert approach to making threaded holes in CFC. 

But this morning,  while waiting for church to start,  I suddenly saw a solution.   This is good because I need to make two more of these brackets to hold the slow motion controls for the Right Ascension and Declination axes.  Machining this bracket out of a single block of carbon fiber would be slow and expensive.   

I have avoided epoxying parts together because I like to make things that are repairable.   This solution only requires gluing the vertical part that attaches to the polar axis housing and the horizontal piece that holds the stepper motor.  The vertical part still has slots allowing vertical adjustment and the slots on the motor mount allow horizontal fine adjustment. 

I used 1/2" thick acetal because I had a big enough sheet of it lying around and i wanted the extra stifness for thr weight of the stepper motor.  I have some 3/8" carbon fiber sheet that I can use for the vertical and this stuff is stiff in a way that Delrin can only dream about.   I am using 6-32 screws to attach to the polar axis housing so there is plenty of material on either side of that through hole.

The 1.09" slot I can cut using a .122" end mill.  This will drop a .375" x 2" x .122" (or a little less) piece of CFC, for which I do not yet have a use but I will look for a way to use it 

The horizontal component that holds the stepper motor is again 3/8" CFC, so far stiffer than required. 

Also, for future blind hole threads, I think it makes more sense and easier to epoxy a 6-32 stainless steel stud into the hole and use a hex nut to bind two pieces together.  Buying 6-32 stainless steel nuts and studs in small quantities seems to be difficult.

Stepper Motor Turning at 1/24th RPM

It took some fiddling but the stepper motor is now at a speed that will turn the worm gear at 1 revolution per day.  I am almost done with the bracket to attach the stepper motor and gears to the polar axis.  Here I am slotting a place for the polar axis housing. 

Yes, I need to rotate this video. But I am doing this from phone in bed.

The slot is deeper than wide because I need some room to adjust in at least two directions for slight variations in positioning of the gear.