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Cave GEM mods, including Byers drives

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#1 dhferguson

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Posted 21 June 2019 - 03:57 PM

Cheers,

 

This long post is about my experience modifying my 1.5"-diam. shafts Astrola GEM to include better latitude adjust, Byers drives, an electric focuser, and a hand controller. I am the original owner and the mount has been well cared-for over the years. Ye Olde US-made mid-market cast aluminum GEM mounts are no longer being manufactured (Parks was the last manufacturer, I think). Rather than choose between a hyperbucks AstroPhysics or a cheap Chinese mount replete with plastic parts, I wanted to keep my Astrola but make it perform the way I wished. BTW, contrary to some posts I've read, the old US mounts can be quite good indeed. For example, the SealMaster bearings used in the Astrola mounts are first-rate. These older designs tends to be slightly more "bouncy" for the weight than modern semi-equivalents, such as Losmandy's offerings, because some (like Cave's) lack thrust bearings and because there is a larger offset between the cradle and the "tee" (allows for bigger RA gears, though). Outfitted properly, the old Astrola mounts can be quite suitable visually for telescopes lighter than about 60-70 lb (mine is at the limit) and--fixed up for auto guiding with better drives--photographically for 35-40 lb or less. Find a well-cared for mount, use a little of your skills, and you too can have a "classic" mount that performs well. Ignore the negativity: this comes from people who unrealistically expect a fifty year-old mount to perform like new without any upgrade or even servicing.

 

Many of you have significant machinist skills and tools, and I greatly admire your handiwork. However, while "handy," I am not in your category, and I expect most of us are not. Part of this post is to show that such skills are not necessary for decent-looking results, albeit not in the class of fine machining. In addition to the usual hand tools generally found at home, I required additional easy-to-find tools. These included: a table saw equipped with a metal cutting blade, a drill press and an x-y stage (Proxxon) to "convert" the drill press into a small mill, small mill bits (no larger than the 1/2' chuck on my drill press), good-quality taps in the following sizes: 6-32, 8-32, 8-24, 10-24, and 1/4-20, and a 2" hole cutter (the kind used for wood will work on aluminum if slowly but will screech horribly--wear ear protection). Also, I required various inexpensive tools to prepare "keystone" wire connectors. Regarding materials, metal of all sizes can be found on eBay and Amazon, as can connectors, fasteners, etc. I am fortunate to have a Fastenal store nearby, which stocks pretty much every machine screw size/head imaginable. Also, I acquired plastic for the drive housings from TAP Plastics. They were very helpful regarding forming techniques, BTW. Also, when you are milling small slots, that x-y stage must REALLY be bolted down firmly to your drill press. Try it with a piece of scrap first. Finally, it is crucial that you wear eye protection goggles when cutting or drilling, especially when using the table saw. The metal chips absolutely WILL get underneath your eyeglasses--plain safety glasses are not sealed well enough. Please heed this warning.

 

One of the two major problems with the Astola mounts is the poor implementation of the drives, especially the RA drive. The clutches are undersized and finicky, and worse the RA worm is mounted within an aluminum "U" that flexes when the polar axis is rotated. I elected to change both drives out. Byers is now selling off the very last of his wonderful drives. I was fortunate to have acquired new two drives in 2014: a 9" 360-tooth gear for the RA axis and a 7.1" 252-tooth gear for the Dec axis. They arrived, and to my surprise and delight they were perfect suck fits to my axes, hooray! I might have preferred the 359-tooth RA gear but they were already sold out and gone. Nevertheless, the acquisition of a 360-tooth gear means I could, if the fancy struck, rather easily convert my drives to DC stepper motors using a Losmandy controller. I nevertheless decided upon old-school AC synchronous motors due to their lack of failure-prone and ... eventually ... near impossible-to-replace electronic components, and the fact that I have unlimited AC power in my backyard. I also acquired a used Lumicon AC drive corrector to modify the AC motor speed a bit, although this would really only be necessary for astroimaging.

 

Oh, CN only allows 500KB images per-post, so I will add posts with the figures I reference here. Figure 1 shows my 10" f/6.6 telescope with the completed drives. I've since completed the electric focus module, and I will provide this image too shortly. I removed the original Cave Dec drive and chose to mount the Dec housing below the "tee" for better balance. That is a standard Cave weight you see and the additional weight is a 2" I.D. 5 lb barbell weight with a bushing made from 2" OD PVC. It works well. The entire tube assembly, including the rather heavy Parallax rotating rings, weighs 68 lb w/o eyepiece but with (not shown) a 2 lb sliding balance weight on the bottom of the tube on the opposite side of the tube from the focuser. The wrapped-up wires are for the electric focuser. In addition to the Lumicon drive corrector, you may notice the AC/DC converter. This provides power to my Argo Navis DSCs, whose encoders are contained within the two drive housings. BTW, the handle on the top plate really helps hold the tube for carrying. I do not find it at all difficult to lift and secure the tube to the mount (I am in my sixties!). Per other posts here and on the cave-astrola.com website, I cleaned, primed, and painted the mount and pier, and also cleaned up the brass fittings with Brasso (avail at Wal-Mart but, apparently, not at Target).

 

The drive plates began as a 3/8" thick  12" x 10" rectangle for the RA and 10" x 8.5" for the Dec plate. These were both tight fits, and I would encourage the builder to carefully lay out all components before sizing these plates, making special allowance for movement (adjustment) of the worm gear block. Figure 2 shows the RA drive plate. I cut both drive mounting plates from 3/8" aluminum plate, just like the originals but of course larger. I used many straight cuts, working my way around the semicircle, and then filed the curve smooth. I used a standard wall mounting plate with 4 keystone connectors to attach the sundry wired connections: (1) from the Lumicon drive corrector, (2) RA encoders to the Argo Navis, (3) Dec encoder to the Argo Navis, and (4) space for an ST-1 autoguider port. All the external wires are loomed. Also, note the stainless steel latitude adjust turnbuckle that connects between the RA plate and the pier. This allows for precise latitude adjustment, and fixes the other of the two major problems with the Astrola mount: latitude adjust. The turnbuckle geometry is arranged to avoid imposing any push-pull load on the mounting plate machine screws threaded into the polar housing. These are 8-32 and threaded into aluminum, so stripping these by overtightening the turnbuckle would otherwise be a risk. The turnbuckle eyes were opened somewhat for ease-of-removal using a vise and pry bar.

 

Figure 3 shows the back of the RA plate. The main gear is removed to expose the construction. Note the encoder wheel and belt (belt supplier is Bando). Length of the belt is critical to get the right fit. The black steel-sheet mounting bracket was salvaged from my old, external JMI implementation. I used socket head machine screws for attachment of components. All my external wiring connections are via junction block for two reasons: (1) inadvertent pulls on external wiring would not damage the internal wiring and (2) it makes continuity testing easy. #2 proved very useful. Also note the three 8-32 machine screws that attach the RA plate to the polar axis and the slotted "RA Motor Block," which allows for adjustment of the worm to the gear. The lock washers are necessary to maintain adjustment, BTW. The RA and Dec motors are actually powered separately but a single double-throw switch turns them both "on" at once.  Very important for safety, and unlike the original Cave wiring, I have grounded both RA and Dec power inputs to case. That is the back of the "on" light located just below the "PWR ON" label, just like with the original Cave! Finally, those of you with sharp eyes will note the RA motor is wired incorrectly. Byers' instructions were inadequate on this point but I fixed it and added the necessary capacitor (see the Hurst Motor specs on the web for better instructions). While I allowed space (lower left-hand corner of the plate), I have not yet wired in the ST-1 auto guider port. I may be asking you all for help on this forum soon! The RA & Dec drives and the electric focuser are all wired into the hand controller, BTW.

 

Figure 3, "RA_Drive" (next post) shows the drive installed without the plastic cover. The bottom of the cover is constructed from 1/4" aluminum plate with 3/4"x3/4" aluminum standoffs for strength at the corners and ends. I attached all these and the plastic too with 6-32 flathead machine screws. I used the same knurled brass screws from the Cave original housings to attach the standoffs to the mounting plate, and they screw and unscrew easily by hand. I used 3/8" thick plastic from TAP plastics for the cover, the plastic being mortised using a table saw before forming to fit the underhang on the aluminum standoff visible in Figure 3. Also, see that the clearance between the standoff and the gear is quite tight. Just for fun, yes, that is the original Cave-supplied Dec controller box wound around the polar axis, it's long since been removed. I used opaque black plastic with a mottled surface to best replicate the look of the original Cave mount (see Figure 1), although I was tempted to use clear plastic instead, the better to admire the innards. Molding the plastic is critical and I recommend you take your time constructing the mold for best-fit. I sized and cut plastic edge trim gardeners use to delineate the edges of lawns screwed to plywood for my mold. I fit the mold carefully to what you see in Figure 3 except with the main gear out. You will need to soften the plastic flat in the oven, then quickly form it about the mold. Also, get the necessary advice on temperatures and softening times from your local TAP Plastics store, they are helpful. Plastic outgasses poisonously when heated. I did use my kitchen oven but I opened up all the windows, then cleaned the oven assiduously with oven cleaner afterward. Oh, you-know-who was out for the day, and 'wondered how the over got so clean. 'Better to ask forgiveness than permission. After forming, the plastic required an additional standoff at the top for strength.

 

Now you've done it, the cover is too tight and the main gear rubs! You might use the table saw to shave away a bit of the standoffs if these are the problem. Or, if it is the plastic cover, you can use a Dremel tool to carefully remove a bit of plastic from the inside surface. I needed to do just this with a slightly too-tight Dec housing cover.

 

Note too that the thicknesses of the housings are also critical, especially the RA housing thickness. By careful measurement, I was able to still install the mechanical 6" setting circle on the RA axis, although that and the locking collar made for a close fit. Yeah (laugh), they are undersized now, and with the DSCs I never use them.

 

I attached the Dec housing to the aluminum Astrola Dec casting using a large split collar that fits around the bottom of the housing. I drilled and tapped this collar in the collar-thickness direction to attach the Dec mounting plate. Note that you can warp the somewhat thin aluminum casting if you tighten the collar too tightly. Tighten it some, then note when the axis begins to bind, then back off. I'm sure it will still be more than plenty tight. I have since experienced zero slippage whatever.

 

Figure 4 shows the electric focuser mounted to the tube. The wingnut atop the plastic housing loosens and the motor assembly inside slides to engage the JMI NGF-1 focuser knob. I bonded a disk of felt to the focuser knob using contact cement for half the clutch. The other half, likewise bonded to a DC 4 RPM motor (Servo City) is cut from a wine bottle cork. There is a 9V battery (3 RPM at 9V) inside the housing. It and the motor are mounted on a piece of aluminum plate that slides back and forth in the plastic case. The wiring exits through the bottom of the plastic case, through the aluminum telescope tube but then underneath the flock board (Protostar) to an exit point midway between the rotating tube rings. A 4-wire connector is used to connect the focuser to the hand controller wiring. Yes, I suppose in retrospect I could have wired the electric focuser directly to my DC power supply but the battery seems to last forever. The plastic box (Radio Shack) is mounted to the tube using cork standoffs that are sized to position the center of the cork aligned with the center of the focuser knob. BTW, the focuser works very well. I use it for high-power observing of the planets with this scope's superb optics.

 

Figure 5 shows the hand controller. It fits nicely in the palm of my hand! Check out Figure 3 again to see the RA & Dec drive controller wiring to the hand controller. The focuser is a separate 4-conducter wire included in the same looming as the RA & Dec drive controller wires. Regarding the wiring, it will save you time to check the continuity for each connection. In particular, the keystone connectors don't always crimp properly.

 

How does it all work? Very well indeed. First, the idea of putting casters on the pier legs was a stroke of genius, whoever thought of it (why did it take so long with suitcases?). It is just about the same effort to roll the telescope mount out from the garage as it is to "wheelbarrow" out my 14.5" Dobsonian to the patio. The Dobsonian is rock-steady but the Astrola mount has a fundamental vibration mode that damps out in about 2.5 s. This becomes quite tolerable even at x480 with the electric focuser. The Byers drives are a massive improvement over the original drives. Movement is silk-smooth and the telescope stays where you put it with almost indiscernible backlash. With the RA drive on, the target just hangs in the center of the field, motionless and wonderful. I haven't evaluated the periodic error but, based on the extreme stability of the drive (as compared with the original, whose tracking was at least acceptable visually) at high power, I expect it to be quite low. The hand controller works perfectly. However, unlike the Cave drives, the speed-of-motion of the Byers drives is now more suitable to astro-imaging than for visual slewing or scan patterns to find targets. Nevertheless, it is fun, for example, to "tour" the moon with the hand controller. The Lumicon AC drive corrector works well and the AC-to-DC power supply has eliminated the monstrous appetite for AA cells by my hungry Argo Navis unit. 

 

Was it worth it? If you enjoy modifying equipment for satisfaction and to avoid paying through the nose for similar performance, yes! If you want a "classic" look in a telescope that will outperform essentially anything else of comparable aperture and size, yes! If you wholly lack mechanical/electrical skills altogether but instead prefer to spend your way to bliss, no. I am not sure if I'll ever do astro-imaging (my Bortle 6 skies suck!). For someone who is absolutely sure to stick with visual-only, you might instead consider adding the Byers (or somewhat equivalent, see the Optic-Craft Machining website) 7.1" on the RA axis only. I selected the 9" drive in-part because the worm is supported on both ends. Flexure for the one-end version that came with the 7.1" shouldn't affect pure visual tracking much if at all. Such a setup would give you excellent tracking but of course no (or original Cave) Dec control.

 

I'll write an honest comparison of my GEM-mounted 10" and my 14.5" Dobsonian at some point, stay tuned, and of course ...

 

Happy observing always,

 

Don

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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  • 10%22-Telescope.jpg
  • RA_Plate.jpg

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#2 dhferguson

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Posted 21 June 2019 - 03:59 PM

Cheers,

 

 ... and the other figures...



#3 dhferguson

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Posted 21 June 2019 - 03:59 PM

Cheers,

 

 ... and the other figures...

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  • Figure 3-RA_Plate(back).jpg
  • Figure4-ElectricFocuser.jpg
  • Figure5_HandController.jpg

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#4 petert913

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Posted 21 June 2019 - 04:34 PM

Thank goodness for photos !  That was way too many words to read :)



#5 starman876

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Posted 21 June 2019 - 04:48 PM

That looks like fantastic work.  I bet the mount performs wonderfully.  With the right talent many items can be made to perform much better.  A lot of people that lack the knowledge to improve on a design have no clue what the potential of any item can be.  I look at everything and figure out how to improve on the design.   If I did not I would be throwing a lot of things away. A lot of people have posted wonderful threads on how to improve their equipment. 



#6 TOMDEY

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Posted 21 June 2019 - 06:07 PM

Congratulations; that's fantastic!

 

I amended a lot of functional upgrades to my old trusty Astrola 12.5 with 2.5-inch shafts. That indeed included a magnificent Byers 11-3/8 inch RA drive and my own concoction very functional Dec drive.

 

I know, I know --- many folks consider that to be rather sacrilegious... but WOW what performance improvements. From terrible to spectacular!    Tom

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#7 CHASLX200

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Posted 21 June 2019 - 06:24 PM

Congratulations; that's fantastic!

 

I amended a lot of functional upgrades to my old trusty Astrola 12.5 with 2.5-inch shafts. That indeed included a magnificent Byers 11-3/8 inch RA drive and my own concoction very functional Dec drive.

 

I know, I know --- many folks consider that to be rather sacrilegious... but WOW what performance improvements. From terrible to spectacular!    Tom

Looks like you have some kind of weights at the end of the shaft hanging out. I am sure them drives are much better than the stock drives.



#8 WoodyEnd

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Posted 21 June 2019 - 06:33 PM

Nice job.  If you could give details on the installation of the encoders I might tackle my Cave mount.


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#9 TOMDEY

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Posted 21 June 2019 - 08:56 PM

Looks like you have some kind of weights at the end of the shaft hanging out. I am sure them drives are much better than the stock drives.

Yep, the front of the scope is loaded with other scopes and cameras... so those weights rebalance things. With the clutches entirely disengaged, the thing is perfectly balanced, even for all rotations of the OTA. I no longer have the thing... sold it off for having way too many scopes and observatories. But it was by far my favorite imaging scope. The drives flawlessly handled even five hour exposures on film, but two hours was my average exposure... with sub arc-sec guiding the whole time!

 

Here's the Cocoon 3-hour exposure from back then, ~1985 single exposure onto film.   Tom

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#10 dgreyson

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Posted 21 June 2019 - 09:42 PM

Dag, now I need to go fiddle about with my Cave after seeing all the great ideas you've had.

#11 65&Counting

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Posted 16 July 2019 - 01:20 PM

Don - thanks so much for this fabulous thread - you've answered in spectacular detail virtually every question I've had about an 'original looking' revamp of the Cave 12.5 I just purchased out of storage and how mount shortcomings should be tamable - and more.

 

I knew that the obvious weak links on mount stabilization had to be be vastly improved by better drive/clutches on both axes and all the other goodies/explanations you've done here invaluable to a new Caveman - and your descriptions of reality are most refreshing.

 

Times have changed to say the least - but the most annoying part of that change is the lack of detail given on parts anymore and I've spent some money already on things that 'should' work or 'might' work but don't. When did loose parts stop having useful details?

 

I got a white tube 70mm Vixen refractor guidescope (largest that would fit within the stock guidescope rings that were still on the 12.5 Cave sans original 60mm guidescope) but the Vixen tube came with a 30mm guidescope but didn't have the orig bracket. No big deal, right? Good luck trying to buy a simple two screw guidescope bracket that will fit! Many are available yet it's seemingly impossible to find a used one on eBay or elsewhere without dropping $25 here or there on some 'guess' about hole spacing, tube sizing, etc. etc. and sellers aren't always very helpful with details.

 

I had the same problem just getting AstroZap tube covers for the 12.5 and be reasonably certain they'd be the right ones based on on-line specs that are vague - a phone call to a very helpful salesperson (who also had to check with others to be sure) - mission finally accomplished!

 

So again Don, I loved your discussion!!! You've obviously thought about a lot of the same things I have - and accumulated a treasure trove of info impossible to find in one place!! Many many thanks!



#12 dhferguson

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Posted 16 July 2019 - 07:02 PM

Cheers, again,

 

I think it would be worthwhile to mention how I obtained "tube caps" for my 12" diameter Hastings Irrigation aluminum tube. For those of you who, like me, hate the aesthetics of the "shower cap" method, we have:

 

Method 1 (1 cap): You might try the rubber caps available from Protostar. Unfortunately, they were out of my size when I tried to order a second cap, although the owner responded promptly and wholly responsibly, despite what you may have read on other threads. Which leads to ...

 

Method 2 (1 cap)--make your own! TAP Plastics sells laser-cut plastic disks in various colors, one of which happened to be just right for my tube diameter. Purchase a long length of 1" x 2*pi*(diam. of your tube) x 1/8" thick plastic in your favorite color. You also should purchase a tube of plastic glue--I believe it is the same glue used for plastic model airplanes, BTW. Using a large flat surface (I used my garage floor), begin by gluing a couple inches of the strip to the side of the disk. You may need to clamp it, I used duct tape. Once dry, glue a few more inches on. Once this too is dry, you can glue all the way around once. Check the fit with your telescope tube. When this is dry (no, the "2" in my formula was not a mistake), wrap the rest of the strip around and glue it to the first layer. The purpose of having two plys instead of a single 1/4" ply is to allow for easily bending the plastic strip around the edge of the disk. Sand off any rough edges. You may wish to paint the whole assembly using a plastic spray paint can (Ace Hardware or Home Depot). Finally, cut three 1/4" thick "feet" from a wine bottle cork for the bottom cap  (if the tube is meant to stand on-end in storage) and use contact cement to attach them.

 

Happy observing always,

 

Don


Edited by dhferguson, 16 July 2019 - 07:10 PM.

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#13 Chuck Hards

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Posted 17 July 2019 - 01:20 PM

I have a Byers drive on my Cave 10" Chrome Custom Super Deluxe, will post pics as soon as I can find them.

 

I also make my own dust caps.  Molded fiberglass.  I have molds up to something like 15".  Here is one that fits an 8" OD tube, for a 6" Newt.

 

6inch001-1.jpg   6inch002-1.jpg   

 

 


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#14 dhferguson

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Posted 18 July 2019 - 09:40 PM

Cheers,

 

I want to add a few additional pictures in the hope they may be of help to some of you. I wrote the OP because I could find very little detail on how actually to implement the changes I wanted to make. I had to, in a sense re-invent the wheel, and I'd like to save you the trouble. 

 

(1) ByersDrive: this image shows the Byers RA drive w/o the semi-cylindrical plastic cover. Note that the flat sides are made of aluminum plate. They are attached with risers of 3/4" x 3/4" aluminum square stock that extend from the mounting plate to the back of the housing per my previous post. Note the many 6-32 flathead screws (Fastenal) used to assemble the housing and the tight clearance between the RA gear and one of the standoffs. Also, note the recessed area on the standoff used to mount the semicircular plastic housing. Yes, that is the original Dec controller box, which I shortly removed,

 

(2) PlasticCoverMortisse: Shown is the flat plastic used for the semicircular housing before the heating and bending step. Note the mortisse cut into the plastic to smoothly fit on the recessed area identified in (1). I used a table saw to make many equally-deep parallel cuts to form the mortisse. The plastic too was attached with 6-32 flathead machine screws,

 

(3) MountPrePaint: This photo was taken before any of the wiring was installed and before any painting was done. Here you can see how the plastic covers are attached to the housings, the rest of which are aluminum.It also clearly shows the latitude adjust turnbuckle. BTW, correct dimensions the turnbuckle and its attachment are critical for proper operation: measure first before drilling. Note too the collar I used to attach the Dec mounting plate to the Cave Dec axis casting,

 

(4) Here is the wiring for the hand controller. Note how zip ties were used to protect the cable from being pulled through. The large switch mounted to the side is a 2-pole, 2-throw momentary switch for the electric focuser. I used the wiring diagram on the right from S&T, Oct. 1989, p317 for the focuser. BTW, the 9V battery is in the motor unit next to the focuser on the telescope, not within the hand controller. I did this for, obviously, spatial fit reasons. Also, I decided to use a battery instead of wiring the focus motor into the DC power supply because I wanted to be able to focus when remote observing, perhaps w/o the bother of carrying a battery for powering the rest of the telescope (I concentrate on DSOs at low and moderate power when observing remotely, not planets at high power). The four switches for RA & Dec control were available inexpensively online from Amazon. The box, including the thin sheet steel plate, trimmed and drilled here, and on which the 4 switches are mounted, was purchased from Radio Shack, although I am sure very similar boxes can be found online at eBay or Amazon,

 

(5) 10"TelescopeRHSide: As those of us with less-than adult-size diameter tubes know, it can be very difficult to attach nuts on the inside of the tube, such as to attach rotating tube rings, for example. It was easy when my son was five years old but ... he is now thirty and no longer fits. Many simply use machine screws but I prefer nuts, and so I carefully cut a rectangular hole in the tube using a hand-held electric jigsaw. For a 12" tube, it so happens that a Clorox bleach bottle has about the right curvature, so I cut a "door" from such a bottle, glued some black felt to the door for inside blackness, and attached one side to the tube with pop rivets. I used Velcro to seal up the other three sides of the "door". Now I can conveniently open the "door" and reach any part of the interior of the tube. Note too the Argo Navis DSCs and the sliding weight at the bottom of the tube, which I use to balance eyepieces (yes, I do love my 20 mm Nagler Type 2 "hand grenade" eyepiece), and

 

(6) WiringDiagram: Here are my notes on wiring up the Lumicon drive corrector to the handset, the focuser to the handset, and the encoders. The top-left diagram is for the original Lumicon controller (before I replaced the handset with another that allowed for AC control of the Dec drive too). As you can see, I paid careful attention to wiring colors and continuity. Such attention to detail allowed me to rapidly wire up the system. Note that it was not always possible to retain the same wire color from one end to the other, and only such a diagram prevented endless confusion.

 

Oh, finally an erratum: when I wrote an "ST-1" guider port in the OP, I meant an "ST-4".

 

Happy observing always,

 

Don

 

 

 

 

 

 

 

 

 

Attached Thumbnails

  • ByersDrive.jpg
  • PlasticCoverMortisse.jpg
  • MountPrePaint.jpg
  • HandControllerDetail.jpg
  • 10%22TelescopeRHSide.jpg
  • WiringDiagram.jpg

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#15 dhferguson

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Posted 18 July 2019 - 10:00 PM

Cheers,

 

Oh, shame on me for not acknowledging the many useful tips and hints I found on www.cave-astrola.com and, in particular, Tom Terleski's posts. I understand Tom got very sick from bird droppings that he was cleaning off a neglected Cave and may understandably have given up such restoration projects. I want to thank Tom, wish him the best of health, and hope he returns with more useful inputs.

 

Happy observing always,

 

Don


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#16 65&Counting

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Posted 19 July 2019 - 12:25 PM

I have a Byers drive on my Cave 10" Chrome Custom Super Deluxe, will post pics as soon as I can find them.

 

I also make my own dust caps.  Molded fiberglass.  I have molds up to something like 15".  Here is one that fits an 8" OD tube, for a 6" Newt.

 

attachicon.gif 6inch001-1.jpg  attachicon.gif 6inch002-1.jpg  

Do you ever make/sell caps for others? Would be very interested if you already have the molds - shame to make them just once!



#17 65&Counting

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Posted 19 July 2019 - 12:26 PM

Don - can't thank you enough again for this outstanding complilation of info.



#18 65&Counting

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Posted 07 August 2019 - 02:14 PM

Don - or anyone - do you know if the 3 screw holes that hold the drive case at the end of the R.A. housing for the Cave 1.5" shaft mounts are all interchangeable?

 

The 12.5" has a larger drive case over the 10" although the stock gear sets (at least on mine) are the same - I'm looking at getting a larger drive case and playing around with different gear sets that will fit.

 

If they're the same (I would assume they would be?) then enclosing a larger gear set becomes easier to manage without a lot of fabrication.



#19 photoracer18

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Posted 07 August 2019 - 03:28 PM

If the mount has 1.5" shafts the holes are the same I am pretty sure.  As do the ones with 1" shafts just smaller. You will have to make a larger drive case. You can either leave the drive out in air like this Meade DS-16 in my collection with an 11-5/16" Byers Starmaster converted to a stepper or build a new mount plate and build a case.

 

DS16-1024.gif

 

 

I think the stock Cave drive plate  might be able to house a Byers drive up to around 7" depending on the motor type.



#20 65&Counting

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Posted 07 August 2019 - 03:46 PM

Photoracer18 thanks so much!

 

I'm really glad you brought up the Starmaster 11 5/16" because I have two of 'em - one older with the attached setting circle (really neat) and another without but both synchronous.

 

Thinking of doing exactly what you suggest and this helps greatly as to options.

 

I've read some posts on CN about adding steppers and I've spoken with Ed about it (recently) but he's about done with it all - have you posted anything on CN about the stepper conversion for this gearset? I'd love to get the stepper motors before it's too late and think Ed still has 'em - he told me I'd have to figure out the electronics & that he has someone do that for him as he's a machinist and not electrician - made me feel better :-)

 

I'd hate to keep adding parts if I can't make 'em work together.



#21 65&Counting

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Posted 07 August 2019 - 03:48 PM

Oh - any chance you want to thin your collection of one 2.5" drive? That's next on my list since the 1.5" isn't made for a 12.5"



#22 charles genovese

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Posted 08 August 2019 - 11:03 PM

I can add to this but a Meade RG mount- the gears were Russian from the MK61 Maks (I got the from Tom Dobbins). I had help with the machine work. The result is this.

 

Attached Thumbnails

  • Meade RG mt1email.jpg
  • RG mt 3email.jpg
  • RG mt2email.jpg

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#23 charles genovese

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Posted 08 August 2019 - 11:05 PM

It has Losmandy digital dries and has about 8 arc sec of PE. I was barely able to fit the RA drive inside the Meade RA cover (with some grinding on the inside of the cover). 

 

 

 

Charles

Attached Thumbnails

  • c14  meade mt 1.jpg email.jpg

Edited by charles genovese, 08 August 2019 - 11:15 PM.

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#24 charles genovese

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Posted 08 August 2019 - 11:09 PM

Cave 2 1/2" mount with Byers Drives

Attached Thumbnails

  • 03160005.JPG


#25 charles genovese

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Posted 08 August 2019 - 11:12 PM

The original Byers motors have been replaced with a SyTech system.  A 10" f/4.5 doesn't look very big on it.

Also note it can be used as a binocular mount LOL

Charles

Attached Thumbnails

  • 03160006.JPG
  • Cave mount2email.jpg
  • cave mount 003email.jpg

Edited by charles genovese, 08 August 2019 - 11:13 PM.

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