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Re: Losmandy GM8/GM11 Encoder Kit
On Tue, Aug 30, 2022 at 02:27 PM, George Cushing wrote:
The 311K encoders are pretty good when used with a Nexus DSC. You cannot move the mount by hand fast enough to over run the Nexus DSC, I tried it clutches fully loos with an epmty saddle on the GM8G, I yanked the CW shaft as fast as I could and no errors happend! Apparently the port sample rate is high enough to never miss an increment. The newer Nexus DSC Pro is even faster @ 100 million tics per second. So I guess the Nexus DSCs are fast enough even with what appear to be a pretty high tic count.? -- Chip Louie Chief Daydreamer Imagination Hardware? ? ?Astropheric Weather Forecast - South Pasadena, CA? |
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Re: Gearbox replacement instructions for G11+OPWB
Hermant,
If you have a gen I OPW where the gearbox attaches directly to a plate fastened to the machined OPW you are going to have to remove the entire assembly as a unit. This is one of the major advantages of the early OPW, it allowed the use of a solid coupler because perfect gearbox to worm alignment was possible because the worm and gearbox moved as a single assembly. Unfortunately to gain access to the set screws on the coupler you must remove the entire assembly as a unit as access is from under the OPW.?? The gen II OPWs will also likely mess up your backlash adjustment. But at least it is easier to gain access to the set screws because you can just remove the OPW from the blocks by removing the bearing block retaining fasteners and lifting the OPW block carrier backbone gaining access to the set screws to allow separating the gearbox (which is attached to the mount's worm gear deck plate) from the worm coupler.? I have never seen or found any written directions for the gen I OPWs. For gen II OPWs I think there are videos on YouTube.?? -- Chip Louie Chief Daydreamer Imagination Hardware? ? ?Astropheric Weather Forecast - South Pasadena, CA? |
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Re: rehab a G11
Hi Bob,? The teardown, cleaning, and re-lubrication is easy to do.? You'd need a few common chemicals (maybe degreaser from local auto parts store).? Anyways, its easy to do.? The needle bearings have tiny like 1/8th inch diameter rollers, and these need to be easily rolling.? Old grease tends to "gum" the rollers with a coating of "varnish" and this is where the automotive degreaser chemicals can dissolve those varnishes.? The harsh chemical "Berryman B12 Chemtool" is one such powerful degreaser.? To use that, you must work outdoors for fresh air, and wear heavy rubber chemical gloves, and use metal pails (this chemical will dissolve?plastic too).?? To clean the needle bearings, you'd unscrew the clutch knob (start with DEC axis on the top), and remove the parts.? Note the order they are assembled, or else look at Mark Crossley's website:? ? for his recommendation for parts order.? That works better for most owners and for me.?? Start by removing the DEC axis dovetail from the mount. After you lift out the DEC axis 1.25 inch shaft, you will see the needle bearings... upper and lower.? Try rolling the needles with your finger if you can reach in.? If those feel hard to roll, you'd put a rag into the bottom of the axis, put a pail below the end of the axis, and pour in some of that Chemtool B12 and let the chemical do its job.? The rollers will come free.? Then after all is dry again, re-lube.? Many people suggest using Superlube with "syncolon" but that is really teflon.? Or I use lithium based spray grease by CRC that you get at the auto? store.? Any of these will work just fine to keep those needle bearings rolling smoothly. This is a good time to also clean the plastic clutch disk area.? That area tends to get oils from the bearings that creep in to the surfaces, and of course, once oils are there the clutch will not hold..it will slowly creep under any kind of imbalance.? Or contact me for high friction clutch disks that will hold much better and seal out the oils or moisture.?? Then...do not yet reassemble the DEC axis.? With the DEC axis off, remove the RA axis and repeat the cleaning for the RA axis.?? Then reassemble the RA axis, then the DEC axis. You do have to lube the worms too to reduce the rubbing metal to metal friction as much as possible.? There are good lubes for this.? If you are in a warm location like me, the grease recommended by the factory is Artic Jetlube.? However, from the specs on friction alone, there is a better low friction grease: CRC Brake and Caliper Grease sold at auto parts stores.? You must paint that grease into the teeth of the worm wheel (aka ring gear) all around.? Then the worm.? Then assemble the worm so its threads are inserted well into the ring gear teeth.? Then gently push the worm inward, and cinch down the left and right bearing blocks.? While you are doing that inward motion on the worm, also you must compress the worm along its axis so the worm blocks (their tiny bearings on either end of the worm) hold the worm from left to right motion.? In this way you eliminate?the time lags (hysteresis) in the drive mechanism.?? Once the worm is adjusted and its worm blocks locked down, test the mount drives using your Gemini (if so equipped).? If you have a tucked motor system, you can adjust the spur gear to spur gear mesh by shifting the gearbox position on the lower spur gear.? If you have a spring loaded worm system, you must also adjust the worm "back off bolt" so that the heavy spring does not put undue friction on the worm to ring gear rubbing surfaces.?? I find it best to use an ammeter on the DC current going into the Gemini, in order to have a "dashboard" for these adjustments.? If the ammeter shows the Gemini motor current going way up, I know that the drive threads are in too tightly.? The motor current is also a good way to judge an imbalance in each asix.? You put the axis horizontal and slew the motor back and forth in direction, and if there is an imbalance, the currents will be different.?? That's not all, of course.? There are recommendations to "supertune" your mount and I've described those in various writings. No sense repeating those instructions here.? If you need some of those supertune parts, let me know.? ? Work on these mounts, even old ones, have demonstrated a PE down to under 1 arcsec RMS.? It can be achieved, but takes some elbow grease and upgraded parts like superior worm bearings.? These parts are quite reasonable in price.?? Don't be daunted... the mount is a simple design, not an automobile automatic transmission!?? All the best, Michael On Tue, Aug 30, 2022 at 3:34 PM Robert Hancey <rdhx@...> wrote: Bob Hancey here, have received some posting for rehab work. May well be the path to repair, but working for success at this point, but the mount may require more than my skills i.e., professional/ divine intervention. Respectfully submitted --
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Re: Losmandy GM8/GM11 Encoder Kit
On Tue, Aug 30, 2022 at 09:43 AM, Daniel wrote:
This type of encoders are great for turning manual Alt-Az mounts or even dobsonians into semi-goto systems.? For a GEM, once you have goto capability its cost and hassle is hard to justify. OTOH, a retrofitting kit for turning the G11G2 into a G11G-EC would be great!!Daniel, As much as I like the Losmandy Gemini 2 mini on the G11G and GM8G as well as the previous Gemini 2 and Gemini 1 GOTO controllers on previous Losmandy mounts I have owned there is nothing? quit as satisfying as being out under a dark sky picking an object then using the Nexus DSC and/or Sky Safari to help locate an object in the eyepiece as the Losmandy mounts were designed to be used, PUSH-TO operation. Think of it like this: GOTO operation = Blasters, PUSH-TO operation = Lightsabers. A lot is lost when all you do is push a button and look at objects without working a little to find and learn about an object.? ? -- Chip Louie Chief Daydreamer Imagination Hardware? ? ?Astropheric Weather Forecast - South Pasadena, CA? |
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Re: Help with PemPro on G11/Gemini
On Tue, Aug 30, 2022 at 05:50 PM, Bret Stott wrote:
Yes, a?direct Ethernet connection works (see earlier post).?DHCP does not. ?This is new mount/controller so my?expectation is that it should be fully functional.?Then Gemini is working, and it's a problem with your network configuration. Perhaps your mesh network or WiFi adapter does not allow Gemini to see the DHCP server from where it is. Try plugging in Gemini ethernet into the router with no intervening WiFi or mesh to see if DHCP starts working. You can also allocate and assign Gemini a static IP address on your subnet, so DHCP will not be required. As for USB vs Ethernet differences with PEC -- this is true, there are these and other differences between USB and Ethernet, and some are big. Ethernet has a lot more capabilities, is faster, and more reliable over long connections. If you want to use USB, you'll need to accept that there will be some functional limitations with that connection. That's just the reality. Regards, ? ?-Paul |
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Chip Louie
Michael Herman
Paul Kanevsky