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Welcome!
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First post and attachment test. Do you see an image in this message?
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Plain text with attachment - I hope
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Members qualitfications
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Paul, How will you regulate the members? Is there a "test" for becoming a Losmandy Hacker? Is there some skill level or capability required to be specifically in this group? How do you prevent a newbie from joining and asking beginner Losmandy questions (not related to mods), and questions that don't even have anything to do with the Losmandy mount itself, like we see on the regular group? Bob
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Here's my simple mods
Gear cover with easy access and a place for the right hex key: https://www.thingiverse.com/thing:4168538 My version of a shelf for the gm811G. It's pretty simple, cut it out of some door skin and shellac it. https://photos.app.goo.gl/WiiaT7jMaLahBkya9
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Hi all, I reverse engineered the Losmandy G11 RA extension from public photos and videos. I did this because I needed an extra 1/2" of clearance over the 1 1/2" that the official extension provides, in order to clear the direct coupled stepper motor that I used in my OnStep conversion. Hopefully this might help someone else. Drawings and photos are here: https://thefamilee.co.uk/public/Losmandy%20G11%20RA%20extension.pdf Full CAD (free viewer/export) is here: https://cad.onshape.com/documents/e09e979c77dafb113c0ad588/w/8949c9aeab4373d2a618b13d/e/fa1b67b88f0f196a82405c9c Ed
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Spring worm shaft washer.... first report.
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OK, just started a quick session tonight with the reworked RA and DEC worms. I added the spring washer between the worm and the bearing on both axes and fine tuned the worm engagement. The result was startling. Before rework but with preloaded bearings: RA would take several minutes to settle down after starting tracking. There were usually several large plus and minus excursions before it settled down to about 1" RMS in average seeing. DEC backlash was reported during guiding as between maybe 100 and 1800 mS in any given sesison / part of the sky. After rework: RA settles in about five seconds and currently is reporting 0.37" RA and 0.29" DEC, combined = 0.47" (that's arc seconds, not pixels). PHD2 is currently reporting DEC backlash is 48mS, which has not changed so far during the session. Good enough for me (so far, at least). I will say though that after playing with the worm on the bench, I think at least part of my "pre-rework" performance was due to a slightly too tight worm engagement, causing either sticktion or wind-up. I used to set the worm engagement so that there was a very light load at all times and higher on the worm high spot. I now set the worm engagement so that there is zero load except for a VERY small load on the worm high spot. I think this is the better setting. Easy to do if you listen to the motor during a slew as you adjust the backoff screw. Paul -- Paul Goelz Rochester Hills, MI USA pgoelz@... www.pgoelz.com
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Just wondering, Has anyone tried using a spring loaded setup (similar to the existing worm pressure spring) on the bearing block pivot and slide bolts so that the blocks are held against the base plate by adjustable / consistent spring tension instead of simply tightening the bolts to some hard to judge pressure? Paul -- Paul Goelz Rochester Hills, MI USA pgoelz@... www.pgoelz.com
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Searching
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My experience with IO groups is that it is an unsearchable bit bucket where everything disappears over time, in the sense that it is too hard to dig up old posts. So before I start posting my mods, is there a way in which I can find my stuff, and related stuff? Regular message boards have all kinds of folders and subfolders where you can easily navigate and find your topics after decades. Is there a way in which we can enhance the searchabilty? I have never used hashtags, is that what we should do, and if so would it help to define some? Clearly, OnStep, Ekos, spring loaded worms, and bearings should be among them. I see hash tags yet. How can I create topics that I can easliy find back later, and point others to them, and how can I find all OnStep related posts, for instance? Excuse my ignorance but searching IO groups has never worked welk for me.
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Creating a 3D Solid Model of the Basic G11
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Here is where I am at in creating the G11 in 3D cad program. By doing this, I can then examine any modification before I actually try it on the real thing. This allows me to determine correct tolerances, etc as some of the mods being considered remake parts or modify them to new configurations. I would rather get right in CAD, do 3D printer validation model to make sure things work before I start cutting chips on my CNC.I am attaching an e-drawing. To view it download viewer from here https://www.edrawingsviewer.com/product/edrawings-viewer this is supposed to allow to work on android/ios https://www.edrawingsviewer.com/product/edrawings-mobile I am hoping this works. It works on my computer at home.
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Here is my DIY spring loaded worm design. It is quite simple: - Have a plate to which the stepper motors are attached (mine were from a 3rd party control kit that I abandoned for OnStep but you can make one from aluminum). - Find a screw with the right thread into the motor-side block, tighten it with a nut and insert a spring between the plate and another nut on the screw. - Adjust the inward force by changing the location of that nut. - Tighten the 2nd block with your fingers not super tight, then tighten that position with the regular screw, as usual. - Leave both blocks floating with as little play as possible. I used a Belleville washer at the bottom side of the motor side block. The spring will push the motor side pivot into a somewhat stable position, and the worm into the ring gear. The reason why I needed this is because the mount came with much more backlash than I wanted and tightening it up made the motors bind up. Something is not quite round! After this I never had a problem slewing. The pressure on the worm is not huge but you don't want it to be because that just causes unwanted friction. I think the worm eases into the ring gear as it turns rather than clamp it instantly. It can handle my 48 lbs. 12" Newt. This is my first post with attachments. I don't see a preview button so let's hope the attachments show up as advertised. SearchTag: HenkSB_SLW -- G11S mount with HD tripod. Modifications: OnStep controller with stepper motors, DIY SLW, belt drive, DIY "Medusa" on-scope power/Pi4 rig with Ekos for high level control. Scopes: 12" GSO Newt astrograph, Z12 Dob, ES ED127CF, RC6, MN152. ES ED80, Skymaster 20x80.
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Cheapskate as I am, I got the G11S because I thought the Gemini cost more than it's worth to me. I had built a stepper motor-based controller for a dual-axis barndoor drive for my 10" Coulter Dob so I thought in the worst case I can code up my own. After using the (very nice) setting circles a couple of months with the 492 controller I got fed up and found OnStep. My OnStep is configured as follows: - A Wemos with 2 cores that runs FreeRTOS with Arduino on one core and WiFi/Bluetooth on the other IIRC. They cost $0.99 a piece with $3 shipping or something ridiculous like that. - A CNCv3 stepper motor board plugged into the Wemos. This is easy to configure and works well for simple stuff like just motor control. Complex stuff I do on the Pi4 with Ekos, like Wifi too. - 17HM15_0904S Nema stepper motors. At first I ran them at 12V now at 24V for quicker response, I also added a timer belt for 3x the torque. - TMC2130 stepper drivers wired up with SPI for mode switching (slow for tracking, fast for slewing) - High level control is done by Ekos AKA KStars on a Pi4b. In the pictures you see a Pi2b that I rarely use, the Pi4b is in a rig on the OTA. Since I don't have a Gemini I can't tell if this is better or worse. It works OK, on a good night I get 0.5" RMS total with my 12" Newt that weighs 48 lbs. but 0.7" RMS makes me happy, that is more regular. Of course the atmosphere plays a role too. The tricky thing with steppers is that the incremental torque decreases with the stepper resolution so it's a compromise, and I have no idea what the stepper pulses to the motor look like and how well the motor responds. The more torque the better. Steppers with higher torque have a larger form factor so I want to hold off on that, I added the timing belt and switched from 12 to 24 V. -- G11S mount with HD tripod. Modifications: OnStep controller with stepper motors, DIY SLW, belt drive, DIY "Medusa" on-scope power/Pi4 rig with Ekos for high level control. Scopes: 12" GSO Newt astrograph, Z12 Dob, ES ED127CF, RC6, MN152. ES ED80, Skymaster 20x80.
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After I decided to go all in with an ASI2600MM and ASI2600MC, a ZWO filter wheel for a 7x 36 mm set, an OAG and ZWO-EAG electronic focuser, I needed a Pi4 and power. I built a rig that is so ugly that I named it Medusa. Features: - It runs on 12V either from an adapter or a battery so there's just a single power wire. - A Pi4b with 8GB, 2 x USB3, 2 x USB2, 1 ethernet, Wifi, running astroberry. I added Samba so I can mount the disk directly on my Win10 laptop - 12 to 5 V DCDC - A powered 7 x USB2 hub (I only need 2 x USB3 on the Pi4b for the imaging - camera and autoguider) - Strapped to the OTA with a rubber band from an old bicycle tube that is permanently on the OTA. Very easy to attach and detach. This rig lets me run all the above hardware. At home I use WiFi. In the field I use an ethernet cable. I log on to the Pi4b desktop with VNC. Ekos works super and has everything I need (autofocuser, plate solving also for PA, planetarium, camera and filter control, autoguiding, schedules you name it. SearchTag: HenkSB_Medusa -- G11S mount with HD tripod. Modifications: OnStep controller with stepper motors, DIY SLW, belt drive, DIY "Medusa" on-scope power/Pi4 rig with Ekos for high level control. Scopes: 12" GSO Newt astrograph, Z12 Dob, ES ED127CF, RC6, MN152. ES ED80, Skymaster 20x80.
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To get more torque I added 3:1 timing belts for RA and DEC. The torque helps but the slewing is slower. If OnStep can do about 4 degrees per second, with the belts I get about 1 degree per second. But that's OK because mostly I choose one target per evening so I only have to do it once, sometimes twice for a meridian flip. - I made the frames of plywood with oval screw holes where needed and csrews with washers to be able to adjust the tension. - The motor is now on the other side so I had adjust its direction - The large wheel's axis goes through a bearing that was hammered into the hole in the plywood, to reduce pulling the connector down - I use flex connectors that I borrowed from a 3rd party controller kit that I abandoned for OnStep Not pretty and they are sticking out more than I like but they work fine. I added a picture of the over all rig too. SearchTag: HenkSB_Belts -- G11S mount with HD tripod. Modifications: OnStep controller with stepper motors, DIY SLW, belt drive, DIY "Medusa" on-scope power/Pi4 rig with Ekos for high level control. Scopes: 12" GSO Newt astrograph, Z12 Dob, ES ED127CF, RC6, MN152. ES ED80, Skymaster 20x80.
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Worm removal G11
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Is there an easier way to remove the worm on a G11 wo taking the gear box off for either OPW block of standard non OPW block version on standard non tucked motor G11. I've noticed the Oldham coupler when loosened does not have enough room to slide to the left toward gear box on gear box shaft to remove worm assembly when worm block bolts removed. Is this the only way? Thanks
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Locked
OT: Adjustable secondary mirror mount based on Kelvin Clamp
I started a thread over on Cloudy Nights and felt that some of us might have some useful contributions to make. <https://www.cloudynights.com/topic/819936-adjustable-secondary-mirror-mount-based-on-kelvin-clamp/> Please post there with your thoughts Thanks, David
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Ok, I went out this weekend to test software, computer, scope/camera and mount. First time in 3 months the sky was clear on a weekend. Tested ceramic bearing I installed. Not as good as hoped. In switching it back to steel, I remembered a mention of out of round bearing blocks somewhere here. I looked and noticed wear on opposing sides of the block. These are the original blocks. The wear is from pressing in non-altered bearings. Measured with a micrometer and they are out of round. Even measured the inner block at its widest point, locked it down then rotated the block and the caliper's inner measuring fingers got tight in the location showing wear. See photos. Carefully placing a bearing partway in the block then wiggling it I noticed the bearing will tilt back and forth toward the looser side but not the tighter side. Kind of a little conformation of out of round. To me this explains why some report it's easy to remove bearings and others have a hard time. I do note that when placing free spinning bearings in the block they tighten up unless they are the sanded versions with washer mod. I can only assume it's because of the unequal compression force on the bearing causing some people problems. Picture links below https://flic.kr/p/2ndXeQw https://flic.kr/p/2ndUus9
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I have a question regarding typical G11 worm block gap width encountered and set on user G11s that do not have the OPW plate but have the brass precision worm. This configuration is consistent with all my 3 G11 mounts. I have two G11 mounts which have a minimum set point of the pivot block with worm to be around 92- 98 mm. This the closest I can push up on pivot block with worm inserted while the right most block is loose using feeler gauges to verify gap width. Once, I set the pivot distance and tighten, I then move in the right block to same distance to make a constant level mesh of worm and spur gear. I noticed one of my mounts that I acquired recently has the left pivot block gap at 70mm and the right most block is 80mm. Occasionally, I get the heavy RA and Dec message on the Gemini2 with just the balance bar during a slew but do not get any binding or stalls on RA or DEC movement. Even the sound of the motors during a slew seems reasonable under stress. Current monitoring during slews seems to be 0.5 amps and below. It might need a re-grease job as well on each axis needle bearings. But I'm thinking this may be too tight and not meshed evenly anyway. I'm about to make an adjustment but wanted some guidance on typical block distance gaps seen by users where backlash is minimized and no binding or high current messages from Gemini 2 are seen. My guess is current between 0.25 and 0.45 amps on slews is normal and anything above that is where the Heavy RA/Dec messages start reporting. I've enclosed a picture of the block gap width in question... Thanks Dale Thanks Dale
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Here is what I have been working on. Next I will incorporate the spring design and finally the new plate too mount it on. Will be able to adapt for current gearbox setup, belt drive with servo or stepper motor, even a direct drive. Making it will be fun. Included is a 3D pdf file and the EDrawings file (free downlod for viewer. More updates to follow. [Image.jpeg] Steve Ruttenberg Photographer Amateur Astronomer 928.968.3444 www.steveruttenbergphotography.com<http://www.steveruttenbergphotography.com> https://formatt-hitechusa.com/?rfsn=5874558.2511d09&utm_source=refersion&utm_medium=affiliate&utm_campaign=5874558.2511d<https://formatt-hitechusa.com/?rfsn=5874558.2511d09&utm_source=refersion&utm_medium=affiliate&utm_campaign=5874558.2511d09>
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GM811 wind susceptibility
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Guys, I haven't posted here since I added the wavy washers. Mostly because I was quite happy with the results. I get guiding very consistently to about 0.6 arcseconds RMS. Until this evening, when it all fell apart. Had me stumped for a while.... the stars would move back and forth enough to move out of the PHD2 multiple star circles as if I suddenly had a major amount of PE. When I went out and stood by the scope to see what was going on I realized the issue was WIND. I'm currently imaging with my 8" LX200 OTA and with the dew shield, it has a pretty large cross section. The wind is currently gusting to 14MPH and the stars would move enough to cause plate solves and autofocus to fail ;) BUT, that got me thinking... where is the springiness coming from that allows movement in wind gusts? After my imaging run tonight I'll do some simple tests, pushing on the tripod legs, base, axes, OTA etc. to see where the majority of the "give" is. But I suspect a good part of it is that danged SLW assembly and the fact it can move sideways. I can feel (and sometimes see) it move when I apply pressure to the OTA. Has anyone else looked into why the GM811 is as susceptible to wind as it is? Just curious. Another avenue to explore as we hack the mount ;) Paul -- Paul Goelz Rochester Hills, MI USA pgoelz@... www.pgoelz.com
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I have made substantial progress on the redesign of the G11. The first image shows essentially the entire design, minus a few items that will get added in. I am going to redesign the "worm cradle" the piece that holds the bearings. I am going to redesign it to something similar to the bearing caps like on a crankshaft or connecting rod for the gear heads in the house. I am trying add as much precision and repeatability to the design as is practical. The second image shows how the plate will be split (mostly for manufacturing purposes) and will eventually be precisely assembled using 10 precision shoulder bolts. I need to do a a little more work on it to finish it. This design will be able to use the Losmandy motor as a 6 or 10 to 1 belt drive system, a Nema 17 or 23 .9 or 1.8 stepper motor thru belt drive, and then for the penultimate a direct drive set up. I am also going to redesign the worm at some point to an ovoid type worm (it has a radius on it that matches the worm gear to allow more teeth to contact each other. Two other options or maybe 3 are variable pitch, and variable tooth thickness. Also, will increase the diameter of the worm teeth to allow for greater adjustability/ Depending on how this goes, I may look into a redesigned worm gear. Although, my attention will be shifting to the shafts and housings next to modify them to accept a better bearing arrangement, like a small cone bearing or something to remove the slop from the shaft to needle bearings. Mostly, need to get my cnc finished (waiting on 1 part to get repaired) and convert all this to the G-Code used to do the cnc work. A lot of this will be custom made ? I included the edrawing file for those who want to download the free viewer to better peruse the design. I have been keeping good notes as I may well patent this as this design could be used on any telescope, even ground up if wanted too. Another nice aspect of this design is it will eliminate the current clutch set up and will have a positive lock system and the balancing., etc should drastically improve.
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Image Name
Sat 8:39am
Sat 8:39am