12.5 " F5.6 Homemade Dob , mirror ground and figured by myself 10 " F4.0 LXD55 Meade 6" F8 Homemade Dob , mirror ground and figured by myself , Sears 60mm x 900mm Refractor
ATM Nut.6" F15 Jaegers Refractor on Homebuilt EQ mount12.5" Homebuilt NewtProjects:16" F7.2 Reflector
Quote:...Second thing im wondering about is what a common diameter for the counterweight shaft should be. Currently I designed it for 1-1/8" which is the same as the Losmandy counterweight shaft. Is this a good generic diameter or should it be different?
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Quote:Adam,I am a machinist, and can give you some feedback if you are interested. One thing I recommend is not doing much on the drill press, but rather a milling machine like a Bridgeport. Give me a nice lathe and a Bridgeport with digital readout, and I could make just about anything. Problem is I have neither, nor access to them.I believe that the capacity will much depend on the internal gears and bearing size. The bigger, the more capacity.As for the counterweight shaft, I think the Losmandy size would be fine, but if you need something a bit beefier, you can go with the Casady size bar.
Quote:Adam I do have some CAD experience. your sketch does not shows much details. Could you post actual pictures and full cross sectional drawing with all of dimensions here?? Just curious, where are you located: Nigeria??
Quote: Just curious, where are you located: Nigeria??
AT6RC; C6R; 8" R200SS; 10" SNT; RV6; PST Vixen GP + Starbook-S Warped LXD55 G11 Gemini-1 & DSC Gone! HGM-200 Gemini-2 Orion Starshoot DSCI2; DFK 41AF02 Sky Commander 4 SkyShed POD XL3 14.5" f5 folded Newt Finished. Now in storage. Mount for 14.5" Portable obs on 7ftx16ft utility trailer wi 8ft dome Trailer Plans Approved, Jig Built! http://cleardarksky.com/c/MCAOobMDkey.html
14" Meade LX850 80mm Meade 6000 ED APO 90mm Meade ETX 60mm Focal (First Telescope) Orion MiniGiant 9x63 Mallincam Xtreme EXview HAD Canon 5D Mark II Canon 100-400mm f/4.5-5.6L Canon 24-105mm f/4L
Quote:From someone who has built a large mount, the challenges for me were how to drive the axis. Figuring out clutch arrangments for the RA and DEC that would hold and move nicely with a gearing assembly that was easy to make yet strong enough and precision enough for a large scope was very difficult. People who look at my project now have no idea how many renditions or drafts I've built to get to where it is now! If you check out ATM vol 1, there is a section on mounts and what ingalls says holds true to this day, a telescope mount is only as good as the junctions between the dec axis and the tube as well as the RA and the dec axis. Those two junctions should be your focus. Everyone always gets hung up on the size of the bearings when in reality, mounts move so little bushings are often a better choice. If I could have machined bushings, I would have, but I had to go with bearings myself. The other "rule" is to keep the counterweight shaft as short as possible and have the OTA as close to the RA shaft as possible. I am envious of your Computer skills, I have to use "mind-cad"
Quote:Quote:...Second thing im wondering about is what a common diameter for the counterweight shaft should be. Currently I designed it for 1-1/8" which is the same as the Losmandy counterweight shaft. Is this a good generic diameter or should it be different?I think you'd better check the specs on the diameter of the Losmandy counterweight shaft - it's larger than you mention - much closer to 1.25" than 1.125".
Quote:I found some neat ideas from looking at the Mach1. The polar fork is not a single-piece casting or anything but several machined billets that are bolted together.the RA axis is simply a large tube that is bolted to another billet (that is then held in the polar fork).the mount was obviously designed so that castings are not necessary. I'll try to post some photos of the internals when I get a chance.
Quote:Quote: Just curious, where are you located: Nigeria?? Charlton, MA is not very close to Nigeria, but some of us from Worcester used to think so. For a project that is designed to be low cost and simple, I'm thinking this is quite sophisticated. I am familiar with the pillow block and plate designs when it comes to simple.I agree that the broad brush concept is very nice. Details are what make it easy/difficult, and these issues come out in either prototype building or in detail CAD drawings that work out all the clearances, sizes etc. of components. As the details get worked out, please post. I'm interested in producing a nice GEM someday, as I consider a scope finished when I've star tested the optics, and I've got a lot of fine OTA's kicking around.Love the open source concept. Sharing works.go man, go!
Quote:Adam, If you want beefy, & simplicity take a look at the Opticcraft mounts. http://www.opticcraft.com/ They use a lot of pillow block bearings & heavy shafts in their designs. The biggest machining issue looks to be the RA & DEC gears. I think they use Byers gears & thrust bearings for the drive mechanisms. I'm not a machinist by any means but their design seems simple, modular & solid.I'm planning on a 8 or 9 for my 14.5" trailer scope.Clear Dark SkiesStartraffic39.138274 -77.168898
Quote:RE: ccaissieI was just curious and I asked him because he didn't mentioned his location until it was asked in my post…(until 4th post)To be honest, I had similar experience at another forum with a scam artist who had quite good knowledge of the astronomy and he asked me if I could help his sick sister studying at UK and send her some money. (and Nigeria had similar reputation). Adam's project sounds nice AND If it is "open source" as he mentioned, he must have built it (he says so), lets share it here. Also if it is real, I would sure do my contribution but not by sending him money. Sorry Adam, I hope you are not one of the scam ??(My apology if I am wrong). I am looking forward to hearing from Adam and knowing his machine design experience as well.My next question: Is he willing to meet any of us from here and show the real project (and the progress)??( I would warn everyone to be aware of SCAMS on any forums here at Cloudynights.com ).
WO ZenithStar 71mm Doublet ED Celestron C6S ASGT Univ. Optics 8" f/7 Newt. Sears 60 f/15 Refractor Celestron Skymaster 20x80 Bushnell Sportview 10x50 Nikon D80 Stock Logitech Webcam Pro 9000 Modded for AP
Nikon Action 8x40 binos C4-R, mountless 114NT Everglades Astronomical Society "When the Moon is a couterfiet, better find the one that fits, better find the one that lights the way for you." ISTAR Scope Club
Quote:I should know a little about the OpenSource licensing since Ifollow alot of OS projects, but I don't. Adam can join the G+community "Makers, hackers, artists, engineers" community runby adafruit.com and get the answers there. I like this open source astro equipment trend. I have(just got)a 3d printer. If the cad files are in a Blender friendly formatI can get them to my printer and print them to see how they fit together. If the files can be exported to a '.stl' file, even better. If proto-typing in plastic will help I can be ofservice.
Quote:you can get the gears from Aeroquest:http://www.aeroquest-machining.com/pricing.phpsmaller one for the DEC. or, if goto is not necessary, use a tangent-arm DEC. it would be simpler, cheaper, and suffer less from backlash and stiction.i would vote for a Raspberry Pi (or Chipkit32 Arduino) for the Goto controller, if Goto is desired.the 10 Micron mounts use an embedded Linux SBC, not the cheesy low-RAM microcontrollers that are generally used in mounts.
Quote:A lot of nice looking work can be done using pipe fittings bored to suit bearing inserts etc. Clearly you want to get past the "sawmill" look on your mount.
Quote:Nice design Adam!How do you plan to mount the worm gears on the shafts( if that is what you are going to use)?It would be a good idea though to use roller bearings instead of ball bearings for a better precision and as a sophistication you could use taper roller bearings on the back end of the shaft, especially if you want to go with the preloading idea. Also it would be a more efficient way to deal with the axial and radial forces when the mount points in different positions. I believe Takahashi uses this set up in their mounts.If you want to go Losmandy way then you should consider mounting the worm wheel on a bearing on the Ra (or DEC) housing itself making it independent to the shaft and avoid the small errors due to flexing or bearing runout. The most important thing I see with this set up is that the worm and worm wheel keep the same contact which will help accuracy. In this way the shaft is driven only by the friction between the worm wheel and the flange of the shaft.http://www.astro.uni-bonn.de/~mischa/mounts/g11_experiences.html http://www.astromaster.org/esperienze_file/G11maintenance_e.htmHere's also a new ukrainian series of mounts using pretty much the same design with very good accuracy, not very hard to build on a lathe.http://www.youtube.com/user/WhiteSwan180/videos?flow=grid&view=0
Quote:You need to add a flange or washer that covers the seals on the exposed side of the bearings. Eventually during transport, one of those will get hit and damaged.allan
Quote:Alright, Sorry for the delay on the cutaway and dimensions.
First, the cutaway:
As you can see, The gear end of the 2 axes are supported by 6218-2rs deep groove bearings. At the far end of the housing, there is another bearing with a bearing pre-load nut. This is tightened down to take all the backlash out of the bearings and provide a fluid axis. The RA axis will be set up the same way.
You can see at the top of the DEC that I have been playing with a clutch design. This is based on the clutch in the Losmandy G11. The tan layer is a piece of cork used as a slip/friction surface for the clutch pad. This would have a secondary shaft through the center of the main shaft and a hand wheel on the end to adjust clutch tension. The thing that worries me is if the end plate and shaft are not rigid enough, they could flex when the clutch is loose and cause inaccuracy. I think bushings would be sufficient for holding the clutch shaft concentric with the axis shaft.
If this is acceptable, I will replicate it on the RA axis.
Here is a rough dimensional drawing. The ones marked "True" are radiuses.
All measurements are in Inch's.
Im still looking for suggestions on the range of latitude the mount should be capable of.
In my opinion, 6218-2RS is not a thrust bearing. It is rather just a radial bearing. ( single row deep groove ball bearing with two seals )(suffix RS ). (Although, it can be used as a hobby project, but it wont be a perfect design).
Also, are you suggesting preloading it by the nut to somehow eliminate the bearing's own internal clearance?