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astrosathya

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Posts posted by astrosathya

  1. Hey Everyone,

    I first made a 6" f/10 telescope back in 2002. It was, as everyone called it here "the minimum size you should make". So I went ahead with it. The f/10 was because some gentleman had ground the glass to f/10 and abandoned it in the local astronomy club and the president of which handed to me.

    After having used the scope until 2009 (I went to UK for my Masters and bought my GOTO setup at the Telescope showroom I was working.  I am primarily an astrophotographer, but one can never forget ones roots can we?

    So, long story short, I am back to grinding a 6' f/8 this time, The FL now stands at 49" (f/8.1). I had finished fine grinding with 1000 grit SiC and moved to 1200 grit SiC but only to realize (after 30mins of grinding) that the seller had incorrectly labelled the powder as 1200 grit. I ended up with large pits all over the mirror and had to resort back to the "actual" 1000 grit SiC. This was yesterday. Now, after about 2 hours of 1000 grit, there are about a dozen pits of varying depth. I think another 30 minutes should get rid of them.

    I tried making a polishing tool from White Portland Cement using the mirror as the mold and aluminum foil as separator. Disaster struck as the cement ate away the foil and got stuck to the mirror in the form of a thin layer (thankfully) and I was able to remove all of it by mild scrubbing and later grinding with 1000 grit SiC. The misadventures that I deliberately get into. 😕

    Hopefully I can start polishing soon. 

    Wish me luck folks. I will post al developments here.

    • Like 6
  2. Hi Everyone,

    I am planning to build a Mirror-O-Matic machine, but since the designer Dennis Rech is not responding to emails anymore, I would be very grateful to anyone who could kindly share the plans of the machines you've built. Anything would be helpful. Images, plans, cur lists, advice etc.

     

     

  3. Recently, almost two months ago my Sky-Watcher HEQ5-PRO mount broke down. We all love our trusty mounts and also knowing very well that importing a new board for it (from UK to India) would be very expensive, I researched online for opensource options and chanced upon the OnStep Mount controller. I built one of its simpler versions and now my mount is back in action.
    The link to the video is below

     

    • Like 11
  4. 9 minutes ago, skybadger said:

    That may be true and is the way mine is setup but the OP was not planning to use the tmcxxxx drivers due to them needing the spi bus wiring up. 

     

     

     

     

     

     

     

     

    looks like if i need to use my 8729 drivers i need to wire up M0 and M2 on the CNCV3? or am i getting it wrong?

  5. 8 hours ago, John78 said:

    The trinamic drivers in either drive mode stealthchop (silent) or spreadcycle deliver more torque than a conventional driver in half step mode, and spreadcycle 256usteps delivers only slightly less torque than full stepping, they're amazing pieces of tech, the issue used to be generating the clocks to accelerate and run them at high rpm in 256usteps, but with modern processors that's not an issue, no way could an arduino do it.

     

    Thanks to OP and repliers for highlighting onstep - have ordered some MaxSTM boards from JLCPCB today to change from astroeq (which has a really frustrating windows bug) to an OnStep controller.  The ascom info required seems to all on this site.

     

    edit: let me rephrase that, windows has a really frustrating bug, that requires the astroeq to be powered before you plug in the usb - it works fine in linux as it handles the ports properly.

     

    http://www.stellarjourney.com/index.php?r=site/software_telescope

     

    initially i was not really sure about the opensource boards and only because a friend uses AstroEQ, i gravitated to it but soon found that they give little to no support on their forum. I then looked at the OnStep Wiki. 10 minutes later, i got hooked. Now there's no turning back. :) We need to highlight such work because there are many folks out there who'd like a nice goto mount but cannot affor paying $$$$. OnStep is an amazing, economic and vastly superior tech compared to the boards supplied with commercial brands like SW etc.

    • Like 1
  6. Some more progress. After finding a few arduino UNO CNCV3 cases on Thingiverse, i realised "what if it doesn't fit"?. I then found a 3D model of Wemos D1 R32 on grabcad which i used as a refernce to design a case. Now the idea is to of course stack the CNCV3 on the Wemos + the heatsinks for the drivers. After a quick measurement, i found the height to be 47mm and to be on the safe side i put in the designed height as 52mm, enough for any errors. The ports were projected to a new construction plane and given a positive offset of about 1mm as wiggle space. Below are a few screenshots of the case. It will have a simple text on it. If anyone has SVG files for the LOGO of OnStep, please do share, i'd be grateful. I have ordered the 3D print.

    Capture12.JPG

    Capture13.JPG

    Capture14.JPG

    Capture15.JPG

    • Like 1
  7. 14 hours ago, lenscap said:

     

    Hi @malc-c,

    I posted a question about whether or not OnStep will run on the UNO,  on the OnStep forum and here is the reply from one of the developers;

     Just completed my second OnStep (WeMos D1 R32/CNC V3) when a colleague pointed out that according to this section of the Wiki;   https://onstep.groups.io/g/main/wiki/19670 , OnStep will run, albeit with limited features, on an Arduino UNO with CNC V3 shield. I'm sure I've read somewhere that it won't. So my question is (just out of interest) will Onstep run on an UNO or not?
    Thanks for all the great work.

     

     

     
    No, the Arduino UNO will not run OnStep.
    That page should be reworded to remove any reference to the UNO.

    In the Arduino family, only the Mega2560 will run OnStep because it has the required 256K flash storage to hold the OnStep program image.
    Even the Mega2560 is the slowest of the boards that run OnStep, and suffers from an inaccurate clock, which needs to be mitigated with an RTC.
    You are better off with the R32 which has a much faster microcontroller.

    yes, i read your post and the replies. :) The boards are arriving today (yaaaaaaayyyy :P) Other components are yet to arrive.

  8. 4 hours ago, DuncanC said:

    Hi, Thanks for the interest. I can see this becoming quite addictive! It seems nobody ever finishes just one mirror. You either don't complete it, or if you do finish it you go on to make several more! Quite rewarding I have to say. Just wish the sun would come out today so I could check the focal length again.

    I have a tub in the second hand kit I bought labelled "Cerox" - but no idea if it's still any good or what grade. Will buy some more if needed - luckily there's a couple of suppliers here in the UK. From what I've read in India getting blanks and grit isn't too bad, but pitch is difficult to come by.

    If the Cerox is offwhite colour, almost like but smoother than Flour or Skimmed Milk powder, then you are near optical grade. The others are off pink colour. 

    You could think of automating the grinding/polishing by making a simple fixed post machine too. I've recently built one, but haven't tested it yet.

    • Like 1
  9. 3 hours ago, lenscap said:

    Your Config looks good except for the microsteps. The DRV8825's are limited to 32, and the A4988's to 16.

    For 64 microsteps you will need the LV8729 drivers.

    Yes, I have cancelled the order for the a4988's and instead ordered LV8729's because of the 1/64 requirement. All parts are on their way from different suppliers. Sourcing has become a major issue due to the prevailing lockdown in our city. 😕

    • Like 1
  10. All the parts i've ordered from various vendors are in different stages of shipment. I will hopefully have everything in hand within a week. Till then i can only read up on the work of others and obsess and imagine etc, maybe design a 3D printable case. I calculated the config parameters for the config generator. 

    HEQ5PROOnStepCalcs.JPG

  11. Gld to see a fellow ATM'er. I just completed 400 grit on my 6" f/8 visual only scope (I am otherwise an astrophotographer). I've also procured an 8" blank which was half finished to 800 grade by <God knows who>. I have a 4.5" f/10 ready to polish 😛

    Its going to be fun.

    I hope you have procured optical grade Cerium Oxide 2-3 microns?

    • Like 2
  12. Hi Everyone,

    I am planning to use the OnStep to control my now dead HEQ5-PRO mount, and for that I have to input the gear ratios. The EQMOD website shows it as 705 and 135 teeth on RA, but no info is given for DEC axis. From my last year's Belt mod of the mount, I can assume they are similar, but if someone could help me with the actual numbers, I'd be very grateful.

  13. 1 hour ago, malc-c said:

    I wasn't suggesting you compare the data sheet with the motors you have, I was suggesting you compare it to the stepper drivers specifications you are intending to use, and the requirements of the projects abilities.  I personally don't think there would be an issue as (AFAIK) most SW mounts use NEMA 17s.  But sometimes manufactures may change things like microsteps etc which could lead to the mount tracking at the wrong rate as the software can not account for this.  I've never built one so can't really advise, so hopefully one of the others can chime in and confirm if your motors are OK. 

    But I thought you had an HEQ5 and will be using that, and AFAIK the HEQ5s use NEMA 17's 

    Malcolm,

    My HEQ5-PRO is from 2012. I can assure you the dimensions are 35mmX35mmX34-37ish mm as measured using a ruler corresponding to a Nema14HS13 as I found independently online. as teh L max is 35-37mm ish for the HS13 . I have a Nema 17 which i used for the MyFocuserPro2 and thats much bigger and wont fit into the space inside the mount.

    Regarding the drivers, I now have 2 different sets, the DRV8825's and the A4988's, so i will have choice on which to use as both will work.

  14. Keep it coming guys,

    I absolutely love it when there's a lively discussion happeneing.

    36 minutes ago, malc-c said:

    Read the wiki and then check the data sheet for the motors..

    wiki  and datasheet

    to quote the wiki

    If it's not able to run the software then why include the statement below... no wonder why people find it confusing !

     

    i checked the datasheet, obviously I have teh exact same motor. I am guessing the connectors also have the 0.1" pitch between the pins. I have ordered the drivers, i just need to wait for them to be delivered and off i shall go. While I can easily design a box for the controller using Fusion 360, if theres one already available, i'd be happy to use it :)

  15. 9 hours ago, lenscap said:

    Hi Sathya,

    I believe you need a Wemos D1 R32 board which has an ESP32 processor and not the item you link to which has an ESP8266 chip.

    You need the CNC V3. I think you may  link to an earlier version . Not sure if it will be OK.

    I strongly urge you to study the Wiki until you are familiar with it. It has all the info you need including links to most of the main components and it explains the reasons for choosing various options. Keep the questions coming.

     

    .

    purchasing components/boards from abroad, especially China is not really an option because of heavy custom duties (41%) and prolonged delivery times due to the severity of the pandemic.

    I found the ESP32 board on Amazon. I think this should work? Its absolutely identical to the one linked in the wiki. 

    I think i can safely order this. I checked out the CNC Shield. Other than the colour scheme, everything looks identical. if they dont match, i'll perhaps return it.

    I will definetly have more questions once the board/components arrive and i begin the build.

     

     

  16. 14 minutes ago, skybadger said:

    They are standard pitch 2.54 mm and yes the du pont jumper cables will fit. 

     

    Meanwhile i found a seller with the Wemos D1 8266 board. Hope this will work. What do you think please? The CNC shield is also available with the same vendor. If you think they are the right ones, i'll order them right away. Thanks again for your help and guidance. 

     

  17. 11 minutes ago, skybadger said:

    They are standard pitch 2.54 mm and yes the du pont jumper cables will fit. 

     

    Thats excellent news for me. I have a tonne of them lying around at home. :)

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