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OuterObsession

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  1. Yeah I'm thinking of experimentation with a geared nema 14. I need to do the maths but it seems like I'm not getting enough precision with the setup I have currently. I think that the microsteps are going to cause too many issues in the long run and I just need to change more of my setup to reflect using full steps.
  2. Wouldn't small changes from night to night require you to refocus anyway? If the stepper motor can't hold a position less then one step without keeping the coils energised shouldn't it just use full steps? Also does anyone know of a method for auto-focusing for planetary/lunar photography?
  3. And thanks for combing the Arduino sketches, I was going to do that originally but thought there were to many differences to justify it.
  4. Hi, IanL Depending on how the optical train and focuser is set up on your telescope the stepper motor may turn the wrong way. The same thing happened to me, I forget if I reversed it in the Arduino sketch or via my astro software - don't think it really matters. What does AAF2Test report the position as? You should also try other astro software that supports ascom focuser like Astro photography Tools. Maybe you made a typo in the Arduino sketch relating to the go commands? In any case knowing the starting position isn't really important for a lot of autofocuser routines. So it doesn't really matter if your astro software is reporting the same focuser position as long as the value that it's moving the focuser by is correct. What I usually do is manually move the focuser into close focus then run the auto focus routine on Astro Photography Tools, this way the stepper motor doesn't have to run as much. You just need to be careful that you don't run past the end points on your focuser. Because my ED100 uses a crayford focuser it just slips so not really a big issue. As a side note of noticed that my nema 14 doesn't have as much precision as I first thought. It seems to focus really nicely but I might try some gearing just to see if it makes any difference. Cheers, Jameson
  5. Also the 3D printed plastic ended up cracking in the middle of where the 4 screws hold it, I had to cut a small strap of aluminum to reinforce it. I plan on getting a future version cnc'd out of billet aluminum and anodized in black. The nice thing about my design is it works on basically all the Skywatcher, Vixen, Orion telescopes fitted with a Crayford focuser.
  6. Yes that's one of the things I changed in the final sketch. My solution was to toggle the EN pin after it's done moving positions to switch the FETs off. On top of that I added some additional heat dissipation so even with it on for extended periods it doesn't get too hot. The Easy Driver board still heats up moderately but that's normal operation and the chip will shut down if it exceeds 103c.
  7. Ok here's the modified sketch for people using the Easy Driver board. Keep in mind this only works with the Easy Driver and not 28byj-48 steppers. You can find more information about the Easy Driver here: http://www.schmalzhaus.com/EasyDriver/ and they can be bought at Sparkfun. The sketch performances identically to tekkydaves original sketch with the exception of two things: 1. The sketch allows you to set the precision at which the easy driver should run at, 1/8th (highest precision) gave me the best results but was the slowest. (lines 95 - 119) 2. The sketch disables the FETs to conserve power when not adjusting the focus. When the FETs are disabled the stepper motor has no holding power, with them enabled it has holding power but will use full current. The EN variable toggles FETs ON/OFF (HIGH = OFF) Let me know if anyone has problems I'll try to keep an eye on this thread - at least for a little while. Cheers from down under, Jameson AAF2_EasyDriver.ino
  8. Yes I've already got everything figured out, just need to clean up the code. The nema17 gets very hot even being driven at low currents, I'm going to stick a heat sink on it which should fix everything up. Apparently stepper motors just run hot sometimes when they get pushed hard. Atm the pressure plate for my crayford focuser just has a 3D printed replacement in there that lets me use the nema17 with a 4-6mm shaft adaptor. It pulls alright straight vertical with canon 70D on the back which is more weight than most setups. Unfortunately the plastic part has already cracked but the end plan was to get it cnc'd in billet aluminum if it looked all good anyway (which it does) I've looked at R Brown's stuff overkill for me atm but maybe in the future. Also the easy driver is much more simple to run from the arduino then other stepper drivers, it also can do 1/8th steps by using some trickery but at the cost of less torque etc... I need to play around with the different precision settings more see what works best for focusing, might set it up so it does low precision when it has to move a longer distance. You can read more about the easy driver here: http://www.schmalzhaus.com/EasyDriver/ Also I ran my 28byj-48 stepper at 12v but it didn't really help, one thing that made stuff worse was the fact that I wasn't directly driving the stepper shaft like I am now.
  9. Hey I've been following this project for a while now and think it's really cool. After not having a lot of success with the 28byj-48 stepper motor (too weak) I switched my setup to use a nema 17 stepper motor. Because of the larger motor I now needed to use a different solution to drive the larger motor, I found the easy driver board to be a great solution! As a result the code isn't compatible with the different board, unlike the 28byj-48 stepper motor which uses a uln2003 to drive the motor you don't have to manually switch between each set of coils to get the thing to turn. The really great thing about the easy driver is you just tell it when to make a step, which direction you want to step in and the resolution of the step. So as we speak I'm in the process of creating a 'B' variant of the 2.5.0 arduino sketch designed to work with drivers that simply take step commands. This will help people out there who are struggling with the arduino stuff who have used something other than the uln2003 to drive their motor. I'll share it when I'm done so people can at least get the sketch from here or tekkydave can add it to the sourceforge if he's still hanging around Happy imaging and cheers from down under, ~Jameson
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