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Blog Comments posted by Gina
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I have further tested and adjusted the 3D printer and changed the centre hole in the escape wheel for better fit on the shaft and things do seem to be better.
The escape wheel has printed pretty well but when spinning it on it's shaft there is some variation in the points of the teeth but I think this is due to the difference in filament laying angle around the wheel rather than the accuracy of printing. A Cartesian printing system is not the best for a polar form of object.
I've looked into the various escapements to see which would be best for 3D printing but most were superseded by later ones on account of accuracy. I've mainly been trying the Anchor Escapement but have tried the Deadbeat as well. It is said that the Anchor escapement is less bothered by tolerances than the Deadbeat so the Anchor seemed best. I have tried some of the less popular ones too. However, even the Anchor escapement is critical of any variation in the radius of the escape wheel teeth and this is what has been the problem so far. Either the pendulum stops or it skips teeth, depending on the torque driving the escape wheel and the Anchor to wheel spacing.
Having not been able to get the Anchor escapement working and with its inherent problems I think I may have another go at a Deadbeat type. Also, it has occurred to me to "fudge" the issue by driving the pendulum separately from the escape mechanism in the style of a Slave Clock. If I go this route I think the Deadbeat escapement would be better.
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This is a starting point. To date I haven't managed to print an accurate enough escape wheel but I have made improvements to my 3D printer recently so I'm ready to have another go.
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Circuit Diagrams :-
Cooling :- The Peltier TEC is run continuously on a low level at about 5v to stop the camera overheating in the thermal insulation. For night viewing, the TEC is run from the full supply of 13.8v switched by a GPIO pin on the RPi. The J438 P-channel MOSFET is turned on via the EL8217 opto-coupler providing the full supply voltage to the TEC.
Dew Heater control :- In this case the dew heater is connected directly to the main supply and the return is switched by an N-channel MOSFET (IRLZ44N) to control it. Again the power circuits are isolated from the delicate RPi data side with an opto-isolator.
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PARTS LIST :-
- Camera :- ZWO ASI 178MC USB 3.0 Colour Camera
- Lens :- All Sky Lens for QHY5-II and 1/2 Inch Camera
- Dome :- 3.5" Clear Acrylic CCTV Dome
- Case :- 3D Printed
- Case Sealant :- Gorilla Versatile Mould-Resistant Sealant, Clear
- Desiccant :- Dry & Dry 10 Gram [25 Packets] Premium Silica Gel Orange Indicating(Orange to Dark Green) Silica Gel Packets Desiccant
- Dew Heater :- Dew Heater Module - All Sky Camera
- Peltier TEC :- Peltier Module, 54.6W, 4.4A, 20V, 40 x 40mm
- Waterblock :- CPU Water Cooling Block, Waterblock Liquid Cooler 50mm Copper Base for Intel/AMD
- Coolant :- XSPC XS-EC6-CL Non Conductive Coolant - Clear
- Radiator :- BQLZR 80 Row PC CPU CO2 Water Cool System Heat Exchanger Radiator
- Fan :- Coolink SWiF2-800 Fan 80 x 80 x 25 cm
- Water Pump :- Decdeal Mini Brushless Water Pump DC12V 5W Ultra-quiet Waterproof Submersible Fountain Aquarium Circulating 280L/H Lift 300cm
- Computer :- Raspberry Pi 3 Model B+
- MicroSD card :- SanDisk Ultra 16GB microSDHC Memory Card + SD Adapter with A1 App Performance up to 98MB/s, Class 10, U1
- HAT :- DIY Proto HAT Shield for Raspberry Pi 3 and Raspberry Pi 2 Model B/B+ / A+ KB
- 5v PSU :- LM2596 DC to DC Buck Converter 3.0-40V to 1.5-35V Power Supply Step Down Module
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Latest...
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Thanks @RadekKI'll try that.
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I have the new micro SD card in the imaging rig RPi and what I have connected is working. The focusing seems reasonable with the resolution set to 2 which makes me think I was wrong when I thought I was using 16x microstepping. The 28BYJ-48 already has a 64:1 gearbox which, allowing for the approx 3x stride angle of a NEMA17, still makes around 20x the resolution of a NEMA17. Then there is the reduction ratio of 10:1 of the focus gears. Countering this is that the focussing range of the lens is from a few feet to infinity and we need very precise focussing.
The full focussing range was previously of the order of several tens of thousands of counts and it needed the focus count to be within around 10 counts to get good focus. The focus position for Ha used to be around 8000. Now the range is 12,000 counts with the focus position for Ha at about 4000 counts so a resolution of 5 counts should work for the auto-focus routing. I was using 20 counts before which was the default as I recall - I think this was a bit course and the reason manual focussing gave better results sometimes.
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Those worked, giving status of progress and reducing write time to 15m - a third of previously. The different make of card could have made a difference though. Previously Kingston and this time SanDisk. The SanDisk 16BG cards seem to have a few more MB of capacity, so Kingston to SanDisk was fine. Kingston to Kingston was fine too with exactly the same capacity.
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Hmm... seems to be more to it than that. Set to 5 but the Options tab still only allows 2. I'll look into it tomorrow. If I have a problem sorting it out I'll just preset the microstepping to 16x. That will work whichever imaging system I use - just might be a bit slow on some.
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No problem - changed from 2 to 5 in file rpi_focus.cpp in astroberry-diy directory.
Maximum resolution switch 1 - 1/1 2 - 1/2 3 - 1/4 4 - 1/8 5 - 1/16 6 - 1/32 Note that values 3 - 6 do not always work. Set to 2 by default */ #define MAX_RESOLUTION 5
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The clone works.
One point though... The resolution is limited to full steps or half steps. For my lenses I want 16x microstepping so will have to patch the code.
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Cloned working SD card to SSD and now trying to clone from image to new card. Using dd. Trouble is there's no progress bar or any other idea of how far it's got.
Card to SSD
gina@Mint-Desktop ~ $ sudo dd if=/dev/sdf of=~/rpi_img_backup.img [sudo] password for gina: 30244864+0 records in 30244864+0 records out 15485370368 bytes (15 GB, 14 GiB) copied, 246.319 s, 62.9 MB/s
It seems to have worked eventually (over half an hour). SSD to new card
Disk /dev/sdf: 14.4 GiB, 15485370368 bytes, 30244864 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x00000000 Device Boot Start End Sectors Size Id Type /dev/sdf1 8192 30244863 30236672 14.4G c W95 FAT32 (LBA) gina@Mint-Desktop ~ $ sudo dd if=~/rpi_img_backup.img of=/dev/sdf 30244864+0 records in 30244864+0 records out 15485370368 bytes (15 GB, 14 GiB) copied, 2551.79 s, 6.1 MB/s gina@Mint-Desktop ~ $
Hmm... writing time was 42.5m - nearly 3/4 hour. Now to put card in RPi and see if it works. This is a 16GB card. Just ordered an 8GB card to create a full system on to use fro cloning as cloning to same size card has proved dodgy in the past - may depend on make as to exactly how many bytes the card contains. 8GB card are dearer than 16GB cards!!
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I might as well implement all available settings that Radek has provided including changing focuser resolution, particularly as this same hardware will be used on telescopes as well as lenses. The very fine focussing I use with the lenses may not be needed for telescopes where I use the 28BYJ-48 geared stepper motor with the fine focus knob.
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From the C++ code I could see that the stepper driver type was a switch in the Options tab and this confirms it.
I also see that the resolution (microstepping) now has a setting here.
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There is a switch to set which type of motor driver module. MS3 (16x microstepping) is used if the driver board is A4988 which mine is. When I checked some time ago, Ekos didn't alter the resolution (motor speed) but maybe now it does otherwise I don't think Radek would have added the code. Speeding up the motor for faster focussing may be advantageous. OTOH I've found 16x microstepping fine so far.
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Checking the default Astroberry GPIO assignments against my current hardware :-
Astroberry default
/ For BCM2835 use P1_* pin numbers not gpio numbers (!!!) #define DIR RPI_BPLUS_GPIO_J8_07 // GPIO4 #define STEP RPI_BPLUS_GPIO_J8_11 // GPIO17 #define M1 RPI_BPLUS_GPIO_J8_15 // GPIO22 // M1 // M0 #define M2 RPI_BPLUS_GPIO_J8_13 // GPIO27 // M2 // M1 #define M3 RPI_BPLUS_GPIO_J8_18 // GPIO24 // M3 // N/A #define SLEEP RPI_BPLUS_GPIO_J8_16 // GPIO23
My connections:-
- DIR GPIO4
- STEP GPIO17
- Sleep GPIO23
- MS1 GPIO22
- MS2 GPIO27
- MS3 Gnd
Only difference is MS3 which currently has a link to Gnd. Now to see if GPIO24 is actually used in the code.
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Both Astroberry Focuser and Board are showing in the INDI Control Panel. Next to check the GPIO connections and make sure the hardware matches the drivers.
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WOW!! Thank you James - that worked. Next to check with Ekos...
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I'll try that - thanks.
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Thank you @RadekK
Tried that and got
gina@img2:~$ git clone https://github.com/rkaczorek/astroberry-diy.git fatal: destination path 'astroberry-diy' already exists and is not an empty directory.
so deleted astroberry-diy and contents and tried again. git clone seemed to work fine but the second command failed.
gina@img2:~$ sudo rm -r astroberry-diy [sudo] password for gina: gina@img2:~$ ls AstroPi3 Desktop Music Templates bcm2835-1.50 Documents Pictures 'Terminal 1' bcm2835-1.50.tar.gz Downloads Public Videos bcm2835-1.50.tar.gz.1 indi-astroberry snap wiringpi-latest.deb gina@img2:~$ git clone https://github.com/rkaczorek/astroberry-diy.git Cloning into 'astroberry-diy'... remote: Enumerating objects: 13, done. remote: Counting objects: 100% (13/13), done. remote: Compressing objects: 100% (11/11), done. remote: Total 288 (delta 3), reused 8 (delta 2), pack-reused 275 Receiving objects: 100% (288/288), 132.38 KiB | 774.00 KiB/s, done. Resolving deltas: 100% (162/162), done. gina@img2:~$ git checkout 3283e99 fatal: not a git repository (or any of the parent directories): .git gina@img2:~$
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OTOH without focuser I could just use the card that's in the img2 RPi. With dew heater on all the time I don't need the Astroberry Board driver. But for any sensible imaging I really need remote focussing!!
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I wanted to clone the card so put it in my desktop reader. Listing drives with fdisk couldn't have destroyed the card and it worked in that card reader when I copied data off. Very odd!!
Maybe I can purloin the RPi and card from my ASC but this doesn't have the Astroberry Focuser. Focus on the rig is currently set for Ha (if it hasn't moved). Possible in desperation, I guess.
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PLEASE NOTE :- This Blog is now out of date and has been superseded. The Git repositories have changed and the information here no longer applies.
Longcase Pendulum Clock 2021
in Clocks made with 3D Printed Parts
A blog by Gina in General
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Looking at the action of the deadbeat escapement I think it may actually be easier to get this right the the acchor. It would seem to be less critical of the tooth radius. Basically, the tooth wants to slide off the anchor when the pendulum is at it's centre position.