Astro-Geek

Yes, a very useful chart John, thanks for posting it. Just one question, there are no statistics for Maksutov scopes. Would they be the same as the equivalent aperture SCT scopes ?

I've shortened several vixen dovetail bars for my equipment. All of the ones I've encountered are aluminum, so nice and soft to cut with a metal cutting hacksaw blade. The trick is to make a nice straight cut, if neatness is a concern (it is for me ! 🤓), although it is not essential. As the cross section of the bar is fairly solid and large, it's very easy for the cut to slant away at an angle. The trick is it mark it all round very carefully with tape, and then saw to a depth of about 5mm all of the way around the bar, turning it as you go, before attempting to cut right through. The partial depth cut will then guide the blade neatly at exactly right angles to the bar. I would use a full size hacksaw rather than a junior hacksaw, as the blade is twice as long and stiffer, and much easier to guide in a straight cut. The more difficult part is to then drill and/or tap any new holes that are required in the shortened bar. They can also be achieved very neatly but not without a fixed pillar drill and screw taps (and the standard threads are often UNC, not Metric !)

I must admit I do have a garage and a large conservatory too, but unfortunately their rear garden access is nearly two feet down via two steps, and the rear garden is "paved" with gravel. I did consider creating another adjacent decking, but the view from my existing "high level" decking by the shed gives a much better all-round view of the sky. Yes, I'll have to see how I go with vibration, but at least it's very substantial decking, on 5x2 joists. Here's a couple of photos of the Asgard shed/store, one from the manufacturer and one from someone who has fitted insulation (to a similar store that has a lift up lid).

I've had a good search around in here, and indeed also Google, but haven't come across this sort of thing. My garden site-specific need is for a roll into observatory, as the only space available to me is some raised decking alongside a shed. It has good sky visibility as I back on to open fields with few trees, and no street lights and few neighboring houses. I'm intending to use a high security Asgard metal bike/garden store, so that I can keep my 300p goto DOB and my wheeled pier mounted EQ6 in it, ready for instant use when wheeled out on to the decking. I realise this will mean no firm concrete base and that I will need to polar align the EQ6 each time, but having these heavy bulky items already out there and at ambient temperature will save so much time and effort. Indeed, one of the main reasons is to not have to lift them, which always wakes up my ancient Hernia repair opp.... 😲 I can also keep my observing chair and other bits and pieces to hand as well. The security aspects of these Asgard metal sheds are very high too, so the Astronomy kit should be safer in there than in my house ! I'm mindful of keeping condensation at bay, (ventilation and insulation). Has anyone else tried anything similar ? The attached Sketchup diagram is exactly to scale, with my 2 foot high decking and 5ft high adjacent shed wall. The "Asgard Addition" bike store is to scale, as are the 300p DOB and EQ6 pedestal inside. The only thing not to scale is the burly looking chap. He's the same height as me, but much fitter looking 🤓

Thanks Robert. regards, Paul

Good emphasis there from Rob, I should have qualified my remark about casually wiping the underside of the mirror. That's fine, as the glass blank is very thick, but the top surface that is coated and shouldn't even be touched. This photo of a ten inch mirror removed from the tube but still in its metal holder shows just how thick the glass is compared to the diameter. Needless to say, removing the Primary mirror "cell" like this should only be done with extreme caution and under extreme circumstances. It's too easy to drop it or touch it with hands or tools, which could immediately damage the mirror coating which lays on the front surface of the glass, unlike household mirrors which are coated on the back surface.

When you say alloy plate, if you mean the whitish coloured disc in the centre, that's the underside of the primary mirror. A ten inch primary mirror blank is solid glass almost two inches thick, so the dried water droplet marks are totally isolated from the crucial front silvered surface. I'd agree with the theory that they're where droplets have evaporated from condensation. You could safely wipe them gently with a dampened piece of kitchen towel if you wanted to make certain, but there's no need to do even that really.

A very neat solution, and as you say, one would think that Berlebach would offer it as an option. When I built my outdoor pier I wanted it to be able to carry my EQ6 or my EQ5, so I made the top plate compatible with both. It's a Skoda brake disc, (they're incredibly cheap to buy new !), with a centre hole 65mm diameter. I bolted a 6mm thick stainless steel crossbar underneath the "dome" with a 10mm clearance hole. This then accepts either an M8 or M10 long stud with a threaded knob on one end and a wingnut halfway along. I can then simply use the correct stud for either mount and screw the stud in for half an inch or so and then tighten the wingnut to pull it down onto the brake disc. Although the Eq5's 59mm diameter can potentially move around in the 65mm hole, in practice it doesn't when the centre bolt is tightened firmly down. The North locating stud is also removable via an M6 bolt, like yours.

I'm much obliged to you Robert. 👍🍺 That will make the 27:1 gearbox a really good all-rounder choice for all of my focusers, the "stiffer" ones as well as the lighter ones. Having now made many tests with the non-geared 2 amp, a 5:1 geared 1.6 amp, and the recommended 27:1 0.4 amp, the PG27 seems to be a really good combination of torque and minimum amps drain, (as your PDF had said). There's only one very minor thing that still intrigues me, when I test the manual hardware in/out buttons, the step position counter on the LCD display suddenly reverts to 0 after a dozen steps or so, (with the LED lights flashing correctly). The position counter performs perfectly when controlled by the computer, with all the stepping increments, in and out, and the numeric step position is always mirrored correctly in the LCD window on the box.

I'm having trouble getting EQMod working on my Skywatcher EQ5 Synscan goto mount. I'm using the Hitec USB direct lead shown in the photo. It's connected to the Synscan controller box in place of the Synscan hand controller. I'm running the latest version of Windows 10 pro and have installed the Hitec astro driver. When I look in device manager, it shows up as "Prolific USB-to-serial Comm Port (Com6), and it seems happy, with no yellow marker against it. So far so good...... But when I run the EQAscom diagnostics and try to setup the Skywatcher telescope, there are no com ports listed in the drop-down.... 🙄

Thanks Mark, I'll give that a try.

No need for apologies, my posts on this thread have shown how I've blundered around with this. I find it tricky to judge the set current, via that tiny preset on the DRV8825 board, turning it till the motor "sounds happy".... I've just acquired another geared Nema for testing/comparison, a secondhand 5:1 Nema 17 with a rated max current of 1.68 amps. It worked ok, but was a lot heavier than the PG27 with max 0.4 amps, so I'm still admitting that the 27:1 recommended in Robert's PDF is certainly the best all-rounder for me. 🤓

Thanks for the link Julian. It actually looks like the same firm I've been buying them from via Ebay. Better to get them straight from the source though, and their website is very well laid out with the various choices, with the option of selecting the UK warehouse too.

Ditto all the comments about Dobs. 👍 Simplest, best all-rounder, mirrors - so no Chroma fringing, wide field f5 and high mag when necessary with Barlows. I've tried Eight, Ten, and Twelve Inch Dobs, and it depends completely on how far you will need to carry it. My twelve inch goto synscan flextube (bought secondhand), is amazing, but I can only move it by wheeling it around, and (only just possible) carrying it through an external doorway in the two constituent parts. I used to have a ten inch GSO solid tube Dob, and that was a monster to grapple with, like cuddling a four foot long heavy torpedo, so it was actually trickier to move than the twelve inch flextube. I kept my original solid tube Skywatcher eight inch Dob because it is so easily manageable in the two parts (base and OTA). I've had no experience of an eight inch flextube, but I think there would be little advantage of the folding in that size, as the solid tube is still quite manageable at about one meter long and quite light.

There's another level of thought needed when considering ways to store eyepieces (and indeed, diagonals, filters etc..) I'm a sucker for neatness, and there's a couple of pictures of my cases on the "show me your eyepiece...." thread already mentioned on here. Once a collection builds up above a certain number of items though, (as it always will ! 🤓), it becomes more awkward and perhaps risky to carry it to a dark and possibly dewy outdoor observing site. If one is lucky enough to have a permanent home observatory (lucky devils), then no problem, they can all be kept to hand, nicely cooled down, with less chance of dropping or losing anything. If though, the observing is done in the open air, in a back garden or a remote dark site, then carrying these fragile and often very expensive ancillaries needs careful consideration. The old adage "all your eggs in one basket" comes to mind when an eyepiece collection amassed over time could be worth well over 4 figures. When I tried various cases I was wary of potential mishaps, such as could the contents fall out if the case came open at an angle or fell off a table etc., or is there even any possibility of it being stolen... 😱 My much evolved system is therefore two-stage. Permanent storage is in foam lined flight cases and drawers indoors, and selected items for a predicted clear sky session are temporarily stored in individual eyepiece bottle cases in an oversize photographer's multiple pocket gilet. (It's oversize so that it can easily fit over other bulky Winter clothing). I use bottle cases so that the eyepieces are all ready to use, with the top and bottom caps already removed, as they are so easy to lose in the dark. The "loaded" Gilet is then left in my unheated conservatory late afternoon to keep it close to outside temperatures.

Well I've made a start (with my Avatar)......... If anyone is searching for ideas on equipping a home observatory, there's always Google image searching, like this one: https://www.google.com/search?q=diy+observatory&client=firefox-b-d&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiJndHb7_jkAhVgURUIHSVbA0MQ_AUIESgB&biw=1535&bih=768 I torture myself with it on quite a regular basis..... 😥

Yes, Robert's very comprehensive software/firmware does have provision for backlash compensation, even different settings for each direction. True, a significant advantage for absolutely precise positioning. ---------------------------- Further testing developments.................... My cunning plan to use geared and non-geared motors interchangeably with the same single controller box has the disadvantage of only having one hardware setting, (the drv8825 driver board's pot) for the motor current. My two Nemas have widely different current ratings, (0.4 and 2 amps), so it's best that I stick to just one motor, to be able to set it and leave it. Also - re-reading Robert's PDF, the 0.4 amp geared motor puts far less stress on the drv8825 driver board, whereas the non-geared Nema's 2 amps is right on the limit. I therefore think I'll just use the 27:1 Nema on all of my scopes, (as per the original recommendation in the PDF ! "Mega Uber Overkill" regardless !! 😀

More thoughts..... The difference between the power of the Nema geared and non-geared motors is quite quantifiable. My non-geared motor has a torque of 45 NCM, or just under half a Newton Metre, My 27:1 geared motor has a torque of 3 NM, three Newton Metres, six times as much, despite drawing a quarter of the current, (0.4A, instead of 2A). The 5:1 geared motor (that I was tempted to get) has a torque of 97 NCM, just under one Newton Metre, so less than a third of the 27:1 (quite logically I suppose !) Second thoughts on trying to edit Robert's firmware code too, the stepsize limitation to 1-50 is within his windows application, not the Arduino firmware.

Further testing developments................... 🤓 The direct non-geared Nema 17 gave very fine movements when coupled direct to my SCT Crayford Focuser, even at full stepping. I was focusing my Skymax 180 Mak and didn't even need to go down to single steps, plus/minus 10 gave the smallest discernible adjustments. However..... There is another problem instead. When I tried it on my 150 achro refractor, the Crayford focuser on that is much firmer (though still smooth and adjusted correctly). Consequently, the non-geared Nema 17 wasn't man enough to step, so it did need gearing. I then fitted the 27:1 to it, and it steps comfortably in full steps at full speed. It still has step size set to 50 microns, which is the maximum with the firmware version on it (290 - the latest). If I could up it a bit, it would then be a good all-rounder for all of my scopes. (maybe I could look through Robert's code, and find the range limiter ? )

Wow...... I hadn't realised I was erring on the safe side so much ! Before I slightly reduced the current from my drv8825 board (in accordance with Robert's instructions), the motor was just slightly warm, after about 5 minutes holding......

I can appreciate the strong holding torque of the geared motor, even without the focuser powered up. That's the problem for me though, it's quite immovable manually with the motor clamped to the shaft. So far I've experimented with coil holding current on and off, (via the remote option in Robert's operating software). My motor doesn't seem to get hot when the coil is left on, but even when I turn it off, the normal friction resistance of my Crayford holds my ZWO camera with no problems. Maybe with a heavy DSLR it may be a problem though, I must admit.

I thought I'd start yet another new thread to concentrate on this specific aspect of remote focusers. (sorry ! 👀) Further to my previous threads on my build of Robert's myFocuserPro2 , I'm now putting it through its paces on my scopes. I made my attachment brackets modular with a standardised quick-release fixing method so that I can attach either of my two Nema 17 motors to any scope. The two Nemas are a simple non-geared Nema 17 with a 2 amp rating, and a 27:1 geared Nema with a 0.4 amp rating. Either of them runs happily via Robert's myFocuserPro2 controller. Robert's general recommendation is for the 27:1 geared model, and many users expressed a preference for the the geared model due to it's greater holding power with the coils energised. I have to admit though, I much prefer the simpler non-geared Nema 17. When I run it in half-stepping mode it hums along nicely, has plenty of torque to turn my SCT crayford dual speed focuser, even with the tension knob set to quite firm to avoid slippage of the mechanism. The motor is attached directly via a flexible drive, so there is no gear train slack. The range of movement is still very fine, with plus/minus 100 steps getting you quite close, then plus/minus 10 steps being as fine as I need to go, so the plus/minus 1 step is almost imperceptibly fine. When I try the same SCT crayford focuser with the 27:1 geared motor, the reduction in speed becomes more of a hindrance than an advantage, and the gearbox adds significant weight and bulk. Also, when the geared one is connected to the focuser shaft, it's impossible to turn the manual knob, even with the coil current off, whereas the non-geared Nema can still be turned manually, if the coil power is off. When I searched the subject of focusing motors, opinions varied widely, with one person describing the 27:1 as "Mega - Uber - Overkill" ! and others feeling that even the Nema 17 itself was overkill, and that smaller steppers could be used. All opinions on this gratefully received.... 🤓

I must admit, did download his pdf for it..................... 😱 (note to self - must spend more time actually using these things.................. 🤓)

This is a follow up to my thread asking about Nema motor choice https://stargazerslounge.com/topic/341158-myfocuserpro2-stepper-motor-choice-again-sorry/ I'm grateful for all of the member's assistance in helping me resolve the teething troubles in getting it completed. It's now fully working and I'm extremely happy with the result. Robert's very benevolent free source project works really well, and is very comprehensive, as all of the threads about it on here have shown. I made quite a few small mistakes along the way, which I thought I'd publish on here, to possibly save anyone else having the same problems. Here's the random notes I made as I went along: use instructions from the more recent PDF, "LETS MAKE A DRV8825 HW203 FULL myFocuserPro2 Controller.pdf" The 5v buzzer must be "continuous" type add a 247k resistor to the red LED to dim it down add a 10k linear pot to lcd screen backlight to control brightness add a 4.7k resistor across jack socket tip and ring to get temp probe to work. (it's in the circuit diagram, but not clear in the schematics) add the resetable polymer 3a fuse to the power on switch (not shown on vero schematic) edit the Arduino IDE burner preferences with "Display Line Numbers" , "Save when verifying or uploading", "Show verbose output during Compilation" in Arduino IDE programmer, select TOOLS>Processor>"old bootloader" (the default setting didn't work for me, so I found this in a Google search). Locate the folder myFocuserPro2libraries, and in that folder There should be SIXTEEN folders, Bounce2,LCD5110_Basic, myAFMotor, myDallasTemperature, myDHT21, myEEPROM, myHalfStepper, myI2cKeypad, myIRRemote,myOLED, myQueue, myRotaryEncoder, myTFTv2, myUTFT, newliquidCrystal,OneWire Move these folders to Documents\Arduino\libraries folder (for windows). Replace any existing folders or files. Do not edit or replace any of these files. They have been edited and modified to use with the myFocuserPro firmware. Edit the main myFP2_DRV8825_2**.INO file in accordance with the instructions within to enable the various add-ons you have fitted in your hardware build. Then burn the firmware onto the Arduino After I completed the build, I found that the RS232 connector cable that I had used between the controller and the Nema motor was too thin for the potential 2 amp current, so I changed it for a 4 core cable with 18 awg conductors. The final hiccup was the issue that was quickly resolved with all the prompt help from here, namely the firmware release that I was using ( *****288), which had a few bugs in it, causing the steppers to run slowly and noisily. After advice from here I re-flashed the Arduino with ver 290, and all of the problems were resolved. The 27:1 geared Nema now completes a revolution in 20 seconds, (instead of nearly 2 minutes), the motors now give out a moderate hum, rather than a loud rattle. I built the controller into a transparent-lidded waterproof project box to save cutting a hole for the LCD display. I didn't like the idea of repeatedly using the built-in miniUSB socket on the Arduino board as the working connection to my PC, so I added a right-angle adapter and a miniUSB to USB-B panel mount socket adapter to bring it out to the case. https://www.amazon.co.uk/gp/product/B00S6GY0VU/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1 The controller now hangs via a velcro strap from my mount and is controlled by my dedicated "Astro" NUC pc, also attached to the mount with everything connected by short leads and powered by a 28 amp SLA battery pack in a waterproof food container. It's therefore completely self-contained and I can run any Windows based AP or mount software from any PC in my house via Windows Remote Control. I made the Nema motor attachment brackets modular, so that I could use either the non-geared or the 27:1 on any of my telescopes. I don't have to worry about limiting the travel, as they are all Crayford type friction, rather than racks, so there's no danger of mangling anything up !

I have to confess that I've been focused (almost a good pun there), on getting it to work and seeing how good it is. Robert's instructions and advice are incredibly detailed, and despite him saying read everything twice before you start, I found I'd never get going with it ! I did understand the need for calculating a 'scope's focus limits and critical range, but in my case all of my focusers are Crayford friction, rather than Racks so there's no danger of mangling anything up. Also, I've built mine as a modular add-on, with interchangeable geared and non-geared Nemas, so that I can use the same controller on my Skymax 180 Mak, my Celestron C8 SCT, my 200PDS Newtonian, and my 300 flextube (goto) Dob. This was the last piece in my universal remote control setup, so that I can do AP on any of my scopes in the garden whilst I sit nice and warm in the conservatory or even the house itself. Everything runs from a NUC pc running Windows 10 that I can remote control from any PC in my house via the local network. I'm very grateful for the help I've had in responses to this thread, they solved so many queries and problems that I had. I think I'll start a fresh thread on here, illustrating my specific build of Robert's focuser, explaining all of my (mostly self-inflicted 🤓) pitfalls, in case it may save others from some of the grief if they're embarking on a build.