SnakeyJ

Very encouraging Neil - hoping to get out for a few goes myself this opposition

After over a year out, I decided to reclaim my observatory for the spiders and creepy crawlies on Saturday. Work had really paused in here last summer with the drive rotation, though between work and caring for my daughter, it had really slipped. After a through wash outside, I opened up with the hoover and removed cobwebs and a surprising array of critters that had setup home. Then set about updating the computer, installing and sorting out Cartes de Ceil, Ascom, Firecapture and drivers for mount, filterwheel, camera and steeltrack (the last took much longer than it should). The dome drive was set to manual with a couple of screwdrivers providing the required drive wheel clearence. Reasonably sorted I then managed a few hours to tweak in the evening with some star test collimation, pa and trying to get Jupiter on the sensor of a small chip planetary camera at 3.5m focal length with nothing more than a telrad that is loosely stuck to the OTA. It soon brought back the many hours of fun Quite rewarding views on camera, but video captured in the end. Unbelievable amount of spiders brazenly re-occupying the dome after a very thorough cleaning, so have purchased some spider repellent as an experiment - at least it smells nice and minty. Hoping for decent weather and some time to play in the coming months.

Thank you Amazon - time to start a war (of persuassion) Hopefully, LCpl Jones may be proved right, "They don't like it up em!" according to the reviews - we'll soon see

With the small diagonal on a planetory camera and 1.25" ADC, 1.25" barlow would be a good fit. I had very good experience with the relatively cheap Baader Q barlow which could be adapted to fit directly on adc or with extension tubes. With barlow, adc and camera the main issue is to take any slop out of the focuser and image train.

Good show Neil - very nice

Great guns for such low elevations Neil - nicely done.

Thankfully the relays arrived today. I'd been rather taken in by amazon and these had definitely been on the proverbial long slow boat from China, taking five weeks to arrive! On the plus side it was cheap! https://www.amazon.co.uk/gp/product/B07BKXTMPL/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1 Now I just need to work out the circuit diagram http://www.dppobservatory.net/DomeAutomation/Schematic.pdf and work out how the relays match in. A bottle of wine and some late night project boarding over the weekend should do the trick....

Belt and motor installed and we have rotation! VID_20200629_210526.mp4 The noise at the end was the power supply falling off the humidifier, which concluded this test - no harm done and already to go once my relays arrive....

Sorry Steve, the links from Google photos weren't working. I've uploaded the images to SGL and changed the links.

Some progress in the workshop - I've completed the motor mount. Kit of parts: Assembled: The springs are old collimation springs from my OO VX 250, I might have to cut them down a little if too stiff - but allow 8mm travel to keep tension on the belt. I cut some HDPE washers from a milk bottle to reduce the friction on sliding, the bolts are threaded and countersunk in the top part and have 10mm slots milled in bottom bracket - this cost me two 5mm hss end mills, trying to do this in one pass in 6mm aluminium! The gold washers were inherited, I believe they came from Saunders-Roe/British Hovercraft and were used for rivetting the skirts together. The motor is three wire, with red, black and blue wires (I disconnected the polarity reverse switch under the gear box). Red to 12v+ / black -ve gives the fastest rotation and blue to 12V+/ black -ve gives a steady half speed and more torque. Mounting anything to the wall of a dome is a bit of a pain, so I've used copious amounts of Gorilla construction adhesive to glue mounting timbers - I even have a little shelf for the dehumidifier. Once this goes off, I'll pack out and mount the motor bracket. Once I have this in place I can glue in the belt and see how it drives. I'm stil waiting for the relays, but everything else is ready to go.

Hi John, apologies this link is not working, but the link was not my video but a quote showing Steve's (Sloz1664) own of his belt drive in his converted mk1 Pulsar dome. The link works fine for me, but resolves to an MP4 upload on this site. https://stargazerslounge.com/uploads/monthly_2020_05/1073342923_DomeRotation.mp4.c74559901b811422d0cdbb2a0cdf16f3.mp4

I had to turn up a shaft to mount the drive pulley and encoder. Poor quality steel, but a bit of recycled weight lifting bar. The bit was turning a 10mm to 8mm 10.5 deg internal taper in the end to cover the spline and screw tight to the thread of the windscreen wiper drive shaft. A little rough and ready, but certainly man enough for the job. Now to come up with a solid mounting plate to secure this to the curved outer wall of the dome....

It's been quite a challenge to find a safe and solid way to mount my router and allow me to round out and true up the timber drive ring. After several attempts I made up some aluminium foot plates for the base of the router and a clamped frame to allow me to slide it in and out. Not perfect, but it's taken most of the eccentricity out of the inner ring of the dome.

Minor setback - unfortunately the Gorrilla Glue did not bond well to the fibre glass (probably the underseal), so I decided to bolt the timber ring in place. It took a few days for the stainless countersunk bolts and bits to arrive and something like 90 fixings for the 6.3m circumference. I've filled all the holes and gaps now with car body filler and, once I work out how to mount the router, I will skim the inside of the ring to true it up before fixing the belt. I'm still waiting for the aluminium angle and relays to drive the motor, so probably about as far as I can get this weekend.

HI Steve, I'll follow your lead with the Evostik Impact for this. I used Gorilla glue to fix the pine to the fibre glass, as it has good gap filling properties, but otherwise pretty horrible to work with! I've got the springs ready, but waiting for some aluminium angle to construct the motor mount. I might see if there's a good way to mount the encoder closer in for protection, even if it involves a pair of spur gears.

It's taken nearly three years to get to this point, but I'm finally getting around to automating my dome (a new style Pulsar 2.2m dome), which I brought second hand back in 2017. To be honest most projects have been held in obeyance with work and my daughters continuing care needs, but 'all work and no play' would be dull and I'm gradually shaking everything out ready for some summer glob hunting and Mars. As I'm now swinging a 14" meade ACF, there is precious little spare space within the observatory and I generally end up having to crawl around on my knees to avoid the scope and counterweights. The plan is to automate azimuth only at this stage, so I can retreat indoors and control things remotely. I might add shutter control in later depending on time and money, but not a priority at this stage. No great invention, but following in the footsteps of giants, I've decided to go for the Lesvedome ascom driver, with a belt, pulley and encoder setup (similar to @Steve 1962 setup Although my dome is simpler to do, the fibre glass moulding are quite irregular, so I've trued this up by routing the bottom of the lip level and I've steamed/bent some pine strip which I will skim with the router to get an even surface for mounting the belt. never enough clamps when you need them! The sharp eyed may notice that I painted the inside of my dome with underseal to cover the flaking paint - don't repeat my mistake! Still waiting for the relays, some heavy aluminum angle and a few bits from the postie, but have my motor, belt, pully and the Vellerman board ready to go. I went for the 15mm wide HDT5 belt and pulley from belting online - this was quite a bit cheaper than T10 and finer pitch, but feels very positive. I rounded up and went for 6.4m, which should allow a little slack after I've reduced the internal diameter by 5mm or so. Bit of a WIP at the moment, but hope to start assembly over next weekend.

Thanks Adam (tooth_dr), this thread came along at just the right time as I'm finally getting my obs and gear sorted after managing occassionally with a long extension lead from the house.... The current setup brings everything to the mount on an external 16A supply, 5 way PDU and then plugged in to my mount power box, containing 12v PSU, USB3 hub and power for dew tapes. The other side of that 16A to 5 way PDU is currently rather more haphazard. I would like to improve this with a small consumer unit on the outer wall, with power outputs for lights, dehumidifier, dome drive (currently in build) and run an earth bond for the mount. I might also add a small UPS 1.5KVA to smooth out the power and keep things running through any blips. Good to see some of the ideas posted here. Once the dome drive is running, I will run this remotely from the house with a SFF PC running headless at the base - the 2.2m dome is barely big enough to swing a 14" Meade ACF.

Still a work in progress - just need to turn up and bore the acetal and then drill and tap for the clamping screws. Truing up the second billet One bin full of swarf later .... Comparison - the colour difference is poor lighting rather than a difference in materials, but I like the almost gold anodised impression. My CGE shaft diameter is 31.72mm, so I will probably bore out a little more to allow for 3mm tube thickness for the acetal.

Hi James - It worked on my screen, not the best photograph - I had copied and pasted from Google images, but lets try and upload properly.... How's that?

HI Mark, thank you for sending some over so quickly. I've had a bit of a busy weekend so have only just started the job, facing and turning the 17/4 ss billets. Really nice material to work with and decent surface finish without resorting to suds. I'll polish the whole thing up once I have bored them out, then machine the inserts from the acetal and drill and tap for the locking screws.

Warning.... Or, in this case a lot of bubble wrap! And inside the bubble wrap, 1 large Astrozap Dew Shield, Baader Diamon Steeltrack and Steeldrive. It'll take a few days to sort this little lot out and no doubt the clouds will set in for several months once everything is ready to test! Thanks to FLO for excellent service and bomb proof packaging

Thanks Mark, OD would need to be 36mm+ and around 70mm long would do both weights - happy to make a donation + pp if you find anything suitable.

Thanks Mark, that sounds sensible - I did look at alcatel, but it looks expensive in tube form especially if I cant find a suitably sized off cut. Nylon sounds good - I wasn't so sure about aluminium and stainless due to galvanic corrosion.

I need to knock up some stainless steel counterweights for CGE, having found a couple of reasonably priced 7" 304 grade billet ends. Nothing too smart, but should be able to get a decent finish and polish them up. Given that the shaft diameter on the CGE is 32mm, I'd like to find flanged bushes to open up a little wider and will probably drill and tap the weights to accept an M6 nylong tipped bolt to lock off. Commercially they seem to use a hard plastic material, but I was considering olite bronze or similar - any suggestions, or should I simply bore out and chamfer and save the pennies and fuss?