Gina

Having sorted out the Z carriage, the next thing is to look into the Z drive. (The XY drive is already designed.) The Z drive will consist of four cords one to each corner attached to the wheel spacers, and going up and over pulleys to the back - that's pretty much as far as I've got. The Z stepper motor will have a small pinion which will engage with a large spur gear that will connect to drums that wind up the cords to lift the Z carriage and print bed. I have yet to decide how I run the cords to the drums. I'm thinking probably more pulleys. I have already tested the viability of cord pull-up and gravity pull-down for the Z carriage in my "GinaRep Titan" printer. It works well and has been in almost constant use for some time now, producing good prints.

Popped out to help a friend with a problem but back now and taken a couple of photos showing the print bed frame and Z carriage. I've placed the glass plate on the base to show the proportions. On top of the wooden base will be a half inch thick layer of polyurethane foam insulation then the bed heater pad and finally the glass plate on top. A 3D printed frame will hold it all in place and the heater pad against the glass plate. I could replace the 12v 220W heater pad with a mains voltage 300W heater pad with adhesive backing to stick to the glass plate but already having a non-adhesive heater pad and foam to press the heater pad against the glass there's probably little point.

That is going to work The two V-Slot rails that were originally designed to act as the Z rails now become thee sides of the bed. I have tapped the ends for M5 screws and mounted V-Slot wheels on M5 bolts screwed into the ends of the rails. One end fixed and the other with adjustment to fit the wheels to the upright rails. The base of the bed is a piece of 6mm plywood bolted to the rails with 4 screws. The holes for the screws for one of the rails have been elongated to allow for adjustment to make the wheels exactly fit into the grooves in the rails.

No clear night skies forecast so this project may take a back seat for a while depending on how I feel.

Been looking into where I could put the electronics box (or boxes) and the motor drive box could go next to the telescope focuser with an extension to the clip/bracket that holds the focus motor and another clip further up, the other side of the solar finder. I think this will want printing in three parts to avoid a lot of support material so I'll print it in ABS and solvent weld the parts together with acetone. I have yet to make up the electronics yet. Two or possibly three stepper motor driver modules plugged into sockets on stripboard plus RPi 3 and buck converted to provide 5.1v for the RPi. The third stepper motor would be if I add a camera rotator - nice but practicality doubtful. We have rather watery sunshine ATM which might improve later but I can't see my being ready for solar imaging today and I'm not pushing myself - only results in mistakes!

I've had another idea for the Z wheels that keep the print bed located - I could use the corner upright rails.

Been continuing with construction of the printer. Printed the Y carriages and assembled both them and the X carriage with extruder and Z probe. It looks as if the Y carriages would sit fine on the rails without bottom wheels as long as the print speed was kept fairly slow but with very fast changes in direction and rapid acceleration/deceleration the Y wheels could lift due to the larger mass above the Z rail. I don't really know if this is a problem and I think I'll try the printer without bottom Y carriage wheels. It would be no problem to add extra rails later if required. I think that with the Y drive being by the pulleys above the rail the masses of the motor and the X rail may cancel out

Had another idea - keep the current framework but add new Y rails above what were supposed to be the Y rails leaving space between for the wheels.

A lovely orange full moon rose in the east a little while ago If you like that sort of thing "Harvest Moon" I believe It's lighting up the passing clouds beautifully

Found a massive design boo-boo The wheels on the bottom of the Y carriages run in the underside groove of the Y rails and as I've designed the frame would run into the Z rails!! The Z rails will need fitting to the outside of the Y rails and bottom frame rails as in the design of my Giant printer. I may need to buy some more brackets. The printing height will be reduced by 40mm but I think this will still give a build height of something like 220mm which is alright.

With the new camera and just the 0.15mm spacer I get about 49.5mm (0.03mm tolerance) making a total of 56.0mm as near as I can measure so that's it :)

Here is a photo of the two cameras, one with EFWmini and the other with single filter in filter adapter inside the 11mm F-F gender changer extension tube with a pair of 55mm f1.8 Asahi Pentax Super Takumar prime lenses.

I've added the Delrin spacers and measured the spacing again. 49.92+6.5 = 56.42mm. Hmmm, a discrepancy of several tenths of a mm - I don't think my measurement is all that accurate or maybe the rings compressed when I measured them with the digital calipers or there might have been dust on the surfaces or ...

Regarding the back focus distance for the SW Esprit 80ED Pro field flattener :- And the back focus for the camera :- The filters are 3mm thick so add 1mm to the required FF back focus requirement giving 56mm. Measured spacing from FF to face of camera = 49.05mm. Adding in the 6.5mm camera back focus gives 55.55mm. ZWO also supply thin Delrin spacers of 0.40mm and 0.15 mm so if 0.4mm one is used as well the back focus distance becomes 55.95mm. I would say that's as close as could be expected With both Delrin spacers the back focus distance would be 56.1mm. I could try with and without the 0.15mm spacer but I doubt I'd detect any difference as the camera sensor is 21.9mm and the stated coverage of the Esprit is 33mm so I'm not using the whole image from the scope.

The weather forecast is not good for the next few days though there might be an odd couple of hours tomorrow night. Solar imaging or observing is out until at least next weekend so I shall concentrate on my DSO imaging rigs though I might think about PA on the NEQ6 using the Esprit rig which is ready to go. One of the adapters that came with the new ASI1600MM-Cool will provide the spacer between EFWmini and FF on the Esprit.

My second ASI16600MM-Cool camera arrived this morning - a definite improvement on my other one which is the previous version and suffered from the nasty habit of the front coming unscrewed when detaching the camera. The new one also came with many extras including a soft carrying case - nice feature but I doubt I'll use it. But more importantly, there are many more adapters included than before and some of these seem to provide the exact distance required to satisfy the back focus required by focal reducers and field flatteners. This would be just right for my Esprit 80ED Pro with field flattener. Furthermore the diagram in the booklet with the camera shows a narrower than usual OAG and on checking the FLO website I see there's a new ZWO OAG that matches the diagram. So if, as I suspect, I need guiding on my Esprit imaging rig, that's another imaging rig sorted out ZWO really seem to be getting it together Very impressive Corrected an error in this ZWO diagram - spot the different typeface

Something I've noticed in the diagram above - comparing the bottom two rows, the OAG has to be 16.5mm unlike the one's I have which are 21mm and won't give the right back focus. I wonder if ZWO produce ultra slim ones A bit later... Yess!! They do :- ZWO Off Axis Guider (OAG) Yippee, just what I might want for the Esprit rig if not for the widefield I have to say I'm very impressed with ZWO They seem to have everything sorted

ZWO have added several more adapters to what's in the box since this listing This includes what would appear to be exactly right for the back focus on focal reducers & field flatterers for telescopes (with the ZWO EFW) so I'll add all the bits to my Esprit FF and carefully measure the spacing. Plus, apart from the filter adapter ring a spacer that would appear to give the right spacing for camera lenses though this isn't shown in the diagram. Item 1 in the diagram would be replaced by extension ring and camera lens (with or without "Russian" adapter). Also, new since I bought my last one is a very nice soft carrying bag for the camera. A nice addition though I doubt I'll use it. This is the an upgrade from the version I bought before which had a tendency for the front to come loose. I've corrected an error in the diagram. (Spot the slightly different font )

I've been looking at a single widefield imaging rig. I've found the information in this thread. I have the ASI1600MM-Cool with EFWmini filter wheel attached to a 28mm f3.5 Asahi SMC Takumar lens and dew shield. All ready to attach to the a mount except for the focus motor and electronics box. I can use the electronics box from the Esprit setup and the motor from my (now abandoned) rotating turret widefield rig. (The stepper motor on the Esprit rig hasn't got a long enough cable.) I should have a pinion for the motor but I can't find it so I'll print a new one. The rig attaches to the mount with wedge shaped 3D printed parts one on the lens as shown in the photos below and another on the camera near the back. One of these should be around somewhere but if I can't find it I'll print another. The software is ready to go - INDI drivers on the RPi and KStars/Ekos on my Linux Mint desktop. The electronics box from the Esprit rig has been tested and works fine. (See a little way back in this thread.)

Sounds good Dave I never did think those 4-start ones were suitable - too coarse. Well done on finding single start ones - when I looked I couldn't find any. I think using three would be a good idea. Maintaining the bed at the same level throughout the Z range is difficult with wheels and rails, even with these superb V-slot rails and wheels though I have to say I have conquered it with my Titan printer. But for my new printers I'm going to use three cords/strings for the Z axis and a simplified guiding system on two V-slot rails, one either side of the bed. These then only have to guide the bed in the XY plane, the height and levelness being taken care of by the cords.

I have created blogs for the individual projects and this thread will continue to be a general overview of my astro imaging rig projects. I've also included the link to my blog about the hardware and software I'm now using for imaging. Ha Solar Imaging and Observing Rig Widefield Narrowband Dual Imaging Rig Setting up a Raspberry Pi for Astro Imaging and Hardware Control

For some reason I decided to look at what's included with the ASI1600MM-Cool - there must have been something in the back of my mind from when I bought my first ASI1600MM-Cool camera just over a year ago. I've highlighted the relevant item in green Problem solved!! I can use the mini filter wheel with one camera and the adapter ring for a single filter in the other.

I think I have a 1.25" filter holder amongst my astro stuff. The only one on FLO seems to be Baader and only for the bigger filters (50mm etc.) - when you add up the parts needed it comes to over £150 - it would make more sense to buy a filter wheel. Otherwise it looks like a 3D printed jobby

Another thought was to buy another ZWO EFWmini but I can't think what for on second thoughts...

Regarding mono images, if you want to just collect twice as much Ha data on the same object you will need two Ha filters and Astrodon 3nm Ha filters are expensive. 5nm filters are cheaper though. I have both though I don't know how well mixing data from both would work. Have to say, I do quite like Ha mono images - they seem to provide beautifully sharp and detailed images. Adding in OIII for a colour image makes for a prettier result but seems to reduce the sharpness somehow. Or at least that's how it looks to me. A third wavelength makes for a better result and I don't mean a synthetic green. Although some seem to get reasonable results, I haven't had much luck with that. Another thought I had was to have a 3nm filter on one and 5nm on the other providing Ha data and NII by subtraction. I have tried the subtraction process with two separate batches of data and it works. Using data sets taken at the same time on the same object should produce better results. This data would be collected after a decent run with Ha 3nm and OIII 3nm filters. I could arrange for this if I were to use my ZWO EFWmini on one of the cameras. This could contain 3nm OIII and 5nm Ha filters and save manually changing filters.