Gina

The single widefield imaging system is nearly ready - just needs a pinion printed for the remote focus. Dual widefield NB imaging rig requires support structures and remote focussing systems for both lenses and electronics. Esprit Imaging rig just needs assembly - all parts ready to go and now includes OAG for guiding. Ha solar telescope imager needs a couple more printed parts and electronics box.

Ah I see And thank you Peter That's what I thought and why I'm using the scope focuser - simplest solution. I've redesigned the motor bracket and scope ring to allow attachment to the electronics box and also designed another ring for the other end of the box.

The print bed frame has finished printing on my Titan printer and seems fine. I reduced printing speed to ensure success but I shall be experimenting with increasing the printing speed of the second and subsequent layers. Printing time was 2 hours as predicted.

Like my other imaging rigs this will also be controlled by an Raspberry Pi 3 with INDI drivers for the camera, filter wheel and focuser - it will also control the EQ8 mount which I shall be using until I get my DIY fork mount made. Client software will likewise be KStars/Ekos running on my Linux Mint desktop PC.

Here are a couple of photos of the rig less the electronics box that controls the lens focus and captures the images. Between the lens and the filter wheel are a "Russian Adapter" which converts the Pentax M42x1mm to T2 thread (M42x0.75MM) and a T2 extension tube to obtain the correct back focus for the lens. The support brackets for the camera and lens attach to the jaws of a mount which not only grips the brackets but closes them onto the lens and camera, doing two jobs at the same time.

This is based on the ZWO ASI1600MM-Cool CMOS astro camera and vintage film SLR camera lenses. In particular the Asahi Pentax Takumar, Super Takumar and Super Multi-Coated Takumar lenses. I plan to use this rig for LRGB and where I have only one lens of a particular focal length for NB imaging. Between these is the ZWO EFWmini filter wheel.

It wasn't my Titan printer - it was me It's working fine now. And I'm feeling a little bit better A few odds and ends arrived from Ooznest including brackets for the rear XY pulleys so I've now used them to attach the pulleys. I'll have another go at the print bed frame shortly - Titan is currently printing a bracket for the camera on my widefield single imaging rig.

Titan is playing up and I've picked up a bug so no progress.

In addition to the 0.8mm nozzle I have also been printing with a smaller 0.4mm nozzle and produced quite high resolution prints using 0.3mm or 0.2mm layer height. Both these nozzle sizes have been used with ABS, PETG and TPU filament successfully. The genuine E3D V6 hotend with E3D Volcano heater block and nozzles has enable printing with the very soft and stretchy TPU filament which needs good support right from hobbed shaft to nozzle. I am now printing with a large 1.2mm nozzle which this larger printer was originally designed for. The Volcano heater block and nozzles provide much faster heating and enable speeds of 50mm/s even with the 1.2mm nozzle. So far I've used only PETG filament with the 1.2mm nozzle. I'm using a 1.0mm first layer height with 120% filament feed whilst the rest are with 0.8mm layer height and normal 100% filament feed rate. I'm using half speed printing for the first layer to help with adhesion to the print bed. Software is Repetier Host with CuraEngine slicer. Firmware is the latest version of Marlin.

Didn't quite print properly so I've adjusted some of the CuraEngine slicer settings to correct this and now it's printing well Increased first layer speed and reduced the others also increased the filament feed rate for first layer and reduced layer heights. I'll post more details in my RepRap Titan printer blog. Printing time is now 1.5 hours with 20% infill which I think will be enough.

The printed frame was the right size in length and width but a little too high so I've reduced the height by 2mm and added blind holes to tap for fixing screws. Now printing the new version having changed the nozzle on my Titan printer from 0.4mm to 1.2mm to reduce the printing time. Printing at 60mm/s it will take an hour and a quarter with 50% infill.

Two photos of the frame placed on the Z carriage - one with the carriage at the top and one at the bottom.

Now printing the bed frame on my Titan printer. Two screenshots - one from SketchUp showing the frame right way up and the other form Repetier Host showing how the frame is actually printed.

Thank you Dave Here's a view from the front of the whole printer.

They look nice I'm sticking with cord for my printers. Just finished the 4 cord drive on my "GinaRep Mini" printer.

Now have the Z drive set up and working from the stepper motor. The 10mm stainless steel axle makes a much better thing to wind up the cord onto. The larger size and smooth surface makes for a much narrower wound up cord.

Z drive gear.

I might be able to advance the Z drive without waiting for the 8mm x 400mm brass rod to arrive. I've found a 440mm 10mm stainless steel bar that came from the Velleman kit and no longer used. I won't attempt to drill this for the cords but I could make collars to clamp onto the bar. I could use this with plain Nylon bearings rather than ball bearings. Polished SS in Nylon bearings should be perfectly adequate for this application - I have found this combination very good in my clock projects. With a 33t spur gear and 8t pinion on the stepper motor the Z resolution would be the same as my Titan printer. I have been using 0.2mm layer height on the Titan quite satisfactorily so I think this drive for the Mini printer should be fine. I have upgraded the Titan hotend system to a genuine E3D Volcano right through from the extruder (also E3D). I have found a significant improvement in using genuine E3D parts over Chinese copies.

Here are some photos of the Z drive shaft bearings and a method of adjusting the cords so the the bed is approximately level. Cord adjustment is by slackening the screw and sliding the screw and backplate along the groove and tightening up when adjusted. Exact levelling is dealt with by the auto-bed-levelling routine in the Marlin firmware.

Well, it does need focussing so how do you suggest I do it? Are you saying that once I get the scope roughly focused I can rely on tilting the etalon to fine focus? Haven't had much chance to try things as there's been very little sunshine since I got this scope No surprise there then!!

Progressing with the Z drive - have two ball bearings mounted and one of the two pulleys. Also, designed the gears to drive the axle.

A C to CS adapter then one of the ZWO cameras works well. I use the ZWO ASI178MM USB 3.0 Mono Camera

This seems to be workable but the length of the wound up cord sitting in the thread is 16mm whereas on a plain rod it would be only 8mm as the cord is 0.5mm diameter, which would be a lot better. I have ordered a 400mm length of 8mm diameter brass rod (to match the ball bearings I have on order, though I guess plain bearings would be adequate) and could either tap it at the ends to take nuts or just use tight fitting 3D printed sleeves. I can drill it to attach the cord. ATM I have a 500mm length of M8 stainless steel studding that came from the old 3D printer kit.

With the above idea, care has to be taken that the offset due to winding along the shaft (or drum for that matter) causes a minimal error in the Z axis and that the bed remains level as it descends during printing. This means that the geometry must be arranged so that the cord is at right angles to the shaft when Z = 0 and deviates from this as the bed descends, minimising the error since the error angle is minimised and the difference between the adjacent and hypotenuse (Z axis error) is minimised. (The Z axis is represented by the adjacent side of the triangle and the actual cord length by the hypotenuse.) I'm afraid those not conversant with geometry will just have to take this as read (or ignore it and think "I guess Gina knows what she is talking about but I don't" )

I have alternative idea to lots of pulleys - an M8 threaded rod along near the back (say 25mm from the back) could lift the rear side of the bed and the front would go over pulleys also onto the rod. The rod would need to turn 16 revolutions to lift the bed the full distance and a 50mm pitch diameter spur gear could drive it with the same resolution as with my Titan printer. I need to check all the movements for interference but the initial look seems promising. I'll see if I can produce a sketch or set up a test rig.