Carbon Fibre Filament job update

I completed the task with one failure (the first with BigBox) and some disfiguration due to snot drops but the final piece, shown here, was very good; note the layer 1 finish, which has been exemplary throughout all the prints. Some might say it's over-extrusion but the rest of the print, including the top layers are equally good and any extrusion changes were done beforehand; see my posts elsewhere on the forum. I'm still on the original Z bushes so this is not too bad. The last image shows the temporary assembly, which is all 3D printed apart from the cross pieces, the red focuser assembly and fixings. The sharp-eyed among you might see my super hotend cooling fan modification to address a finger poking issue!!! Ordered fans did not arrive before the weekend so a piece of flattened 3mm PLA and some superglue restored the balance. I should also point out that the grey stuff was produced on my old K8200 and will be remixed later.

 

Sorry Miriam, I modified the profile but it was just based on the ColorFab XT with 250C/75C temperatures, 0.2mm all layers, extrusion multiplier 90% (saved messing with the steps calibration), retraction 1.5mm and Z-lift 0.25mm, print speed 50mm/s (higher than the ColorFab figure of 30), 30% triangular infill with no changes elsewhere; both nozzles were heated to try to iron out any droppings. The bed was prepared with 5:1 water to PVA juice, having cleaned it with ethyl alcohol between each print. On reflection, I might have made the layers 0.25mm to reduce back pressure in the nozzle and change the infill pattern to rectilinear, all to reduce the collection of snot drops and that might need lifting the extrusion multiplier a bit but you would need to do a first layer check. Triangular infill is strong but means the nozzle deposits over the same crossover points 3 times with no change in layer height and that increases the chance of pickup My suspicion is that the fibres in the filament get caught by the nozzle and wick the plastic around the nozzle tip. Perhaps I should think about Volcano and larger nozzles in the future as I have more to do in the next phase of the project update.

 

It is part of an astronomical telescope that I built a few years ago and had used 3D printing for some of the parts and I have decided to upgrade parts that were made from metal to being made from carbon fibre filled filament. What you see is the end that has the eyepiece and focusing and turns the optical path through 90 degrees; there's a 45 degree mirror under the grey cover. This involves some fairly tight engineering to ensure the optical path is true and remains so. The size of the ring you see is 430mm diameter and was made in 8 parts but I could have made it with 4, having modified my build to Hybrid and could get the full 300mm width but couldn't be bothered!

 

I currently use the hardened nozzle for all printing and it is OK.

 

Unfortunately it's only 14" but the ring is about 16" to allow for the physics of light! The telescope exists and has for over 3 years and is why I bought my original 3D printer; these are major updates to see if big telescopes can be made successfully using this technology and the next phase is the primary mirror cell that is in aluminium at the moment. After that comes the struts and framework that was originally CNC cut in plywood.

Edit:
Clouds? Smog? Don't know as I spend more time indoors making parts for it!

 

Updates will appear here!

 

I did the design myself with SolidWorks. The secondary assembly is now all printed other than the spider, which is brass but the primary assembly is all aluminium at the moment and I am in the process of redesigning it. The image of the telescope shows the very early version with all metal secondary and different secondary mirror mount but the new verson is very different with warm air feed for dew control built in. I can make the STL's and CAD files available on Thingiverse but will need some time to do that as I have changes to make. You can PM me if you want more information.

 

I have not replaced the plywood yet as I am concentrating on the metal parts. The secondary cage ring is now complete and weighs about 300gm less and could be better when I reprint the other parts in the same carbon fibre filament. The stiffness of the replaced parts is very good and I have little doubt that building a new cradle assembly with this material will be OK.

 

That's a neat little scope and using the Pi is a great innovation and well within the reach of many 3D fans as the mirrors are reasonably priced for that size. A driven mount is also a project that can be achieved.