Chriske

While changing hotend I do not swap cables at all. I designed it to be as easy as possible. To swap hotends I only have to remove two screws. All stays in place as a unit. In both XY-carriage and hotend I have two littlt PCB's with contacts. The contactPCB in the XY-carriage has a little bit of play to avoid tension on these PCB's in case of little positioning errors. But as far as I can feel all works very smooth while inserting the hotends in it's carriage. I also have to remove the partscooling nozzle(2 screws).

I was planning to do that...

The smaller 1.75mm diameter filament and it's higher speed result in a flow that can be controlled far more accurate compared to 3mm filament. I even use 1.75 mm filament with a 0.7mm nozzle, it gives me smooth prints with no issues(except for the layers itself of course). Layerheight 0.52mm..! Lucky me (except for the nozzle) I make my hotends myself. I have a lathe and a milling machine. I integrated a fast exchangeable hotend in my printers. (I do not believe in fast exchangeable nozzles) A few days ago I also bought a 1.0 and a 1.2 mm nozzle... And I read somewhere printing with a 2mm nozzle can be done with a 1.75(!)mm filament..

Gina, I saw in one of the pictures you use 3mm filament. you should try printing with 1.75mm filament. Print quality will improve significantly.

Gina, what software are you using to make these drawings..?

Nicely done...

Gina, Will the dome be removed manually or is it a two section dome that will rotate out of the way..?

Here's a list of all electronics involved in this telescope : 1- DSC system. Own design and except for the small gears(mod 0.5) all parts are printed. Connecting with the software(tablet) is done wireless. DSC connection between scope and rocker is done with a timing belt. 2- Green laser pointer(I do not use finderscopes). Push button for that laser is located in the Crayford focuser. Mostly used to initiate the DSC system at the beginning of a session or just to find/point easy objects. 3- Heat control for the green laser. Laser is kept at 18°C all the time, even in mid-winter. 4- Primary mirror cooling fans. Speed control for these fans is located in one of the Alt-bearings. 5- Boundary layer (Primary mirror) fans. Push button for these fans is located in the Crayford focuser. 6- 2x2 battery compartments. One set is located in the rocker, the other in the scope itself. I use them in series so I become 14.4 volt for each compartment. 7- Locking system on the altitude bearing. (not yet electronically) Purpose is to allow smooth eyepiece switch without the scope sagging away, losing the object out of the field of view. Problem is the big difference in weight between my smallest end largest eyepiece. When done I slide a counterweight to compensate and release the scope again. Working on : 8- Dew control for the secondary (that's why all 3 curved spider vanes for the secondary mirror are colored red in the drawing). The 3 metal spider vanes act as leads. 9- Stepper motor for the Crayford focuser. That's why the Crayford is somewhat larger. There is also a micro-switch involved to 'home' the eyepiece. All electronics are designed and made by Guy, our electronics guru.(mentioned higher up in this thread).

That's a difficult one to answer... One of the goals was to hide all electronics and its wiring in the telescope's parts itself so I spent lots of time thinking/drawing how to do that. So during drawing I constantly had to keep in mind and decide whether a part was candidate to include invisible canals to allow all wiring passing through. Assembling the scope and rocker was not easy with that 'wiring-problem'. Many times I had to start all over again because a wire was missing or lead through the wrong parts, ending up at the wrong side of the telescope. A second important time consuming item was how to make such a large telescope printable on a standard bed. The only solution was to print small parts and bolt or glue them together. To answer the question : I have no idea, one year, maybe more. Printing itself took me about 60 days(I think...). All red parts in the drawing are 'hollow' or have 'canals' to allow wiring to pass through or for PCB's or batteries to install. This is one of the (easy) parts were wiring will pass through. in this case the wiring is very near the parts inner perimeter.

Well I do not know about that, I suppose it is lighter. I did not had a lightweight telescope in mind during designing. I just wanted the telescope to be printable on a standard 200x200mm(8"x8") bed. The tube's weight is 7.9kg(about 17lb) The rocker's weight is about 13kg(about 28lb), batteries included in both parts. If I would print it again I would consider setting the infill of all parts a bit lower. All parts have now infill 35%. Both parts have separate power-packs as a lot of electronics is involved.

The black (thin wall)l tubes are hardened aluminum, the outer diameter is 35mm(1.4") so the scope itself is very stiff. The Dob's rocker is made of a (thin walled) steel structure so it is very stiff also. The triangle based structure makes it even stiffer. The green 21mm(0.8") diameter steel tubes are plastic coated.

Except for the aluminum tubes this Dob(own design) is completely printed using a Prusa i2, all is in dutch but the many pictures tell it all. (It took me a few months to draw this thing.) Enjoy... The man on the right is Guy, our electronics guru, left is a visitor during our open door.

Completely off topic, I know, sorry... but I couldn't resist after reading Pete's post... Pete, show your wife this jewelry box ..... If she likes it I'll send you the stl files just in case... Busy drawing/printing a spare set of (8)wheels/brackets for the lower basket of our dishwasher this very moment. Cost on ebay 15(!)£, selfmade 1.16£..!! (+ I had the pleasure designing a far better and stronger version of these brackets). As Gina said dozens of things to be made with a 3D-printer, I lost count how many things(not toys) I made/repaired for the house. Sorry again for the off topic post...

Jim, Depending on the sensitivity and the range of the camera you could observe the boundary layer of the primary, see how long it takes to get rid of.

Not only will it be difficult to remove that mirror, but cooling the mirror before observing would go a lot faster if there is a gap between mirror and holder. Astigmatic error will be an issue imo. I've done lots of repairs in the past, lots of these secondaries were glued like yours and suffered from that problem. I would do what Nigel suggested using silicone-blobs.

Indeed, in a situation like this I'd use threaded rods, Make a slit with a hacksaw or a dremel(grindingdisk) and you're done. That slit doesn't have to be very deep at all. I would make the slit just wide enough to allow the spider to fit in without any play. To prevent these parts from moving I use a small bolt instead of a pin. Tightening that bolt will secure it all in place. So a (M6) 1/4" bolt or threaded rod would do fine in this case.

I think it is something like this. But I'd use a threaded rod instead, so fastening can be done with 2 nuts/washers for each vane. And there is absolutely no need to use two rods for each vane Jim.

Correct Gina, We never had any problems with these A4988 drivers in the past either, let that be clear. But in the end the result is far better with these TMC2100 drivers. And maybe, just maybe it also could be a combination of different items I integrated in my own designed printer.

Dave, You should consider using TMC2100 drivers, at least for X and Y-motors. It improves perimeter quality a lot as it uses microstepping. And also quieter movement of the XY-carriage is the result. If you do buy them take care: they should be mounted reversed..!!

Like I said, changed a few settings : lowered printingspeed drastically to 30mm/s, lowered printtemp, enlarged retraction to 2mm, lowered retractionspeed...same result as before... As I read it, it seems to be very difficult printing PETG without stringing. Maybe some other brand worth trying..?

Done some printing with PETG myself, lots of stringing. Changed slicersettings a few times to no avail...

Dave, Make that printer as sturdy/stiff as you possibly can..!! During the past 3 years we've(3 friends - telescope and printer nerds) built about 20 different types of 3D-printers. None of them produces 100% perfect perimeters. I now have finished a printer of own design. It's casing is a very strong wooden box and that is one of the main reasons it outperforms all previous printers we've built in the past. No more ripple on the perimeters and no more ghosting around holes. As a matter of fact, it was very strange to have these perfect perimeters after 3 years of building and testing printers. Second reason why it performs so well is that I abandoned these LMUU linear bearings. I make my own (adjustable)bearings. So there's absolutely no play on the axis at all.