Chriske

I removed all parts in the drawing leaving only the reduction system. This is how the inside looks like, the red wheels are in fact all gears. I was to lazy to draw the teeth...😊 The black friction-wheel is a rubber O-ring. Working with the dual speed knob(left) I first push the knob toward the focuser, so the two conical gears do connect. When I only use the eyepiece-barrel I first retract that same axis. That is btw why that dual speed knob-axis is so long. But in fact there's no need to retract the dual speed unit. When I leave it in place during 1:1 speed the reduction system runs at high speed and makes a funny noise

A while ago I started making printed focusers. My goal was to make, every time I designed a new one, try and make something completely different. Planning to make some more. I have a few more ideas, but these new designs are not labelled 'urgent'. To be clear some of these are not my design, most of them are. This is what I got so far. I know, some have been posted already here on this forum, but I wanted to have them posted all together in one single thread. I hope you enjoy this thread. 1- Collapsible focuser. This one can handle very heavy eyepieces and camera's. Due to its design there's no way it will slip. It also have the ability to push the eyepiece very deep, even a bit in the scope's main-tube. Completely collapsed the focuser is only 28mm high. It's action is very smooth and there's no play at all. Disadvantage of this one is it's size. And one more thing it needs secondary hole in the main tube to allow passage of the threaded rod. I usually use a M16 rod, hollow out. It also has a dual speed unit on board. I designed this one to discover only a few weeks later that someone made this type of focuser before me. But the (US)guy made it completely in aluminium(very nice one btw) 2. Rack and pinion This is an old design. Not mine of course. Need to work on this one. It's action is way to fast due to too large teeth. 3. Helical focuser Again an old design, not mine either. I could not have it working without play or smoothly. Maybe it needs some more 'tuning'. 4. Helical Focuser BB That threaded Helical focuser gave me an idea. Instead of threads to do the focusing action why not use ball bearings instead. The ball bearings in the unit are all tilted at a 4° angle. It works very smooth, there's no play at all and I can adjust the pressure on the eyepiece barrel. 5. Helical Focuser BB dual speed Almost exactly the same as the one here above. But this one I added a dual speed unit. I can rotate the barrel just the same as the one above or use the dual speed knob. 6. Crayford focuser. Not mine but this one is own design. I have two versions. The second version has a very small stepper inside. Working on that one. Here too, play can be eliminated completely. I also decided not to add a plane onto the focusing barrel to run along. Works just fine. Also dual speed. 7. Inversed focuser Not my idea either, but I redesigned it. The focusing barrel is pulled toward the observer. Pressure is controlled by springs in this case. This version has no aluminium barrel. The ball bearings are pushed against two thin strips of brass. 8. Crayford (Printed barrel) The inversed Crayford does not need a aluminium eyepiece barrel, this one does not either. Both Crayfords here above do have aluminium to run smoothly. The first one has a aluminium barrel for the ball bearings to do the guiding and the Inversed one has a external aluminium plane. This one has very large pieces of tie-wrap instead of a aluminium plane. There's a rubber O-ring around focusing rod running against a third tie-wrap. It works surprisingly well. 9. Timing belt driven focuser. What I used for this one is a timing belt, a few pulleys and also 2 LMUU8 linear bearings to do the guiding work. Works perfect and also very smooth action. In this case I used a somewhat larger knob instead of a dual speed unit. Tension on the belt is adjustable. 10. Reversed Crayford Instead of a fixed focuser and the eyepiece barrel going up and down together with the eyepieces, this one works the other way around. The complete focuser is moving up and down along with the eyepiece around a tube. More to come...

sigh....!! today rain...tomorrow rain, the day after tomorrow...rain, the day after.... and so on... Dam...!

I think PLA is the most used filament.

EQ6, yep it is.

The head strongly reminds me : Alien..?

This is how the primary baffle will be collimated. At both ends of the primary cell-a are 3 slots in which 2x3 M6 nuts are inserted. In all nuts 6 grub-screws. Around the primary baffle are glued 2 metal(brass) rings. Setting the grub screws the baffle can be pointed in all directions. Needles to say, when the baffle is mounted in it's cell only minor adjustments will be needed.

The fourth pole arrangement stops at the dovetail. There's no need to add a additional fourth pole alongside the primary cage. That lower parts is stiff enough as it is. What's more, when we were testing stability of the combination mount/scope, we were very surprised how stable it was. Hitting the scope very gently, it moved a little bit and stood still almost immediately. I would expected a scope this long to keep on moving for at least a few seconds or so. We're very happy with the result...! Last thing to do is polishing the secondary mirror and adding a shroud around the primary mirror. That shroud will be added only if stray light is hitting the PM.(or in case of damp weather). And also a few surfaces needs to be blackened.

The object in Marc's garage is a Maslow and that 'thing' in the middle is a router.

This is very sturdy...!! That extra(fourth) tube(not present in this picture) did the job. The complete setup is very stiff now, and non of the bolts are set. Just the heavy friction between tubes and stiffening parts made it very stiff. There's no doubt in our minds that this thing will sag. We did use a rubber mallet to assemble this scope. In the picture we were busy testing for COG. The stiffening parts are not at the correct location. They need to be relocated so they all are separated at the same distance + one on top of the secondary tube. Weight of the scope 7.8kg

Bit strange, black PLA did not deform in the sun Neil...??? This is what I did, tested a few materials, a few years ago. Ring 150mm diameter, the material was printed hollow. ALL perimeters were only 0.8mm thick. Different materials, different colours. Wheight : 1liter water in each bottle. Left hanging in the sun from spring untill Autumn. nGen - Black ABS - Blue PLA - black PLA - white Early spring To speed up things I added water after a few weeks. mid summer Autumn : The absolute winner : PLA-white

As promise, one last picture. Four of these have been installed at our observatory.

Don't think so Gina. AI was imo..😉

Several inches...??? 😱 I think you mean mm..??

I always use the same procedure to find out if a scope does sag (or not) under it's own weight. Installing a laserpointer at the very end of the scope, make a marking where the dot is(at the other side of the scope) and start rotating the scope in every possible direction, while observing what happens with the green/red dot. If the dot does move away from it's initial point while rotating, then you do have a problem. Embedded in Inventor is a 'Strain detector', but I hardly use it. Making a scope using tubes or trusses (correctly installed) there's no problem most of the time. But in a cases like this one there are many possible things that could go wrong. It is not the first time I make a scope this way. I anticipated possible failure, and so it did. Because I wanted this scope to make a bit more elegant I used smaller tubes(22mm) and positioned them in a shallow angle. To correct this I added a extra tube, but this time at a 90° angle. It's less elegant but this version will not sag at all, I'm sure.

One of the things I might try out design(IA) and print bevel gears. I do have a 0.2mm hotend..😉

I'm just a mechanical engineer owning a few printers. As I said before, with a few old fashion machines in my workshop + these printers combined, the possibilities are end-less. thanks anyway for the kind words...😉

yep, me too..

Not stiff enough, so plan 'B' is activated. These part will be added.

indeed... But I could have printed them in white of course. Gears with these large teeth are perfectly do-able. They were lying there, waiting to be used, so...

modified IPD unit. This one runs very smooth. 2.5mm/revolution

Indeed, bit strange they make them so high.

Lead guitar or not, what would we do without them...😊

The man in the picture is my pal Marc btw...😉

The COG is VERY low in this case. The sec cage is very light + the sec. mirror has almost no weight. It's only 10mm thick. In case of torsion, as you mentioned, I do have plan 'B'. Thanks for the warning. Chris