kbrown

While I could just use my camera ball head attached on the free bolt on the L-bracket and make an adapter that would allow me to put the finder scope on it, I thought I'd explore my original idea a bit further. Mainly to see if I can overcome the challenges I've faced and learn something but also to keep the overall weight of the kit down. 

Here's a clamp style variation that seems to hold up a lot better than my original design. I printed it in two parts and glued them together. This allowed me to print them in orientation optimal to the structural stresses when in use. I can now tighten the M6 wingbolt quite hard and it's not crackling at all. It's also quite easy to roughly match the DEC angles between the primary and guide scope. 

Bah. Don't think this design will hold up as is. Not 3D printed at least. No matter which way I print it, it will crack (layer separation) when I tighten the locking screw. 

Might have to thread the end of the rod and fasten it between two nuts or something... 

1 minute ago, JamesF said:

I think that's an interesting point that has occurred to me before now.  With this mount the possibility exists of putting useful kit on the "bottom" end of the mounting bracket to help balance the weight instead of just using a lump of steel.  All that's required are sufficiently rigid mountings.

James

Exactly. I remember someone here (thinking of) putting the battery there. Perfect counterweight and would serve a purpose.

I'd rather have it at this end of the rod than on top of the scope as I'm already pushing the capabilities of this little tracker with all my gear attached.

1 minute ago, vlaiv said:

Interesting.

I do have one question - will it work as a guide scope?

Raising this question because I can't get my mind straight right now if there will be impact of it sitting on the opposite side. Both main scope and guider rotate in same direction, but mount moving ahead in RA on scope side will mean lagging behind on guide side (or will it?) - wonder if calibration is going to take care of that.

I'm sure it'll work as the calibration figures out which way it should do the corrections...

Inspired by an article I saw online a while back I thought I'd design and print a similar guider scope holder for my Skywatcher Staradventurer's counterweight shaft. It'll be RA guiding only but I'm hoping to at least improve the nasty periodic error it seems to suffer from. The holder accepts the standard Skywatcher finder scope shoe. 

I've put helicoil thread inserts in the holes for the locking screws so it should last a bit better. 

Only issue I have is the structural strength of it. I get layer separation if I tighten the butterfly screw too much. I'll print another one in another orientation to see if that's stronger / strong enough. 

6 hours ago, Demonperformer said:

If yours is anything like mine, getting your SLIK tripod ready for "proper" astro work is going to be quite a challenge. I will follow your progress with interest.

5 hours ago, Stargazer McCabe said:

I quite agree. In the merest breeze mine was as shaky as my Labrador in the Vet’s waiting room ... 

Good luck with the project @kbrown ?? Be interesting to see how you get on...

Thanks guys. Yes it's not the best solution but it's not the worst either. Mine is the SLIK 504 QF-II. It came with a video head which I have removed completely as that was the main source of flexures. I've attached the Star Adventurer wedge directly to the height adjustment centre pole which I always keep at its lowest position to minimise any remaining flexures. I may even look into permanently fixing the pole in this position somehow. Here's what the original tripod looked like:

As some of you already know I've been recently concentrating on getting my smaller DIY refractor in a usable state. I already can use it with my DSLR but ultimately I'd like to be able to use it with my Atik 383+ and QHY5L-II mono cameras and my (DIY motorised) filterwheel. Ultimately I'd like to also motorise the focuser on the scope and be able to control that via INDI like I've done on my 10" newt in the past but that's something for the future. All this of course presents some additional challenges especially when trying to keep everything reasonably portable. Would be great to be able to fit everything in a single large rucksack.

This thread will be mostly about building a tripod tray for my old SLIK camera tripod I'll be using with this scope. The tray will be a platform for things like a Raspberry Pi or similar for running the INDI server for the cameras, filterwheel and gps plus a power source for all of these and dew heater(s) etc.

Here's a rough idea I'm thinking of at the moment:

The green parts I've already printed. The white parts (three of them, one of them hidden above to show what's going on) form the tray itself. The reason why it's split in parts like this is that I intend to 3D print them to keep the weight down but due to limitations of my printer I can't print the whole thing  in one go.

Most of the tech bits and bobs and wires I'll try to hide under the tray.

Thanks Chris. I did start wondering about this after my last post. I then had a look at the hole I made under a USB microscope and it actually wasn't even all the way through. The light was just shining through a very thin layer of plastic so this is another downside of just using plastic -> it might not be opaque...

Anyway carrying on with my experiments I pushed a needle through the plastic just enough to feel the tip on the other side. I then took a piece of 1mm fiber optic and pulled it slowly under heat to thin it out as much as possible. Took a few attempts but I managed to get it hair thin in one end. I then pushed the fiber optic through the hole and cut and sanded it flush to the front of the cone. This resulted in a very round light dot. It's just a bit too big now after all my attempts.

I'll probably try the same again but with a thin sheet of aluminium or brass like you suggested in front of my 3D printed cone.

Had a go at it indoors with my diy 70mm refractor. The light was only about 4-5 meters away so I don't know if this tells me anything useful other than I've got dust in my optics ?. I had to add an extension to be able to go both sides of focus. Took these images through a 10mm EP with my phone. Guess the chromatic aberration seen here is typical for an achromatic objective...

1) Inside focus

2) At focus

3) Outside focus

Bought this weather proof led light torch from B&Q for £12 and thought I'd try to turn it into an artificial star. I just replaced the front "window" with a 3D printed ring and the reflector with a black cone with a small hole in the front (also printed). 

The cone had another hollow cone inside which converged right at the front. I then sanded it just enough to get the hole visible. Don't know if it's small enough though. Remains to be tested. 

1 hour ago, Chriske said:

I will lower speed now and start printing that thing.
 

Is this your own design or something downloadable?

Houston, we have a problem...

14 hours ago, Chriske said:

It is adjustable in height, it needs to be.
This tester is also equipped with a green laser. Purpose of that laser is to adjust the tester in a matter of seconds.
The very first time the tester is adjusted toward a mirror the old fashion way. It always takes some time for that to do so. Especially for novice ATM it is very difficult to adjust the white lightsource and reflect it onto the knife.
Once the mirror and tester's white light are 'in line', the (adjustable)laser is lit and pointed toward the exact centre of the mirror. The reflection of the laser-beam is visible on a very small screen very near that white light-source.
Now, the next time you need to adjust the Foucault-tester toward a mirror you only need to lit the laser, point that laser beam toward the very centre of your mirror and then adjust the mirror stand so the reflection point to that little screen  located at you're tester and you're done. When the initial setup is performed correct, the reflection of the white light falls exactly on the knife, every time again.
there's only one 'but', I'll explain some more when the new tester is assembled.
Because it's a printed version it is very light, so I added a 2kg steel weight at the bottom of the tester.

Needles to say, when someone do setup a Foucault tester toward his mirror only once, there's no need to use that laser at all.
It's only when the tester needs to be removed from that location and setup again the following day or so, then the laser comes in very handy.
Also in my case when different mirrors needs to be tested (during course) that laser is also a very handy tool. It saves me LOTS of time.
 

Am I correct thinking that once everything is aligned properly, you only adjust the distance of the knife from the mirror? Does the light source and camera move with the knife?

Following with great interest. Focault/Ronchi tester has be on my to do list too but having never used one or the other I don't have the knowledge or experience to design one. 

Is it essentially just a platform that moves along the optical axis and carries a light source and a camera plus another platform that moves across the axis and carries the knife blade or the Ronchi grating in front of the camera? What about height? Does that need to be adjustable too? 

I put off getting a 3d printer for years. I just though I don't really need one since I already had a CNC router/engraver that I've successfully used to "mill" rather complex plastic, aluminium and even stainless steel parts. Then little by little the idea of getting a 3D printer overwhelmed my resistance and I finally got a Prusa i3 Mk3 kit. Now on hindsight I'm thinking why didn't I get it sooner. There's been so many things small and large that I've done with it and I get a new idea almost every day

Sorry to barge into this thread (have to admit I didn't read it all). I'm curious which actual sensors are you guys using that can talk to an Arduino? I'm interested in writing an INDI driver.

Hi,

Thought I'd share my latest thingamabob. In the past I had an astromodified Canon 60D and an Astronomik ProPlanet IR807 infra-red pass filter for it. Since I stupidly managed to break the camera (don't ask) the filter has been just gathering dust in my drawer until now. I thought it would be great to be able to use it along with my 2" filter wheel with my tiny QHY5L-II mono camera. Bit of CAD + 3D printing and thread milling and I came up with this solution:

Fits like a glove. Yay :-)

The 3D printed cover for Frankenwheely just arrived. Had them print a few extra parts too due to their minimum order of £40+vat. Totally happy with the result. Might paint these later for an extra protective layer...

Mine is fixed at 5 filters for now but it would not be hard to add the counting. I'm not keeping track of the absolute position of  the wheel. I just run the stepper until one of the sensors detect a magnet. Then I run a little more to see if any other magnets come into "view" so that I can read which slot we're at. On top of this I apply the user defined offset so that the slot is aligned properly. Seems to be very reliable as long as I don't move the sensors. Neodymium magnets are said to lose less than 1% of their flux density over 100 years so that shouldn't be a problem either. Don't know how temperature changes will affect things. Remains to be seen...

Quite an arsenal! Which one do you like the best? 

Thank you Julian. That is very kind of you! I got a reasonable quote from www.3dprint-uk.co.uk so I went with it. I'm printing a few other bits at the same time as well. They're doing them in polished black nylon. I'm curious to see what the result is.

Out of curiosity which printer do you have? I've been thinking of geting one as well...

Here's a demo of the first working version of my Frankenwheely arduino firmware and INDI driver talking to each other. Had to add offsets for forward and backward search directions separately as the triggering of the hall effect sensors varied a little depending on the magnet configuration per slot and the direction they approached the sensors. Shouldn't have to tweak these values from here on as they are stored on board in the arduino's built-in EEPROM.

Now I just need to somehow fabricate the lid for this and do some field tests. I could just mill the lid out of a block of plastic using my CNC mill but that feels a little wasteful. Been thinking of getting it 3D printed somewhere instead. Can anyone recommend 3D printing services in the UK?

Had to do a couple of mods. Added a bracket to hold screws on top of the sensors. They'll serve two purposes: They'll prevent the sensors from moving and also redirect the magnetic fields toward them. Also added a voltage divider from Vin connected to one of the free analog inputs so it's able to detect when running from USB power or external power which is needed to run the motor.

Preliminary firmware is now on board. Just need to get the INDI driver in a better place so I can start doing proper tests