ChrisLX200's DIY Projects

[ChrisLX200]

Yes you're probably right there Gina, but I'd worked out in advance where the socket was going to go and was puzzled when it obviously wouldn't fit, I thought I'd made a measurment error (again... ;-) )

ChrisH

[ChrisLX200]

Little vid of Rob Brown's NANO/DRV8825 focuser circuit running autofocus via SGPro.

Motor is a 12v 5:1 stepper (NEMA17). Backlash compensation is enabled in SGPro - hence the 20-step reversal at the end of the run. The motor is running in full-step mode (modes down to 1/32 are available), the camera selected in SGPro is simulator v.2 and a random image off my hard drive. HFR calculations are obviously rubbish as it's the same image each time (with synthetic noise added) but it's enough to demonstrate the functionality of the focuser.

ChrisH

[derrickf]

That looks pretty good and should do the business when you fit it to the FT focuser using your 3-D printed adapter. Does this motor overcome the issue of the heating effect you were concerned about with the high holding current of the Nema17 motor you initially considered using?

On a different subject - did you design the thumbscrew caps you showed on Page 1 of this thread yourself? I have tried to find them, or something similar, on Thingiverse etc. but came up empty.

 

Derrick

[ChrisLX200]

Thanks Derrick. The thumbscrew caps I did see one on Thingiverse but it was only one size so had to adapt them to 5, 6 and 8mm. I've attached the .stl files for those.

Shapeoko_3_Thumbscrew_Caps.rar

Had a slight problem with voltages for the motors I have, the NEMA14 19:1 geared stepper is listed as being a 12v motor but in fact they are 5v according to the spec sheet (and indeed they are when I test run them - they don't like 12v much but are fine with 5v). That means they won't work with the DRV8825 driver circuit which needs a minimum of 8.2v to operate. These 5v motors just stutter @ 12v with this controler. This also means they a bit less convenient to use at the scope because the power outlets on my pier are mostly 12v (though I do have one 5v outlet I use for some relays). So I've incorporated a little DC-DC circuit inside the controler box such that it can be plugged directly into a 12v supply. It works fine on the bench. The earlier heating problem was due to running the 5v motors (using the UNO/L293 circuit - which does actually work at 12v) where the holding current/voltage caused the excess heat. The one on the scope at the moment actually runs on 5v plugged into the relay PSU outlet and is perfectly happy. So to get around this generally (for these 5v motors) I'm going to swap over to these controlers with the DC convertor. A bit ugly but WTH ;-) :

I also have some NEMA17 5:1 motors which _are_ 12v motors and the spec sheet confirms it, these have no problem at all operating with the DRV8825 circuit. So much for trusting the Chinese adverts then... Same goes for those 4-pin connectors which were advertised at being 8mm when they actually require a 12mm diameter hole - I've emailed the oriental gentleman concerned who asked for a photo of the problem and said he would sort it out... Yeah, right.

ChrisH

 

[derrickf]

Thanks ever so much for the STL files, I'm printing some as I write this - I ended up buying a Flashforge dreamer which, when used with Simplify3D, has so far produced some excellent quality prints.

I hadn't spotted the difference in voltage between the product page on Stepperonline and the full spec sheet of the geared Nema 14 motor until you mentioned it - as you imply it can sometimes be frustrating to deal with offshore suppliers.

Derrick

 

 

[ChrisLX200]

I used the Wanhao 3D printer to make this PCB holder (downloaded from Thingiverse). Handy for working on little PCBs - soldering components and so on.

ChrisH

[Pan Euro]

Very dinky, like it.

[ChrisLX200]

I 3D printed another work holding utility over the past few days, this one more compact and its multi-purpose jaws make it useful for holding things other than just PCBs. I'm always fascinated by the capability to print screw threads using a 3D printer because intuitively (with an engineering background) it doesn't seem like it should work - but there's no denying that it does ;-) This gizmo uses a leadscrew with both LH and RH threads so the jaws self-centre as they open and close. It's not my design and there are a few things I have changed - and a few more details I should modify which I noted after finishing printing it. Nevertheless, it's entirely functional as-is.

ChrisH

[ChrisLX200]

Recently added a small 16x2 LCD display to the focuser made to Rob Brown's design - mainly because I had ordered the parts weeks ago and they finally turned up in the post! It doesn't offer much extra utility for a remote rig like mine but it could be useful if stood at the scope making adjustments (hence it's an extra plug-in unit)

ChrisH

[brown_rb]

Hi Chris

That is pretty neat. I am much the same, in terms of the LCD, plugs in when needed, except its not in any case, it looks like a 3D printer might be in the running for a purchase sometime soon,

Yellow makes it look very cool, all those colors are fascinating. Impressed by the innovation.

Cheers

Robert

[ChrisLX200]

Thanks Robert ;-) You know, when I bought this 3D printer it was just for something to play with and I had no specific use for it, now it's in constant use for so many different things that I've worn one bearing out (which I replaced). Despite that I can recommend the little Wanhao 4S because it produces excellent quality prints.

I've made 4 focusers to your design now, one in use, 2 spares, and one with the DRV8825 circuit. I have lots of scopes though and all would benefit from being motorised. Going this DIY route means I don't need to worry about something failing and having the expense of needing to buy a replacement - I can just plug a spare unit in. That's a luxury you don't have with expensive commercial units. However, the one I use most (on the ODK12) has proven to be very reliable so far. So thanks for the effort you into your design, and for making it public. You could easily sell this system as a commercial product and make a million (-ish...) ;-)

ChrisH

[ChrisLX200]

I finally got so fed up with the under-sized tightening knobs on the Baader dovetail clamp plate that I did something about them! They are just too small in diameter to reliably tighten by finger strength alone, and they are designed to be torqued up with an Allen key (which I used). But it was annoying holding the scope in place with one hand, rooting about for the key with the other in order to tighten them properly. The original ones shown here:

and the replacements:

Actually, they are not exactly replacements (for the life of me I could not figure out how to get the originals off!) these fit over the top and are held in place with a few grub screws.

ChrisH

[ChrisLX200]

With the impending delivery of a Quark Ha filter I wanted to adapt my SW Equinox ED80 Pro to autofocus because this is what will carry it initially (and I want to be able to capture image data from the comfort/darkness of the remote Obs control room rather than squinting at a laptop screen in full daylight). This is another example of the usefulness of my little 3D printer as the necessary bracket was quickly designed and printed. Well, not that quickly printed - the filament broke twice causing aborted print runs, then I left it over night to finish but at 3am Windows decided to install updates when 95% complete! So this morning I finally completed a usable print which thankfully fitted without further adjustments. I also disabled automatic Windows updates... ;-)

The SW focuser was a lot easier to work with than my FeatherTouch focuser (on the ODK12) which I swear was purposefully designed to make adapting to any motor other than their own all but impossible! Anyway, with the SW I just needed to remove one screw and the knob pulled off revealing a nice cyclindrical housing to which I could attach a simple motor bracket:

There's even a convenient 4mm thread hole already there which could be used to secure the bracket. So the design was simply an extension of this with 4 holes in the outer flange to which the motor would be screwed, and the overall length sufficient to accommodate the flexible drive coupler. The near end required a scallop so the bracket would fit closely to the focuser body:

This part was then printed and attached to the motor (a NEMA14 19:1 geared stepper), and the drive coupler clamped in place:

The assembly was a push-fit on the housing, and a single dome-head 4mm Allen screw used to secure it:

And that was it - job done ;-) I already have several spare controler boxes that I made previously so one of those will attach to the scope somewhere with a USB lead running to the 7-Port hub on the pier.

I think I might do the same thing for my TV Pronto so I can compare the performance of the two OTAs, and I also have an 90mm f/11 Vixen Achro refractor which may also perform well at longer focal length so that's another possible candidate.

ChrisH

PS. Attached the .STL file in case anyone wants it..

 

ED80 focuser.stl

[ChrisLX200]

Currently printing a support platform for the stepper controler which will simply clip onto the scope tube (in any position), the controler will be velcro'd to the platform. Can't believe this will take 7hours to print though!

ChrisH

[NickK]

Keep showing Sandrine (mrs) the 3D printer and small hobbit CNC milling machine.. both I could easily use for things...

[ChrisLX200]

Show her all the pretty vases etc., on Thingiverse and maybe she could get into designing and printing stuff herself ;-)

ChrisH

[ChrisLX200]

Support platform printed OK, I won't be needing the LCD display so I'll disconnect the ribbon cable later and remove it.

ChrisH

[ChrisLX200]

So I bought a Quark for solar imaging ;-) And adapted my SW Equinox 80ED to work as the OTA (with remote focus):

So far so good, but (for me) the Quark + CCD camera produces horrendous Newton's rings which are the result of the CCD sensor face and etalon being perfectly aligned resulting in a n interference pattern. The solution is to tilt the CCD sensor slightly which removes the interference and Daystar offer a ready-made 'tilt adapter' which will do the job, albeit at a premium price! I figured there must be a way of making something with similar functionality using my 3D printer so I loaded up SketchUp and started to design something. It's here where SketchUp (the free version) really annoys me: it lacks functionality when dealing with complex solid objects. It's fine for designing cookie cutters but when the going gets tough it falls apart. I should say the paid version _does_ offer good ability for working with Solids but it costs a lot of money, the free version is, well, free - so I shouldn't complain really.

I'd decided to use a split adapter - 1-1/4" female on one side to accept the camera, and 1-1/4" male the other to fit the eyepiece hole on the Quark. Between the two is a spherical interface and clamping flanges:

To make this work the two mating spherical faces needed to be the same, and the radius equivalent to the distance between sliding surface and sensor face (in order to avoid losing focus when making tilt adjsutments). To do that I drew the upper and lower sections first (right and left respectively in the image above), and then created a sphere of the correct radius and which was embedded into the surface of each. When the shpere and component were intersected and excess sphere deleted what remained were the required spherical seats - or at least, should have been... That's where the operation went wrong and the interface became horribly mangled and took a couple of hours to repair! Anyway, eventually I ended up with printable components. The upper one printed OK and the lower one is printing now. The print quality looks functional although I did need to smooth the spherical face with fine emery paper.

Upper section:

I'll update when the thing is complete and assembled...

ChrisH

[brown_rb]

Hi Chris

I made a tilt adapter from ages ago - video is here, might be another design though

 

[ChrisLX200]

Thanks Rob, I think mine is similar (I guess there are only so many ways you can make something tilt!)

Anyway, the print completed successfully overnight and I assembled the thing this morning. It seems to work (i.e., it tilts and holds position). I just need to test it now.

ChrisH

[ChrisLX200]

Re: SketchUp mangling... I read somewhere that if you scale everything up to larger sizes (like, using CM instead of MMs) then the problem with the mangling of fine edges goes away. Then you scale it back down again. I'll have to try that.

ChrisH

[happy-kat]

You make it look so easy :-) I'm having a rest from my model as so far haven't fixed the bits that mean I can't get it printed. I did try scaling it up but perhaps I need to scale it even larger.

Chris on your tilt adaptor have you used brass heat push in threads or relying solely on tapping through the plastic please?

[ChrisLX200]

22 minutes ago, happy-kat said:

You make it look so easy :-) I'm having a rest from my model as so far haven't fixed the bits that mean I can't get it printed. I did try scaling it up but perhaps I need to scale it even larger.

Chris on your tilt adaptor have you used brass heat push in threads or relying solely on tapping through the plastic please?

On the tilt adapter - the threads are straight into the plastic (I used 3 outer shells/layers during printing which provides 1.2mm thickness of solid plastic for the cut threads). Once the adjustment is set it won't be moved again so wear on the threads is not a worry, also the load is lightweight and (I believe) there is enough strength in the PLA for the camera to remain secure. It would have been easy enough to embed some steel nuts but I just didn't think it was worth the trouble.

ChrisH

[derrickf]

Looking good Chris, let us know how it works out if we see the sun again this year. Did you model and print the threads or tap the holes after printing? I've had reasonable success with modelling and printing M8 and larger threads but haven't tried anything smaller yet.

The glass transition temperature of PLA is pretty low - around 65C - so you might want to keep an eye on it if you are using the adapter on a very hot day - you should be fine but it's probably worth just checking first time out.

Apropos Sketchup: when I decided to buy a 3D printer I didn't have any recent experience using any of the free 3D design software; I tried Sketchup but quickly got frustrated with its foibles - I'm sure it's a marvellous tool if you're designing buildings 

I played around with various other systems and finally decided to learn Fusion 360 from Auotodesk - free for personal and small business use; there is a wealth of instructional material on-line and though the software initially appears somewhat daunting, the learning curve has not been too steep even for a mechanical engineering dunce like me. Fusion 360 is an integrated system that incorporates parametric sketching, solid modeller with assembly modelling, surface modeller, animation,  FEA, and CAM. It produces mathematically robust models that can be output in STL format using the in-built 3D print module and I have not yet found any issues slicing these models with Simplify 3D. I understand that somebody who has invested time in learning one modelling system is unlikely to change to another but I would encourage anybody thinking of learning modelling for 3D printing to consider Fusion.

 

Derrick

[ChrisLX200]

Thanks Derrick I'll be keeping an eye on the camera to ensure it doesn't melt off ;-)  I would have used ABS but I have no black filament right now, but I can always print another when the next reel gets delivered if necessary. I have yellow, pink, white, red and turquoise in ABS - none of which seemed suitable :-)

If I were starting from scratch I would certainly be using Fusion360 and not SketchUp, I have it installed and played with it a bit but the menu system is so totally different and it's a lot of work learning a new program. If SketchUp ever prevents me from making something then I'll relectantly bite the bullet and change over. It would have helped if it were possible to import my previously drawn models into Fusion360 but it refuses to talk to SketchUp in any format.

ChrisH