@parkerrupe

I worked on preparing for shipping this project.

I made most of the BOM, took some renders, did some Github Repo formatting. I am so ready to be done with this project but I am worried about budget as my PCB is rather expensive with tariffs/shipping. Maybe I reach out to PCBway for a sponsorship or something. Ugh, I don’t know.

Anyways, peep the cool render.

Controls Planning, Preliminary Firmware/Drivers, Wiring Diagram, and Finishing Touches.

Submission is upon us. Well, just me.
I planned out the full control scheme in a spreadsheet so that I could keep track of it all.

Top level is PINS https://github.com/nitr57/pins, which controls the entire shooting session, stages photos, etc.

Plate solving is handled by ASTAP https://www.hnsky.org/astap.html . This is how the polar alignment mount figures out where it needs to move.

Guiding is handled by PHD2 https://openphdguiding.org/. This is how the equatorial mount figures out where it needs to move to look at targets and track them.

Mid level is handled by Indiwebmanager https://github.com/knro/indiwebmanager . This hosts an INDI server that communicates control signals between PINS and my mount drivers.

Then we have custom drivers https://github.com/ProgrammerTurtle/SpaceMount/tree/main/Control/drivers here that handle transllating control instructions from PINS into actual signals the SKR pico can parse.

Lastly, the lowest level is the firmware on the SKR pico, which is here https://github.com/ProgrammerTurtle/SpaceMount/tree/main/Control/firmware . This is low level motor control, mainly.

That’s it! The last two were written during this session.

Lastly was the wiring diagram and final prep for submission. The diagram is pretty simple, thankfully. Otherwise I just double checked submission requirements and everything in my repo. I think this is the last entry before I ship.

Godspeed!

Instruction Manuals!

I wrote complete assembly instruction manuals for every part of this project. One for the Polar Mount, one for the Equatorial Mount, and one for the Guider Scope.

The polar mount manual is 47 pages, the equatorial mount manual is 24 pages, and the guider scope manual is 15 pages.

It took sooo much time but I am glad I did it as they are pretty neat to have! I doubt anybody will ever use them besides me but that’s ok!

I actually discovered a few errors while I was doing it too, since I hadn’t spent as much time thinking about assembly. Mainly errors on the internals of my gearboxes, as assembly planning for those is a nightmare due to the complexity and sheer volume of parts. So, I am glad I took the time and discovered those before the full release/ship!

Attached is one example page from each manual!

BOM, Readme, Renders, Finishing touches, and More.

This was a long session! I started off with some finishing touches here and there like an adapter plate for the arcaswiss mounting so that I can actually put this mount on a tripod.

Then, I wrote the BOM. Boy oh boy. I thought i was doing so well on budget! Turns out, I am at the full 1000 dollars. Oops. I mean, when you think about it, this kind of setup commercially would be well over double that. So it isn’t actually that bad? But it is a bit rough. I was looking into some DIY imaging scope stuff earlier because I thought I had the budget spare but boy was I wrong.

Anywho, I got the BOM done, including accurate counts of every single screw type. That isn’t something I have done before, but I feel like this project deserved the effort.

Then I wrote the README and thus had to take some renders for it! I took one of the whole project and this really cool one of the gearbox exploded - they are attached to this devlog. I am pretty happy with how they came out.

Anywho, we are getting very close to submission, I just need to write some preliminary firmware for the SKR pico. And then I think we are good to go? Not sure.

Nonrotating Helical Focuser

I designed a new focuser for my guide scope, a Non-Rotating Helical Focuser. This basically means there is a nut/dial that you spin and it pushes/pulls the lens WITHOUT rotating it. This keeps a much clearer image during focusing, thus making focusing easier and faster.

I also designed an additonal mounting clamp option in the form of Mini-Vixen, in case I want to use that. I think I will end up using the first clamp I designed, but still.

Time for the scary part - writing a BOM.

Electronics!
I designed the electronics assembly and guider scope for this project.

The electronics assembly is an SKR pico with a Raspberry Pi 4b. I chose this pair because they are identically sized boards, so they stack well, and the SKR pico has 4 motor drivers, the exact number I need. The raspberry pi will allow for onboard plate solving/tracking control and lessen the need of always being connected to a laptop. I already own the pi and the skr pico is cheap enough. The two boards are mounting into one assembly and that gets mounted to the rear of the polar mount.

I also added HDMI to CSI connectors for the polar mount camera so that I can just run an hdmi cable between the mount and my electronics, which will handle the motion way better and be way less fragile than using a long ribbon cable. So that’s nice!

As for the guider scope. I am using an IMX290 camera sensor, a 182mm focal length 50mm diameter lens, and a custom wound carbon fiber tube for the body. This allows for higher rigidity and lower mass, and is completely overkill but it looks awesome. This scope is heavily inspired by the OpenAstroGuider scope but mine has a simpler focusing mechanism.

I designed the Equatorial Mount section. For this, I just used two of my cycloidal gearboxes stacked at 90 degrees with a bit of fancy mounting. I honestly could have done something a lot more complex, but the fact of the matter is I don’t need to! I do worry a little about strength of my gearboxes, but that’s what iterating is for.

Long story short, I got sidetracked for the first while of this recording by a red herring on an issue with my gearboxes. I was seeing concerning numbers on the calculator when it came to pressure angle on the gear teeth, but I determined that the calculator maybe can’t be trusted so I don’t know how accurate it is. I’m just gonna send it tbh, and if something goes wrong we iterate.

The mount is made up of more 1/4” aluminum, this time with me trying to spice up the shape a little. I also used more Vixen mounting hardware on the output and mounting.

Finished up the polar mount.
I added a camera module from aliexpress as well as some final structural touches to complete the mount. I decided that for tensioning I am going to try the fight during assembly thing, but if that doesn’t work out then I do have an aluminum extrusion crossbar that I added that I could either use to add tensioning or use the mounting holes of to add tensioning. Either way there are options to solve my problem. Now, I move on to equatorial.

I designed the altitude axis in its entirety, minus belt tensioners and the alignment camera. It is constructed out of more lasercut aluminum and a few aluminum extrusions with minimal printed parts to maximize load capacity. I need to think of a clean way to do belt tensioning - maybe i just undersize the belt a bit and fight it during assembly? No clue. I will think about it.

Mount assembly and altitude work. I worked on integrating the gearbox into the mount, mounting the altitude motor, and then some more detailed work on the altitude axis. I have this cool idea to use a 4040 extrusion as the “shaft” with lasercut alu for the actual bearing interfacing part. I think it will be cool and hopefully will be quite strong.
I added an aluminum plate to the bottom of the module as I felt iffy about all the weight being supported by plastic. So now, it gets 1/4” aluminum, and I am not worried in the slightest. It does make me need longer screws but thats ok.

I designed a dual stage, 81:1 reduction cycloidal gearbox to replace the huge 41:1 from yesterday. Not only is this more compact (in xy), it is a much higher reduction. It should stall somewhere around 35-40 Nm, which is a great safety margin for this project. It uses two stacked 9:1 reductions (9x9=81).

I worked on a bit of gearing for the altitude axis, mainly adding pulleys, bearings, and the shaft, and then decided to make a custom cycloidal drive gearbox for the azimuth axis that bolts to a slew bearing, replacing the entire existing bearing assembly of thrust bearing with normal bearing and pulleys.

Began work on SpaceMount today. I am starting off with the polar alignment portion of the mount since it is basically a high load turret. I am heavily inspired by the Zenit Align Mini https://zenit-astronomy.com/products/zenit-align-mini for this portion of the mount. I am unsure if it will be standalone from the main mount or not, though. Decent bit of research and some design.

Final CAD touches.

Wow. That went quick.

This is the final cad entry though.

First things first, I had to split the casing into two sections that would fit on my printer. These sections would be joined with M3 bolts and heat set inserts.

This is a simple overlapping butt joint with 4 screws per side. Nothing complex, was just a few sketch and extrudes.

Next was building up interior structure, which you can see part of in that screenshot. I basically just needed mounting for the screen and board.

This is what I came up with. I also added the port cuouts on the side while I was at it.

This one interior strucutre has mounting holes for both the screen and the lattepanda carrier PCB.

Here is the other side. Unfortunately, this will need supports to print, as I couldn’t think of a way to avoid them, which hurts me. But it is what it is, I will make do.

Here is the interior with the components. Looks good!

Lastly, I added 4 antennas. That’s right, 4.

One is on the inside in this corner!

The square one internally is a GPS antenna. It is a ceramic active patch antenna. The other 3 antennas are simple “rubber ducky” antennas for Wifi+Bluetooth and LORAWAN. Short and simple.

That’s it for cad! Now I just need to take renders and put the repo together with a BOM and stuff!

Wait, I forgot screws.

Now we good. I also added slits to the back for cooling! They will just be lasercut into the aluminum.

Okay, alll done for real this time. Now we move on to renders and stuff.

I spent 2 entire hours putting the full printer cad together.

It looks so good!

Parker, how could adding just the gantries take 2 hours, you ask?

Well well well. Basically, each ball joint had to be defined as a ball joint in fusion with proper motion limits and whatnot. And fusion does NOT like this.

Fusion crashed 3 times. It errored out unrelated things for no reason more times than I rememeber. It took multiple MINUTES to load each ball joint at times. It was pure torture.

But I got it done! It’s pretty cool, I defined all the linear rails as sliders and stuff and so I can literally drag around the effectors and they move like a delta should.

One note, the bed has been lowered to 160mm instead of 180mm. This is because of some future plans and also because it just feels better in terms of proportions. It looks so nice now!

Oh, and I had to make the printer taller. We are now using 600mm rails instead of 500mm as my arm length was incorrect.

Turns out, you can’t just optimize for a 90mm gantry, because the quantum delta side needs way more travel than that. It was actually pretty funny when I first put the cad together with the short arms.

Squatted delta. I think it’s funny. Anywho, I got it all done eventually and got fusion to stop crying about it (mostly). It does take noticeably longer to open the document now and timeline changes take a significant amount of time to fully propagate through all the joints.

But, because I had to increase the arm lengths, I suddenly didn’t have enough travel for the carriages. Hence why the frame is bigger now.

Idlers!

I started out with a simple sketch that shows part of the extrusion profile and the linear rail profile, then used that to align my idler hardware (two bearings, a pulley, and a shaft).

From there, I made a sketch for the mounting block.

This would wrap around to the other side aswell, bolting onto both sides of the vertical extrusion and holding out the tensioner.

I guess I should talk about my tensioning method. Basically, I am going to have two idlers “floating” in the middle of the frame vertically. One for the top belt, one for the bottom. These then get pulled towards eachother by bolts and nuts, pulling tension on both top and bottom at once. I think it will work? The only issue is any differences in assembly or belt length will render this useless.

Once tension is pulled, the side bolts get clamped down hard onto the vertical extrusion. Easy peasy.

So anyways, the body gets doubled to the other side and connected at the middle.

I then added nut recesses so that I don’t need to hold the nut while I pull tension, and flattened one side of the roundover on the end. This would be the mating surface of the two idlers, so it makes sense to be flat.

This gets mirrored to the other side along with the hardware. Boom, now we have two idlers that meet at the middle.

A couple fillets here and there, assigning materials, and adding bolts gets us to this result.

I think this turned out really nice!

I actually initiallly had some issues with where my mounting holes were and how long the idler was. Turns out I added 8mm somewhere I shouldn’t have. Took a minute to figure out where the discrepancy was but it was an easy fix.

And with that, we can install it in the cad!

Looks great!

Okay, spoiler. I immediately hated it. I don’t trust that I can build both sides identically and I don’t think I can easily get enough travel on the tensioner. Plus, the amount of tension directly correlates to how far my effectors can move instead of that being a fixed value. That is so stupid. Ugh. Back to the drawing board.

Literally, let’s make a sketch.

So this is my idea. Some sort of mechanism to pull up on the upper span of belt so that I can have stationary idlers. I think I can pull something off. It would integrate with the motor module well I think and lets me make the tensioner and idlers out of sheet metal - so, the entire belt path is sheet metal. The whole thing! That is so freakin cool.

This time I actually started with making a sketch of one of the side sheets. The assembly would overall be similar to the old one, except there wouldn’t be anything bridging the gap between the two sides besides the idlers. The side pieces would also be further apart to accomodate for the size of the aluminum extrusions. This just meant I would need a longer shaft. That’s fine.

This gets extruded to create the sheet. These are 3/16” thick aluminum sheets that will be lasercut by Oshcut (not sponsored, just cheap).

Then I literally just duplicate it and assemble everything.

4 bearings, 2 pulleys, 2 35mm long 5mm dowels, 2 9mm spacers, 2 4mm spacers (both printed), 4 m5x10 bolts, and 2 sheets.

All assembled into the double idler! Oh there will also be 4 T nuts for mounting but I am not cadding those as my PC already doesn’t like how many components are in this assembly and I would have to align each and every one by hand.

Integrated into the cad, they look awesome! Gosh this printer looks good.

Anywho, we have one thing left - the motor side tensioner. This is relatively straight forward.

I started by just getting the tensioner hardware into place.

Then, I added side plates that would make up the tensioner body.

These are super simple and will just be held together with 2x M3 bolts and a printed part.

Of course, the motor module side plate needs a cutout for the idler! This cutout is not only for clearance, but th

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Oh. My. Gosh.

I made the sheet metal motor mounts affordable!!

I just had to switch all the lasercut parts from powdercoated steel to uncoated 5052 aluminum, and do some trickery to get the motor mounts down to 2 plates instead of 3. Badda bing badda boom, it’s somehow super affordable now!!

Like, super affordable. Especially since I have a 50% coupon. This means I can use more lasercutting elsewhere! Like… an electrical panel!!

Anywho, I decided to fully redesign the motor mounts. I kinda had to since to get them to fit as 2 plates instead of 3, I needed to move the motor back 5mm and out like 2.5mm ish. Which isn’t bad.

Started the same as last time with a pile of hardware, just with slightly different spacing.

Once again, I like to work from the motor mount. I really don’t know why I do this - I should be doing the entire plate in one sketch so that my timeline stays cleaner and they are easier to edit, but eh, old habits die hard.

Turn it into a full plate by adding the bores for bearings and pins (which are currently oversized, oops). Then I double it for the second plate. Just a simply copy and paste.

Now I fix the bores and widths on the plates. These are 0.188” thick 5052 aluminum. I need to double check how I should be tolerancing my bores so that they work as interference/light press fits. Right now they are just exactly matching the part OD for the bore ID, which I think might be fine because of laser kerf? Dunno. I will ask my brother what he did.

I also shortened the plates by removing some from the side that is against the vertical extrusion. Or, correction, WAS against the vertical extrusion. Because of how far off center these plates are, I needed to just have it not go up against the vertical otherwise it would hit the horizontals. Shifting it to be centered would take a lot more offseting of the motor, which is something I really want to avoid.

Next we get a big printed spacer. This serves as the buffer between the two plates and is also how the modules will mount, with heat inserts in top/bottom (m5 of course).

Because of that part, we also need these cutouts in the sides of the plates. These make it so that I can actually still manage to route the belts despite them being somewhat encased in material - this un-encases them. Hopefully it is enough to be able to route the belts. I think it’s gonna be a bit tight, expecially once installed in the frame, but it should be possible. Hopefully not too painful. We will find out!

You can also see I added mounting holes in that operation. Same cutting op, just added a bunch of M3 holes. These either thread into the motor or thread into the back plate. Since the plates aren’t getting powder coated, I am willing to deal with tapping them now.

Add some screws in the sides and screw holes on top/bottom and we are done with the new motor modules! The mounting holes on top are identical to those on bottom. They are off center so that they are centered with the belt path and thus the rest of the printer. Helps things look nicer from the outside.

And here they are integrated into the machine! Gosh, this looks awesome, and will be incredibly rigid! In fact, this means that the only part of my motion system that isn’t metal (or, at least, structurally metal) will be the idlers/tensioners! And even then, I might be able to do something about that… Maybe. Gonna mess around with lasercut designs, CNC designs, and even SLM designs. We will see how this goes!

I love how these turned out and I love even more that I managed to fit it in my budget. This is so exciting!!

Bulking up the printed motor mounts because sheet metal is too expensive.

Alright, so. Sheet metal adds about $250 to my costs, so I cannot do sheet metal for these motor assemblies. But that’s fine, I don’t need it.

I started by going back to the blocky version. I extended out the tall bit so that there is more material over the bearing and idler shaft for strength.

Then I actually started making the walls thicker for more material/bracing. Because the end of the part is constrained to 30mm, I need that little divot on the front right.

I did the same to the opposite side and brought the curves back! These curves look pretty nice.

They start out matching but then the front one diverges into its own thing.

It was at this point I realized my walls were now thick enough to utilize the 4th screw hole on the motor. This will help a lot with making everything more rigid.

On the initial version I wasn’t able to use this hole because I was optimizing for the entire part to be 30mm wide rather than just the end of it. This would have been fine, but this new bulkier appraoch is just better.

Lastly, I added mounting. I added one M5 screw on the rear vertical wall that will actually use a T nut to bolt to the vertical extrusion, while I also added top holes (and unseen bottom holes) for M5 heat inserts for the top/bottom plates to bolt to. This forms a printed and metal sandwich, which is great for rigidity.

Integrated into the assembly, it looks great! It kinda bothers me that the screw holes are off center but I might be able to fix that later.

That’s motor assemblies done. Yay! I just need to do idlers/tensioners and the “core” of the printer will be done.

Motor module 2 electric boogaloo??

Ok so, a friend told me to make some motor modules out of sheet metal. This is a good idea! Unfortunately I think it is out of budget… but it is nice to have around!!

Anywho.

Start with the same layout as before.

Create a motor side plate. This plate is not thick enough for the bearing on its own - it will need stacked with another. That makes these motor modules 3 plates each. 3 times 6 is 18 plates total. Youch, my wallet.

Extend it and create a matching idler side plate. This plate can be thick enough for the bearings on its own, so it won’t need stacked. This is good for budget.

There’s that second stacked plate. Each thin plate is 0.1”. The thick plate is, you guessed it, 0.2”.

From there I made these simple printed part structural spacers. These are designed to be minimal at the top so I can still hopefully route belts. I think it will be difficult to route belts in this design no matter what I do, but this could help.

Last, I just add screws and nuts that go through the whole sandwich. This is the easiest and most rigid way I could think of assembling. And I think it turned out really nice!

It’s just… these would add $200-$250 to my budget… I think I would rather bulk up the printed part. So that’s what I will do next entry - bulk up the printed version! It is such a small part that I think it is fine - end to end, this thing is like, 110mm. So it really shouldn’t matter much.

Actually, one last thing.

This cutout will help a ton with belt routing.

Ok that’s all for real this time.

Motor assemblies!!

These motor assemblies are required to get horizontal belt pathing without moving the motors outside of the frame.

You can see my preliminary sketch here. I will be using bearings and live shaft idlers to offset the motors about 72mm. Now, moving the motors out of the frame would be a 45mm offset. So, the difference is about an inch. That’s really not bad! I am willing to accept that.

Anywho, I take that preliminary sketch and use fusion’s Derive tool, which I just discovered, to move this design into a seperate document. That way we can keep the timeline of this part and the overall printer a bit cleaner. A bit.

I am using 605 bearings basically everywhere here since they are nice and beefy for high tension 9mm belts. You can see them on either end of the pulley on the right as well as standalone slightly to the upper left of that pulley as an idler on the back of the belt.
This setup mimics having the motor aligned with the carriage path without it actually being, as otherwise the motor would hit the frame.

I always like to start with doubleshear on the motor. No particular reason, that’s just where I start.

From there it just gets extended.

Then I add the 30mm shafts for the idlers and some countersinks for the motor screws! That way I don’t need super long motor screws.

I actually then extended up one end. I figured I can use this part to help locate the linear rail! So this print extends to exactly the height the linear rail needs. Since there is one on both top and bottom, it will sandwich the rail and align it.

From here, I decided to challenge myself a bit. I wanted this part to be organic! Not as blocky.

So, I made this nice spline! This curve is pretty nice looking and is just defined by some random points and the idler bores.

With a few fillets, you get a pretty nice result.

Slight issue, however, is that this part is centered on the pulleys being centered. Which is fine, except that the pulleys have hubs.

You can see those hubs here. So the actual belt is currently not centeed. This is a relatively easy fix!

The one big constraint is that the end of this part, where the belt is coming out and the highest point of the part, needs to be 30mm wide. This is because my vertical extrusion is only 30mm wide. So, if it is wider, it will hit the horizontal extrusions of the frame.

With a couple extrudes here and there, some press pulls, blah blah, we get this!!

The part looks super organic with the recesses on the sides and whatnot. Those are mainly there to provide enough material for the bearing but still keep the part thin enough at the end to fit between the horizontal parts of the frame!

And here they are in place in the frame. Currently they are mounted by 3 screws bolting up through the bottom plate and no other mounting. I may change that a bit though… Like, I could bolt to the extrusions, or I could bolt to the top plate of the frame sandwich, all for higher rigidity!

For now, I am done though. I am pretty happy with this part as is.