My current solution for a dew shield is very low tech. I got a dollar store version of this metallic accordion-style foam insulated car window reflector. because it accordions down to a small size and fits perfectly in my telescope’s bag. I attach it to my scope with a single 7″ diameter elastic headband. It works great!
My Introduction to Astrophotography
I’ve been interested in astonomy my whole life, and a few years back, I got a second-hand Meade LX-10 telescope. This is a 8″ diameter scope… definitely not a toy. It is great for planetary viewing and can even track the planets as the Earth turns. I have used it from time to time to try to take some pictures of celestial objects, but not very good ones. Astrophotography is a growing interest of mine now and I found the learning curve quite steep. I’m throwing together everything I’ve learned over the past couple of years including links to software and such into a few posts. There are multiple steps involved in this project and it took me a long time, working here and there and amongst about 1000 other projects, to finally get everything together for this.
To take amazing amateur astrophotography images you need to decide whether you want to look at deep space objects (DSO) like galaxies or nebulae, or if you want to focus on planetary viewing (within our own solar system). You don’t really want to zoom very much if you want DSO images because zooming narrows your field of view and most DSOs you want to get are very dim so you don’t want to zoom in to make their light spread out across your eye or camera sensor too much, you want bright pictures. You can take some amazingly cool pictures with just a DSLR and a “barn door” tracker. (This is just a device that rotates counter to the Earth’s rotation so your camera will continue pointing at the same object for minutes or hours at a time, meaning it moves a full 360 degrees in 24 hours).
In my case, I want to do a little of both planetary and DSO. So I have my LX-10 telescope, which has an 8″ diameter mirror, meaning it can collect a lot of light, and it has a tracker so I can point a camera at one point in the sky as long as I want. However, unless you perfectly align the scope with true celestial north, the scope will still drift a bit over the night. This is because it is an open control system. You just point it at a star, turn it on and hope you aligned it well when you started. The best images are taken with closed-loop control systems. That is, they continuously look to see if it is drifting off target, then takes actions to move back on target when needed. This guy has my telescope and has taken some amazing pictures of planets, sunspots, and DSOs. Some are mindlbowingly good! To be fair, he’s using some reducer lenses like this one to change his F-stop to make it much quicker (for example F/3.75 and F/4.6 in some images), oh and he’s using a 4x Powermate lens a lot which costs as much as I spent on my entire telescope… But what is great about his site is that he tells all the settings he used for the images. This is similar to Reddit’s astrophotography subreddit.
My scope is what they call “slow,” “long,” or “dark.” This refers to the F-stop number. This is also called the focal ratio or relative aperture. It is a ratio of the len’s focal length and the diameter of the scope. THe focal length of my telescope is 2000mm. And the aperture is 8″ or 203mm. The F-stop of this would be about 2000mm / 200mm = 10. So this means my scope is a F/10 lens. The higher the f-stop number is, the darker the image will be (all other things being equal) when compared to a lens with a smaller f-stop number. For example an F/4 is considered a pretty “fast” telescope. My F/10 number basically means that to take a nice bright picture of Jupiter for instance, I need to play with the “sensitivity” or ISO number of the camera sensor (used to be film) as well as the duration I leave the shutter open on the camera.
You might say, “Well I can just crank up the sensitivity then. Higher sensitivity will make the image come out brighter, right?” The answer is yes and no. You can raise the sensitivity, but then a lot of other things (such as heat) can trigger a pixel to register a value in a digital camera. This will increase the noise in the image, making it staticy.
You might then think “Ok, the other option is to just open the shutter for a long time, exposing the camera sensor to more light over a longer time period.” yeah… not really. This can work as well, however you will increase the overall light pollution in your images and worse, you risk blurring the image. Since the Earth keeps on spinning, objects in a fixed telescope’s field of view move. Without tracking perfectly, long exposures will be blurred.
Even if you can fix all that, there’s blurring you simply cannot fix. This is due to heat inversion in the air column between you and the object you are viewing. The Hubble space telescope was designed to fix this problem… by simply being above all the air on earth orbiting in a pretty high orbital plane (at the farthest reach that the space shuttles could fly). Air at different temperatures has different densities. This acts like a prism to bend the shape of a beam of light. Look at a straw or pencil in a glass of water. Notice how it looks like it’s broken in half at the interface of the water and the air? That’s an example of the different densities acting like a prism. Since air is, well, air… it is gaseous and mixes and moves around a lot. It is in constant motion (unlike the water in your glass compared to the air sitting on top of it.) Hot air rises and cool air falls, making all sorts of weird prism effects in our viewfinder. In the column of air between you and the top of the atmosphere where Hubble is, there’s also a lot of dust. The dust as well as the temperature inversions is what makes starts look like they are twinkling.
Side note: Planets don’t twinkle in the sky when viewed by eye. This is because a star is so far away, you are only seeing it as a point light. This makes it easy for dust or temperature inversion to affect your view of it. But planets are much closer, and their light is spread slightly wider across the retina in your eye. This means there much less of a chance that a mote of dust will block it, or temperature inversion will guide the light too far from your retina.
So how do you fix the problem of having a dark image from the telescope without getting errors from too high of a sensitivity setting or blurring from too long an exposure and temperature inversions? You can thank Woz for the home computer! Using a laptop, I’m going to connect a closed-loop control system to my computer to track the objects I want to image very closely, reducing blur of long exposure images. I’m also going to take multiple images of the same object, then do a process called “stacking” where a computer algorithm will take the sharpest views of different parts of the planet, for instance, and stitch them together into a composite image that is overall much sharper. Then I’ll be able to do some image processing on the composite image to get some great results. Stay tuned for more posts on this theme!
Xcarve and Fusion 360 CAD/CAM
It has been bout a year now since I last had a chance to play with my CNC machine, so I figured I’d give an update on the progress so far and what I’ve learned.
Hardware:
Firstly, I got the Dewalt 611 router and router mount. This is a huge upgrade from the no-name dremel knock-off I had. After test cutting just once with the old router, the brushes were shot. I sprung for a real tool instead of a toy. As a bonus, it makes the machine look nicer as well. In order to fit 1/8″ shank bits, I had to get a 1/8″ collet for the DW611. This wasn’t terribly expensive if you compare the cost to replacing all of my router bits with 1/4″ bits. I got all of this late summer 2015 and literally had only enough time to attach it all to my machine before life got crazy busy. I never even had a chance to test it until now.
I also recently got the Suck-It from kickstarter. This goes a LONG way into keeping dust to a minimum. A warning, however, I tightened the screw too tightly on my Suck-it and accidentally drove the bottom edge into one of my makerslide rails since I don’t have endstop switches. This promptly shattered the Suck-it acrylic into incredibly sharp shards. While you can purchase additional parts from the Suck-it website, I opted to make my own replacements from wood, which is a bit more forgiving.This also gave me a great chance to finally learn some CAD software.
While testing, I finally realized that the ACME screw inventables sent me last year as part of my upgrade kit is warped. It binds in a couple of places when I try to move the Z-axis up all the way. I thought that I could fix this by simply getting a stronger motor, so I ordered the NEMA 17 from inventables. This was stronger, but still couldn’t overcome the bend in the screw. The bend also causes the very tip of my bits to wobble ever so slightly. It is almost imperceptible, but makes a big difference when I mill multiple passes of the same shape or try to do PCBs.I contacted Inventables and Mo in customer service worked with me over a couple of weeks to get my Z working great. It turns out that Since I upgraded from Shapeoko1—> Shapeoko2–> Xcarve, I had the wrong spacers on my router mount. The ones I had were about 2mm too short. Mo helped me get the right length spacers (9.5mm long) and bolts(35mm). My short spacers and bolts were causing the ACME screw to bend back towards the gantry at a significant angle. When installing the new spacers, be sure not to use washers as this will also change the angle of the ACME screw. With the new spacers installed I can get all but 7mm of my Z axis working perfectly smoothly. Thanks Mo!
I also bought this clear tube for my suck-it vacuum mount. This was about 63mm in diameter, so I had to same the interior of the acrylic suck-it plate to fit the tube. I also cut it to about 9 or 10 inches in length. At this height, the tube is about the height of the router itself. This gives me more visibility to see what is going on with the business end of my router rather than the black coupling tube that the suck-it came with.
CAD/CAM:
I wanted to learn a real CAD package since my FabAcademy training in 2014. I only had experience with Sketchup which, while very good for beginners, it doesn’t really follow the same kind of workflow as professional engineering CAD/CAM packages. I wanted to learn something along those lines. I had played with Creo, Solidworks, Antimony, and was looking into Rhino/Grasshopper when I saw Fusion 360. Autodesk has been going crazy buying and building awesome CAD/CAM tools for the hobby market as well as for industry. Fusion 360 is a complete engineering tool that can start with a 2D sketch or a 3D body and allow a user to create objects, render them realistically, stress test them with finite state analysis, and export 3D print or CNC toolpaths. Oh, and did I mention that it is free and has a very active community online as well? So I downloaded it and gave it a try. I am quite pleased with it in all respects!
Having no formal training, I opted to take some free online courses from Udemy.com. Check out my other posts concerning that. Of course, as with anything, beginning is the toughest part. It took me a couple of days to get the hang of the Fusion 360 workflow, but with all the great tutorials and videos online, it is easy to find answers to your questions. If not, you can post to Autodesk’s forum for help.
Moving on, I played with Fusion 360 starting with the 3D sculpt method at first to get some awesome organic shapes, then moved to learning the 2D sketch workflow. I measured my machine and aluminum rails of the Suck-it. I made quite a few mistakes along the way, and had to start over several times, but I finally figured out how to get what I wanted out of the software. It is still a bit buggy from time to time and crashed a few times when I tried to do certain things, but I think it was partially due to a bad design. I watched a couple videos and fixed my design and was able to create the toolpaths without further issue.
Fusion 360 can do 2D and 3D milling jobs with ease. There are a lot of options, but videos mentioned in my previous post cover most of what you need to know. I’m running a smoothieBoard on my machine and Fusion 360 has a CAM processor script designed for my board, so I simply select “Smoothie” from the dropdown menu when I go to export my design and I’m good to go.
Sending the job to the machine:
The main software people are using to send jobs to the smoothieboard is Pronterface, which is typically used for 3D printing. It’s all Gcode, so it doesn’t really matter, but for some reason, I didn’t like using a 3D printing software for CNC. Last year I tried using Universal G-code Sender with the smoothie and even played with coding in this ability, but life got too busy for me to continue, so I stuck with using Pronterface. What I like about Pronterface is the ability to create custom buttons. For example, I made buttons to zero the axes, reset the smoothieBoard after I hit the killswitch, etc. These prevent me from having to manually type the Gcode in the command window. I can even send smoothie console commands using these buttons.
You can also run the smoothieboard over ethernet. You can do so through pronterface or by using one of several web interfaces (meaning you can control your 3dprinter or CNC machines over the web). This is useful in my FabLab at work where we have a lot of 3D printers running on a 3D print server. You can run the smoothieboard on this as well. It can host several different web interfaces which I hope to go into later, but one of them is basically a webpage that looks just like pronterface.
I feel like I finally have a good workflow here. You can see my results here. I made replacements of the broken acrylic pieces of my suck-it dust boot that I made in Fusion 360. I used scrap wood, so it had quite a few drill holes going all the way through it already. I also did conventional only, and no climb milling which would have given a nicer finish. I used a 2-flute straight 1/8″ but as well, no spiral which would have also given me a cleaner result. Due to my learning curve, I did have to do some manual touch ups to the dimensions of the pocket which explains the nastiness in there you see. 
DIY Art for Your Nursery – ABC I Heart You
With the impending arrival of Baby A, I have been busy crafting up a storm. There is nothing like the drive to get a nursery ready to serve as a great excuse to do all those craft projects you’ve been letting sit on the side burner.
This was one of my latest craft projects and it was one of the easiest. I’ve seen it pinned so many times and I’m sure you have too, but I wanted my own version nonetheless. I used my KNK Zing to cut out the Alphabet letters, but you can just as easily buy pre-cut letters (or stickers) in two or three colors to stick on yourself. I used three colors/designs total – blue for the majority of the letters, a heart design for the “I” and “U”, and pink for the heart.
Here is how it turned out:
I used a canvas frame I purchased at Michael’s on clearance for $7 and three pieces of scrapbook paper on sale for fifty cents each. This puts the cost of my nursery pizzazz at $8.50. I already had glue dots on hand, which I used to adhere the letters to the canvas. It is not a permanent solution, which I liked, because I can see myself reusing this canvas frame for a different purpose in the future (like many years in the future, so I’m not planning on changing it up any time soon).
Have you made ABC art like this before?
P.S. Yes there are random paper butterflies in this picture. They are part of a future project!
Using Fusion 360 for CNC and 3D Printing
Many designers use some kind of computer-aided design or CAD software to make 2D and 3D designs. A common one used by many people is Rhino (especially when used in conjunction with the Grasshopper plugin). Fusion 360 is a newer, easy to use, free complete CAD/CAM package. If you are going to learn any CAD software for practically any purpose (designing, engineering, fabrication, rendering realistic models, etc) it should be Fusion 360.
Fusion 360 is an Autodesk application that can do many useful things for designers. Whether you want to do something as simple as making cool looking 3D models to stress testing (finite element analysis) and even simulating the simple physics of designs and even milling them out or 3D printing them, Fusion 360 has you covered. It can also render realistic materials and surfaces and make animations of your working mechanical devices. Did I mention that it is free and there are tons of free online video tutorials and classes showing you how to use it with example projects? Oh, and so you aren’t reinventing the wheel (or other simple hardware) you can bring in models directly from McMaster-Carr who carry all sorts of nuts, bolts, gears, chains, etc. which can save you loads of time. This is my brain dump for getting started with Fusion 360 and using it with my CNC machine and my wife’s 3D printer.
Download Fusion 360 for free license. They have yearly licenses for hobbyist and I think even small business, or you can get a 3 year license for education.
Learning to use CAD:
At this point, there are two methodologies to use when creating parts in Fusion 360. If you have CAD experience already, you might be more comfortable drawing 2D parts then extruding them into 3D, etc. If this is you, then check out this free training class. The second methodology is sculpting. It begins with simple 3D shapes you can manipulate almost as if it were made of clay. This is great for 3D smooth shapes. Check out this great free training class for this methodology after taking the first section of this class. These two methodologies don’t replace one another, rather they compliment each other. You will eventually need both for complex designs, but start with whichever one is easiest for you so you can progress quicker. I personally love the “sculpting” mode.
Since on a CNC machine, the Z axis is the one you attach the router to, you will need to change the position of the Z axis in Fusion 360. Then set your preferences such that Z axis is the top axis. Within Fusion 360, click your name at the top right->Preferences. In the main window that pops up, about half way down, there is a “Top Axis” option that is set to Y, change this to Z and then “Apply” Now Z is the top axis like on your CNC machine. This will work for all NEW documents, but if you happen to have an older design or are importing someone else’s design, there’s a couple different ways to change the Z axis. The simplest method is to select the up-axis when you “setup the job” in Fusion 360. This is done when you are finished with your model design, and want to start creating the toolpaths.
Now, get into making some stuff. While Fusion 360 can do 2D and 3D designs and generate toolpaths for the CNC machine, there are lots of simpler (dumber) 2D workflows out there that are great such as Makercam.com or Easel from Inventables, etc. I’d use Fusion for more complicated 2D and 3D designs. For example, Easel won’t allow you to use a chamfer bit or V bit for engraving last I checked, but Fusion 360 will. This can make some amazing 2D designs.
- This video is a great introduction to making a sign from a piece of wood in the shape of a rocket. This covers making toolpaths, creating tabs (what they are and why you need them) and milling the actual design.
- A great 3D project from start to finish is this Pinewood derby car. It begins with sculpting and walks you through exporting and cutting on the Xcarve.
You will notice that some of the videos tell you to delete certain lines in the generated Gcode from Fusion. This is mostly because it adds a “home” command and many DIY CNC machines don’t have homing switches. This command might tell your machine to go to the maximum extent of your machines to find the switches, but since you have no switches, it’ll end up messing up something. So many of the tutorials suggest removing the G28 (home) line from the Gcode Fusion 360 generates. If you have a smoothieboard controller, you should be fine to leave it in as long as you have set up your config files correctly.
How to set your origin to a different are of the design for milling. The best setup is one like the Othermill uses which ensures you never cut into your spoilboard. “Don’t spoil the spoilboard” is a great explanation of this method. I hope to make vids on how to in fusion 360 and real machine.
Can export to Othermill, or Smoothieboard, pocket NC, or other mill. Tons of options in the “Post Processing” menu.
You can simulate the milling process. When you do, the paths have different colors. A post on Autodesk’s forum cleared up what they mean:
- Yellow: it indicates the rapid move of the toolpath
- Green: it indicates the lead-in/leadout of the toopath (Lead-in is a cut used to make a smooth transition into the actual cut you want)
- Red: it indicates the Ramping move of the toolpath
- Blue: Most part of the toolpath are blue which indicates the cutting.
- Orange: Is no-engagement stay down linking motion for Adaptive Cleating. Or motion updated when using the Feed Optimization feature.
Here’s my video of an example project I made. It is full of tips on stumbling blocks I came across.