Category Archives: CNC

CNC Upgrade :: z-axis (part 2)

Once the fixed back plate (3/4″ aluminum) and the movable front plate (1″ aluminum) were machined it was assembly time. Here you can see the parts laid out and ready to go. In the upper-right you’ll see two white brackets to mount the stepper motor and tension the belt. These were 3-d printed with the mindset that I’ll mill aluminum ones when the machine is up and running. I found out about the option to put brass screw inserts in the 3-d print too late, but it looks like an awesome procedure and is something I’d do in the future.

Assembly was pretty straight forward. I did have a little binding on the lead screw and had to shim it out a little bit using some folded aluminum foil. Shim stock isn’t something I have on hand!

Minor shimming required where the ball screw attaches to the moveable plate.

And some additional photos of the assembly and mounting to the y-axis.

Once it was on the machine I could locate the z-axis homing switch. I used a fairly inexpensive magnetic sensor from amazon. I mounted the sensor in the back plate, and then drilled/tapped and threaded a hex-cap bolt in the movable front plate. This bolt triggers the magnetic sensor when the z-axis is in the full-up position.

CNC Upgrade :: z-axis

Pro-Tip : Just buy a z-axis. It’s likely not worth the hassle, unless you don’t value your time. Or if this really and truly a hobby and you enjoy doing and redoing things.

That said I built a z-axis! I bought a bundle of parts off ebay and used that as a ground floor for measuring and designing. Having parts on hand provided a good starting point for scale and feasibility in Fusion 360.

From there it was quite a few iterations to draw up what would become the axis. During this process I learned a LOT about fusion, as I wanted all the movements to work so I could watch for clearance issues etc. Saunders Machine Works’ youTube channel was a huge help. The final drawing (looks like 42 edits) looked something like this.

Mounting the stepper that way was a little more work, but it keeps it from sticking out the top, and counter-balances the weight a little bit. Here is a zip file with the fusion model if you want to use it.

I started doing the manufacturing of the backplate the manual way. Lobbed off a piece of 3/4″ aluminum stock and started drilling, tapping, and cutting. Fusion allows you to print out 1:1 sized prints which worked super well. I just sprayed on contact adhesive and glued the template to the stock. It was a lot of holes, and a lot of tapping.

The studious observer may notice the two pockets where the bearing-blocks for the lead screw attach. Those I didn’t get done in my garage. At the high school they have a old cnc Haas mill that we have access to for working on the robotics team. They were kind enough to let me run the pocket operations I needed on that mill. Thank goodness! It would have been nice to mill the whole piece there, including the drill holes but I didn’t want to overstay my welcome.

Quick gratuitous Video of chips flying:

CNC Upgrade :: Need a table

How can we make this project harder and take longer? Oh yes, lets collect new skills in a very round-about path to the destination. In this case I wanted to learn how to TIG weld. I could haphazardly do MIG welding but wanted to learn TIG. This was primarily as aluminum is a key working material for the high school robotics team and being able to weld it would likely come in handy. With a welder in hand I knocked together a frame to hold the new CNC gantry as well as a few drawers.

One of the things that’s not super obvious is behind the drawers you’ll see a ‘divider’ that leaves about a foot of space in the back. That’s where the electronics will eventually go.

CNC Upgrade :: Out with the old in with the new (to me)

I have had this 2×4 cnc machine for 4 years now, and have outgrown it. Made of MDF with aluminum rails and skate bearings it won’t go down in history as a super sturdy machine. That said it served me well and together we made some awesome things. I have been volunteering at the high school robotics team, and having a machine that can mill aluminum with a reasonable amount of accuracy was my design goal.

Doing the slow troll on craiglist and facebook marketplace I came across this guy. Stout steel frame, and nice linear bearings. The z-axis on it was some sort of ink sprayer – not sure what exactly it’s previous life was but good bones for my build. Now I just needed a table, z-axis, electronics, mill.. the little things.

One thing that was interesting/concerning was this used belts instead of ball/lead screws to move the x/y axis. There is an included gearbox with a 2.5:1 ratio off the stepper motors, and my concern was if I could get and maintain the accuracy needed. Overall these rail systems were very well built, and even the belt-tightening mechanism was well done.

Calling this an amplifier build would be deceitful

Its more of a box build.

So browsing adafruit.com a while back I came across a class-d amplifier board they recently introduced. What is interesting about class-d amps is they are very efficient, thus generally needing no heatsinks. Seeing boards like this I am frequently reminded how far things have progressed since my electronics classes in 92/93. In that class I tried to build an amplifier for my car, and really didn’t get much further than etching the board. The traces didn’t etch cleanly, even using the advanced (at the time) sharpie+acid method. After getting board patched up with jumper wires to fix screwed up traces I then realized how expensive power mosfets were for a high school student. End of that project.

So I of course bought this little amplifier board immediately. There has been some conversations around the house that we should have music upstairs. So this board + an old ebay purchased airport express should do the trick nicely. So board in hand, it needed a box. I always skimp on the box, but in this case the board was pre-manufactured so I could afford to put some energy into its home. I haven’t done anything with any hardwoods on the CNC yet, and I had some walnut I got from a friend when he moved. So I set about making a box.

I have no jointer, so surfacing with the CNC, using a 1″ bit.

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Flipped the board over and routed a box + lid.

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The lid didn’t fit perfectly, and required some chisel work on the inside lip to seat properly. The outside also needed some time on the disc sander to be flush all the way around. I really need to upgrade my y/z axis with some linear bearings. Maybe this winter.

With the overall box built i used the drill press to put some holes in the back to mount the 1/8″ input, the 12v barrel jack, and the 4 speaker posts. Of course one of those holes is a square, so I had to spend some time with the files.

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Before mounting anything I needed to finish the back, as it would have been hard to do with all the posts etc in place. I was just going to do a basic coat of poly as this wood was very nice. Got out the rattle-can and gave it the first light coat – which did not work out well. I was not paying attention and grabbed black spray paint instead of my clear lacquer. How could that happen?

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Quick wipe down with mineral spirits, but black was deep in the pores. Decided to just blast the whole thing with black, wipe with spirits, and sand again. Turned out ok, gave the wood a darker appearance – although this wont be my ‘go to’ finishing technique.

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Mounted the amplifier inside with double-sided foam tape, and soldered up all the connections. Pretty basic.

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Functionality test with a 12v 1.5A switching power supply I had in the junk box, and it wouldn’t power up. I kinda forgot that 20w per channel is 40w. At 12v you need 3.5A at full power. I tested instead with a 11.1v Lipo battery from one of my RC airplanes, using alligator wires to the board and all was fine. (fatal mistake)

Double checked everything, glued the lid on, and finalized the finish.

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I sourced an old pc power supply, as they can handle crazy current, and modified it to work w/o a pc. Grounding green wire is all it takes. I pulled out all the un-needed connections and put a barrel connector on it.

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Brought everything inside, connected up the speakers, power, airport express… and it doesn’t work. Much testing ensues, still does not work. Shamefully bring it out to the garage, and bust it open with a chisel.

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Of all things it turns out the barrel connector plug was bad. That was why the initial power supply didn’t work. That is why new power supply didn’t work. The test battery worked because I alligator jumped the leads to the back-side of the connector. Dang.

So now the power supply is hard wired in and everything works fine. This amp does a great job driving bookshelf speakers, and i would use it again. Things I would do differently if i were to do this again (hint : i won’t).

    Not use black spray paint by accident
    Put an indicator LED in the box so I know if there is power
    Turn the box ‘upside down’ and inset a plexiglass bottom that is screwed in (for access)

Overall a fun project, and I learned how nice walnut is to work with. I also finished an amplifier project, that i started over 20 years ago!

Automated airframe

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It appears the road to a GPS-Controlled airplane (Drone) is paved with broken Styrofoam. Pictured above is on of my first automated flights on an old P-47 I had. It lived up to its historical nickname of “Jug” which is how they look when they nosedive in to the ground. To move forward I am going to try to make my own airframes from a $15 AirHog glider I picked up at Target. I have a few of them on hand, and they are pretty big. Each wing is 2′ long. To start I needed to cut off the top, so I can CNC in some pockets inside to hold an arrow shaft (for strength) and to house all the electronics.

I do not have a Styrofoam cutter, but I do have some nichrome wire I used as a electronic firework igniter so I hacked something together. I took the blade out of a tree saw I have, strung some nichrome, added a 12v wall wart and sliced away.

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I have started laying out the electronics, servo mounting holes, and cuts for flaps in my cad software, and will share those results when I get them on the CNC.

Bat Holder

My son plays baseball, and keeping equipment organized is an ongoing challenge. While sticking bats in the chain link fence is a time-honored tradition, I thought I would whip up a bat holder. I can’t take credit for the concept, as one of the municipal parks had a similar solution permanently mounted. Mine is a knock-off using 2″ pvc pipe and some rope.

The machining was very simple, its basically two rectangles per bat. The only trick was to do one series of rectangles, then rotate the pipe 90 degrees before doing the second.

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Sheldon Cooper LineArt

My wife started a new project at work, and as this project is a big one, it meant a new notebook! She got a very nice green moleskin, but the cover was quite plain. As we both love the Big Bang Theory I was tasked to put a likeness of Dr. Sheldon Cooper on the cover. Rigged up a sharipe in a pen holder, and off to the races!

Original picture, and gcode here.

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Tie Fighter in ASCII

I saw this CNC halftones article quite some time ago and setup the the CAM drawing quite some time ago. I never really got around to routing it, as I wanted to test it in two-color plastic instead of the painted plywood the original authors used. As luck would have it, BF plastics had some white/black material on clearance last week so I picked up half a sheet. The material is only 0.1″ thick, so I used 3m spray adhesive to mount it to 1/2″ plywood. About 30 minutes or so with a 60 degree v-carve bit and it was done! I need to pick up a 45 degree bit i think, as this one did go a little deep in places, you can actually see some wood on some of the wider letters. Still looks sharp!

The .dxf and gcode can be found here.

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On the machine:

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Word Clock Build

This project was one of those long-running ones which took almost 7 months from when I saw the first one out there and wanted to make one, to when I actually got started.  One of the big catalysts was Joe’s blog post on his build – so hats off to him!  Joe did perf board wiring, and I wanted to create a circuit board for the task.  The reason for this was twofold: (1) I hate perf board and (2) I wanted to build the atmega circuit and bootstrap it myself.

So if you watch the video below, you will see I failed at getting my atmega to run.  Could not figure it out!  Next time I will surely include additional LED’s (pin 13 anyone?) to aid troubleshooting.  So, that said in the zip file attached you will find my eagle schematics.  If you use them, be aware the microcontroller portion requires some additional scrutiny.  Maybe its fine, and I just messed up the wiring.  Who knows.  If you want to take a peek at it and give me feedback I would appreciate it!

Other big change/addition from Joe’s build was I added a Real Time Clock (RTC).  In my case I used the ChronoDot.  It is much more accurate, and tracking time in code was MUCH easier.  Here is my code, eagle schematic, and .DXF file for the led array.

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