Our New Vertical CNC Mill

Our New Vertical CNC Mill

At Beatty Robotics, we’ve made good use of our gantry-style CNC mill over the last few years. We’ve built all our robots to date with it. Recently we decided to augment our machining capability with a vertical CNC mill. Our current mill has been excellent for machining large flat parts out of sheet aluminum, but now we wanted to be able to machine parts that were deeper and more three dimensional, as well as use coolant and a greater variety of tools. After extensive research of all the various machines available, we decided on a Tormach 1100. We bought and installed the base Tormach machine, then extended it with various add-on kits and our own customizations to turn it into a lean, mean milling machine. We’ve only had the mill for about a month, but we love it so far. The Tormach’s capabilities, features, and price are geared toward professional machinists, small businesses, and prototype shops, so the Tormach isn’t affordable for most hobbyists, but it is an excellent machine. In future posts, we’ll show you some of the parts we’ve made, but for now, here are some details on our installation.

The base machine weighs 1130 pounds, so in addition to the mill itself, we purchased Tormach’s stand kit to make sure we supported the machine properly. The chip tray’s bright white color didn’t fit too well in our shop, so we painted it oil rubbed bronze (in case you were wondering why it doesn’t look like other Tormachs you’ve seen). We then constructed a full enclosure of our own design using 80/20 and 1/4” polycarbonate plates. The enclosure keeps the flood coolant and chips contained, reduces shop noise, and improves safety. Part way through the building of the enclosure we ran out of the metal plates and brackets we needed. It was late on a Friday night and it stopped our project dead in its tracks. No problem. We jumped on the CAD system, designed the parts, and machined them on the mill. Very cool.

Tormach_Overview

The control panel on a standard Tormach is located on the electrical box just to the right of the spindle, which put it inside the enclosure, so we rewired the electrical controls so that they were accessible from outside the enclosure. We also simplified the controls to just what we needed: Emergency Stop, Start, Computer Power Button, and Spindle Load Gauge. Everything else is controlled via the computer screen.

Tormach_Controller

When we setup a part in the machine, we use an electronic touch probe, which allows us to find the X, Y, and Z position of the workpiece very precisely, which is critical to making good parts. We love using the probe, but the problem was that there is a bug in the Mach3 software’s probe wizard. In some cases, when you run the probe wizard, Mach3 turns on and spins the spindle, which yanks out the probe cable, whips it around at high speed, and destroys the probe. To make sure this never happened to us again, we wired the spindle power through a custom bracket we designed with a high-amp lever switch. When the probe is resting in the bracket, which is now its normal storage location, then the spindle will operate as usual. But when we pull the probe out and put it in the spindle for probing, the lever switch will cut power to the spindle so it can’t spin even if the buggy software tells it to. It was a really nice way to fool-proof and simplify the job setup procedure. [Important April 2015 UPDATE: Tormach now offers their new own, internally-developed Path Pilot software instead of Mach3. Path Pilot is a much better, more robust approach for running the Tormach. And best of all, this was a free upgrade to all previous Tormach owners!].

In the picture below, you can see the probe resting in the custom switch bracket we designed in SolidWorks and then machined on the Tormach.

Tormach_Probe_Bracket

Clamping and fixturing is often the most time consuming and troublesome part of running a job, so we put significant time into figuring out the best approach for our particular situation. After studying all the different kinds of parts we plan to machine, we designed our fixturing system around a 6” Kurt Vise with quick-change SnapJaws. Our goal was to leave the vise in the machine for 95% of our jobs. One of the trickiest elements of building the enclosure was to make sure that the vise didn’t hit the enclosure wall during the machining operation. It’s hard to tell from the picture, but the large door on the front of the enclosure is actually extended out 5” from the rest of the enclosure in order to give the vise plenty of room when the table is moving. Here’s a picture of the Kurt vise mounted into place, where it was promptly buried beneath a mound of chips.

Tormach_With_Vise

The mill with the enclosure door open.

Tormach_Open_Door

We also designed and machined a bracket shelf so that we could place the jog controller exactly where we wanted it, hovering on the right side just below the door so that we could use it whether the door was open or not.
Tormach_Jog_Bracket

One of the best things about the Tormach is the Tormach Tooling System (TTS). It’s a well thought out approach to standardizing and simplifying tool heights so that mid-job tool changes are super fast and accurate. Here’s a picture of the tools and tool holders we have so far. The beauty of this system, especially when combined with the quick-change capability of Tormach’s compressed-air-powered drawbar option, is that you can change tools in a few seconds and be certain that the new tool is in the exact position it needs to be. This means that you can use the right tool for each portion of the job without worrying about changeover issues. Our tools include various sizes of end mills, chamfers, radius tools, modular insert mills, a fly cutter, engravers, drills, and taps. It has really expanded our capability.

Tormach_Tools

We are looking forward to making many interesting parts with our new machine. I would like to thank the folks at Tormach for designing and building such an excellent mill, and for their email-based assistance when we had questions. I would also like to thank our friend and colleague Mike Dutra here in Asheville for his help during the installation process. His confidence with a 2-ton engine hoist moving around a 1130 pound hunk of iron was very helpful. He also helped out in many other areas of the installation process. Also, a special shout out to John over at CNC NYC. If you’re into machining, be sure to subscribe to his YouTube channel.  Finally, I would like to give a nod to Camille and Genevieve who couldn’t wait to start using the machine. They started using it even before we had finished the enclosure (chips were a-flyin’ fast and far) and they have already proven themselves to be excellent machine operators. They’ve both made some great parts already and it’s just the beginning. We’ll keep you posted.

Zeroing a CNC

Zeroing a CNC

We enjoy machining custom aluminum robot parts on our CNC Mill. One of the best things about a CNC is that it can cut precise parts by following the geometry of a CAD drawing. We measure the precision and repeatability of our CNC in thousandths of an inch (0.001). But one of the challenges of using a CNC is to to get the raw material setup properly and make sure the spindle starts at exactly the right position. The CNC can only hold a precise position from its starting point. For example, let’s say you want to cut a pocket that is .050″ deep. That’s easy to do, but you need to start the CNC at the exact surface of the raw material so that it knows how far down along the Z-axis to move the spindle. Or let’s say you need to drill a precise hole pattern in a square sheet of aluminum. That’s easy to do, but you need to start the CNC at the exact corner of the square or your pattern will be way off. Finding the exact starting point is called “zeroing” the CNC. There are whole books written on the subject and a whole sub-industry of gizmos for handling this challenging problem. It took us a while to figure out, but this is what we’ve found to be the best solution for us:

1. When it comes to zeroing out the X and Y position of the CNC at the beginning of a job, we have tried a number of approaches, including eye-balling (not very accurate), mechanical edge finders (don’t like these), and even a laser edge finder (not as accurate and cool as you’d think). For our solution, we installed a super-cool USB camera microscope from our friends at Adafruit onto the frame of our spindle. We mounted the camera using a small aluminum bracket that we designed in SolidWorks and machined on our CNC. We secure the camera bracket to the spindle frame using a 4-40 threaded hole that we tapped for that purpose. The microscope camera points downward toward the raw material. It displays a large, magnified image on the computer screen, including crosshairs. When we want to set the X and Y zero point, we turn on the camera and then move the spindle until the crosshairs line up exactly with the corner of the raw material (or whatever position we want to identify as the zero point). Because it’s a microscope, it’s very precise. We then press the Mach3 “REF ALL HOME” button, which we’ve re-purposed and re-programmed to set the X=0 and Y=0 based on the offset distance between the camera crosshairs and the spindle position. This allows us to quickly and easily zero out the X and Y axis to the exact point we need to.

In this situation, we are using the crosshairs of the microscope to zero the CNC to the center of a small hole. The macro will set this as X=0, Y=0.

2. The Z-axis, which is the vertical position of the spindle, is by far the most important axis to zero out properly. For this, we rigged up a very cool solution that works great. We cut a piece of copper-clad circuit board (about 1″ x 1″) and soldered it to a long wire that we ran back to one of the 5 volt inputs on our controller. We ran another wire from the base of the CNC. These two wires, combined with the CNC and the end mill (which are both conductive), become like the leads of a voltmeter that is setup to test conductivity. We then wrote a macro in the BASIC language that runs when we press the “Auto Zero Tool” button on the Mach3 interface. When we want to zero-out the z-axis, we place the copper plate on the top of the raw material and press the button. The CNC moves the spindle slowly down toward the plate. The instant the tip of the end mill touches the copper plate the electrical circuit is closed. The macro instantly stops the spindle, sets the Z-axis zero point (by subtracting the .063″ thickness of the plate), and then moves up .125″ so that the copper plate can be removed. The whole process only takes a few seconds to complete. And the result is that the CNC determines exactly where the top surface of the material is and sets it as Z = 0.

The zero plate is placed on top of the raw material. The macro automatically moves the spindle down until the end mill touches the plate and closes the electrical circuit, which signals the CNC to zero the z-axis. Note the wire soldered to the copper plate.

These two techniques have really helped improve our setup time and accuracy.

A fine new tool in the workshop

A fine new tool in the workshop

Like many people, I love good quality tools. One of the most important tools we have in our workshop is a mini table saw with a 4″-diameter blade. We use it all the time, on pretty much every project we build. Occasionally, we use the full-sized table saw to cut large material, but in general, we prefer the 4″ mini table saw because it’s easier to work with, quieter, safer, and more precise. Thus far, we’ve used two Proxxon models, which is a German company that makes excellent small power tools for model builders. I’ve really enjoyed using their tools over the years. I have always considered their 4″ table saw the best on the market. Until now.

OLYMPUS DIGITAL CAMERA

Earlier this year I read an article about Jim Byrnes, the founder of Byrnes Model Machines in Orlando, Florida. Jim and his crew hand build high-precision mini-table saws for model builders, especially model ship builders. I studied his machines online, read everything I could about them, and then finally contacted Jim with a special request. I wanted him to build me one of his 4″ table saws, but I needed a table and fence that could make up to a 6″ wide cut (other mini table saws can’t cut this wide).

Jim took up the challenge, made the machine in his shop, and I received the package today. It is a truly fine piece of high-precision machinery. I’ve only done a few test cuts, but I’ve already fallen in love with it. It’s by far the finest, most precise power tool I’ve ever used. I’m extremely happy with it and can’t wait to get into some serious projects with it.

Why do I love it so much? Let me count the ways…

First, its smooth, shining, machined metal surfaces immediately strike you as being ultra high quality. The Proxxon, for all its positive merits, had an aluminum table, but otherwise was mostly plastic.

Second, the all-important fence on the Byrnes is far superior to the Proxxon. The Proxxon fence never struck me as completely square and it was often frustrating to work with. I would get my stock in position, but then when I tightened down the fence, the fence would move slightly off square, which wasn’t a good feeling. On the Byrnes, the fence slides wonderfully and seems perfectly steady and square. The Byrnes also comes standard with an excellent, well-thought-out miter gage with set pins for the common angles.

I also selected the “Micrometer stop” option, which provides a true micrometer built into the saw so that you can make very fine adjustments to the fence position.

Thirdly, the saw is just a pleasure to use. I love the smooth movement and tight fit of all the components, and it’s extremely quiet and vibration-free when it cuts.

Finally, I love the old-school feel to this machine. It has a classic steel ON/OFF toggle switch on the front and various knurled brass adjustment knobs. Everything about this machine says MADE IN AMERICA with personal pride and true craftsmanship. A few years ago, if you had told me that I would someday write a review of a table saw, I would have thought you were crazy. But this saw is inspiring. 🙂

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Machining CNC parts for the telegraph

Machining CNC parts for the telegraph

Today, we worked on the wireless telegraph project. We decided to mount the electronics on brass and copper plates, so we designed the parts on the CAD system and then machined the parts on our home made CNC mill (one of our many projects over the last year). Using the CNC to make project parts was a really cool use of what has become our favorite tool. Here are some pics of the CNC.

Here is our CNC mill just after machining the copper telegraph base plate. Top left: the computer and electronics box we built. Top center: Cooling tower for the water-cooled spindle. Top right: The 3-phase Variable Frequency Drive (VFD), which powers the 24,000 rpm spindle, is mounted on the wall. Mounted on the wall just below the computer box: an LCD panel for the CNC user interface. Right hand side: The stepper-motor-driven CNC machinery, which is made out of steel and aluminum. You can see the copper part on the blue riser (which is machinable wax).  Front center: the system’s keyboard, the emergency stop button box we built, and the jog box (for moving the CNC manually).

 

A close up of the copper base plate just after it has been machine by the CNC.

 

Camille showing off her new copper base plate, fresh out of the CNC

We needed two of the base plates (one for each side of the telegraph system), so we machined the second one out of brass instead of copper (using the same CNC file).

Here Camille assembles the telegraph electronics onto the baseplate

Here are the electronics for the telegraph system mounted on the copper plate. The electronics shown here include an Arduino Nano in a screw terminal board, a 7.4v Lithium Polymer Battery, an Xbee Radio, a potentiometer (for tuning the voltage to the Telegraph Sounder), and a small speaker). This copper plate will be mounted inside the base of the telegraph system.

 

 

 

Working on the CNC

Working on the CNC

Up to this time, we’ve been using hand tools to build our robots. But over the last few months, we’ve been working on building a Computer Numerical Control Machine (CNC) that will allow us to precisely cut, drill, and machine aluminum, brass, plastic, wood, and other materials.

Part of this project is to design and build a custom electronics enclosure that will be a combination computer / CNC / motor control system. This will be the “brain” of the CNC. After trying a few different approaches, we decided to build the box from scratch out of 1/8″ acrylic sheet and Microrax, with are tiny, 10mm 80/20 aluminum beams. The enclosure is about 22″ long, 12″ wide, and 8″ deep. The beauty of Microrax is that we could easily cut the beams to the size we wanted and then use small machine screws and brackets to bolt them together. This allowed us to not only construct the overall enclosure, but to bracket the four cooling fans into place, frame the I/O ports, and add an acrylic lid with hinges. MicroRax is very flexible and cool stuff that I look forward to using for future projects, not only for enclosures, but robots as well.

CNC Electronics Enclosure

On the left side of the enclosure we mounted a mini-ITX motherboard, a small SSD hard drive (not visible in this picture because it’s under the motherboard), the RAM (blue), an internal USB hub, ports for communication with the motor controller, and various other computer components. In the center of the enclosure we installed the main power supply (clear) and the fan control system (black). The right side of the enclosure will contain the motor control boards and other CNC-specific components (which we haven’t installed yet).

There are four main enclosure fans (two on the top and two on the bottom) and four smaller internal fans.


Here is the CNC Electronics Enclosure in the workshop, along with the screen, keyboard, and mouse. We will most likely be mounting the enclosure on the wall so that the lower two fans are more effective.[/caption]

In this close-up, you can see that the fan control system displays the rpm speed of each fan and allows you to adjust it. It also displays the temperature of the corresponding sensor. We’ve attached the sensors to the microprocessor heat sink, the RAM, the motor controllers, and other critical components.[/caption]

Here are various parts for the CNC that we’ve been working on, including the CNC’s aluminum T-Slot table, various fixtures, the largest of the three interchangeable spindles the CNC will use (for 1/4-inch end mills), and a block of blue machinable wax.

Here is a close up of the smallest spindle the CNC will use. This is a high-precision 1/8-inch spindle for delicate work. It will be driven at a spindle speed of 25,000 rpm by the brushed motor via the two black belts, which in turn will be controlled by the motor controller, which in turn will be controlled by the CNC software running on the computer. At least theoretically! Keep your fingers crossed! :)[/caption]