Adventures in CNC - Part 7

CNC Electronics - Gathering The Components

New here? Check out PART 1

Now that the body of the machine is coming together nicely, it's time to focus on the 'Brains'.

In order for a CNC router to do anything useful, it will need....

Controller board/Breakout Board

The Breakout Board has two important jobs. It translates the commands from your computer into signals that your CNC motors can understand. The second job is to electrically isolate all your crazy CNC stuff from your delicate PC. If something goes horribly awry, you may blow your board but the PC should be fine. These boards tend to come in Parallel Port versions and newer USB versions. The unit that came with my machine is a generic Chinese parallel port version. The instructions are a little thin but it seems to work well.

Stepper Motor Drivers

The Stepper Motor Drivers receive step and direction signals from the Controller Board and send out pulses of the correct voltage and current to run the motor. The drivers have a set of DIP switches that set options such as the maximum amperage out and 'Microstepping'. Microstepping allows you to turn the motor less than the normal 1.8-degrees it would normal turn in one step. This allows greater accuracy and smoother motion.

Breakout Board (top) and Motor Drivers (bottom)

Power supplies

There are three different voltages that were needed for my system. 48 Volts for the motors, 5 Volts for the Breakout Board, and 12 Volts for the Proximity Sensors. My machine came included with a 48V power supply that is fed to the motors through the motor drivers. I added 5 volt and 12 volt 'wall wart' type supplies for the additional voltages.

Stepper Motors

Three Wantai Nema23 3.0A 270oz-in 1.8-degree/step Stepper Motors came included with the kit. The term Nema23 tells you the spacing of the holes on the motor mounting plate. The 1.8 degrees/step tells you how many degrees the motor with turn with each step. If you divide 360 degrees by 1.8, you can calculate that the motor will take 200 steps to complete one revolution.

Stepper Motors - The tape flags are for testing

Machine Control Software

For Machine Control Software, I purchased a copy of Mach3 from Newfangled Solutions. This seems to be the most popular CNC control software out there. The cost was $175 US.

Proximity Sensors/Limit Switches

Limit Switches are set up to be triggered when an axis of the CNC reaches the end of its travel. This is important to protect the machine from damage. These can be simple mechanical switches or Inductive Proximity Sensors that detect the magnetic field of the metal machine parts without actually touching them. The kit I purchased included five Inductive Sensors.

In the next installment, we'll put these parts together. Stay tuned!

Adventures in CNC - Part 6

Problems & Creative Solutions

Check out PART 1

After enduring a relentless, ice-age style winter, I am back to work on the CNC project with renewed determination.

Things were progressing smoothly until it came time to mount the proximity sensor on the Z-Axis. I had originally run the Y-Axis cable chain across the top of the Y-Axis. Unfortunately, this left no room for any of the sensors which protrude a good inch from the rear of the Z-Axis.

As mentioned in earlier articles, when you choose to assemble a CNC machine yourself, you may need to overcome these types of problems. Be prepared for some creative thinking and on the spot engineering.

After some thought, I finally came up with a solution. By adding a piece of 90 degree aluminum to the back of the Y-axis, I could move the cable chain back to give clearance to the sensors.

The original position of the Cable Chain interfered with the Z-Axis Sensor

Now I needed to connect the top of the Cable Chain to the Z-Axis. I cut a piece of weld steel plate that reached from the motor mount to the new position of the chain. 

Using the motor bracket as a template, I drilled and filed the piece to fit between the motor and motor mount.

Top Bracket - taking shape

Finally, I drilled four holes near the end of new piece so I could attach the Cable Chain with Zip Ties.

Don't forget to file down the sharp edges

Now, everything has room to move. On to the next challenge!
Next part - CNC Electronics

Adventures in CNC - Part 5

Building the Beast

Check out Part 1

Now we are getting somewhere! The time has finally come to turn the random pile of aluminum parts littering my shop floor into something that resembles a CNC router.

Y-Axis coming together

I started by paying a visit to the Forums at the XZero website. There I found a thread with photos and text detailing the assembly of the ViperXZ machine. I read through the procedure a couple of times so I could visualize the steps from start to finish. I find this helps to reduce the stupid mistakes that occur at the beginning of assembly, but are usually not discovered until you try to attach the final part.

Easier than it looks!

The remarkable thing about the assembly process was how NOT remarkable it turned out to be. The ViperXZ requires surprisingly few tools for assembly and all the parts are machined to make alignment almost foolproof. Overall, the basic assembly has been the easiest part of this project.

The only problem I discovered was a slight misalignment of the linear bearings on the Y-Axis. There are two sets of bearings that attach to the back plate of the Z-Axis. I found that when I tightened one set or the other, the y-axis operated smoothly. But when I tightened both sets of bearings, the assembly would bind slightly. The solution was to place a piece of blue tape on one of the bearings. This shimmed the assembly by a fraction of an inch an allowed the Y-Axis to run smoothly when tightened.

Tape! - Is there nothing it can't fix?

Overall, the assembly of the ViperXZ is a painless experience even if you are not the most mechanically inclined. A few Hex Wrenches and some patience are all that are required. Also, assembling the machine myself has really increased my knowledge of the workings of the system which will come in handy when it comes time for maintenance.

Check out Part 6 - Problems & Creative Solutions

Adventures in CNC - Part 4

A Leg To Stand On

Check out PART 1

So you have finally purchased your CNC machine and are anxious to slap it together, power it up, and start cutting. But before you touch the first bolt you have a very important decision to make...where are you going to put it, and what are you going to put it on?

This may seem like a trivial question considering the number of expensive decisions you have been forced to make to get to this point, but it is crucial to the overall stability and function of the machine.

CNC machines are heavy beasts with a lot of kinetic energy and love nothing more than trying to throw themselves around your shop. You need to provide a rock solid base not only for safety, but also accuracy. A wobbly base can actually effect the precision of your cuts.

Location also matters. It's a good idea to think about things like access to power outlets, dust collection, noise reduction, and accessibility for maintenance.

I considered many options when planning for my new CNC. I looked at plans for everything from wooden workbenches to welded steel tables. All I knew was that I wanted to do it right the first time.

While researching the XZero CNC machine I ultimately ended up buying, I noticed that they also sold some pre-fab corner brackets specifically designed to help make your own CNC stand. You just supply the steel in the size you require. The price of the brackets came to $120.

XZero Brackets

I bought some 2" x .100" HSS Square Tube Steel from a metal supplier and had them cut it to length. I needed the following pieces:
4 x 52" pieces for the length of the table
4 x 34" for the width
4 x 28" for the legs

The total came to just over $100 for the steel.

I clamped the brackets to each steel leg and drilled through it with my drill press and a 3/8" Milwaukee Cobalt Drill Bit (do not try to drill steel with a regular wood bit). This way I was able to correctly align the holes. I took it slow and used plenty of lubrication to keep the bit from dulling and in the end, I managed to complete the job with one bit.

Cobalt Drill Bit - Strong enough for steel

Use cutting oil

After the drilling, I primed the steel with Tremclad Grey Primer then gave it a coat of Tremclad Safety Blue - Professional Rust Paint. My neighbours must have thought I was getting into modern art.

The next step was to bolt the table together using 3/8" x 16 bolts, washers, and lock nuts.

Finally, I cut two pieces of 3/4" thick plywood for the tops and secured them with 3/8" carriage bolts.

This table is rock solid and does not move an inch when pushed so I am confident it will stand up to anything the CNC can throw at it.

Total cost for this little adventure:

XZero brackets - $120
Steel tube - $100
Bolts and hardware - $100
Plywood - $50
Cobalt Drill Bit - $12
Paint - $15

Check out Part 5 - Building the Beast

Adventures in CNC - Part 3

The BIG Purchase!

Check out Part 1

This is the exciting part! After weeks of indecision and exhaustive research, I finally pulled the trigger on this major purchase.

After carefully examining all the CNC Routers that fit my needs and price range (see Part 2), I decided to go with the ViperXZ machine from XZero. My reasoning? After comparing the specs and prices of different CNC packages, the ViperXZ seemed to provide the most 'machine' for my CNC dollar. The parts are stronger, the linear bearings are of higher quality, and the whole machine just seems 'beefier'. Plus I could get a 30 x 48" table size which is larger than the other units in this price range.

The tradeoff is I will need to assemble the whole system from the ground up myself. This is not entirely a bad thing though as you really can't underestimate the knowledge gained from putting your hands on every nut and bolt of the machine. With this intimate understanding of how the pieces fit together, you will be much more confident when it comes time for repairs and upkeep.

When dealing with any small company, you need do your research to make sure they are actually legit and not some fly by night deal. Luckily, XZero is a regular poster on the CNC Zone forums so I was able to read many firsthand accounts from other owners. I emailed George (the owner) with a list of questions and he was nice enough to give me a call to discuss things. I also found out that George actually lives somewhat close to me which was a huge score! He was nice enough to deliver the parts to my house personally which saved me a ton of shipping expenses. He also made several additional trips to deliver some back ordered parts.

George made a good point in suggesting that I start out with a router and upgrade to a spindle later which makes sense. If I'm going to make any rookie mistakes, I would rather damage a $100 router than a $1500 Spindle. For this same reason he also suggested using a MDF tabletop for a while before installing the slotted aluminum one.

Costs so far

The package total came to $3600 and included the following:

- 30 x 48" CNC Router kit
- Router Mounting bracket
- Motors, Motor Drivers, and Power Supply
- 5 Proximity Sensors
- Aluminum T-Slot Tabletop

I purchased a Hitachi M12VC Router from Amazon for $130 delivered. I still need to buy software and a few more accessories to get things running.

All said and done, I am now the proud owner of a few thousand dollars worth of machined aluminum lying on my shop floor. A lot of work ahead! Stay tuned for Part 4

Adventures in CNC - Part 2

Buyer Beware

Check out Part 1

The world of CNC, once a tool only available to large industry, is now making its way into the basement shops of hobbyists in a big way. CNC manufacturers are scrambling to produce lower cost machines for this expanding market. The trick is to figure out the difference between 'low cost' and 'cheap'.

Hobby CNC is still a relatively niche market, and due to the complexity and cost of these systems, most users tend to be technically inclined folks who love spending hours fine-tuning an extra thousandth of an inch accuracy out of their machines. Because of this complexity, it is difficult for large tool manufactures to produce a 'Home Depot friendly' CNC solution. This has allowed a cottage industry of small manufacturers to spring up to fill the void. The products of these small shops will most likely not be reviewed in many mainstream publications so you will need to do a lot off digging to see if a given system meets your needs.

When shopping for your machine, you should have a clear idea of the type of work you need it to perform and a clearer idea of your budget. Then scour the internet for every last shred of information you can find. If you can find reviews from actual owners, all the better. When comparing prices, it is important to make a list of extra items you will need to buy to get things running. Sometimes a seemingly good deal will cost you more in the long run.

The Bottom Line

For my CNC router system, I came up with this list of requirements to help narrow down the field.

• I want to keep the budget at approximately $5000
• I want the size to be large enough to at least handle a full sized guitar or bass body
• I would like the machine to be somewhat upgradeable (Software, Cutting Tools, etc..)

So Many Choices

Here are some of the machines I have been looking at and the thought process I used when evaluating them:


-SHOPBOT Desktop - Shopbot

PROS: Shopbot is a well respected CNC manufacturer. I was hard pressed to find any negative reviews of their products. The also have a great support community. It is a robustly built machine using industrial grade parts. The machine comes mostly assembled and includes a specifically designed software suite which will allow the newbie to get up and running fast. The base model ($5000) comes with a router mount but can be upgraded to a industrial spindle for $1600 more.

CONS: First the size. The cutting area of the machine is 24" x 18" x 3" which may be a little small for some of the projects I have in mind. Then there is the cost. $5000 plus god knows how much extra shipping and duty to Canada is steep for a small desktop machine.

EXTRAS REQUIRED: Router $360, Control PC


 -iCarver 40-915X - General Tool

PROS: This is another ready built - 'turn-key' solution which means I would be up and running quickly and at $4700, it just fits within my budget. The General Tool line is distributed by some local tool stores so I could pick this machine up avoiding shipping fees. It comes with a Spindle as standard and includes software. General tool is a reputable manufacturer so I am confident that service and support would be adequate.

CONS: The iCarver has a somewhat smaller work area at 15" x 20" x 4" which may make it unsuitable for my applications. The iCarver uses a Proprietary Control box instead of a external PC. The final g-code files are transferred to the box via USB memory stick and run from there. While his does make the setup easier, it seems like it would limit the flexibility that an external control PC provides. The construction of the machine seems to be geared towards light-duty hobby use and the spindle is limited to 1/4" bits. It is also not upgradeable if you wanted some better motors or spindle in the future.

EXTRAS REQUIRED: While the unit does come with ArtCAM Express as it's CAM software, it is a bare-bones version. ArtCAM allows you to buy extra modules to add functionality to their software. These modules range in price from $150 to $800 so you can see how the price can add up.


-CNC Shark Pro - Rockler

PROS: At $3800, this is one of the more affordable CNC packages out there. It comes with VCarve PRO and Cut 3D software which is a nice package that will handle most jobs. It boasts a 25" x 25" x 5" cutting capacity which is slightly larger than its competition.

CONS: No spindle option, it is designed for handheld router use only. Some of the earlier models were reported to suffer from inaccuracy due to frame flexing although I have heard that this may have been improved in later models. This is definitely a light duty machine. Rockler only ships this machine to the continental United States so international buyers will have to find another supplier.

EXTRAS REQUIRED: Router, Control PC


-Viper XZ - XZero CNC

PROS: XZero is a small local CNC builder in my area. I came across their products while reading some product reviews on the CNC Zone Forums. XZero seemes to favor over engineering their products using custom machined aluminum parts and high quality Thomson rails. This is one beefy machine for the price. The basic frame for their lower cost Viper model starts at $2400 for the smallest 30 x 24 x 6 inch footprint but can be sized up to 30 x 48 x 6 for an extra $350. It can be outfitted with mounting brackets for a Spindle or Router. At present, the Viper XZ comes included with 270oz motors, motor drivers, a 48V power supply, and a parallel port breakout card (I'm not sure if this is a limited time offer).

CONS: Since this is a true DIY kit machine, what you save on the initial purchase price you are going to pay for in sweat. You will also need to factor in the cost of software and miscellaneous extras to get a true cost estimate. Also, since this is a small company, long term support may be limited.

EXTRAS REQUIRED: All software, Router or Spindle, Control PC, hookup wire, cabling and miscellaneous.

Stay tuned for Part 3 - The big purchase!

Adventures in CNC - Part 1

The saga begins....

The time has finally come. After years of wishing and wanting, I am finally going to invest in a CNC Router system.

In this series of articles, I am going to chronicle my experience acquiring a CNC router. Please keep in mind that this is my first experience with CNC so this will be a trial by fire learning experience for me in the extreme.
I hope that by sharing my experiences, I can help other CNC newbies avoid some pitfalls, or at the very least provide some schadenfreude filled comedy as you watch a guy flush a few grand down the pipes. If all goes well, I will end up with a fully functional CNC Router and not a $5000 abstract aluminum sculpture. Stay tuned!

Some basics

CNC (Computer Numerical Control) is a catch-all term that describes the automation of tools via computer control. Many tools can be converted to CNC such as lathes, mills, welders, and routers. 3D Printers also fall into this category.

XYZ Axis
CNC machines of any kind will have a number of axes of motion. The standard is 3 axes labeled X, Y, and Z. The X and Y Axis are the motion of the tool across the length and width of the table. The Z axis controls the height of the tool above the workpiece. By manipulating these axes, the tool can be positioned in 3D space.

3D or 2.5D
A CNC router like the one I am building can be used to carve intricate 3D shapes in your workpiece. But is it really 3D? Not quite. My system is actually considered a 2.5D machine. Where did the extra Half-D go? The length (x-axis) and width (y-axis) are fully covered. But the depth (z-axis) can only perform 'Top-down' cuts. For example, if I was trying to carve out a model of the globe, I could carve out the top hemisphere, but nothing below the equator.

You better shop around

Getting into CNC is a big investment so it pays to do your homework. Like with any major dollar purchase, spend time looking at all the options. Join CNC related forums, read reviews, and Google till your fingers ache. Here are some things you should be considering:

What do you want to do with it? 

It seems obvious but you really need to think about your needs now and into the future. If you are planning to make custom guitar bodies, it is no use getting a machine whose cutting surface is too small to fit a standard Strat. Don't forget about the Z axis (depth of cut) when calculating this.
What material do you plan to work on? Will it be only wood or do you want to do some metal work? You will need a stronger machine to cut harder materials. If you are looking to do a lot of metal work you may be better off looking at a CNC Mill.
You also want to consider how heavily you plan to use the machine. A system that is expected to run 12 hours a day in a manufacturing environment will need to be much more robust than one used occasionally for hobby use.

Shipping and Handling

Don't underestimate this! Even shipping a medium sized machine locally can easily add $1000 or more to the purchase price. And if you need it shipped internationally, make sure you are sitting down when you get the estimate! Don't forget about the taxes and duty that will be added as well.

What tools can it use?

Better CNC routers will be able to use an Industrial Spindle as a cutting tool while cheaper models may only have brackets for standard hand routers. A Spindle will add around $1500 to the price but will run longer and quieter with more power to boot. Then again you could buy a lot of $120 hand routers for that money.

Build Quality

This is a big one! A CNC router is in theory a simple device. If you break it down, it basically consists of three components that move along guide rails using linear bearings. Threaded ball-screws are turned by motors to push or pull the components along the rails. The rest of the machine consists of a frame that holds the guide rails in alignment.
What makes a CNC machine complex is the precision required during these movements. Any sort of flex or distortion in the frame will result in errors in the desired cut. A cheaper machine will most often cut costs by using cheaper ball-screw assemblies or lighter materials in the frame construction. This results in less accuracy.

Assembly required

Some machines come in a crate fully assembled and ready to run while others will arrive as a box of parts requiring you to do all the assembly. Make an honest assessment of your comfort level in assembling a complex machine. You can save some money with the kit but only if you have the tools and know-how to DIY.

Motors & Electronics

This is what makes your CNC machine move. When you break it down, the electronics in a basic CNC system consist of three motors connected to a computer. The computer precisely rotates the motors which in turn moves the three axis of the machine.
The components required to connect the motors to your computer consist of:

• An interface board that connects to your computer via parallel port or USB
• A motor driver board (one for each motor) that receives signals from the interface board and routes power to the motor
• A power supply capable of providing power to all the motors

Fully assembled machines have all this built and connected for you. If you go with a DIY model, you will most likely have to buy these components yourself and wire up the machine. Expect to spend around $500 if you need to buy these yourself.

Software

Beware, this is a budget buster! Like any computer system, a CNC machine requires software to run. Some of these programs can be ridiculously expensive for a hobby user so be sure to include this in your budget.
First you need something to design the part you want to make. This is done with CAD (Computer Aided Design) software. CAD programs allow you to draw models of 3D objects to precise dimensions and can range in price from free (SketchUp) to incredibly expensive (AutoCAD).

After your part is designed, you then will pass the file to your CAM (Computer Aided Manufacturing) software. CAM programs take the model of your part and calculate how the CNC router will move its cutting tool to produce the object. The result will be a list of instructions your CNC machine can understand in a format called G-code. More advanced CAM programs can actually contain CAD functionality so you can design and manufacture the part in one program. These programs tend to be expensive so expect to pay $500 to $1000 for something decent.

Finally, you will need CNC control software to drive the actual machine. The control software takes the bare machine instructions (G-code) and tells the motor drivers of your CNC what to do. Mach3 tends to be the popular software for this and retails for just under $200.

As you can see, your software bill can be quite high when all is said and done. Some CNC packages will come bundled with software so be sure to take this into account when comparing prices.


Check out Part 2 where we look at some actual machines and try to sort out the men from the boys.