Building A CNC Machine
Info on Building a DIY CNC Machine
A get a lot questions about my CNC machine. It was just something I created from scratch one day to help me make panels. It is now my most prized tool and use it for nearly everything. There are time where it runs for weeks at a time (usually in the run up to Christmas). Initially, I was supposed to use the machine to create another more accurate version, But it has performed perfectly from day one without fault. I have upgraded some of the electronic components so that I don't need an antiquated computer with a parallel port. Its going to cost you around £1000 for a similar unit to mine. Of course the smaller you go the cheaper it gets.
The working area is 42cm x 42cm. This isn't quite big enough, and wish I was able to make a bigger version (Nobody in china seems to be willing to ship here in Brunei, so for the time being, I'm stuck with this old girl)
If your thinking about creating one, I would recommend 60cm x 60cm if you have the space and money.
I have a 3 axis CNC (x,y,z), but 4 & 5 Axis are available if you require it.
As mentioned above, I moved away from parallel port connection to USB. This is much better for me, I can design in fusion now and use the same computer for the CNC.
You will need software to run the CNC and I use MACH 3 at around £100.
Since Starting this page, many people have got in touch to say they have bought the cheap 3018 CNC from eBay. Prices are so cheap these days and this particular machine is under a £150. It also comes with both a CNC spindle and Laser (which is perfect for making sim panels). After seeing various photos of peoples custom panels produced by this machine (which look awesome), this could really be a good way to start getting creative for very little money.
Please be aware I do not endorse this machine as i have never even seen it personally, but it comes from word of mouth from people who visit this website.
The CNC rails
The CNC rails are very important part. They should be precise and of a size that will not bend with any load placed upon them. The movement between the bearing and rails needs to minimum, this will affect the accuracy of the machine.
When buying rails, remember you will not get the full length of the rail. You have to deduct the size or the carriage assembly. I bought 600mm rails, but with the carriage unit fitted, I only have a working area of 420mm. The larger the carriage width, the more stable and accurate the CNC.
Regardless of size/length of the machine I would recommend a minimum rail diameter of 16mm. These are sturdy enough to be precise over there normal operating length. 8mm if your building a mini CNC machine, but these tend to move under the load/weight of the spindle. You can go to a homemade rail system and there are many methods out there. I started out using ball bearing drawer slides, but poor accuracy became apparent after a few cuts.
The image shows the rail type used on my CNC, SBR16. Fairly cheap, and reliable. Be Careful putting the guides on to the rails for the first time. Incorrect alignment can cause the ball bearings to fall out!
There are allen key screws located on various plains of the guides to remove unwanted play and stiffen the units up.
If I was going to upgrade my CNC, I would buy the newer, more accurate rail system HGH20. But these are a little more expensive.
The CNC Ball screws
Once again another important part for accuracy. These are pretty standard and try to get the sets that come with the attaching mounting blocks so that you have the correct items to start with.
Try and stay away from belts, these are not upto the job! Unless you are on a very limited budget.
My top tip, is to buy a complete rail and ballscrew set. This way everything is compatible and all the parts will be correct. It also works out cheaper than buying all the individual parts.
The CNC Electronics
These come in various packages, but you will need:
Stepper motors
Drivers
Controller board
Limit Switches
Power supplies
I used the Nema 34 stepper motors because of there increased torque, but these will require drivers that can provide adequate power.
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I used the TB6600 drivers, one for each axis. I have had to restrict the current as they overheat when th motors pull 5A. I actually probably need a more powerful driver. These are fine with the smaller Nema motors.
I can highly recommend this board. It allowed me to use my windows 10 computer and USB port. Not many new computers these days come with a parallel port which is/was the standard cnc connection.
Your probably going to need at least two of these. One for the spindle, one for the controller board, one for the nema driver boards.
The CNC Spindle
I started off with this cheap 24V spindle. They do the job, but i went through 4 in a year. All breaking with the same fault. The spindle shears off completely. Another downside is the noise they produce is deafening.
In the end i went with this air cooled 1.5KW. Its fantastic! It has a much larger operating range and is quiet compare to the spindle above.
