My DIY CNC Machine

This post is about the CNC machine that I made from scrounged up parts and a few box store drawer slides. I have been pleasantly surprised at the cut quality that I have been able to achieve from this little machine. It took just six drawer slides some plywood and some electronic components to make a fully functioning CNC machine. The first iteration of the machine used 3/8" rods for the X and Y motion axis which worked okay but the major lack of speed was a significant hinderance especially when jogging around the work area. The major and best upgrade to this machine was moving to belt drive.

The upgraded GT-2 belt drive is so nice. As you can see I used GT-2 belting and as not pictured I used 20 tooth pulleys on the stepper motors. Since this was a very DIY and rough design often functionality is king and looks go out the window. As you can see from the pulleys above... 

For the Z axis I used a 4x4 mounted to the base, it works okay but it doesn't offer significant rigidity for the axis. Honestly I don't have any other ideas on how to strengthen the axis. So for now I just have to limit my layer thickness, but this really hasn't been a major limitation for any of my projects thus far. 

When I first made the machine I had a Dremel tool in place as the spindle, I have since upgraded to a Bosch Colt trim router. This was a huge upgrade that allowed for significantly faster cuts and deeper passes. The major limitation of the Colt router is that it only has a 1/4" collet. Recently I purchased an 1/8" collet adapter from MLCSwoodworking.com the collet has worked okay. However I have found that once its been mounted in the router the adapter must bend slightly so removing an end mill is extremely difficult. I end up having to jam a flat headed screw driver into the opening in the adapter to be able to remove the bit. One of my end mills was purchased from China and I believe that it was specified as 3.175mm not 1/8" on the package, so maybe there could be slight imperfections in the diameter of the shaft. Okay I retract that statement, I just went out to my garage and measured the end mills...

As you can see two of my end mills are either exactly .125" or just under.

As I measure the Collet Adapter I find that it ranges from .119" to .124" based upon where I place the caliper. So this is a definite disappointment with this product. The best part of this deal is that it is a very cheap part and it still works just fine, I just have to pry bits out every time I need to make a change.

I wouldn't exactly recommend this adapter but like I said it works and that is fine until I am willing to spend more money on an actual 1/8" collet for the Colt.

As I wrote earlier, when I am building I usually don't do aesthetics but more function. As can be clearly seen in my Z axis, especially the motor mount. Due to the non solid nature of the motor mounting bracket it actually allows for flexibility due to the inaccuracy of my lead screw and nut. Thank you blessing in disguise. 

Conclusion

Some details of the machine, I am using Nema 23 Stepper motors, the most expensive drawer slides that I could buy at Lowes (which doesn't say much) and for control I am using the gShield from inventables.com. Thus far my experience with the gShield and GRBL has been wonderful. Many years ago I used Mach 3 and a cheap ebay stepper controller and I can honestly say that the gShield and GRBL combo is awesome. I love that I can use any program to send my code and my calibration and other setting are saved directly on the Arduino. 

My experience with this CNC machine has been fantastic, it cuts everything that I want but this will not be my final CNC machine. I am hoping to upgrade to a Shapeoko 2 as soon as I can justify the expense. If you have any questions please feel free to ask. Thanks for taking the time to read.