CNC Router Build – Post 2: Lessons Learned and Design Begins

Published on by Mike  (Leave a comment)

Kimmy Inspecting My Work
Kimmy Inspecting My Work

As I begin then process of the CNC Router build, I am going into new areas that I haven’t had much experience in. A big example is metals. While it is possible to build much of the machine from wood, and there are many good examples of CNC machines out there, for best rigidity going with metal is the best way to go. Obviously the rails and ball screws are steal, but other components are going to be made from aluminum. Part of what goes into coming up with a design to build this machine is researching materials, and more importantly the cost of these materials. This has involved considerable research, from Google searches to eBay. It really pays to do this, as one site may have a component for one price, and another for 50% less. For example, I will need two lengths of angle aluminum. After doing searches on the web, eBay, and a few other metal vendors, I have found the best price, after shipping, is 80/20.

While the materials is an important component, getting the right measurements is critical. As I mentioned in my first post, I already bought the rails and ball screws, along with the bearing guides, mounts, and other parts.  During the process of attaching the ball screws to the mounts, I discovered that one wouldn’t go on.  In my effort to work on this, I decided to remove the nut from the screw.  BIG mistake.  The reason they call these ball screws isn’t because the threads are rounded.  They are rounded so that ball bearings can travel inside of them.  I did not discover this until I had the nut partially off, and ball bearings started coming out.  I quickly grabbed a magnetic bowl to collect the bearings.  After some advice from Jason, watching a couple YouTube videos, and about 2 frustrating hours, I was able to get successfully get the nut repacked.  Needless to say, I will not be making that mistake again!  Once I got the burs filed off, I finally was able to get the ball screw rods assembled, and I got my measurements, and recorded them in OneNote.  I go over this a bit in the video I posted as well.

I am utilizing OneNote considerably for this project.  As I mentioned, I am reaching out to new areas where I am finding that there is a LOT of information to digest. Simply put, I can’t keep track of it all in my head.  So I am doing a lot of documenting along the way, including everything from measurements to tracking my orders, to how much I have been spending, all kept in a OneNote notebook.  

Gantry Design Option 1
Gantry Design Option 1
Gantry Design Option 2
Gantry Design Option 2

I have begun designing the machine in SketchUp.  The 3D Warehouse is absolutely invaluable for this.  All the the rails components are in there, which has allowed me to work on an accurate as possible design.  I am looking at using some 80/20 components.  They have all their profiles in various CAD formats, including SketchUp, available for download.  On top of that SketchUp does a GREAT job of going between metric and imperial measurements.  At this point, I have the main platform designed, as well as most of the gantry.  My next update will go in to my next steps of the design.

CNC Router Build – Post 1: Research & Planning

Published on by Mike  (Leave a comment)

CNC Router Rails, Screws, and Hardware
CNC Router Rails, Screws, and Hardware

Before I get started, I want to put out a big THANK YOU to Jason Beam.  He has provided an absolute wealth of information and inspiration to help start to make this project a reality for me!

This is likely going to be one of the most complex projects I have undertaken to date.  However, the process to build this project is the same as any other project.  Every complex project is broken down to individual tasks and challenges to be solved.  Some will take more time and effort than others.  Like any woodworking project, this build is done one step at a time, until the end result is a working CNC router.  Something I am doing a little different with this build, as I am using Microsoft Onenote to keep track of the various aspects of the build.  Everything from part specs, to the number of screws needed.  This is going to help keep my head straight as I move along on this project.  It will also help provide some of foundation for future posts too!

The first thing I needed to determine, was how big of a CNC router did I want.  First I have to be realistic, as much as I would love to have a large machine, I simply don’t have the room for one that is too big.  So the first decision I made was an approximate size machine I wanted.  In my case, I am looking to build one that is approximately 3’x2′.   While it is not real large, looking at the types of projects I often take on, I don’t do a lot with sheet goods, and I don’t typically have work pieces that exceed that size, so this really should be sufficient to my needs.  With the size determined, I can start the real planning.

Before I can really start designing the machine, I need to determine how the router is going to move.  This took a significant amount of research, as honestly I had no clue where to start, and if the was even feasible for me.  Think back to your geometry and algebra classes, a CNC works on the X, Y, and Z planes.   Each direction direction or plane is referred to as an axis.  All CNC routers have at least 3 axes, which is what I am building.  More complex machines can have more than 3, but for now that is more advanced then what I am willing to take on.  With getting each axis to move, it is imperative that they move in a stable, and precise manner, while supporting the weight of the router, gantry and other moving parts.  This actually is a lot of mass to move.  Any extra movement results in reduction in precision of the machine.  A few basic Google searches reveal many solutions to accomplish this, from home grown options to various rail and screw systems, each with its own pros and cons.  With the help of Jason and his wisdom, I did go with a more premium option, with using SBR20 linear rails.  I was able to save quite a bit of money by ordering a rail and screw kit through a company that works through eBay.  The kit I ordered came in very close to the size I was looking for, and included all the mechanical elements needed to make this move well.  This includes the SBR20 linear rails, the linear blocks, C7 ball screws, and all the needed mounting hardware.  These parts are heavy duty, and will help form a strong foundation for my machine.

It may seem a little backwards to start buying parts before drawing up any plans.  However, there is a method to my madness here.  Right now I have several mental images of how I want this to look.  Beyond that, I really needed to see how the rails and screws are put together.  This will allow me to move them around on the floor, and get measurements from them.  This will allow me to start drawing up the designs in Sketch Up.  

My next few posts will go into further details of planning and design.  In the meantime, feel free to post any questions in the comments, and I will answer them with the best of my ability.  Till next time, happy and safe woodworking!