CNC router | macteam

/CNC router build

Introduction

I really never thought too much about having a CNC router of my own. I priced them out a few years ago, wet my pants, and parked that idea for when I won the lottery. Entry level machines were north of $5,000 and something that would suit my needs was more likely $10,000 to $15,000 when you add in the software and tooling costs.

Then issue #242 of Woodsmith Magazine landed in my mailbox. After a few casual reads and dismissing it as being way beyond what I could do, I decided there and then to just do it. Some quick Excel spreadsheet work showed me I could build this thing with a custom made base unit for about $2,500 Canadian. Yes I'd have to add in software and tooling costs but that was for later.

I fired off some e-mails to Chris Fitch who is the author and designer of the machine. We discussed design ideas and I knew I was hooked. I spent the next month Googling everything with the word "CNC" in it and watching untold hours of YouTube videos made by professionals down to aspiring CNC'ers such as myself. There is a wealth of information out there!

I knew there were some things I wanted to change from the original article... the biggest being the decision to use ball screws instead of threaded rods and anti-backlash nuts. I wanted bigger motors to handle the load and I wanted to source as much as I could from within Canada.

I began a blog on Lumberjacks. There are over 117 replies to date so lots of good reading. Click here for the article.

From Woodsmith

I had a nice mail back from Chris Fitch who is the author and designer of the Woodsmith CNC router at the heart of this discussion. He made several good points:

”The goals that I had for the project:
1) Create a machine that could be built by the most number of woodworkers with average equipment in a reasonable amount of time.
2) Create a solid high performing machine for the lowest possible cost so that it will be accessible to the most people.
3) Create a machine that could be reasonably explained in 24 pages of a woodworking magazine (not so easy).

My hope in this machine is to provide a simple, obtainable starting point for people to enter into the world on CNC machining. I hope that people will take the base design and modify it, upgrade it , customize it, and share their ideas.”

I think these comments are right on the money and well serve to justify the design…. no this isn’t an industrial quality, production CNC machine. It’s meant for a woodworker who wants to stick his/her toe into the CNC arena and see what it holds with some assurance that they will come out with something tried, proven and very useful at the end. This is where I am at.

The Build

I am not going to describe every step of the build here. I have included a selection of photos taken along the way that show how it progressed.

Ball Screws

The decision to go with ball screws over lead screws was a long and involved one… before I started this project I didn’t even know what a ball screw was. There are lots of articles online expounding on the advantages/disadvantages of them vs lead screws but really it boils down to one thing – accuracy. And in the world of CNC accuracy is king. You will get virtually 0 backlash with a ballscrew and the bearings on each end ensure the screw runs perfectly true. I bought mine from China – LinearMotionBearings2008 –
The owner, Chai, was fantastic at answering all questions, helping me select the right one and shipped it all DHL Air Express, I had all the parts in my hands a week after ordering! Don't be afraid to order from China, it's easy!

Here’s a few videos and articles that helped me make the decision to go with ball screws. And yes ArtMann is quite right – friction is also a huge enemy of stepper motors and the ball screws do an awful lot to reduce it.

Motors and Electronics

For the Y and Z axis I used the followng:

438 oz-in, 57HS112-4204-03, Nema 23

For the long X axis I used the following:

1200 oz-in, 86HS115-4208-05, Nema 34

Drivers were:

Nema 23 Micro Stepper Driver 2DM556
Nema 34 Digital Stepper Driver 2DM860H

Power supplies Used:

Mean Well 48V Power Supply 120V / 240V AC input. 48V – DC output 12.0 amps.
Mean Well Multi Voltage Power Supply 5V, 12V, 24V – DC output 7, 4, 2 amps (this one runs the auxillary bits, cooling fans, lights, breakout board, etc)

The 36V power supply referenced in the article is inadequate for motors of this size.

All of my components bought through:
The Stepper Motor Store
Jon is excellent to deal with BTW!

The Costs

When it was all said and done here is the exact costs I incurred:

Baltic Birch plywood for the machine $267
Ball screws $319
Motors and electronics $1,164
Hardware incl rails, bearings, paint $489
Components for base incl 24" slides $330

Total $2,569 Canadian

Vectric Desktop Pro $655
Mach 3 $230
Tooling (basic set) approx $500

Grand Total $3,954 Canadian

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Lessons Learned

The plans in Woodsmith are a starting point. Do not take them as the gospel. Don’t be afraid to make changes to the design to suit what you want.
2. Check then double check every single dimension in the plans. YES THERE ARE ERRORS IN THE PLANS! Your motors, your drive controllers, your mechanics will vary in size from what’s in the plans.
Be sure your calipers are accurate. 1/64” matters! Most of your components will be built in metric mm so use that if you’re comfortable with it.
Draw up full size plans of all the critical areas (gantries, bearing locations, motor mounts, etc)
A 48” wide drafting table is a valuable thing to have. :-)
Consider using ball screws instead of lead screws and anti-backlash nuts. They are WAY more efficient and practically immune to backlash. Yes you will need to redesign the motor mounts and static ends but it is well worth the effort. If you need help locating them contact me. I used 1500mm for the X axis. 900mm for the Y axis and 400mm for the Z axis. Do it, you will never regret the decision. All 3 of the ball screws including the BK12 and BF12 end bearings, drive linkage and the bracket that connects the ball screw bearing to the moveable plate were under $300 Canadian.
Don’t think that the sources listed in Woodsmith are the only place you can buy these components. I’m not knocking BuildYourCNC.com but there are lots of alternatives and many of them much cheaper.
Buy the stepper motors, drive controllers and the BoB (breakout board) from one source. That way you will have some assurance that they all work together. Buy from a dealer who will assist you with the endless questions you’ll no doubt have. Plug here for The Stepper Motor Store they were fantastic to deal with.
Buy a bigger stepper motor for the X axis. That gantry carries a lot of momentum when it gets going.
Add LED lights to the underside of the gantry. Really helps you see what’s going on.
Add plastic drag chains to the X and Y axis. I used 18mm x 50mm and they fit perfect. Really helps with wire management.
You must use SAE washers next to the bearings. If you use the larger 3/8” diameter ones they will bind on the bearings.
Think in modules. Logical units of the build. For example, run your motor wires to terminal blocks. Then run your wires from the drive controllers to the terminal blocks. This way you are not trying to make a single connection from the motor all the way back to the electronics. Another example, put a 115V outlet on the gantry. Now your router just plugs into it, no need to cut the cord, need to take the motor off for repairs? No problem just unplug it.
Consider adding a second fan. There is a lot of heat generated from those electronics for one little fan.
A 36V power supply is marginal especially if you use a bigger X axis stepper. I used a 48V unit.
Consider adding a second power supply for the 5V and 12V needs. Easy to do.
Paint as you go. Don’t build the whole thing and then think about painting it. :-)
Build a dedicated base. This thing takes up a considerable amount of floor space, you can capture a lot of storage space underneath it. Be creative!
Don’t forget about the cost of software in your total cost estimates. It is significant!
When you think you’ve used enough screws, add a few more. Rigidity is absolutely mandatory here!
YouTube is full of great videos on building CNC routers. Spend a lot of time watching them and making notes about what you want YOUR CNC to look like.
I installed a UPS (uninteruptable power supply) so that in the event of a power failure mid-rout I’m not left in the dark and can shut things down gracefully.
Connect a USB numeric keypad so you can jog the system around with a handheld unit instead of from the keyboard.
Install an Emergency Shutoff switch. This has two connections, one for the system and one for the router. When all hell breaks loose you have one button to press.
Only build with the best quality Baltic Birch you can find. Do NOT use Home Depot grade plywood!
Install 5 limit switches for X+, X-, Y+, Y-, Z+. These were not in the Woodsmith plans but very easy to add and it gives you an assurance that the system will not self-destruct at the limits of axis travel.
I purchased a dust boot specifically for the Dewalt router. TBD if that was the right decision or not but it is well made (3D printed) and fits perfectly.
Buy your wife flowers – often – this build is very addictive and you’ll be spending a lot of time and money on it!
Buy a flattening bit and use it on your brand new 3/4" MDF spoil board before doing anything else. If you are doing anything that is Z depth sensitive like V carving you MUST have a surface 100% parallel to your Y axis.
You will likely have as much fun building it as you will using it. Take your time, be a perfectionist, be very accurate and you will have a unit you can be proud of.

Here is a link to the entire original articles from Woodsmith #242 and #243. Enjoy!

Happy CNC'ing!