CNC Basecamp E024: Best of Basecamp - CNC Basics

I knew that I had a lot to learn when we started CNC Basecamp two years ago, but each project has offered lessons in both specific techniques and general operation of a CNC router. Twenty-three projects later, and here are the things I’ve learned...
Straight Bits Rule - I’ve tried a lot of different router bits with our CNC routers over the last few years, upcut, downcut, compression, single-flute, two-flute, three-flute, coated, uncoated, large and small, long and short. You’ve got to have specialty bits for certain materials and situations, but my go to bits for 90% of cutting operations are a ¼” and a 1/8” straight bit, each with a short length of cut. These bits produce smooth cuts, are versatile, tough and reasonably priced. Check your bits before use and know when to say goodbye -they only work well when sharp. Note: Top quality bits will be the diameter stated, however hobby grade bits can be surprisingly smaller than the stated size. This can cause all sorts of grief with parts that don’t fit, so when a project demands accuracy, get out your calipers and verify the bit diameter.
Faster Feeds and Slower Speeds Save Bits - It’s never a good feeling when you look at that expensive router bit in your CNC machine and see that it is black from heat. Using the correct feed and speed is super important. It ensures the best possible finish on the cut and allows you to get the full life from an expensive router bit. To arrive at the correct feed and speed numbers there are chip load formulas. I have tried to use the formulas and carefully apply the numbers but it’s tough with hobby machines and small projects. Nearly two dozen episodes has taught me to use the rule of ½ the bit diameter for the depth of cut, use a spindle speed between 15,000 and 16,000 RPM and a feed rate of 110-120 IPM for solid wood, plywood and MDF - the chips are big, the bit stays cool, and the job gets done. So, no babying the bit... push it along and make it work!
Deal with the Dust - I find it frustrating, and a bit depressing to go into my shop and realize that everything is coated by fine dust. The first rule of dust control is to eliminate processes that create the dust in the first place - that’s a tough one with a CNC router. The second rule of dust control is to capture the dust at the source. That I can do something about. The dust boots I have all seem clumsy and ineffective or just get in the way. My plan for this year is to design dust boots that don’t go up and down with the Z axis but remain a fixed height off of the work piece, are small in size so that they won’t bump into hold downs and will work with a dust collector rather than a vacuum cleaner - definitely a challenge!
Pre-flight Checklist - We have all been there. You start a cutting routine and the machine slams into its extents, a bit goes into the material unexpectedly deep and breaks, the bit chews up a hold down, or the material shifts during cutting. Things go wrong and the outcome is not what we planned. Anyone who thinks CNC woodworking is risk-free or brain-free woodworking has clearly never done it. I’ve been able to eliminate some of these moments by going through a checklist:
Use the preview feature in your toolpath software - make sure it is showing what you have planned.
1. Use the preview feature in your toolpath software - make sure it is showing what you have planned.
2. Do I have the XY datum point set correctly? Sometimes I use the center, sometimes the lower left, and sometimes I forget which I chose.
3. Will the bit and dust boot clear the hold downs, screws or registration blocks? Air cutting can help find trouble before it happens.
4. Is the material secure? Hold downs, screws, wood blocks and hot melt glue can help.
5. Do I have the plywood’s grain oriented correctly?
6. Did I remember to re-Zero the bit after changing it out?
Efficiency Matters - Watching a CNC machine dance over a work piece and transform it is exciting, but after many hours of noise, what’s exciting is when the machine shuts down and you can take off your hearing protection and get busy building. Here are some steps I take to maximize efficiency:
1. Plan the order in which you cut parts to minimize bit changes.
2. Use the full format size of your machine and maximize the number of parts on a workpiece, doing so means less set up time, less start up time and less baby-sitting the machine.
3. Use the Time Estimator in your toolpath software. I am often surprised at how small tweaks in bit depth or percentage of overlap can cut machining times by over half - so work with the variables. The best results are often not the most time consuming.
More on CNC Basecamp: www.woodsmith....
If I were to list one more item that I’ve learned, it would be how limitless the possibilities are in the world of CNC woodworking. It has proven to be fun, exciting and endlessly entertaining. I’m looking forward to more CNC Basecamp episodes for years to come.

[@glenncampbell839]

Hello Chris,
Grounding the dust collector hose and all moving parts will eliminate intermittent issues caused by static electricity. Especially the dust collector. I hope this solves your issue.
Love all the shows you guys do. Have a great day.
Glenn

[@kevinwillis6707]

even though im not a begginer, i appreciate your putting these videos out for people new to the hobby, cheers

[@WoodsmithShowandmagazine]

Thank you! I find CNC woodworking fascinating and really enjoy sharing some of my experiences.

[@OpaOmaHorst]

Thanks Chris for this summary and for all the free CNC Basecamp videos! I watched them all in the last two weeks, very helpful and instructive. Apart from the technique, most helpful are demonstrating the things that can go wrong, so you know what to look out for.
I almost finished building the Woodsmith CNC router and looking forward in the coming two weeks or so to start cutting 😀
Before I started the construction, I had to convert inches to mm and adapt material sizes to what is available locally, so I first designed and drew the CNC router in mm in Sketchup to get a good idea of how things would fit together.
In the Woodsmith video of issue 242 you mention a wooden clock as example. Would it be possible to make a CNC Basecamp video about building one, including the clock-gear calculations? Would be great if you could! 😀

[@rednecksareeveryware]

You could make the dust boot in two pieces and use rare earth magnets to hold the two pieces together.

[@WoodsmithShowandmagazine]

Good idea! Thanks! I'm going to start making prototype boots for the machines and easy bit changes in a priority.

[@scotttovey]

Something that will make it easier to remove your dust boot is to replace the thumb nut with a toggle bolt like they have on bicycle wheels and seats.

[@WoodsmithShowandmagazine]

That's a great idea - thank you for passing it on. I'm determined to do something about dust this year!

[@brandonbevan6426]

I wonder what you guys will find on Pinterest to copy? I hope you use this break to come up with content for this channel this is brutal

[@WoodsmithShowandmagazine]

This is a FREE video series with FREE content. I do these videos because I enjoy CNC woodworking and want to share my experiences. I make no claims that all the projects are 100% original - some are and some are not. I use the internet, including Pinterest, books, magazines, items I see at stores and etc. for ideas. Don't you? As you are not paying for the content your comment is out of line.

[@brandonbevan6426]

Try disclaiming where you found your inspiration then!! Again you guys have made so many things for over 30y I’m sure!! why not use old projects and create them on the cnc? Teach the people that they can create projects directly from the magazine!! There’s so much you can do with this channel and it’s disappointing to see trivets or v-carvings being made. Yeah it’s called cnc basics but that doesn’t mean as basic as “ this is my first project”!! The past 3-4 episodes as very basic as they can get!! You said so yourself I want to think of this machine as the only machine I have in my shop! Then prove it!! Challenge yourself season 11 episode 1 simple box and the lid is a double sided project. Bam it’s as easy as that!! No need for Pinterest just look back like I’ve been saying and teach the viewer how to use plan’s from your magazines and show