Homebuilt CNC Router #2: Simpler, Stronger, Prettier

Man, you really impress the hell out of me. Wow. I am humbled. Keep it up.

-- Bob Vila would be so proud of you!

What an incredible design.

-- Hard work spotlights the character of people; some turn up their sleeves, some turn up their noses, and some don't turn up at all!

Great project!

Looks like you are using steppers and not servos. Do you have encoders on them?

What are you using for a controller?

Gary

-- Gary, East TX -- The longest journey begins with a single step.

Thanks guys.

Gary, they are stepper motors so there is no feedback or encoders. Servos are a bit too much for me to handle. The machine is not allowed to miss a step, and it doesn’t. Those motors are really strong. I can barely hold back the gantry when it is moving. They have about 300 oz/inch of torque and 200 steps per revolution. I am micro-stepping them with 16 pulses per step. Each revolution is 1/4 inch (4 tpi), so that is 12,800 pulses per inch. I am still amazed that it all works. The controller is a kit from HobbyCNC.com.

Steve

-- Stevethepeeve -- I'm no rocket surgeon

Nice! With this setup, how many inches per minute is the cutter moving? (avg)

Good heavens this is fasinating. I just wish I wasn’t so old, I try to figure it all out. But I’m paying attention and learning.

-- Thos. Angle

Thanks,

My rapids are set at 150 ipm, or 2.5 inches per second. This is the rate that I can move the router around when I’m not cutting anything. The cutting rate is set by the CAM software depending on what conditions are; depth of cut, type of wood, bit RPM, diameter of the bit, etc. Just like hand routing. I am pretty chicken about pushing it, but I could take it up to the rapid rate if I wanted. Doing something like a mortise at 60 ipm or 1 inch/sec is still impressive to watch, for me. I cut something like that with successive cuts, dropping the Z about 3/8 inch per pass. So the simple answer is about as fast as you would cut it by hand.

Steve

-- Stevethepeeve -- I'm no rocket surgeon

Thanks for the quick answer!
What is the max travel on the X/Y and Z axis?
(Can’t wait to start in building mine… it has been on my list for a year now)

Steve,

Great website. Thanks for the link. Seriously thinking about this. A few questions.

1. Are you plugging this into your parallel port on your PC, or a USB port with a parallel adapter?
2. Does the CAM software just output g-code and then you use a different program to send the code to the controller?
3. Do you know of any software that can take a dwg or dxf file and use that to create g-code?

Too bad about no encoders. If they were being used by the controller it would allow the steppers to skip and not lose their position. I worked with servos in the automation industry and I guess I an kind of spoiled.

Gary

-- Gary, East TX -- The longest journey begins with a single step.

”...on my list for a year now” Hmmmmm.

Careful. On an earlier post Steve said he built one version in a weekend.

He’s got the whole thing planned out. You ought to be able to make if before breakfast on Saturday.

I, on the other hand, am going to sit back, pop a root beer and watch ‘cause this is too good to miss.

-- No piece is cut too short. It was meant for a smaller project.

”...on my list for a year now”

Don’t do it man.
PUT THAT THOUGHT DOWN AND BACK AWAY FROM THE DOOR.

You really have to ask yourself why. What do you want to do with it and how much do you want to spend in dollars and time. For me, I just wanted to do it, and fell into it. I had no expectations or real cost targets. That is probably not a good way to go for most people. I saw it more like the guys who restore an old car. You can’t ask them why or how much. They just want to do it. They spend a bundle and only drive it on Sundays, but I admire them for it. Building it drove my uber practical Dad and my artsy Sister crazy. The first argued that I didn’t need it, and the second argued that anything that it produced would be just look machine made anyway. I am tired of those arguments.

What is the cutting envelope? I haven’t really measured it. The basic size is about 2’ x 4’ because that is what fit in my shop. It can get kind of expensive to keep increasing the size, just like a boat. A lot of newbies want to cut 4×8 sheets, and they soon find out that will cost a lot of money. Remember flex and whip?

My stepper driver card and controller (Mach3) combination uses Windows XP and a parallel port on a PC of at least 1Ghz. I guess that rules out a lot of modern PCs, or you just buy a cheap PCI to parallel port adapter. USB is talked about a lot, but for the DIY it is not there yet. I am pretty sure that a USB to parallel dongle won’t cut it.

The main purpose of a CAM program is to convert DXF, EPS, and other line art type files (for 2D) to a G-code file. The fancier ones also help you pick feeds and speeds along with a simulation. I do this upstairs, copy the G-code file to a flash stick, carry it downstairs and feed it into the machine. A .dwg file is more like a .doc file. It is a design file that contains much more info than is needed. So you export it to DXF from your CAD program. For 3D (think carving) the CAM input file is more like a mesh file. The output is still G-code. Go to Vectric.com and download their demo. It was originally a sign making CAM, but it has a user friendly look and feel and you can get a better idea how this all works.

Steve

-- Stevethepeeve -- I'm no rocket surgeon

I had just sent you a PM in regards to another forum question, when I saw this. This is truly fantastic. Great Craftsmanship and detail.
God bless

-- Gene, a Christian in Virginia

Great job Steve. Keep it up and we will see a new CNC router on the market!

-- Bill, Turlock California, http://www.brookswoodworks.com

Hi, I am Brazilian and living in Brazil! His CNC was fantastica, would pass the measures of CNC (X, Y, Z)

Great job. Nice design.

-- What happens in the workshop stays in the workshop. No wait that doesn't sound right. Karson Southern Delaware karson_morrison@bigfoot.com †

Wow. A most impressive piece of equipment.

-- When you give someone a chance it may well be their last.

Holy cow! What a project.

I love what you have done and would love to build one myself.

This certainly brings back memories for me as many years ago I was contracted by an electronic equipment fabrication firm to write the software to control/program their printed circuit board scoring machine. The firm used a PCDSP card from Motion Engineering so we didn’t have to write PID algorithms we did have to tune them. Unfortunately the boards ME had were in the 1000’s of dollars so not necessarily suitable for the hobbiest.

I am not familar with G-code. Does the kit you purchased support this out of the box?

Steve,

It never ceases to amaze me what comes out of this site. This is absolutely wonderful and I look forward to seeing you put it into action.

Wow!!!!!!!!!

-- With God's help all things are possible- even woodworking. Woodworking is not just a hobby, it is an (expletive deleted) expensive hobby.

People climb mountains because they can, because the mountain is there and I admire those who do.

Most people talk the walk, few walk the talk…........my hat is off to you!

Wheres the vacumn to hold the workpiece down?......how do you hold the work piece down?

-- http://www.furnituremann.ca/

Thanks guys. I need to find time to get back to using it. I am in the middle of a complete shop re-do right now. The shop that is in the pictures now is over twice the size, with new tools (Yea!), and is taking more time than I want just putting it in order. So many things to do, so little time.

Bill,
G-Code is the language that most CNCs use. It is analogous to Postscript or PCL. It is the intermediate command language between a CAD system and the hardware controller. For most systems it is a three step process. So the workflow is kind of like this:

1) Draw something in a CAD system, and save it in DXF format.

2) Take this DXF file and read it into a CAM program. The CAM program will let you pick the size of router bits, determine the feed speed, and figure out the XYZ commands to follow to cut out or carve your part. Many allow simulation to allow you to see if it will all work out. This is all saved in a G-Code file.

3) Take this G-Code file and feed it into the controller. In my case this was another PC running a special program that would control the stepper motors to move around and route out the design. A simple driver board connected this PC to the motors.

As far as I know, the CompuCarve contains all of this in one box. It does not use G-Code but instead its own proprietary version. Many CNC people think this is one of it’s big down falls.

Roman,
Building it was quite a ride. I was obsessed with it, maybe not a good thing :) A Vacuum press hold-down system would be nice. Someday. Right now I have T-tracks mounted in the table. I also have the front vise. I am pretty excited about this vise for mortising and dovetail type stuff. It is pretty unique as far as CNCs go. This use interests me more than ‘CNC carving’ uses.

Steve

-- Stevethepeeve -- I'm no rocket surgeon

I used to work on a CNC high-def plasma machine, so I can appreciate how much effort went into building this – lots and lots of effort! Your straightforward design and explanations make it seem much simpler than it is.

-- http://www.north40custom.com -- http://north40studios.etsy.com --

That’s pretty cool, man.

-- He said wood...http://hickbyassociation.blogspot.com/

The outboard vise is brilliant, I haven’t seen that before but what a great Idea! That is the most beautiful cnc I have ever seen.

-- A thing of beauty is a joy forever...

It’s been said above before, but this is really a nice blog. Good work, and the machine is impressive. I’m a bit confused over the software side of this project, but the rest of it makes sense to me. Maybe I’m just so out of date that the computer action is overwhelming to me.

M

-- Mark DeCou - American Contemporary Craft Artisan - www.decoustudio.com

Ive read you blog about your adventure building the cnc machine. I love your tanasity and creativeness, it does not matter if you will you it that much or not it was just something that had to be done. Congrats!!!

-- Billp

This an amazing CNC I can’t imagine making such a great tool, fantastic job

-- Jim from Heirloom Woodshop Southern Oregon

brings me back to when I made my cnc, looked pretty much the same, except aluminum plate for the Z. I was using the motors and such from hobbycnc which were nice since they came in a bundle. My only drawback was that I was using 2 screws on the Y with only 1 motor and a toothed belt. Worked great for small setups, but then I got big headed and tried a 6’ version and that’s where the problems started.

If you plan on cutting through at any time, I took a sacrificial board and made a g-code to route on all the area with a 3/4 bit to “plane” it, then you have a perfectly parallel surface and can set the depth just a bit below the bottom of the workpiece.

Great machine! How hard is it to learn the computer aspect of setting up and running one of these? I won’t have trouble with the mechinical aspect of it. Darl

This machine looks very well designed and built, great job!

A while back I worked on a machine that a company was trying to sell that looks almost exactly like this except made out of metal:

I think you might find it interesting. The metal design uses the same concept for v-bearings, leadscrew, and anti-backlash nuts and how they are all mounted and put together. I think the version in my picture was built around 2006. I ended up using LinuxCNC (EMC2) to control the machine and we could mill/surface 6061 aluminum and abs plastic as well as wood, although feedrate in metal and plastic was fairly low (around 0.5-8 ipm depending on depth of cut). Rapid was around 180ipm.