Instructables
Picture of How (NOT) to build a CNC
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This was my first generation CNC.

I had two objectives when I built this:
- Cheap as possible
- Worked

It was cheap (relatively), and it worked (albeit not as good as i hoped).  The problem with the CNC was it did not have enough lateral strength on the X- or Y-Axis.  That meant it would not be too accurate, I could not repeat the same cut twice, and the machine was only good for drilling holes.  So as I move on to the next generation, I thought I'd share what I learned this first go-around as I deconstruct my first CNC (on my wife's kitchen table).

MATERIALS (Remember, I tried to keep it cheap)

Things I bought:
- 3-Axis Kit from Probotix (works like a champ, saving for another project)
- Drawer Slides as Linear Rails (2 for the X-Axis, 2 for the Y-Axis, 1 for the Z-Axis)
- Two 1/2" MDF handy-panels (2' x 4' each)
- 1/4"-20 threaded rod for lead screws
- 1/4"-20 coupling nuts
- small set screws (3)
- Wood Glue

Things I had laying around:
- Dremel Rotary tool
- Screws; all shapes and sizes
- Scrap wood
- Angle Aluminum

Tools I used:
- small drill press
- table saw
- hand drill
- screwdrivers

Lets get started with the deconstruction...
 
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Step 1: 3-Axis Kit

Picture of 3-Axis Kit
I purchased my 3-Axis kit from Probotix.

Its a solid kit, included power supply, breakout board, drivers, and steppers.  I bought the smallest one for this venture.  ribbon cables were provided to connect the drivers to the breakout board.

To connect the driver to the steppers, I used standard CAT5e network patch cables.  I punched down the wires of the stepper into a RJ45 jack to accept the patch cable.  Cheap and effective.  My buddy doubted the CAT5e, but I was pushing such low power, it didn't matter.
jim.funicello2 months ago

At the begining you said you did'nt have enough x and y strength but then at the end you say it's deflection in the Dremmel tool. So then the steppers were strong enough? They look good sized to me. I'm guessing nema 23, probably 200 inch/ounce?

mykiscool1 year ago
I learned that I need to be cautious if using a dremel as the cutting tool. You should make an updated version using a c02 laser!
etlerd2 years ago
Actually, it sounds like you did well. What if you found a small bearing for the shaft (outside the dremel body) and mounted that to the holder?
etlerd etlerd2 years ago
Put the bearing around the shaft between the body of the dremel and the collet. Attach that to the dremel cradle by putting it in a piece of wood below the current bottom part of the cradle.
pfred2 etlerd2 years ago
I think I'm going to need some diagrams ...
pfred22 years ago
Now that you've made an attempt you know where you are strong, and where you need to improve. That is something. I think you need to set your sights a little higher to achieve something that as you put it is, "as good as i hoped".

The best advise I can offer is plan to discard many plans before you begin construction. Try to work with some solid data.

Like for instance exactly how fast can your motors run and still generate useful torque? This you can know now. Using that number you can calculate what to use as your linear motion hardware. With 1/4" X 20 TPI all thread if you run at 1,000 RPM you can go 50 inches per minute. Is that fast enough? Can you setup a 1/4 X 20 lead screw to handle that speed? Theoretically you can (just barely), but it requires some difficult engineering. Maybe you'd like to avoid that?

Failing to plan is planning to fail. You seem to have the desire, now you need to exhibit the determination.

I've been working on a CNC machine myself off and on for a long time now. I'm not quite done with it yet, but I haven't painted myself into any corners yet either. Well, not too badly.
mcraghead2 years ago
Howdy!

I have small router table set up with an older version of this: http://www.makita.com/en-us/Modules/Tools/Default.aspx?CatID=31; called a "laminate trimmer" but it's really just a small router. looks like around $100 new but there are certainly used/cheaper alternatives out there. It's considerably heavier than the Dremel, but if you could get it mounted well I bet it would work well in this context.

Best of luck with V2!

Mike
Rob3112 years ago
It's an iterative process, use V1 to build a bigger, better, V2. Then use V2 to build a V3 and so on and so forth.

You're not off to a bad start. Maybe convert it to a large 3D printer? It wouldn't need to be as structurally strong, and all it would need is to replace the dremel with an extruder.