Building a CNC machine

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
Back in January 2021 I got an inexpensive CNC 3018 router just to get my hands dirty in this area. It was a great opportunity to learn everything I need to know about CAD and CNC machining. Then I though that this little fella needs a big brother. Finally, all the components ordered are coming in and I though that I should document the build along with the issues and mistakes.

CNC 3018
CNC3018.JPG


This big fella is going to be 1000 x 600mm on 4040 extrusion.
CNC 1000x600 build.JPG
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
Four axis steppers are NEMA 23 with DM556 drivers.
motors.JPG
Tested my first motor and it runs nicely.
NEMA23 Test.JPG

The first error I made was since everything is going to be in metric units I ordered motors with 8mm shaft.
Then I noticed that all the ball screw drives were being shipped with 6.35mm couplers. Fortunately the motors were not yet shipped so I managed to have the order changed. I supposed I could have lived with 8mm shaft and would have had to order 8mm couplers.
 

BobTPH

Joined Jun 5, 2013
3,308
Did you get your 3018 machine to work reasonably? I bought one those and found it totally useless. As soon as it started cutting something significant, the board would crash and crash the USB controller on my computer. Changed to a completely different controller board, no help. Changed motor, not help. Added snubber network, didn't help. Replaced spindle with line powered Dremel, helped a little bit, but still never made it work.

I wanted to use it to cut copper on PCBs to isolate tracks. Even with the auto-leveling, the depth could not be controlled to even 1/10th of what I needed. Gave up on it.

Bob
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
The next issue was the two 1000mm rails had be mounted on the 4040 extrusions with 20 screws on each.
There is not enough room below the surface of the extrusion to tap an M5 thread. I had to order an M5 bottom tap.
Then it was down to painstakingly locate, drill and tap forty M5 holes. I'm glad that's done and happy with the results.

M5 tap.JPG
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
Did you get your 3018 machine to work reasonably? I bought one those and found it totally useless. As soon as it started cutting something significant, the board would crash and crash the USB controller on my computer. Changed to a completely different controller board, no help. Changed motor, not help. Added snubber network, didn't help. Replaced spindle with line powered Dremel, helped a little bit, but still never made it work.

I wanted to use it to cut copper on PCBs to isolate tracks. Even with the auto-leveling, the depth could not be controlled to even 1/10th of what I needed. Gave up on it.

Bob
Yes, my CNC 3018 is running fine. No issues to report.
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
Major issues are how to mount and assemble the rails and ball screws together. That takes looking a each situation and solving it one step at a time.

By far my most major problem is sitting down and tallying all the nuts and bolts that will be needed and sourcing all the parts. I have spent countless hours, day and night doing this. Of course, when I find a different way of doing the assembly, everything changes and I have to redo the tallying.

The Catch-22 situation is to build a CNC machine you need a CNC machine. I have considered making it work with what I have and then use it build the components that I really would prefer. I can be a bit OCD at times.

Total cost so far is US$1200, estimated.
When I have to add up all the incidentals, such as having to buy a metal cutting blade, I would have to say that a realistic cost is close to US$2000.
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
While I'm at it I should show my cyclone dust collector.
The lit is cut oversize and sits on top of a plastic garbage pail. Vacuum holds the lid in place.
A shop-vac sucks air from the top. The side vent is connected to the wood planer which generates a lot of wood chips.
The 3D printer came in handy for creating the right sized hose adapters. The trick I have found is to taper the diameters so that it will always fit. I will be looking into creating a vacuum connection to the CNC machine.

cyclone.JPG
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
March 22, 2021, the day of reckoning has arrived.
Did my first test cut on the CNC!
The messy wiring will get organized after I move the machine out from the basement.

CNC 600x1000.jpg
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
I used ballscrews.
The controller is Bitsensor BSMCE04U and the motor drivers are DM556.
I can get up to 3000 mm/min but I am going to drop down to 2000 mm/min to be safe.
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519

cmartinez

Joined Jan 17, 2007
7,332
When I think of lead screws I think of fancy threaded rods designed for linear movement whereas ball screws have circulating ball bearings in the ballscrew nut and they are more expensive. The little CNC 3018 in my post #1 came with leadscrews.

https://blog.misumiusa.com/lead-screws-vs-ball-screws-differences-benefits-accuracy/
Lead screws have solid geometric threads on them, like the ACME type of thread. They're good and accurate when the proper atibacklash nuts are used on them, but they're also high in friction. That's why ball screws are preferred for CNC machinery.
 

Thread Starter

MrChips

Joined Oct 2, 2009
23,519
You have to always expect the unexpected.

I have implemented two kill buttons.
One soft button sends an eSTOP signal to the SW controller that then shuts down all motors.
A hardware emergency kill button cuts AC power. This is a latching NC switch that has to be twisted to reset.


1616603180095.png
 
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