Turning a Cheap Mini Mill into a Capable CNC Machine

I've been thinking about converting the Craftex/X2 mini mill I got a few months back into a DIY CNC mill on and off for the last little while. I was looking into getting a DRO for the mill when I finally decided to commit to the project and get designing. Hope you enjoy!

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[johnvybiral]

Nice work, young man! I'm a retired machinist, and did the same conversion on the same mini-mill, a little over 3 years ago. My conversion was a whole lot easier though, thanks to the brilliant design of a Texas gentleman named Bruce Nelson and his mini-company, Heavy Metal CNC. Mr. Nelson designed and sold a conversion kit that only required the 6 CNC machined aluminium blocks in his kit to adapt off-the shelf ball screw assemblies to the mini-mill. No machining of the ball-screw assemblies was required. No stand-offs were required. A truly brilliant design! Sadly, Mr. Nelson passed away in December of 2021, and with it, his company. Still, I would like to offer a few tips regarding this mini-mill that I've learned since doing this conversion 3+ years ago:

1 - Replace the Y-axis and Z-axis "accordian-style" way covers with cheap plastic food storage bags from your local super-market. A single 1-gallon bag covers both the Z-axis and Y-axis (rear) ways MUCH BETTER than the original covers! I attach them to the machine's head-stock and the Y-axis saddle using Niobium magnets. For the Y-axis (front) ways/ball-screw, use a single 1-quart plastic bag and the original hardware instead of magnets. The X-axis ways and ball-screw are covered by the table, at least, with Mr. Nelson's design.

2 - Cover the Z-axis ball-screw with the cheap plastic, flexible, split tubing that is used to organize computer cables. It's easy to install with zip ties, and they keep the Z-axis ball screw clean!

3 - Invest in a 14" x 6" fixture plate from Saunders Machine Works, $170. On many set-ups, I can use just (3) 6mm. SHCS's to locate my work-piece accurately and squarely. Using CAD and the down-loaded file of the SMW fixture plate, I can know where the corner of the work-piece is relative to the machine's X-Y home position. This means I don't have to use an edge finder or a dial test indicator to find the corner of of a work-piece and set X0, Y0. I program it from the machine's home X0Y0. Just set Z0 and go! Of course, this won't work with all set-ups, but for me, quite a lot!

5- Buy some cheap "Halo" LED's and mount them around your machine's spindle. Like the way covers, mine are attached using Niobium magnets. They shine directly on the cutter, not in your eyes. They run on 12 volts DC, so are safe to use, even with steel chips flying around. I think they were about $10.

6 - The belt drive kit from LittleMachineShop.com ($150) is just SO MUCH more quiet than geared spindle motor drive, and nearly doubles the top spindle speed from 2500 to 4600 RPM.

If anybody is using the SMC5-5-N-N 5-axis CNC controller, I've learned a few programming tips that are not even mentioned in the Chinglish "manual". Happy to share!

[instanoodles]

As a retired machinist your videos are driving me towards picking up a mini lathe and mill. They are far more capable than I was expecting, thanks!

With some carbine tooling you probably could have gotten away with milling the flange, just lots of fairly light cuts.

[xnadave]

Well done! I spent $2k designing and building a 1m x 1.25m CNC router from scratch. (Could've bought a kit for less.) I've used it to make approximately $50 worth of wood parts for home projects. I didn't really have a purpose in mind; it was just a fun thing to make.

[swealer]

Awesome Project and nice video!!
You earned yourself a awesome brownie recipe!
Ingredients:
-1 Cup unsalted butter
-2 Cups granulated sugar
-4 large eggs
-1 teaspoon vanilla extract
-1/2 cup all-purpose flour
-1/2 cup cocoa powder
-1/4 teaspoon salt
-1 Cup chopped nuts or chocolate chips (optional)
Instructions:
1. Preheat oven to 350 F (175 C) and grease a baking pan.
2. Melt 1 cup butter, mix with 2 cups sugar.
3. Add 4 eggs and 1 tsp vanilla; mix well.
4. Sift in 1/2 cup flour, 1/2 cup cocoa, and1/5 tsp Salt; Stir.
5. Optional: add 1 cup nuts or chocolate chips.
6. Pour into the pan, bake 25-30 mins.
7. Cool completely, Cut into squares, and enjoy your brownies!

[mariebaxter]

Nice to see young guys doing these jobs, and not getting too worried about day too day errors, I tell myself its the sign of a great engineer, LOL

[stefandebruijn]

Always nice to see so many people using the firmware that I helped build. Good job!

[definitivepepper]

Looks great! On the flat spots in your circle interpolated... circle. A lot of CAM software converts arcs to a series of segments. Check the arc filtering settings on whatever CAM software you're using. I use MasterCAM at work and if the arc filter tolerance is set too low it makes facets on our circular geometry like you're seeing. By tightening the tolerance you can create smaller and smaller segments until eventually you don't see facets anymore. It does cause the cutter path to take longer to compute though. Alternatively, you can dig into the settings and see if there's a way to force the software to favor using arcs instead of segments.

[weiwang]

Those balls are ordered. They come with bigger ones and smaller ones alternating to reduce internal resistance. They should also come with preload tension to further reduce backlash. Make sure you reassemble them right. Good luck.

[CncObsession]

I remember the excitement of the first moves on my cnc build. Congratulations. It takes persistence.

[kusler]

As someone with a similar mill, you can double nut the ballscrews to reduce backlash. Also when you upgrade the steppers, you can get an ac servo for the spindle and really get cooking.

Oh and also coolant will prevent chip welding with aluminum.

Great work on this bad boy!

[HavenInTheWood]

Impressive video! Since buying my mini mill, I have watched numerous videos like this, but this video is the most impressive CNC upgrade for the mini mill!

[DjDoGGoD]

I know the feeling @14.00... When I made my own CNC machine, the idea was to make it do PCBs, and the first use was to mill it's own PCBs, to replace the hand made one. :D great job!

[janvn]

Nice job! To get rid of the backlash you can change out the bearings in the ball screw bearing blocks to annular contact bearings, C5 or C3 type, they usually ship with deep groove bearings.

[koomber]

Building a telescope mount the now using harmonic motors and as soon as I saw the couplings I thought "oooh. That's not going to help his backlash"

Nice build. Glad the algo recommended it to me. Surprising amount of comonality between a CNC machine and a telescope mount

[djl]

Thank God for The Algorithm!
Awesome work. Wish I could do it....

[JeD]

Closed loop steppers only have one advantage.. you will know, when you lost steps but they will not be able to fix those lost steps, because a stepper can't just put out more power, when steps are lost. It can recover the position, when the (over)load goes away but not mid-cut. That load goes away after the cut is finished and your part might already be scrapmetal.

That is where Servos come in. Most of them can put out 300% power for some time and can "fix" the lost steps when they occur and not after the cut.

Just don't ask too much from the OL steppers and you will be totally fine.

[alessandrosuppini]

Awesome project, glad it all worked out in the end!
Looking forward to seeing what you can create with it 👍

[someramdomguy]

Do you have these plans released or a build list etc? This is a AMAZING PROJECT I would love to attempt

[makealready]

.004” Backlash is to be expected from single nut ball screws. It’s the reason double nuts were created. Most cnc software should be able to adjust for backlash, I’ve used backlash compensation in both Mach3 and LinuxCNC.

[gazehound]

Did I just stumble across 600 view gold? This feels like a privilege