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Converting Mini Mill to CNC

Alexander

Alexander

Ultra Member
Administrator
I want a little CNC mill to compliment my medium sized CNC turning center. I am starting this thread to explore what parts would be nessicary to build a cnc mill. I encourage your opinions. If this is not fesible I will buy a a small CNC instead.
CX605_org.1435535603.430.450.jpg

This is the mill I wanted to use. I see Ebay had a cnc kit that comes with 270oz in stepper motors connected to a driver board and the kit includes a power supply too.
$(KGrHqV,!lcE9R8yOOBDBPcvkb27g!~~60_1.JPG

I realize I can't machine a ballscrew I would just have to machine an acme thread for the Z axis. And then machine all of the necessary brackets and mounts. What do you think am I missing something?
 
About the only thing I could think of would be limit switches, and while I see the spindle has a speed control, you might want a hall or optical sensor setup to get more precise spindle speed information.

You already have an interface pc, I assume?
 
Good ideas. I think I will add the limit switches to the build. I will look at what machines they sell with the rpm meter. I know there is a few that come from factory with it for a nominal fee. That rpm meter is not a deal breaker for me.
 
Alexander said:
@Kris Jensen @SLC_FAB

Is this enough hardware to get my machine moving? I will use a laptop for the controller. It has a mill version of mach3 on it and that is all it has.

http://m.ebay.ca/itm/Stepper-Motor-...power-supply-CNC-Kit-/151415114375?nav=SEARCH
Click to expand...


With this kit, what would stop you from using the existing axis screws (that come with the lathe)

Wouldn't you just need to compensate for backlash inside of the software?

The z-axis fine feed knob should interface okay with the steppers I would have thought?

JW

P.s. @Janger @Mphenley and I all discussed this project mid summer last year.

I'm keen to see how this plays out, I've been toying with the idea for my little tiny mill, more for fun really, but keep us posted as you proceed.

Maybe we can save a few bucks by reaching out and making a group purchase?
 
Hey you hit the nail right on the head. You can connect these servos right to the existing acme feed screws that come with the machine. Mach3 has an parameter in the controller for backlash compensation. I predict that you wont be able to doo much contour milling if you just use the stock feed screws because of the backlash but some programs will run fine.
 
@Jwest7788 do you think a mini mill will be big enough to make a handy cnc? What size hole can you easily drill in mild steel? Also if i had a small endmill like a .312" How deep of a cut could I take before it starts to chatter and struggle?
 
Ok so I bought this on Kijiji. It is defiantly too big for a mini mill and possibly too small for my mill. Does anyone feel like trading a small mill drill for my big knee mill? Ok check out this haul of parts. It is everything you could possibly need for a conversion
.image.jpegimage.jpegimage.jpegimage.jpeg
I got three 600oz/in stepper motors, wired to the drivers in a box. Also in there is the breakout board and above that is a computer and other goodies.
 
Those should work fine for your mill.. Just gear them down a little if they struggle. What did that cost you?
 
I paid $260 for everything. I was looking more at them today they are actually 890ozin. I feel like I got a good deal. This system would cost 3 times that right now. Plus it is all wired up and running. Hmm now I have lots of work to do. This is the mill I have. So much for building a mini cnc that I can bring to maker fair.

image.jpeg
 
Looks an awful lot like my mill.. Except mine is a light pink for some reason.. And I'm betting your coolant pump isn't missing the impeller.

You did get a good deal! Maybe you just need to split a picker truck with me to bring it to makerfair
 
I'll pass on the picker truck. I remember you trying to unload a 400lb transformer from your truck with a crane. It was a mini crane disaster!
 
Cant wait to see your beast in action. I've been keeping an occasional eye on Fusion 360. There is actually quite a bit of YouTube/instructional stuff out there, I just haven't had the time to deep dive. People speak favorably of it saying its similar to Solidworks but a fraction of price. The big thing is apparently CAM comes along for the ride. This vid shows the front to end process on a sample project & gives a sense of what his particular 'medium' mill was able to hog through.
 
I had a few hours tonight so I started my CNC conversion on the knee mill. I spent a few days checking out what other people have made on Hobby-machinist and I have made a rough sketch of what I am going to build.
image.jpeg This is the part I am working on first. I will be using a small timing belt to connect the 890 OZ/in stepper motor to the lead screws. This will be time consuming to manufacture from scratch but I can use different size pulleys to get a 2:1 ratio this will give me more torque for heavy cuts. I found the perfect belt at auto value and now I am machining the toothed pulleys from scratch. I spent 2 hours turning the pulley blanks and now I am setting them up on my home made dividing head so that I can mill the teeth.image.jpeg After I dialled the chuck so it was straight with the table I put the blank in the chuck.
image.jpeg

Above is the small pulley that goes on the stepper motor. I have not cut the teeth yet but I will give it a shot this weekend. I just ran out of time,
 
Hey Alex,

Any update on this?

I'm coming close to actually taking a dive and starting to buy components to do my little mill, but still only 95% sure I want to proceed, haha.

Alexander said:
@Jwest7788 do you think a mini mill will be big enough to make a handy cnc? What size hole can you easily drill in mild steel? Also if i had a small endmill like a .312" How deep of a cut could I take before it starts to chatter and struggle?
Click to expand...

Pretty sure this is a solution anyways, isn't it?

Whether or not the conversion will be super useful is the crux of my 5% uncertainty. I do worry about investing just to find out the little guy can't push as hard as I need it to..



This kit you mentioned earlier:
http://www.ebay.ca/itm/151415114375

This kit, and a PC with the appropriate port should be all that's needed for running mach3 or equivelent, correct?


JW
 
A video i made while making parts on my cnc lathe for the mill conversion. This one covers more on how Mach3 works. Mach3 is one of the most popular controllers for hobby cnc.
 
Alexander said:
A video i made while making parts on my cnc lathe for the mill conversion. This one covers more on how Mach3 works. Mach3 is one of the most popular controllers for hobby cnc.
Click to expand...

"It's a good rule, not to click buttons when you don't know what they do, when the program is running"
lol

Looking good. What exactly is left on your conversion at this point?

Edit: Just finished the vid "Chernobyl hot", awesome.
 
So I have the X axis and the y axis moving now. Here is a picture of what the drives looks like.
image.jpeg

Everything works good so it is ready to use for drilling bolt patterns and doing some basic milling. Later I will finish this project by hooking up the stepper motor on the z axis.
 
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