How to make a mini milling machine- manual or CNC!

How to make a mini milling machine- manual or CNC!
I think one of the best things about tools is that they can be used to make more tools! I decided to build a miniature milling machine for machining plastic parts, creating wax patterns and for drilling really small precise holes. I also wanted to design it so that I could convert it to CNC for machining circuit boards and for doing repetitive work.

The finished mill has a 11" x 18" footprint and is about 19" tall. Depending on the motor used it is capable of machining plastic, wax, wood and non ferrous metals. Right now my motor is a bit underpowered due to the power supply I had on hand. It's very quiet- I could use this inside the house at night and not wake up the little ones!

The X axis travel is 6 1/8"
The Y axis travel is 6 1/4"
The Z axis travel is 2 1/4"

If there are any questions about any of the drawings or something just doesn't make sense just ask! You can download larger images so the drawings will be much easier to read- just click on the "i" symbol in the upper left corner. I just added an exploded view sketch that helps show how all the parts fit together.

Follow along and build one for yourself!

 
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Step 1Tools and materials

Tools and materials
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Tools used:

table saw (a miter saw would also work -they tend to be more accurate for precise cuts)
drill press
router w/ 1/2" straight cutter- needs to be mounted in a router table
jigsaw (or band saw if you're lucky enough to have access to one)
cordless drill
bench plane
bench vise
level
hack saw
assorted files (for cleaning up rough edges)
tap and tap handle ( I used a 4mm x .7 tap because I used metric screws but you could also use an 8-32 tap if you want to use 8-32 screws)
#10 countersink bit
wood glue
bar clamps
1 1/4" Forstner bit
5/16" Forstner bit (used for counterbores for 4mm bolts)

Materials/cut list:

3/4" thick Birch plywood was used for the following pieces-
11" x 18" -base plate
12" x 4" -Y axis base plate
8" x 4" -Z axis base plate
6" x 2 3/4" - motor mount base
12" x 9" (make four of these) -for the mill column
2 1/2" x 1 7/8" (make three of these) -for the anti backlash screw blocks

3/4" thick MDF (medium density fiberboard) was used for the following pieces-
6" x 6"- mill table
3 7/8" x 1" (make six of these) -rail end blocks

Aluminum channel- 57/64" x 9/16" x 1/16" wall thickness:
12" long (make four) -X and Y axis rails
8" long (make two) -Z axis rails

3/8" thick Delrin was used for the following pieces (Delrin can be purchased from Colorado Plastics):
4" x 3 7/8" (make three of these) -slides
2 1/2" x 3/4" (make three of these) - handles
3 1/2" x 3/4" (make six of these) -slide retainers

5/16" round Aluminum rod:
1 1/2" long (make three) -handles

1/4" round Aluminum rod:
3/4" long (make six) -inserts for anti backlash blocks

1/4"-16 ACME threaded rod: available from McMaster-Carr part#98935A803
12 3/4" long (make two) -X and Y axis lead screws
8 3/4" long -Z axis lead screw

6 each 1/4"-16 ACME nuts -for anti backlash screw blocks (McMaster part#94815A007)
3 each 1/2" diameter 1 1/4" long compression spring -for anti backlash screw blocks
3 each 1/4" locking collars -these help hold the ACME screw rod in place (McMaster part# 6432K12)
6 each 1/4" bronze flanged bushings (these fit a 1/4" shaft and fit into a 3/8" bore) -for the rail end blocks (McMaster part#6338K451)
3 each 1/4" washers (just about any thickness will do) -these are spacers for the handles

3/4" wide Aluminum or brass plate (1/16" thick):
1 7/8" long (make three) -for anti backlash ACME screw retaining plates

1 3/4" (45mm) long bolts w/ washers and nuts:
12 each- I used 4mm hex head bolts for all the bolts but 8-32 bolts will also work
-these go on the ends of the Aluminum channel rails

1" (25mm) long bolts w/ washers and nuts:
4 each- 4mm
-these go in the middle position of the x and Z axis Aluminum channel rails

3/4" (20mm) long bolts:
38 each- 4mm

6 each 4mm x 1/4" (7mm) long set screws -for the handles

8 each 2" long wood screws -for securing the mill column to the base plate and the Z axis base plate

1/2" diameter wood dowel:
4 each 3" long -inserts for mill column
6 each 3/4" long -inserts for rail end blocks

For the motor assembly/spindle I used a 12v electric motor salvaged form my junk box along with a Foredom #44 handpiece. The #44 uses 1/16", 3/32", 1/8" and 1/4" collets (it's also available in metric) so it fits a wide variety of cutting tools. I also have a #30 handpiece which has a standard drill chuck. Both are extremely durable and are very quiet. You could also use a standard Dremel tool if you want an all in one solution.

For the CNC conversion:

6 each 2 1/2" x 2/12" x 3/4" thick Birch plywood pieces -for stepper motor mounts
3 each stepper motors
3 each motor couplers -I made mine myself from old parts I got from a display but the ones I've linked to are identical
12 each #10 1" long wood screws
6 each #10 2" long wood screws
7/8" Forstner bit
CNC stepper motor controller- the HobbyCNC or Linistepper would be my choice

Some notes about using a router table and drilling holes for screws:

When using a router table you always want to cut in a certain direction- the cutting bit should try to force your work into the fence (see drawing.) If you move your work in the opposite direction, the bit will pull your work away from the fence and it will be difficult to get a precise cut.

On many of the drawings I specify a countersink or a counterbore. A counterbore has a flat bottom (it's best cut with a Forstner bit or end mill) and is meant for flat bottomed screws. A countersink is for flush mounting screws with a tapered head, like most wood screws. The other important thing is to always drill a pilot hole first, then a clearance hole and then the counterbore or countersink. If you don't drill a proper clearance hole, the screw will try separate the two parts you're trying to screw together. It'll also make it difficult when cutting threads for machine screws- see the drawing below.

SAFETY NOTE:
Please use care and good judgment when operating power tools. Always keep fingers well away from cutting tools- use a push stick for cutting thin stock on a table saw and router table. Always wear eye and ear protection and a dust mask- especially when cutting MDF as the dust it produces is pretty nasty stuff.

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201 comments
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Jan 7, 2012. 3:06 AMabo alkader says:
good and useful idea
Dec 24, 2011. 8:23 PMblue_hound says:
Good link for CNC supplies.

http://www.kelinginc.net/
Nov 29, 2011. 6:15 AMblue_hound says:
Cool. I noticed you had issues with accuracy with your build and started a much more expensive one. I was wondering if the slides were where you think yo lost accuracy. I was wondering to make the oversize and shim them to suit while using bolts through the outisde face of the aluminum to maintain the parallel integrity.
Dec 3, 2011. 7:01 AMblue_hound says:
Here are my x & y slides retained on the spacer from the outside. I plan on making my delrin a bit oversize and shimming my rails to suit.
IMG_1357.JPG
Dec 24, 2011. 4:58 PMblue_hound says:
Progress with larger spacers due to my different aluminum C-Channel. Anyone need the old ones?
IMG_1394.JPG
Dec 3, 2011. 7:41 AMblue_hound says:
yes. I have some resources that you don't ; )
Dec 3, 2011. 6:08 PMblue_hound says:
It seems my aluminum c-rails are 1/8" wall thickness instead of the called for 1/16. I am wondering if I need the plywood for the y-axis slide. It seems pretty rigid. I guess the design of the y-axis backlash mechanism would have to change to suit also....hmmmmmmm....
Dec 15, 2011. 10:32 AMblue_hound says:
I see the acem nut is only retained on one side. Is it necessary to make a retainer for the spring side or does the spring tension keep it in tune? thanks in advance.
Nov 29, 2011. 3:33 AMblue_hound says:
Yet another question. I am thinking of using 1/4-20 ACME rod instead of 1/4-16 and was wondering if there was a particular reason you chose the 16. thanks.
Nov 28, 2011. 7:18 PMblue_hound says:
I have a question about the main z-axis laminated base. There seems to be a dimension missing that looks to be about 4" on the left side of the sketch. Does that seem about right. Forgive me in advance if I am wrong and don't see it.......again : )

thanks in advance.
Nov 28, 2011. 7:21 PMblue_hound says:
Yes it is expensive when you buy it from the plastic supply store in london (Canada). I wish that I had checked Forest City surplus first. They have it at a very reasonable price.
Nov 27, 2011. 11:23 AMblue_hound says:
(removed by author or community request)
Nov 4, 2011. 12:11 PMthe_burrito_master says:
3D etchesketch anyone? :D
Nov 2, 2011. 8:07 PMiahmed5 says:
can u plz give the complete details of its working i am a diploma studentt in mechanical engineering and i m thinking of making this as my final year project
Aug 23, 2011. 12:16 AMpheenix42 says:
I applaud you! With some knowledge of foundry, you could cast the column from aluminum or cast iron!
Aug 21, 2011. 4:20 PMElectronics Man says:
I want to make a CNC machine but I cant find the right stepper motors. Can anyone suggest a good size of stepper that I should use? I need one strong enough (duh!) but I dont want to pay the high prices. I want to use this board to control it---> http://www.adafruit.com/products/81
but it only has spots for 2 steppers. I need to come up with an idea for a Z-Axis carrige that uses a servo instead of a stepper motor. Can someone please help me???
Aug 21, 2011. 8:08 PMFlying_MashedPotatoes says:
I suggest the HobbyCNCPro 4 axis board. The board is $100 and is really easy to put together.

When i built my own of this machine, i'm using 3Amp 125oz-in Nema 23 Stepper motors. They are plenty strong enough for this machine.

hope this helps.
Aug 21, 2011. 6:32 PMElectronics Man says:
Your right that board does limit the size of the steppers, but I wanted to control it using my arduino and that is the only board that I can find. Can you suggest another way to control the CNC machine without costing me too much more money? I would still like to use my arduino if possible.

The milling software I want to use is MACH3
found here--> http://www.machsupport.com/

And I wanted to use Goolge Sketchup to make the 3D designs.

Do you think I can use both MACH3 and Goolge Sketchup together? If you have any better suggestions for any other software or a different driver board, I am willing to listen because I am lost right now! :)
Aug 19, 2011. 1:25 AMFlying_MashedPotatoes says:
I finally finished build one! Test cuts: http://www.youtube.com/watch?v=dQQABPbr3Kw&feature=mfu_in_order&list=UL
Aug 6, 2011. 9:20 PMChowmix12 says:
Show us how to build an Eager helper! i would want one of those!
Jul 7, 2011. 10:44 PMFlying_MashedPotatoes says:
After a year of on/off work on this, i've finally finished. One thing i'm wondering is, with my 125oz-in 3Amp Nema23 motors, will i have to worry about the amount of friction between the axis sliders and aluminum channel?
May 31, 2011. 11:25 PMluisma.suarez says:
hi! can you please recommend a healthy torque rating for the motors?
i plan on doing PCBs, no sculpting, not yet anyways.
im looking at 2 and 13 oz-in motors
i know you can't say exactly, but on average? is the 2 oz-in too weak?
thanks.

May 11, 2011. 8:11 PMoneaze says:
would worm gear motors from a junkyard 80-90's cadillac or gm vehicle be a good z axis motor?
Apr 29, 2011. 3:54 AMcolincolin30 says:
Hi, I have built a CNC mill but find that the 4 wire stepper motors do not have much "grunt" i powered the drive boards by a 12 volt gel cell but it did not seem to have much curerent. What was the power supply arrangements for your CNC rig, volts and current

regards
Colin
Sydney Australia
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