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

 by Honus
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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 1: Tools and materials

100_0984.jpg
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.

1-40 of 213Next »
mambre says: Nov 27, 2012. 2:58 AM
Can u please tell me the spindle's minimum requirements for milling jewelry wax? I am building a cnc router for making master models from wax. The motor is 50watts 2500rpm 220volts. You have used 12v motor, how many watts is it and amperage?
Honus (author) in reply to mambreNov 27, 2012. 7:21 PM
I no longer have that motor since I am building a new machine. 50 watts@2500 rpm sounds pretty low unless you are using a very small cutter at high rpm. The problem with using very small cutters at high rpm is vibration- minimizing vibration in the spindle is very important.

Have a look at this thread for building a low cost variable speed spindle using a RC brushless motor-
http://www.rcgroups.com/forums/showthread.php?t=1175772&page=2
savant77 says: Dec 5, 2010. 8:12 PM
Awesome mill Honus! Did you figure out how accurate it turned out to be? I imagine it is only as accurate as the tools you used to build it with. I already have a tabletop manual mill, now you gave me the idea to try and make it a cnc mill for easy operation. Thanks so much for taking the time to document this for the community.
Honus (author) in reply to savant77Dec 6, 2010. 9:41 PM
After trying to mill circuit boards I just wasn't satisfied with the results so I started building a new CNC that is much more rigid- plus it will print 3D parts as well.
MultiBotChassis1.jpg
dougrike in reply to HonusNov 20, 2012. 6:24 AM
What are the dimensions of the extruded aluminum?
Honus (author) in reply to dougrikeNov 20, 2012. 9:15 PM
The extrusions measure 1"x3" and 2"x4". I really need to get going on this again...
nduetime in reply to HonusJun 27, 2012. 12:04 AM
Any instructable on this?
Honus (author) in reply to nduetimeJun 27, 2012. 4:58 AM
No yet- I'm still working on it.
hightekrednek2396 in reply to HonusMar 19, 2011. 2:43 PM
how much did the linear rails cost
Honus (author) in reply to hightekrednek2396Mar 19, 2011. 2:54 PM
I don't remember the exact amount since I got them a year ago but I think they were around $600.
tissit says: Oct 30, 2012. 4:39 AM
The word is "Torx". :)
Honus (author) in reply to tissitOct 30, 2012. 7:00 AM
Yes- but most every wood screw company labels them as "Star" drive screws- I didn't want people saying "I can't find Torx screws- I can only find Star screws." LOL!
EngineerJakit says: Apr 27, 2012. 10:09 PM
I recently obtained two small motors from a vacuum cleaner. one is about the size of a roll of Kodak film, the other is larger than a film canister. This also came with a 6V power supply. Seeing as how the vacuum cleaner didn't do well after years of use, could i use the motors for making my own mill or lathe? or maybe some other tools?
Honus (author) in reply to EngineerJakitApr 28, 2012. 6:39 AM
I honestly have no idea. Without having some specs on the motors it's impossible to say.
sixth89 says: Feb 19, 2012. 12:39 AM
can u teach me how to program..?
Honus (author) in reply to sixth89Feb 19, 2012. 11:36 AM
Sorry but I can't. You might have a look at CNCzone.com.
abo alkader says: Jan 7, 2012. 3:06 AM
good and useful idea
blue_hound says: Dec 24, 2011. 8:23 PM
Good link for CNC supplies.

http://www.kelinginc.net/
blue_hound says: Nov 29, 2011. 6:15 AM
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.
blue_hound in reply to blue_houndDec 3, 2011. 7:01 AM
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
blue_hound in reply to blue_houndDec 24, 2011. 4:58 PM
Progress with larger spacers due to my different aluminum C-Channel. Anyone need the old ones?
IMG_1394.JPG
Honus (author) in reply to blue_houndDec 3, 2011. 7:28 AM
That looks great! Are the spacers Aluminum?
blue_hound in reply to HonusDec 3, 2011. 7:41 AM
yes. I have some resources that you don't ; )
blue_hound in reply to blue_houndDec 3, 2011. 6:08 PM
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....
Honus (author) in reply to blue_houndDec 3, 2011. 6:27 PM
It probably won't be rigid enough without a base for the Y axis and the slide will bind under load. One thing you could do about the backlash mechanism is to use Delrin nuts for the lead screws instead as they take up a lot less space. Dumpster CNC sells them-
http://www.dumpstercnc.com/
Honus (author) in reply to blue_houndNov 29, 2011. 10:47 AM
It actually had more to do with rigidity and vibration- that's why the new machine build is all aluminum and uses very rigid slides. The most difficult thing with this build is making sure the slides don't have any slop in them while still being able to slide with as little resistance as possible.
blue_hound says: Dec 15, 2011. 10:32 AM
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.
Honus (author) in reply to blue_houndDec 15, 2011. 11:15 AM
The spring tension keeps in place- it can't rotate in the slot.
blue_hound says: Nov 29, 2011. 3:33 AM
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.
Honus (author) in reply to blue_houndNov 29, 2011. 5:39 AM
It's just what I found locally.
blue_hound says: Nov 28, 2011. 7:18 PM
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.
Honus (author) in reply to blue_houndNov 28, 2011. 8:04 PM
You are correct- it should be 4" long. I had to go back and look at how the Z axis is constructed to make sure (the mounting screws are 2" apart.) I also found a couple of other errors that I needed to fix. I'll make a note on the drawing- thanks! :)
Honus (author) says: Nov 27, 2011. 2:38 PM
No problem- I would have felt terrible if I told you to buy the wrong size material. Delrin is expensive stuff!
blue_hound in reply to HonusNov 28, 2011. 7:21 PM
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.
blue_hound says: Nov 27, 2011. 11:23 AM
(removed by author or community request)
Honus (author) in reply to blue_houndNov 27, 2011. 11:53 AM
The slides, slide retainers and handles were all made from 3/8" thick Delrin. Those are the only Delrin pieces so what am I missing?
the_burrito_master says: Nov 4, 2011. 12:11 PM
3D etchesketch anyone? :D
iahmed5 says: Nov 2, 2011. 8:07 PM
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
Honus (author) in reply to iahmed5Nov 2, 2011. 8:48 PM
All of the information necessary is presented in the instructable. Is there a specific question you have?
pheenix42 says: Aug 23, 2011. 12:16 AM
I applaud you! With some knowledge of foundry, you could cast the column from aluminum or cast iron!
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