Does there exist a cnc machine under 2000 dollars that has a reasonable working bed.
Do you have any machining companies nearby? Sometimes it is less expensive for a company to donate an old CNC to a FRC team than it is to dispose of it. FIKE Corporation in Kansas City did just that for us between the 2011 and 2012 seasons.
I don’t have one, but I’ve watched Taig CNC mills on ebay for years. New they’re a little more than your budget ($2500), but used they’re sometimes pretty low priced.
They’re really small, essentially a jewelry mill, but most stuff on a robot isn’t so big.
You’ll need the right computer to go with and software and tooling, but I’d consider this.
You can also buy the mill with manual cranks then upgrade to CNC later, to spread the budget out.
Absolutely:
You did not say that does not read punch tape or punch cards 
My MaxNC 10 was < $2,000 used with software and some tools.
My MaxNC 15 was < $2,000 used with software and some tools.
My MaxNC T2 was < $2,000 used with software and some tools.
My CNC retrofitted Sieg X2 with Freak mods from Hoss was < $2,000 with no tools at all.
My manual ShopMaster 2000 with CNC plates ready to be populated was < $2,000 in 2004 with a box of rusty tooling.
If you watch long enough you’ll no doubt find a Bridgeport or clone that has a retrofit but again you might find yourself with a 19" computer rack and it may read punch tapes or punch cards.
To put this simply: G-code is older than you high school kids.
If you can find some used X/Y/Z tables with steppers you make a CNC very easily.
For less than $2,000 you can purchase a fully loaded CNC Router, X-Carve by INVENTABLES. It comes with the basic tools to get going on machining, what some might see as a down side is that you have to assemble and wire it yourself.
Other than that it seems like fine router for the budget.
subtotal:$1,399.90
shipping cost: $228.61
Grand Total: $1,628.51
Edit: Build Area is 1000m x 1000m | 39.4" x 39.4"
Do you have any personal experience with the x-carve?
I love my X-Carve. It’s real good with wood and polycarb but not real good for aluminum.
the x-carve website says it can handle alminum just as well… what’s wrong with it?
“handle aluminum” is relative. To put it simply, it is not a mill.
Using a light-duty router to cut aluminum is similar to using a small hammer to break up a sidewalk: It’ll work, Be careful to take it easy and you won’t damage the hammer, but it’ll take a long time.
Exactly, engraving AI is OK but any serious work requires slow feed rates, shallow cuts and lots of oil. It takes a couple hours for even a small bracket.
Note, a default X-carve has trouble milling aluminum. Really nice for wood and plastic though.
*RIP others said it first
Cheap CNC milling/engraving machines tend towards open loop steppers.
Steppers deliver maximum torque near the lowest RPM.
If you go too fast you miss a step and then your computer can not see that and everything gets offset till you ruin the work.
Mind you 3D printers and plasma tables use these same motors but the forces acting against movement are magnitudes less.
MaxNC put encoders on their closed loop axis steppers.
If they miss a step they try 8 times then give up and stop.
Servos with DC brush motors are available but add to the machine cost quickly.
IMSRV makes a Globe motor reduction to bolt on in place of a NEMA23 stepper.
At the cost of a new control and a few hundred an axis.
Really good machines use brushless AC motors for the servos.
Rigidity comes into play. As you push tools into the aluminum it ‘pushes back’. A frame rigid enough for wood or plastic may not be rigid enough to push into aluminum without deflecting making the cuts worse or breaking tools.
Even my MaxNC uses a Taig spindle. That spindle is turned by a Baldor Universal AC/DC motor and maxes out at 3,000RPM. There is a single stage reduction. I could go faster but my steppers can not provide the force to move to match the spindle speed.
If you must run a high speed palm router for wood you can get a SuperPID that will slow it down so you do not rub the cutter. However you give up some HP in the trade. Good spindles are closed loop and will hold RPM even under cutting load.
By the time you optimize that X-Carve you are over $2,000.
Someday I want to take FRC parts and make a router suitable to build FRC robots.
Probably have to float a battery to handle the low voltage CIMs but it could be done.
(https://lh3.googleusercontent.com/TkRjsJpCAiUsG4bRvcNfkmtBscLQ3vxEY9ekDYJZnw-gkjXDj2X0bQRprvMklfrZ1qRadFljXa8BZk-GSmY2LKp0qrKm9BMZiJcGt24rrBhxAplsDaJXf8B3_aUBouRGTqAbhkE-YeZwtb0lXicx6R6skC6tcc2td7gYMLt5fIc0SFm-I3cKcZSvMK794AI8Ewrbrou6_ccQEW1UgxKENdbb6jTw7vqNSBhTBfhNI5p2MFvcKly_lgVrIhO-EyhSpIIW-zEDfGVsw-yrkEmOp462oye5QZC4-KoTO-65Sp_ggGFKNb1ROEja9yaVHYRX0tkAgz1pRcDsBzUcyaUzx0k8AsR4w7ei2SRVLwnYuz_7gzv6b_CsT2Q5lzW1DT7b_4h7SLha6QgsVGvNE1N3DVDj_RuULRxm4f7Vd-KyBkwWm8LZm7zTtbendKWZhl5sxctNiFvn8_IS0BzMZ5YdbCJ6erelYfhQFk0ueGra58G45tChz3mb_PAq4SZag1RU1WJhrWgTVIFdPZGTcwze5un4AxpzrZg60cOeARyld-vDCDw4XQnLPgnDDZHTmMP85nKb=w1306-h979-no) (I haven’t built the enclosure yet so it’s a bit of mess). It cuts aluminium better than X-Carve or Shapeoko IMO, I can fairly easily do 1/16 DOC at 15 IPM with a 1/8 Carbide single flute end mill. I cutthis sprocket on it in about 15 minutes. It’s definitely not something I’d recommend to someone new to CNC machining but a practical machine for aluminium can be made for well under the price of an X-Carve.
At $25 a stepper plus say $30 bucks an amp.
That is about $150 to get controls alone unless you salvaged.
I assume $500 is the machine itself?
Prusa 3D printers are in this price range now at not nearly that build quality.
Thanks, I’m planning on writing a build log about it soon. The only thing that is custom on the machine is the spindle but that could be made on a drill press if need be. To keep the costs down I imported almost all of the parts directly from China
ACME screws or standard threaded rod?
What kind of accuracy and repeatability are you getting?
I bought the steppers for $3.50 each and thedrivers + CNC shield+ Arduino was another 20$. The frame was about 280$ including ball screws and linear rails. Shipping accounted for about 1/4 of the cost of the machine.