Cheapish CNC machine
 

Does there exist a cnc machine under 2000 dollars that has a reasonable working bed.

Re: Cheapish CNC machine
 

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.

Re: Cheapish CNC machine
 

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.


http://www.taigtools.com/cmill.html


http://www.ebay.com/sch/i.html?_from...+mill&_sacat=0

Re: Cheapish CNC machine
 

Absolutely:

You did not say that does not read punch tape or punch cards :D

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.

Re: Cheapish CNC machine
 

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"

Re: Cheapish CNC machine
 

Do you have any personal experience with the x-carve?

Re: Cheapish CNC machine
 

I love my X-Carve. It's real good with wood and polycarb but not real good for aluminum.

Re: Cheapish CNC machine
 

the x-carve website says it can handle alminum just as well... what's wrong with it?

Re: Cheapish CNC machine
 

"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.

Re: Cheapish CNC machine
 

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.

Re: Cheapish CNC machine
 

Note, a default X-carve has trouble milling aluminum. Really nice for wood and plastic though.

*RIP others said it first

Re: Cheapish CNC machine
 

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.

Re: Cheapish CNC machine
 

I built this machine for about 500$ USD (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 cut this 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.

Re: Cheapish CNC machine
 

That looks really good! Any chance we can get some plans?

I've seen Shapeoko 3's out-of-the-box cut aluminum, albeit slowly.

Re: Cheapish CNC machine
 

Could you share a bit more about how you made this machine. That is gorgeous and the price is a gamechanger.

Re: Cheapish CNC machine
 

I would love it, if you are capable of sharing the plans for this. The 500 dollar price range is insane

Re: Cheapish CNC machine
 

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.

Re: Cheapish CNC machine
 

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

Re: Cheapish CNC machine
 

ACME screws or standard threaded rod?
What kind of accuracy and repeatability are you getting?

Re: Cheapish CNC machine
 

I bought the steppers for $3.50 each and the drivers + CNC shield+ Arduino was another 20$. The frame was about 280$ including ball screws and linear rails. Shipping accounted for about 1/4 of the cost of the machine.

Re: Cheapish CNC machine
 

Ball Screws :D, I wouldn't settle for anything less. I haven't tuned the machine yet but the tolerances are higher than my chinese digital caliper can read (perfectly acceptable for FRC use)

Re: Cheapish CNC machine
 

You sir, are a master

Re: Cheapish CNC machine
 

Our team will do anything, to have access to something like this. There have been several situation this past season where a cnc machine would have been a god send.

Re: Cheapish CNC machine
 

I have a cheap Chinese CNC router from Ebay at home. The electronics were done poorly and we had to re-work the stepper controllers, but mechanically, it is a fairly good machine. We use these router bits for aluminum and have had great results. They cut much cleaner and faster than a standard end mill, but still are not fast.

Re: Cheapish CNC machine
 

Very nice! Will look forward to the build log. I do not know of any sources for good multi-turn ball screws and ball anti-backlash nuts in a price range like that. Usually they resort to threaded rod or nylon blocks heated then pressed and sooner or later that bites you from wear.

Kind of suspect your CNC shield is a RAMPS 1.4?

Re: Cheapish CNC machine
 

Thanks for the advice, will keep it in mind if and when we hopefully get a cnc router :P

Re: Cheapish CNC machine
 

What are the differences between an x-carve and a shapeko3? The shapeko 3 website shows videos of it milling into aluminum pretty easily....

Re: Cheapish CNC machine
 

A couple of things to note video is terrible at showing:
Accuracy, repeatability and grade of aluminium.

I have no doubt you can force aluminum into a drill press with an X/Y table as well and it will cut. Eventually the drill press will fail from that but I know folks do it. Some even toss the drill presses and replace them because the presses are -that- cheap they are literally disposable.

Re: Cheapish CNC machine
 

We actually used the X-Carve to machine our practice robot this year and it did a pretty good job. We put a LOT of work into learning how to properly use CAM software and feeds/speeds but eventually we found the sweet spot for both 5052 and 6061 with our setup. We machined our bellypan, chassis rails, superstructure gussets, and shooter components from components .050" to .1875" thick. You definitely will have better luck with with an actual CNC mill, but for a router, the X-Carve (with mods) can take you just about as far as you are willing to put into it.

Re: Cheapish CNC machine
 

What is the thickest block of aluminum do you think it can work with? (just wondering about the height of the z axis)

Re: Cheapish CNC machine
 

You can get about 2.25" of max height if you:

• Use the stock wasteboard
• Use the stock z-height plates

If you make your own brackets or sink a hole into the wasteboard, you can get a theoretical maximum of about 5-6". There's guides on youtube; it is opensource after all.

Re: Cheapish CNC machine
 

Cool. What bits did you guys use?

Re: Cheapish CNC machine
 

These work wonders Carbide 3 flute with a special coating, $15-12 for the 1/8 and around $20-25 for the 1/4.

The seller, drillman, has great deals on some high quality bits; I recommend you read some of the FAQs about the Destiny line as it has a unique coating that more or less saves you from getting the bit stuck in 5052 and gooey materials.

Re: Cheapish CNC machine
 

GOFIRST is currently looking at getting a Routakit CNC router. Even with some upgrades, it comes out around $2000 if you get a standard version. Specifically we're looking at getting the SD with the SDX upgrade kit and improved spindle. It looks like a pretty solid machine, and they have a pretty cool forum post documenting the process of designing their first one (I think it's somewhere in the Shapeoko forums but can't find it right now). They're also super nice and responsive-- I've emailed them a few times with questions and am really hoping it makes sense for us to get one.

Re: Cheapish CNC machine
 

why is routakit better than xcarver or shapeko3?

Re: Cheapish CNC machine
 

I'd be interested to hear what settings, speeds/feeds you used. I really couldn't get the one I had access to for a short while to do that much with with aluminum. I used Autodesk 360 to do my CAM and my guess is that I had some depth/plunge and speed/feed rates wrong.

Re: Cheapish CNC machine
 

Take a look at the construction and specs:

X-Carve:
DeWalt DW611 Router (or choice)
140 oz-in NEMA 23 steppers (or 60 oz-in NEMA 17 steppers)
Arduino with g-shield
Lead Screw or Threaded Rod z-axis
Max 31" x 31" x 2.55" work area
0.075-0.13 mm resolution
GT2 belts (pitch not specified, assumed 2mm)
~$1400 fully loaded

Shapeoko 3:
Router not included (DW611 recommended)
120 oz-in NEMA 23 steppers
Proprietary electronics
Belt-driven Z-axis
Max 16" x 16" x 3" work area
No apparent claims on resolution/accuracy
GT2 2mm pitch belts
$999

Routakit SD (no upgrades):
600W spindle
175 oz-in NEMA 23 steppers
PlanetCNC controller (which one not specified on page)
Ball Screw z-axis
Max 59.1" x 59.1" x 4" work area (30" x 30" x 4" default)
Repeatability 0.025 - 0.05 mm
Accuracy +/- 0.127 mm
9mm wide, 3mm pitch GT2 belting
$1799

Routakit SDX (what GOFIRST is looking at)
1500W spindle
30" x 15" x 4" work area
SDX upgrade for greater rigidity
$2179

We're looking at it for somewhat similar uses to what I expect a team would want-- the most intense thing we expect to cut is maybe occasional 1/4" aluminum, but mostly 1/8" or polycarbonate. I haven't heard good things about cutting aluminum on an X-carve, and the Shapeoko doesn't have the work area we want. It might not be the right option for someone else, but it seems to be the closest to right for us, given our budget, without spending a lot of time designing our own (and, to be honest, we're probably going to mod the crap out of anything we get anyways, because we're all tinkerers).

Re: Cheapish CNC machine
 

Course you might not be able actually get those mechanical results without electronics that insure at full step enough power is supplied. Once you microstep all bets are off.

If 750W is about 1HP.
A 1500W spindle is 2HP.

Now the important questions about the spindle are:
1. At what RPM is maximum mechanical power output? Does the motor driver effect that?
2. Is that RPM a good match for the feed rates these NEMA23 steppers can deliver and honestly the answer in all 3 cases is likely no.
So the quality of cut and the tool life will diminish. Though obviously the results can always be good enough and someone could always get more tools.

Re: Cheapish CNC machine
 

I purchased a bare bones X-Carve 500mm last December for the team. Several of the parts and electronics were purchased separately. Total cost to put the machine in service about 690.00$. A stock X-carve will cut 6061-T6. However, it is not acceptable from a precision and speed perspective. The main problem is x and z axis torsional stiffness. I modded the x axis maker slide with a 40 x 4 500 mm Al plate to tie the 2 maker slides together. The torsional problem did not go away until I replaced the Delrin wheels with metal wheels. The machine can now cut with reasonable speed and precision, but not like a 12000$ commercial unit. It has been a great addition to the team and made many parts on our 2 robots. I should mention that about 1/2 the parts cut were 7075. With all the mods 7075 is not a problem. Stock it is. Looking back I could have built a better machine for the same money. However designing a machine from scratch takes allot of knowledge that I did not have last December. Be careful of the eBay Chinese stuff. Some of it is good and some terrible. Yes, a sub 1000$ router can be a great addition to a team. One thing I should note is that 1 requirement for our router was that it had to be portable. We do not have room for a permanent set up. The 500mm x-carve fits this requirement.

Re: Cheapish CNC machine
 

Has anyone worked with a router from Probotix? They seem to be significantly more rigid than most. They additionally use screw drives instead of belts.

http://www.probotix.com/ASTEROID-CNC-ROUTER

Re: Cheapish CNC machine
 

Delrin anti-backlash nuts will wear faster than ball nuts or ACME spring nuts.
Not an issue, unless you don't check your run-out till you start ruining work pieces.

Re: Cheapish CNC machine
 

Another key aspect I failed to mention was the frame construction, which impacts pretty much everything. Routers are a complicated thing.

There's also a major difference between using a standard woodworking router or an industrial spindle. The ShopBot FAQ has a good explanation of this.

Re: Cheapish CNC machine
 

Yeah, the description of the machine says just that. I figure I could replace them with a better nut.

Re: Cheapish CNC machine
 

Take a look at what Brandon Satterfield is doing at http://www.smw3d.com. I built an OX using his kit of parts and the quality is outstanding. He also has some ther devices that are more comfortable with aluminum.
Plus, he supports FIRST teams with a discount.

Re: Cheapish CNC machine
 

We've had pretty good experiences with our X-Carve, as others have said it's great for wood and polycarbonate, but you have to take it slow with aluminum (and use cutting fluid).

Really it all depends on what you want to build. In our case we built our chassis out of 3/8" polycarbonate so using it to cut our chassis side panels is no problem, and the tolerances are more than enough if you're building a chain drive; however when we cut some custom 1/8" aluminum gearbox mounting plates for our 3-CIM Ball shifters, we had to intentionally undersize the holes and then finish them on our Bridgeport CNCs.

Basically our X-Carve is pretty good at positioning accurately, but not great at making round pockets consistently. If all you were doing was drilling straight holes and not doing any pockets, you could likely do it all day long and not have any issues with accuracy.

I don't think I would try to build an entire robot out of aluminum using an X-Carve, but using it for mostly polycarbonate parts with only a few, small aluminum pieces is certainly doable.

One thing to note for these machines is that you either have to babysit them with a vacuum or construct some sort of dust collector for it, because even the slightest bit of material flying off the part can get lodged between the tracks and the wheels and throw off the positioning of the entire unit, ruining the part. If you wanted to get really creative, adding a closed-loop control system to it would also solve the problem, and improve accuracy.

Re: Cheapish CNC machine
 

The frame looks very similar to the common chinese 3040 CNC router/mill you can find on eBay. I too would be very interested in plans/sources for the frame parts. I can't wait for the build log!