CNC Router vs 3D Printer
 

For several months I have been considering purchasing either a CNC Router or a 3D printer. I have been doing research into both categories, and wanted some help making final decisions. Currently, I am leaning towards a 3D printer, but the right router could sway me. I'll first outline my use case, design requirements, and similar info to ensure that we're all on the same page. Sorry in advance for the long post…

Use Case:
At this point, I envision myself using the device as a tool for personal and school projects (I'm a junior in college), as well as possibly for FRC. I would like a personal router or printer as opposed to using the tools at my college's machine shop because I would like to have unfettered access. That is, I want to be able to use it for projects outside of classes without having my motives questioned, so to speak.

General Requirements:
The requirements of course differ for each machine, but a few are shared. First, my max price is $4000, but I would prefer to keep it in the $2000 to $2500 range. Second, because I want to use these for projects and not have the tool be the project in and of itself, I would prefer to use a well-developed kit or a turnkey system.

Machine specific info:
CNC Router:
Minimum area of 2x3 feet, would primarily be cutting aluminum sheet/plate.
I have currently priced out two options, details for which can be found in the attached Excel document. My main concern with a router is both size and mess: as a college student, I don’t have too much room to store a router, and machining would create messes that are potentially hard to contain and clean up. This is the primary reason I am leaning towards a 3D printer at this point.

3D Printer:
The primary requirement here is material strength. Again, I want to be able to use the parts it produces for projects, not just for pretty models. I have experience with the Dimension/Stratasys uPrint SE and found that it produces very durable parts (made a decent number for my team’s robot my last year as an FRC student). After this, my priorities are build area then surface finish.
After doing some research, I have been considering the Makerbot Replicator 2 and 2X and the Solidoodle 3rd Generation printers. This is a website that has aggregated information about 3D printers that I found very helpful. If you have experience with any of these, I would love hearing about it. Also, if you would suggest a different printer model, I would also be interested.

Well, that’s it. That’s what I have in mind at this point.
Thanks in advance for all the help!

Re: CNC Router vs 3D Printer
 

The budget doesn't leave you a lot of options. It really depends on the type of work you plan to do. I have access to both, and the router sees far more practical use, however, I'm not a fan of doing aluminum on a router. It's a real mess, and painfully slow compared to a mill with rigidity, horsepower, and flood coolant.

Re: CNC Router vs 3D Printer
 

Still a very useful machine. We did all of our gussets and a good deal of large plates on our 2012 bot on it.

For the 2013 bot we did all our gussets, and nearly all of our tubing.

It's a workhorse in our shop, certainly orders of magnitude more useful than a 3d printer.

Re: CNC Router vs 3D Printer
 

I'd agree with Adam, if you're interested in making stuff that's more versatile, go with a router.

At least at this point in their development, most 3D printing systems don't produce parts that are very strong at all. Sure, they do require little human input once they're running, but they're slow and I would not trust any of their parts structurally. If you like making little plastic parts to show concepts or as models or something, go with a 3D printer. Otherwise, a router is the way to go. In my experience, you can make basically everything you'll need for macro scale personal projects and for FRC on a 2.5 axis CNC machine like a router.

Lots of people are making a huge deal out of the "3D printing revolution," but the truth of the matter is 3D printers are only good for very small run, complex, non structural plastic parts, like trial electronics cases or miniature sculptures. There will be no real manufacturing revolution (as some reporters and politicians are hoping for) unless 3D printers start printing much more durable materials, become much much faster, or become able to print electronics as well as plastic materials. For the moment though, I'd prefer using a subtractive CNC tool (like a router) any day of the week.

Re: CNC Router vs 3D Printer
 

You're not really up on what 3D printing is currently used for in the real world, are you?

First, let me set something straight: "3D printing" can refer to any one of 5 processes. Yes, 5--FDM, SLS, DLD, ULA, and Objet are the acronyms. At least 2 of those 5 can print metal--I've seen them, I've handled the parts they've produced (Selective Laser Sintering and Direct Laser Deposition). 4/5 processes have very expensive machines, think 6-7 figures for the price tag, per machine. I know for a fact that at least a couple of those 4 can produce parts that will take anything you can reasonably throw at them--otherwise, the aerospace industry would throw them out and do something else. It might take a couple of days or so--but if you're comparing to several weeks, the 3D printer is downright fast--and it can do some things that would be VERY difficult to do on any other machine. (Trust me, I walk by my company's SLS unit every day--it's got some fun stuff in the window, but the machinists would freak out if it was handed to them to build.)

What you're talking about is one specific type of 3D printing. The 5th process won't work with metal, but because it doesn't use a laser (the other 4 do) it can be made relatively cheaply and sold to just about anybody. This process, which is known as FDM (Fused Deposition Molding, or something of that nature), is what most people will think of when you mention a 3D printer. It's basically a hot glue gun, only with plastic.

This process is, shall we say, under iteration. The thing about most of the users, at least of the RepRap model types, is that they will monkey around with build parameters if they can to get the best result they can. Some companies are playing around with different materials to see if they can get something better than current. I've seen several robot teams with 3D printed parts--I believe 207 printed wheels for their robot a year or two ago, with excellent results, though I don't recall what process they used.


Now, I haven't played around with any CNC routers. I have played around with 3D printers. If I was looking for a large build area, I'd pick up an inDimension3 Glacier Steel unit (if they happened to be available--they're currently out of stock), partly due to the 12" square build area (they can go bigger, but that goes out of your budget) and partly because the company is experimenting with better materials. (And partly because they're a new incarnation of a company I've dealt with for 3D printers in the past with excellent service.)

Re: CNC Router vs 3D Printer
 

You're right, I was referring to that type of 3D printing. We've got an early model MakerBot, and I've played around with parts off other machines too. That process in specific is very weak in my experience, because you're left with a bunch of layers weakly joined together, like a wood grain. We've made a few sensor mounts and stuff like that, but they're fairly inaccurate and shatter into layers very easily. As far as I know, there's no 3D printer within an average teams budget that doesn't use this process, so my comments were mainly in regard to printers of that type.

I've also gotten some stuff printed online through an SLS process, and it was quite weak too. Instead of layers being fused together, it was grains. I was very pleased though with a part I ordered cast in silver from a 3D printed mold (of course, I can't think of any reason a team would need to make something like that). I've never handled metal SLS parts, but I'd imagine that they'd suffer from weakness in the same way that SLS plastics would, because they're still composed of fused grains.

I have heard hype about 3D printed titanium or aluminum through SLS, but for the moment I'm inclined to believe that this is has yet to break though to traditional manufacturing or even mainstream prototyping. We're certainly not 3D printing replacement car parts yet. I'm very interested to hear that aerospace companies are making parts through SLS, but I suppose that with the kind of performance they'd require, they could afford to be an early adopter.

Maybe by the time I'm out of college, well be seeing cheap metal 3D printers in the wild. At that point, I'd become very interested. However, I think we're still a little bit before the time when 3D printing can really break through into the mainstream.

Re: CNC Router vs 3D Printer
 

Funny, I've not seen those issues. Maybe you had a bad printer, or a lousy parameter set (the only problems I've seen tended to stem from lousy parameters in the build). Or, as you note, it's an early model and some bugs may not have been worked out.

Yes, they are composed of fused grains. Name a single metal that ISN'T*. Just some are more fused than grains. I'm not an expert in SLS, but there is one who hangs out on Chief Delphi. Suffice it to say that the strength--from what I've seen--is pretty reasonable compared to a solid piece, though certainly not 100%.

Actually, you're right. Most of the manufacturing I've seen, in large scale at least, is DLD, which is a VERY similar process. This includes parts for a Formula SAE car. :D P.S. 3D printing is not traditional manufacturing, by any stretch of the imagination.

Or the amount of time they don't have, or the costs they need to drive down. I've heard that a part that could take months to get done via conventional methods (machining and molding) lost to an SLS part that could be done in a week, mainly because it was needed the previous week.

I doubt that, at least on the metal side. Most of those use a laser. Guess what happens to need a lot of shielding, which costs money? Just something else for someone to work on.


tl;dr: While the layer structure or grain structure may appear weak, it can actually be quite strong if built properly. Proper building may take some time to achieve; once achieved, it should stay that way for a while.


*All metals have a grain structure. Whether you notice it or not is another question. If you go into mechanical engineering as a career, you'll hopefully get a lab on materials which includes looking at grain structures in a microscope. It's quite interesting. Sometimes you can see it in a fractured section of metal.

Re: CNC Router vs 3D Printer
 

His point stands. There is zero practicality in looking at SLS, SLM, or EBM in FRC. You couldn't even afford the powder for one of those machines with the budget OP is looking at.

Sure, it's good for a prospective engineer to understand how those technologies work and the applications they're good for, but FRC isn't one of them.

Re: CNC Router vs 3D Printer
 

I would argue that saying that "most 3D printing systems don't produce parts that are very strong at all" is what most folks would call a "hasty generalization". It's not the same as "most 3D printing systems that would work for FRC don't produce parts that are very strong at all", not by a long shot. It just happens that most, if not all, 3D printing systems that produce strong parts would be illegal for use in FRC--which is another matter entirely. Lumping all 3D printing systems together is like lumping all milling and lathing machines together--and then saying that they're all lousy because you happened to get a cheap mill/lathe combo that broke after the tenth use.



The other factor, as I briefly mentioned in an earlier post, is that there have been FRC teams who used 3D printed parts, of the FDM variety, in high-stress applications. See http://www.chiefdelphi.com/media/photos/38032, which has the machine in question listed in the comments, http://www.chiefdelphi.com/media/photos/38033, and http://www.chiefdelphi.com/media/photos/38034.


Basically, he's taking results from an older-model machine and applying the results to current technology and saying they're the same. I maintain that the results have gotten better, due to the continual development. (This is something that is pretty common across almost all new-ish technology.) Taking a 1st-run RepRap Mendel model and comparing it head-to-head with a 2011 Mendel or some of the spinoff companies' units is apples and oranges and bananas. The printers have improved multiple times. So have the control systems. And the price for something in that range hasn't gone up much if at all.

Re: CNC Router vs 3D Printer
 

I own the following personally:

Heavily modified SoliDoodle 2 ($400) and an Up! 3D printer ($1,600).
A ShopTask Mill/Drill/Lathe with CNC retrofit (my own tinkering).
A small gantry router I cobbled together myself years ago.
Several small X/Y/Z axis robots made from Intelligent Actuator linear systems.
2 LPKF Protomats (older series with paste injectors no auto tool change).

If your goal is to make 'normal' parts out of aluminum you can use the 3D prints to make molds and pour aluminum into the molds. Cast aluminum...real cast aluminum...is quite durable. Though metal forging seems to have made it's way out of most school metal shops Mount Olive High School did have a casting sand forge until it was removed. That forge was used to educate high school students so I know it is age appropriate. I decided to take it upon myself to build my own forge at home. It really is not all that hard to make a standard small forge but it is an art and the tools are not as important as the technique. Luckily I know a very talented metal worker and she has been helping me out. In reality you can liquify aluminum cans on a barbeque just to make ingot. I am constantly tinkering on a vacuum forge as well but for the moment I can only liquify steel in small quantity.

As far as the durability of the 3D prints themselves. I disagree that they themselves are not durable. If you are clever you can make working gears with a 3D printer. There are many restrictions to this but it can be done. I find this device as invaluable as a tool for making oddly shaped parts for brackets and the fella I bought my Up! printer from was a NYC photographer who used it to make crazy mounts for the film industry in his quite normal 8th floor apartment.

The rigidity of most bridge (ShopTask), turret (Bridgeport style) and some knee mills is usually desirable over the gantry when milling aluminum is the core achievement. However the work handling size of a gantry mill makes them a perfect fit for larger and professionally production wise softer pieces. Odds are you wouldn't want a piece of 4'x4' metal sticking out the front and back of your bridge mill on an unsupported keyway so it only makes good sense. Also a grantry mill is a nice gateway to a plasma cutter table or sometimes the other way around. If hot jagged metal everywhere is an issue for you you might consider where you plan on using these tools.

As someone that contributes to the RepRap project and the SoliDoodle if you want something 'out-of-the-box' that just prints you will be spending more than $1,500. If you want something out of the box that could print something really properly high end in the industry right now you'll be spending easily more than $5,000. This is why making firearms on a 3D printer out of: nylon, polycaprolactone or ABS is sort of silly. You could easily buy the firearm for *way* cheaper than the printer most people are designing those plans with. So that is really more FUD than practical application.

I will say that if you want to learn how to build a 3D machine the basics can be learned from a 3D printer kit. You've got: slicing, G-code, M-code, backlash, injection rate, friction and PID loops. All sorts of things you can learn. All sorts of things you will be learning or your print outs will be: warped, twisted, ovoid and otherwise defective. My Up! printer is the sort that 'just works'. I rarely need to do more than level it and keep it in an enclosure I made for it. In fact sometimes I use it to modify my SoliDoodle printer.

Ways to contain the mess from routers and plasma cutters. Plasma cutter slag assuming the actual cutting arc issues are considered and dealt with are sometimes controlled by cutting on a water table. Plasma arcs will easily flash off any water that gets in the way of the torch. So yes you could be pouring 240VAC and 50A into a plasma cutter system with a torch moving above a piece of metal laying in a pool of water. Doesn't that sound comforting? Your work volume is small for your router so may I suggest an enclosure with a shavings tray you can remove at the bottom? Think of it like a bird cage with a metal eating bird.

I am personally quite serious about making plans for a CNC gantry mill with axis driven by FIRST CIM motors in a closed loop and compatible with a PC based CNC control like EMC2 or Mach3. I know it can be done and I intend to do it and produce plans to help others turn their old robot parts into robot making tools. I am not going to commit to an immediate time frame on this. Team 11 just got a Haas mill and for the moment my more immediate goal is to get them going with it and potentially a CNC lathe. If anything I will use the CNC gantry I am constructing right now as a gateway tool for them and potentially a starting reference for what I would like to make.

Re: CNC Router vs 3D Printer
 

What kind of projects do you expect to be working on while you finish up school? Do you usually design more 3D parts than you do 2D (or tubing)?

Hard to weigh in without totally understanding what you want to create for your projects, but for prototypes of mechanical systems, I would think a router would be a good way to go. As we've seen before, you can cut out your own plate sprockets and such, and cutting chips on the router would still be faster than waiting for something to print (usually). Also, don't forget about being able to prototype in plastics and wood! I think the decision also depends on what machine at your school's machine shop is usually more readily available.

Personally, I love FDM printers and have used printed parts on many occasions, and the kids on 11 got to use a few critical printed parts on this year's robot as well. I think our parts were all printed on a Dimension 1200, but I don't recall exactly. The ABS, when printed correctly with the correct parameters, was really great for my applications as well as 11's (gears, spacers, couplers, collars, dog-bone linkage on 11, sensor mounts, etc). Nothing was in high load, just parts that we didn't have time to have sent out for conventional machining, or it was a bit too complex to machine easily.

Just a thought - if you do end up with a CNC router, I would think that modifying a bed and adding a 3D printing head would be a decently easy project for when you have some free time. You could, in the long run, make a hybrid machine with swappable heads, no? Or is that a silly idea? Probably a silly idea :)

Re: CNC Router vs 3D Printer
 

No it is quite doable. Just remember though to add a heated bed to the printer.
Both machines use G-code and M-code. All you need is a head and to list it as the spindle with perhaps a temperature controller which you can get or easily make yourself.

Heated beds are really as easy as a resistor, nichrome wire, or Inconel welding wire. Just put it under the work area with a proper temperature control that you could also use to control the head. An Arduino and temperature sensors like: thermistors, 2N2222 transistors or Dallas Semiconductor temperature sensors is all you need to make a multi-channel temperature controller (you can also buy them off E-Bay). Just make it so you set the temperature from another interface and turn the heaters on and off from the CNC control (this is actually really easy to do). If the entire machine is already enclosed to control swarf the heated bed will work just fine. All the work bed needs to be is a piece of aluminum covered by Kapton sheet or a sheet of glass.

You will want a heated bed for anything larger than 2" on the bed. It will reduce the warping that will start as layers build.

Re: CNC Router vs 3D Printer
 

Your point about the mess and noise of a CNC router - in a college dorm environment - cannot be ignored, and it is not trivial. Plus, CNC routers tend to be heavy, several hundred pounds perhaps.

So simply from a "where can I put/use this thing" point of view, a 3D printer is your better option.

Some different opinions on several 3D printers in your price range: http://kronosrobotics.com/3d/index.shtml

Re: CNC Router vs 3D Printer
 

Assuming you are printing ABS.

OP, I own a Replicator 2X and it has truthfully been a colossal pain in my rear... of course, we own the same one at work and it seems to be configured properly. I think I need to tinker with it more.

For FRC parts, I would agree that the raw printed plastic is simply not strong enough for anything more than sensor mounts. However, if you are not averse to casting some components it should work well for making masters for silicone molds and pouring urethane casts.

Personally, I went with the 3d printer due to the fact that I don't have a garage of any sort at this point in time. If I did I'd probably have gone with a small CNC mill or a mid sized router capable to handling aluminum. In fact, if I ever do get a place with a garage I will most likely be purchasing the router.

Re: CNC Router vs 3D Printer
 

I missed the information about the dorm room.... That's a gamechanger. A router of any real work ability is not happening in a dorm room.

Re: CNC Router vs 3D Printer
 

What is the problem with using school equipment for your own projects? I would think most schools would be ecstatic to have students doing cool stuff with their machinery. At RPI the hand tools were free, and the 3D printers/router/laser/water-jet was available to us at cost, which is stupid cheap compared to buying it yourself. It seems like it might be worth talking to a Dean about student access to machines, because most schools are ecstatic to have students doing their own projects on top of classwork.

Re: CNC Router vs 3D Printer
 

Heated beds also help with PLA. Speaking from experience here, though, a lower temperature helps more with PLA.

Re: CNC Router vs 3D Printer
 

As others have said, a CNC router is going to be a lot more versatile than a 3D printer. However, in a college dorm room, a router is going to be right out. It's going to be loud, heavy, and very messy.

If, for whatever reason you were still interested in a router though, you can build a very nice one on your own for your price range. If you've built FRC robots, you already have 90% of the knowledge required to design and build a CNC router. This fella on youtube is what I always recommend people check out. He built a home CNC router out of 80/20, with great accuracy, and more than enough rigidity to cut aluminum without issue, for I think $2500 or so. He's also mentioned that he's working on a kit version that he will sell if he gets enough interest.

He's got tons of video documentation, as well as a number of videos explaining components that the average person might not be familiar with (Linear guides, ballscrews, etc)

Re: CNC Router vs 3D Printer
 

Our team has a 4' x 8' CNC router, and it is the tool our team uses the most. It's awesome for prototyping, as we can make shooter rails out of plywood or hdpe in less than 10 minutes. If you plan to cut aluminum sheet on it, try to ask the manufacturer/distributor which settings will work the best. You need to find a way to get rid of the chips/cool it/and make sure the feed rate is set correctly. We use the 1/8" mcmaster bits and we use compressed air to make sure the chips don't accumulate. Once you figure out the setup for your machine, you're all set and you don't have to play with it ever again.

We've used 2 3d printers, and while we liked one of them, we didn't think it was that useful. The first one we used was very temperamental, and would often get stuck or make a bad part. The other was significantly more expensive( > $10,000) and we couldn't seem to find a part that we couldn't make with a lathe, mill, and cnc router. Plus, the plastic was REALLY expensive, about $10 per cubic inch!

Re: CNC Router vs 3D Printer
 

Who makes and what is the model number of the 4' * 8' router? Any idea what it cost?

Re: CNC Router vs 3D Printer
 

The 4' x 8' was a shopbot, although I don't know the model number off the top of my head. They don't sell it any more but the replacement was this.

http://www.shopbottools.com/mProducts/prSalpha.htm

I know that when we bought it, the list price was under 15k, and somehow we managed to get it for less. We also went for the spindle instead of the router because we cut aluminum a lot. It's used in all the tech classes in our school, including the electric vehicle class, where it makes the body panels for the cars.

It's the best purchase our team has ever made, and we're really happy with the results. By the end of build season, we have freshmen who have never heard of CNC before who have learned how to operate the thing by themselves.

Re: CNC Router vs 3D Printer
 

I've used plenty of ShopBots they are great machines to have.
Just my two cents.

Re: CNC Router vs 3D Printer
 

Everyone has brought up good points, so I'll try to address some of the major ones.

I'm actually not sure what the policy is at my school (OSU). I will look into it, but I would feel guilty if a personal project got in the way of senior design or class projects.

For the projects I currently have in mind, I think a 3D printer may actually be more useful. The few I have been considering would not experience heavy loads that require aluminum plate or anything of that nature. It would certainly be cool, but not necessary.

As I mentioned, I had some exposure to 3D printed parts in FRC, was pleased with the results, and was intrigued by the possibilities. It isn't based on hearing some online hype. Again, using it for FRC is not the primary purpose, merely an added benefit. I came here to draw upon the community's general treasure trove of knowledge.
I should have made it clearer, but I was in part asking whether the parts produced from a low to mid-range consumer printer would be at all comparable to the high end consumer printer (uPrint SE) that I have experience with.

For those suggesting to get a router, did you look at the system I spec'd out in the excel document attached to the OP? Assuming I was able to solve the issue of where to keep it, would you suggest any other parts or improvements? Or even a different system entirely?

Re: CNC Router vs 3D Printer
 

Frankly I suggest the 3D printer if that's what you want.
Just be prepared it will be obsolete before you blink.

However I have the following concerns about your spreadsheet:

1. What does the first choice use for the stepper controller / driver?
The Gecko is an excellent product I would recommend it.
It is already in the second choice you present.

2. Do the electronics kits include the power supplies?
If not budget for that as well.

Both of these kits (the first I have actually assembled before for someone) are ACME screw kits.
They have power loss in the screws and no provision to gear them (direct shaft coupled).
Their rapids are listed unloaded. In short you won't move anywhere near that fast while doing any operation.
These are more targeted for engraving on aluminum and working softer materials like wood.
You could work on aluminum with this but very slowly.
Neither system includes the coolant you might want for working aluminum.
You could retrofit this into a 3D printer but the Z axis depth might be a limit to consider.

Neither system includes any kind of dust collection or enclosure.

Re: CNC Router vs 3D Printer
 

Oh... yeah a Router is NOT happening in a dorm room. They may not even let you bring in an 3D printer based on the heating element (Mine doesn't let you bring appliances and lava lamps).

For a college your best bet would probably be gaining access to an shop on campus via a club or getting to know the instructor. Or finding an local makerspace or hackerspace.

Re: CNC Router vs 3D Printer
 

Where there's a will. There's an incandescant light bulb bed heater.
It's becomes more an Easy Bake Oven anyway.
What I didn't bring the heater with the printer...I just found it here :)

Re: CNC Router vs 3D Printer
 

I saw a couple people say it but I don't think the community really did latch onto it.

First off, You are in college. You are paying to go to school there. Use the machines and the facilities you are paying for! There is a reason why they have a machine shop. Its not only for research but its also the place you can learn proper machining practices. I cant tell you how much I learned from my shop managers.

Second, learn to manage your time to maximize machine shop usage. Know that the machine shop has open hours, or that sometimes you may not have access due to senior projects. But.... if you get in good with the shop guys then there are untold benefits. (ie running CNC's later at night, or even a paid stipend..)

Third, if you are in a dorm room... it just seems silly to try to pack something like that in. Enough said.. Off campus living then maybe, but then again I would refer to point 1.

When you graduate and get a more permanent place.. then by all means go for it.

But then again that is my 2 cents.

Re: CNC Router vs 3D Printer
 

If the school shop doesn't work out, there might be a maker space within range. I would venture to say your funds would go a lot farther (a lot more tools for the dollar), even if you have to pay a few bills for a monthly membership.

Re: CNC Router vs 3D Printer
 

your soo right about this, the hype is out of control
CNC routers are way more useful if you have some knowledge of woods and how to design for it

Re: CNC Router vs 3D Printer
 

The value of 3D printing depends on the lens you consider it with.

There are many more applications for this technology than what most people consider because they approach it with the lens of PLA, ABS and say carpentry or metal working.

The idea of a small X/Y/Z robot able to deposit finite amounts of material extend into biosciences, aerospace, nuclear engineering and so many other fields. Hence why Dean himself referenced the technology when communicating with the Coca-Cola corporation.

By increasing the size of the community with that know-how the odds of pollinating major changes in technology are extremely high.

However in a consumer society running down and buying the latest off-the-shelf is the way most people are comfortable acquiring technology.

So it all depends on the viewer and their intentions.

As a 'do-it-yourselfer' from early in the RepRap project my expectations differ dramatically from other people.

Re: CNC Router vs 3D Printer
 

You are looking at the "3D Printing Revolution" through a very jaded lens. Allow me to walk you through the process I'm going through right now for some structural parts:

Step 1: CAD Parts
Step 2: Print Parts
Step 3: Assemble parts
Step 4: Simulate loading to failure
If acceptable failure continue, else go back to Step 1 and iterate.
Step 5: Depending on part produce part a mold or make on router/mill

Because I have the 3d printer (and can run it unattended) I can hit print and go work on other things. This means I can iterate a lot faster on parts. And sometimes it's far easier to see problems with a design when you can hold it in your hand.

If you look at it as the end of the manufacturing process it's fairly useless. If you look at it as a step in the engineering process it's much more useful.

Re: CNC Router vs 3D Printer
 

I agree with you here, that is why they are referred to as a "rapid Prototyping machine" meaning they are not meant for major parts only quick samples and models of a practical part.

I would also like to mention that a CNC router can be really noisy and depending on where you live in college (i.e. A dorm or apartment) this may be a problem. I would also say that a router is more 2D objects that you would have to use other tools for to bend and shape defeating your purpose. 3D printing would most likely be the best way to go for college at least.

Re: CNC Router vs 3D Printer
 

Have you considered a roland SRP? http://www.rolanddga.com/products/scanners/mdx15/

The mdx15 is roughly in the range of the 3d printers that you're looking at. It might be a bit out of your budget, but it can do aluminum, and according to the manufacturer produces better tolerances/surface finish than a 3d printer, especially the ones that you can afford

Re: CNC Router vs 3D Printer
 

I used this machine several years ago. Honestly, it's a joke. Your money is better spent elsewhere.

Re: CNC Router vs 3D Printer
 

You could always try a totally different approach to get machine shop access.

Throughout college I got jobs working in and running labs and shops. Not only did I have fun jobs during the school year that paid decently, but I developed good relationships with the machinists and other lab/shop personnel. I (and a few others like me) were allowed to use various shops after hours and on weekends, when they were not normally open. One year I ran the ME prototyping lab (talk about unfettered access!) and my senior year I was empowered to start a welding lab. I wound up teaching a number of faculty and many students how to weld and was invited to sit in on the ME staff meetings as an adviser. I never had any issues getting anything made in a timely manor. It's amazing what a good relationship with the powers that be will get you.

TL;DR: turn your cash flow around by getting a job at a shop or lab in your school, play nice and earn trust to get expanded access, learn how to manage a shop (schedule, budget, safety, etc), balance competing interests, and wind up with some great experience.

I assume, of course, that this sort of thing is an option for you. You might need to set a precedent, but you'll never know if you don't try.

Re: CNC Router vs 3D Printer
 

Could an arch-welder head be used as on a 3D printer?

Re: CNC Router vs 3D Printer
 

You can use a similar CNC technology and a proper table (think plasma table) to do 2D robotic arc welding. Many industrial welders use robots.

You are probably closest in thought to laser sintering, which uses lasers to form layers in metal powder as in a 3D printer.

Re: CNC Router vs 3D Printer
 

Could it? Probably.

Is it going to be useful? Possibly--most 3D printers that could be modified for an arc welder tip are under a foot of travel in any direction, which may or may not affect usability (though it'll certainly affect size of parts that can be welded). Also I can't think of anything that would need that much precision (we're talking in thou here) in terms of arc welding. Might want to try a CNC router modification first.

Is it a good idea? No. There's a lot of stuff that could go wrong, ranging from melting plastic (reprap-type machines) to warping the print surface (VERY bad if you ever want to change back) to any other safety concerns with exposed welding.

As stinglikeabee pointed out, you're pretty close to sintering, but those types of 3D printers are a minimum of 6 figures, not counting material cost--and in some cases, shielding.

Re: CNC Router vs 3D Printer
 

Are you looking for the same print quality? And what are your limitations on build space? I have the privilege to be an intern at the Manufacturing Demonstration Facility, a part of Oak Ridge National Laboratory, in which I mainly work with a variety of consumer printers. We have two uPrints, and the quality is amazing, but I have found that the Afinia printer can have almost equally amazing print quality and it is below your range in price. Although, the build space is only 5x5x5 in, so it depends on what you are working on. As far as structure goes, I have been using HIPS, or High-Impact Polystyrene, with the Afinia for a while now and it works great. It isn't Ultem, but I think it is an upgrade from ABS. It takes minimal tinkering, and fits very well in a dorm room. Also, I have quite a bit of experience with the Makerbots and the Solidoodle 3rd gens, so if you have any questions, feel free to ask.

Re: CNC Router vs 3D Printer
 

Speaking as someone who has used a CNC router table to do MIG welding development... it's not a very good idea. The arc root can jump around, the material is laid down in a non-uniform profile, and there isn't much of a practical way to make 'filler' to support cantilevered features. Weld beads simply aren't consistent enough to get a decent part or hit any meaningful tolerance.

Robotic welding is used quite a bit in industry, in very but "not 3D welder printing."

As other's mentioned, printing in metal means SLS or another comparable process using powdered metal. Though this area is ripe for innovation...