CNC Router vs 3D Printer

[EricH]

Originally Posted by DampRobot

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. [...]

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.

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.)

[DampRobot]

Originally Posted by EricH

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.

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.

[EricH]

Originally Posted by DampRobot

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.

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.

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'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.

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%.

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.

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. P.S. 3D printing is not traditional manufacturing, by any stretch of the imagination.

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.

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.

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.

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.

[Cory]

Originally Posted by EricH

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

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.

[EricH]

Originally Posted by Cory

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.

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.

[techhelpbb]

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.

[Akash Rastogi]

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

[techhelpbb]

Originally Posted by Akash Rastogi

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

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.

[DonRotolo]

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

[AdamHeard]

Originally Posted by DonRotolo

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

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.

[Mk.32]

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.

[techhelpbb]

Originally Posted by Mk.32

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.

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

[kaliken]

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.

[protoserge]

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.

[Arch3Dpt]

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