Building a good quality machine shop may seem to present a chicken-and-egg problem, at least for anyone not willing to mortgage their home for the money needed to buy all of these tools new. Namely, that building good tools often requires good tools. To help solve this problem, [Ryan] designed and built this CNC machine which can be built with nothing other than common tools, hardware store supplies, and some readily available parts from the internet.
Since it’s being built from consumer-grade material, [Ryan] has the design philosophy of “buying precision” which means that most of the parts needed for this build are precise enough for their purpose without needing to be worked in any way before incorporation into the mill. For example, he uses a granite plate because it’s hard, flat, heavy, and sturdy enough at the time of purchase to be placed into the machine right away. Similarly, his linear guides do not need to be modified before being put to work with a high degree of precision and minimal calibration. From there, he applies the KISS principle and uses the simplest parts available. With this design process he is able to “bootstrap” a high quality mill for around $1500 USD without needing any extra tools than the ones you likely already have.
The RIG-CNC as it is known has also been made completely open source which further cements its bootstrapability, and there is a lot more detail on the project page and in the video linked below. This project is unique not simply for the mill build from common parts and tools, but because this design philosophy is so robust. Good design goes a lot farther in our builds than a lot of us might realize, and good design often results in more maintainable, hackable things that work for more uses than the original creators may have even thought about.
Exposed ball-screw = Bad day in the CNC world
You can see the covers in the back. They were probably taken off to better show the internal design of the Y-axis.
I took them off for the video and because I am taking the mill apart frequently, I have a file for a hand cut and folded way cover I will add to the file mix for anyone who makes this. Legit covers are stupid expensive
Thank you!!
IMHO a good benchtop CNC machine envelope to aim for is the Light Machines Prolight PLM-1000/2000/2500. That was an epoxy granite framed bed mill with a decently sized cast iron table with three T-slots that had a 100 pound working load. Nothing before or since has existed in a CNC benchtop mill with such capability. The max XYZ axis speeds of the model 2000/2500 are pretty fast.
The rails are supported round bar on all 3 axes. The model 1000 used stepper motors and the control was in a large, external box with a proprietary ISA or PCI card. The model 2000 used a 3 or 4 axis Animatics servo controller, that was rather under-utilized. It communicated with a host PC via a simple RS232-C connection but unlike the PLM1000 model the PLM2000 was never provided with Windows software. It was firmly stuck in MS-DOS and using Expanded Memory System to load G-gode.
I do have a lot of information and software for the Animatics servo controller these mills used. There are potentially useful tricks like loading G-code into the controller’s built in memory then repeatedly triggering it to make it run completely headless. I want to build a small PC with the ability to run a large amount of LIM EMS 4.0 memory but finding anything with a High Memory Area that has enough contiguous space for the page frame, and isn’t an antique itself, is proving to be a problem. That ancient space in the PC memory map always gets broken up to be used by low level I/O to where there simply isn’t any possible way to configure it for EMS.
Both the 1000 and 2000 had 5K or 10K maximum RPM R-8 spindle options, but no spindle RPM feedback is provided.
The PLM2500 had a 42000 RPM spindle that used some tiny collets and required a one minute warmup before doing milling operations.
The mills (at least the 2000/2500) had a programmable interface port operable via G-Code, but aside from some very bare bones examples in the manual it was up to the owner to figure out what to *do* with the thing, like building a parts loader or tool changer.
The spindle mount attached to the Z carriage with 4 bolts so nothing precluded an owner from taking that off and replacing it with something bespoke.
What would’ve made it even better would’ve been a 30- taper spindle. Emco’s F1 benchtop mill (in manual and CNC versions) was in every measure inferior to the ProLight mills, smaller, lower load capacity, two slot table – but it came with a 30-taper spindle. That allowed the F1 to easily share the exact same tooling as many large knee mills.
Putting an NMTB-30 spindle on my PLM2000 would make it a *very* nice mill.
Some of the huge industrial CNC-routers, think 6×2 meters, (granted, for wood) have exposed ball screws, and still run without problems. Granted they are usually well above the worktable/-piece.
$1500 isn’t cheap either. Especially if it’s “3D printed”.
It’s a good build, but seems to not be everything it is advertised as being.
Just glancing at the machines scale if its at all as good as suggested (which at a glance I think it probably is) I’d call that pretty cheap, and presumably designed to fit the expected need – which is something you cant always buy at all.
Similar sized manual mills that need refurbishing come in a good portion of that budget, and decent quality ones are even closer… The electronics are not going to be that cheap either, it takes pretty hefty motors and motor drivers to be able to push a bit with any speed and depth of cut reliably.
I’d agree it does not look very 3d printed – but that is actually a good thing! Using 3d prints to fill the gaps in off the shelf suitable parts but using better off the shelf materials everywhere else means it doesn’t require a functioning machine shop of suitable scale to build it. And as soon as it is built it can start work on making those parts in better materials.
This machine is designed to bootstrap. I don’t think there’s any intention to keep any plastic in the final build, and all of the purchased parts are selected to be good enough to warrant the upgrade.
He had already milled his own the Z backplate by the time the video was made.
But I think it’s great that he’s documenting the steps along the way, because then you get an idea of just how much you gain by going from plastic to aluminum, as well as what you can expect, best-case, from 3DP bits tying a bunch of good parts together.
I still need to shoot the video but I swapped the plastic for the aluminum already and preliminary results were ~3x stiffer
Did you watch the video? If you did, I’m not sure how anyone could conclude “it’s 3D printed”. The 3D printed parts that matter were acknowledged to be design fit parts to be replaced by aluminum.
I do agree $1500 isn’t exactly cheap, but for the capabilities of what he built, it seems very reasonable. I think I paid modestly more than that for my Taig CNC mill which is probably outclassed by this mill in a few areas (ball screws, more robust spindle, beefier steppers, etc.).
Major props to people who begin by building their own mills! It takes me forever to plan out and develop the things I make WITH my mill. I would take me eons to design and build a mill from scratch.
While it’s good to see what people are doing, different approaches etc. it would be nice if HaD were willing to admit that featured projects are not always pure brilliance and be even mildly skeptical in their presentation.
So;
“World’s strongest 3D printed mill” as featured by HaD;
– Not very strong (HaD has featured steel construction concrete-filled mills before?)
– Not 3D printed (a couple of small brackets or something?)
– Not that cheap compared to a 2nd hand mill / cheap import / cheap drill press + XY table
– Some design flaws / compromises not present in commercial/industrial mills
– No actual measure of performance yet
Honestly the hack here is presenting it as if you’ve saved money or improved on just going out and buying a “real” mill.
Owning a cheap import mill I can say they are far to imprecise and maintenance hog in nature to really make CNC machines – they are just too garbage, even ones like mine that are not really bad design wise, just a bit cheaply put together, with the odd minor design compromise to make it cheaper end up with lots of wasted hours truing it back up and snuggling everything that works loose down again – which is something you doing manual machining will realise you need to do as you check the part fit and measurements as you go, but wont with a CNC till after it has junked the part entirely…
Then even if the one you get is reliable and well made enough to make a decent CNC base the design of a good CNC vs a good manual mill isn’t the same – there are a few reasons ball filled linear rails tend to appear on CNC’s and Dovetails on manual tools, not that either is unsuitable for the other job – its the ol’ engineering design for intended use compromises not outright incompatibility.
The price to quality this will have when its properly finished to me looks pretty damn good, but more importantly as he designed it it will fit his space constraints, desired working volume etc – I’ve been looking to build my own as the next big big project when the current crop have been ‘finished’ for just that reason – I want enough working area to meet the needs I know I have, but it must fit in the space I have too – can’t really buy either, the nearest thing I’ve seen are those really cheap 3080 extrusion ‘desktop’ CNC mills, which are still tempting being so cheap and useful in the interim (currently it is manual machining or 3d printer, and not a particularly good one of those as the good one needs a new brain after the magic smoke escaped), despite being rather too small, especially in Z to meet my expected needs but the next available to buy sizes up just won’t fit the space I have for it, or fit but won’t really be fully useable in the space as the design expects access on sides I won’t have, or slings its bed out too far to be practical etc…
First of all comparing a CNC mill to a drill press with XY table is not fair. Secondly a lot of that 1500 dollars goes into electronics and head which any CNC would need. Thirdly, 3D printed is how he got the parts that were not bought outright and is a way to get there not a final destination. There is no home 3D printable material with the structural properties needed for a real CNC mill. IMHO this is a great build that gets you to where you can replace the 3D printed parts with robust parts made on the mill itself. Brilliant and amazingly capable for $1,500.
Would love to see a more detailed BOM however since the Open Builds shopping list does not seem to be present.
Reading through the comments, it seems like if you can’t hit 0.002″ tolerances with <$500, it's a mediocre project.
This mill looks to have amazing cost-benefit balancing, especially once we get to see the results of further bootstrapping.
Thanks for the response! A more detailed BOM is my #1 priority after I upgrade to aluminum parts. Right now all of the “odd” parts are on the website, everything else can be seen in the 3D model, also available on the website.
Doing God’s work I see
A mill doesn’t constitute a machine shop and it’s not the first machine I’d get. I’ve ‘bootstrapped’ three machine shops. Precision is a skill independent of the machinery. It just takes longer to make precise parts on crappy machines. As far as machinery goes, first machine is a drill press, not a mill. Next is a cutoff bandsaw which also doubles as a small vertical bandsaw. After that, need a lathe and a grinder. Bench and a serious bench vise are not machines but actually need to be in the first couple machines. Likewise your heating/cooling system. Very hard to work when it’s too hot or too cold.
So, mill comes in at maybe number 4 or 5 on the list. Any decent mill probably needs a forklift to deliver. Lathe, not so much. A cheap hydraulic shop crane has worked for me a couple times. Don’t forget the tooling, hand tools and measuring tools which will cost you more than the machines. A moderate assortment of aluminum, plastic, steel and other stock is expensive. And, there’s lots of stuff which is not suited for CNC. You still need a manual mill and lathe. It may take a little time but you can almost always find an acceptable used lathe and mill. A desktop CNC is not a machine shop nor is a tiny mill/drill and mini-lathe.
On the whole I agree… Though when its CNC precision in the machinery is a requirement – doesn’t matter how good you are at making errors work themselves out on a manual machine you just don’t get the chance as the computer is going through all the motions for you and will have ruined the part for you on a shoddy machine before it gives you the chance to measure it.
Also scale shouldn’t negate it being a ‘machine’ shop – lots of clock and watch makers (etc) with a full machine shop in function and abilities just of machines you can probably lift single man, doing the same jobs for small scale parts with high accuracy your massive need a forklift lathe probably can’t even get close to doing as well… And by that argument your ‘need a forklift’ lathe isn’t even close to large enough to do the job of the REAL machine shop lathe – the REAL machine shop lathes are not really moveable at all being built in place for whatever their specific job!
I’d love to have the space for a bandsaw, they are great but I wouldn’t call them required either, the manual saw might be a lot of effort but it does the job about as well taking up a fraction of the space – its not like the sawed edge is ever the finished surface, and spending money on the power tool to save a little time may or may not be worth it depending on what you generally make – if it takes several hours of machining per trip to the bandsaw for new stock.
I’d also say a drill press while nice to have is forgo-able as the mill (and even lathe) can play at being a drill press just fine and unless you really need a better than straight off the mill with hand sharpened tool finish the grinder isn’t needed, just very very useful…
I’ve been looking at various options ranging from buying a mill, new or used to building one. Used prices depend on what’s in your area. This is much less than new. Also, thanks for presenting a site that has links to components and drawings. A lot of DIY projects don’t.
As far as the design itself, the 3d printed plates are sub-optimal from a rigidity standpoint, and kind of gimicky. There are much better options considering that you can buy a drill press for less than a 3d printer. Aluminum plate will clearly be better, but also much more expensive at ~ $40/sq ft for 1/4 inch and . Even cast acrylic at ~ $8.50/sqft would be more ridgid than a 3d print. Will be interesting to see how much it actually impatcts his results, since that’s what really counts.
Use the flexy mill to very precisely locate and centerdrill all the required mounting holes for replacement parts in steel, put them on the drillpress and finish the holes, and bootstrap up that way. When you have a repeatable, accurate, but flexible machine, you still can do some amazing work.
The drag with used mills and machine tools in general is that they pretty much cost $3000-ish, regardless of how big they are, because everyone wants a machine that fits in a small space. Locally I can sometimes find Haas and Mazak industrial vertical machining centers that can do commercial grade work for like $5K. The problem is they’re the size of my entire garage, need 440V, compressed air, and coolant. Or I can find an old Bridgeport for about $4K, which doesn’t have ballscrews and while it does fit in my shop it takes up about 1/4 of the entire shop. Or I can find a benchtop minimill for about $3K, which has a small work envelope, lacks rigidity, and again lacks ballscrews. Monster Cincinnati mills also sell for about $3K, weigh six tons, take up half my workshop, can drive a 25mm diameter mill through steel with a 5mm DOC, but, like, where does the lathe go if I have a mill that big?
And as the the guy who ran Sherline for years used to say, a very small lathe/mill still does like 95% of the jobs you need to do, and that’s way better than not having one at all.
Again:
I repeat what OP already stated in his video.
The easily printable plastic parts were from the beginning meant as an intermediate step just to hold the parts together to be able to mill the aluminum parts.
In the meantime, he also does spring constant measurements in his next video to have something to compare against once the aluminium plates are finished.
I think the idea here is to replace the 3D printed stuff with aluminum once you have the machine up and running.
Thanks! A quick google has me believing cast acrylic is less rigid than PLA just based on Youngs modulus. I just needed the plastic rigid enough to cut roughly round holes to make the aluminum plate upgrades.
With the plastic plates I was getting MRR of ~0.185″^3 in aluminum, with aluminum plates I am up in the ~0.6″^3 range running 5000 RPM. I am assuming I can go higher if I outfit it with a higher speed spindle since the cutting forces go down