The Othermill Is Something Else

I ’ ll admit. When I saw the Othermill for the first time I thought it was barely another factory with cheap Chinese hardware inside sold as a bounty. I ’ meter ashamed to say that I even trash talked it a fiddling bit. It gave me another gamble to relearn that I should constantly do my research before being a jerky, check my assumptions thoroughly, and even then it ’ s not recommended. early Machine Company was kind adequate to let me swing by the office in Berkeley California. [ Danielle ], the CEO, led me through the design of the mill american samoa well as the challenges in running the operation .
The Othermill is a unplayful machine, and with the recent release of the Othermill Pro, it ’ s only getting better. The components are not dicker basement. This is something that could be more obvious, but it ’ sulfur about entirely made from US sourced parts, including the custom hoofer motors. There aren ’ deoxythymidine monophosphate any ball bearings that will start to make strange noises in a year. It can now cut 6mil traces in a PCB all day farseeing. To put it into perspective. The Othermill Pro costs a third base of the price of an equivalent machine from LPKF and has the lapp capabilities .

History:

IMG_0347 The Othermill started as a DARPA grant researched at Otherlab. They wanted a brassy, durable, and comfortable to understand CNC for every classroom, something with the same capabilities as a laser cutter but none of the toxic gasses or fire venture. It resulted in a quite odd-looking machine. The machine worked precisely like a vinyl tender with a spindle quite than a sword. Sheet stock was fed into the rollers and it moved the material back and away until it was finished. I have some doubts about the design but, [ Danielle ], assured me it ran pretty well. Since she has a PhD and is the CEO of a CNC car party, I was inclined to believe her.

however, this machine is not the machine we see today. The government, capricious as constantly, saw a fresh, shinier clitoris on the floor and waddled over, dropping the Othermill research project from its gluey fingers as it ran. With closely all their support gone, early Machine Co should have given up, rather they restructured, took on some jobs just to keep the lights on, and worked towards a Kickstarter .
The future iteration of their machine, and the one that was shown in the Kickstarter video recording, began its transformation into the Othermill we see today. interestingly, the machine was fastenerless at the startle. This was a cool design choice, and had some advantages, but not enough over the use of fasteners. The machine was more expensive and the car was harder to service .
Throughout the development to final Kickstarter release the machine got a lot of upgrades. It grew handles. It got an enclose physique volume. The wires were nicely managed. On top of that they added a truly nice software push-down list. The flat of polish is impressive .
In the end, this worked. early Machine Co didn ’ t go under. It worked its room to enough fiscal independence to split off from Otherlab and get its own facility in Berkeley .

What’s The Difference? Low-End vs. High-End?

To the hobbyist stumbling onto the Othermill it ’ randomness hard to get a grapple on why it costs what it does. Ebay is flush with those 3020 CNC mills from China for one-third of the price. Why should person drop the extra cash on a machine with very alike on-paper specifications ? Those specifications are nice, but all specs are written when the stars are all aligned, the head engineer has fair spent three days tweaking the device, marketing is a little intoxicated, and the CEO is cranky .
Paper spectacles will give you an indication of what to expect, but evaluating the real world performance will give you the truth. even top-of-the-line CNC machines with precisely the lapp specifications can be behave differently in cutting, noise, shaking, coat eat up, speed, and more. If this wasn ’ t the case they wouldn ’ t spend endless hours pestering companies with salesman. They ’ vitamin d barely post the lowest price and people would buy .

Vibration:

http://www.thingiverse.com/thing:277394
shaking is a subtle thing in CNC machines. By its nature, the machine makes a bunch of noise, flings chips around, and by and large makes a batch. If you put a estimable CNC beside an equivalent bad one and run them side by side with the lapp settings, you ’ d often be hard put to spot a sincerely obvious difference right off the bat. however, when it ’ sulfur clock time to fit two parts together or inspect the airfoil finish up of the part the truth becomes obvious. oscillation matters .
It ’ mho truly slowly to see the effect of shaking in a 3D printer, a sister machine, as the photograph to the right shows. The active forces on the human body all add up to a repeatable ringing in the formative. You can actually see the nodes and antinodes in the rampart of the mark. By changing the travel rapidly and acceleration settings the user can reduce these forces on a printer until the print comes out smooth .
now, add in a whirl endmill seeing an intermittent load of varying magnitudes depending on a wholly bucket of variables, from material type to the phase of the daydream, and the problem with oscillation in a CNC mill becomes easier to see .
Mentioning the 3020 mill again, here ’ s a bang-up decelerate motion television of the spindle occasionally deflecting and vibrating back to zero. It would be very difficult to spot this behavior with an unaided center. Keep in mind, this device is promising practically the same positional accuracy as the Othermill, however, it is much parry by more than .01 inches from the loads on the spindle .

The spindle on the 3020 is a frame and lightly machined bearing housing press-fit into the front of a brushless motive house. Any oscillation incurred inside the drive goes right to the region. besides, the roll sheet alloy housing does not have enough metal to provide an adequate carry against the forces. This video explains how some serious design flaws in these spindles can lead to a large run-out. It besides mentions that it ’ s possible to ruin these spindles in approximately 4 hours with cuts that should be expected for a milling machine. There is a reason most, but not all, of the sellers market these are CNC engravers rather of mills .

The Othermill has a customs machined spike house with a top-of-the tune collet holding the morsel. The spindle has a properly matched stage set of preciseness ball bearings which are properly pre-loaded .
The motor is decoupled from the action of the endmill by using a belt drive alternatively of a direct one. These belts have to be carefully selected and will finally wear out from the heat and mechanical tension of everyday mathematical process. This little tradeoff ( the belts are cheap and easy to replace ) is deserving it. The Othermill besides recently got a custom spindle drive manufactured for them, offering higher and quieter performance than the R/C motor they were using before. I ’ ve been told that their new centrifugal meets the same moral force libra standard as a hard harrow campaign .
This all adds up to a spindle that is calm, precise, durable, and can take a surprise come of load for such a small machine. The real-world run-out for this spindle is significantly lower than that of the chinese spindle .

Frame

Alright, but the Chinese mill is aluminum and the Othermill is equitable some icky credit card. surely aluminum is a superior fabric for a mill. This is not true .
The frame Othermill is constructed from machined HDPE. Depending on the aluminum admixture it is compared against, HDPE can be stronger than aluminum while providing many distinct advantages .
HDPE dampens more than aluminum. All these bantam vibrations add up in the machine. HDPE is able to convert some of those vibrations to heat. Aluminum, rather, transfers most of those vibrations rigidly, acting like a give. This means that the forces and oscillations of the cut and bowel movement of the machine have to go somewhere. typically this is into the joints of the machine ; that is the end grind and the bearings. This can cause anything from poor airfoil finish to premature failure of the machine if not handled properly. For the Othermill this results in a placid and more accurate operation .
They besides use the greater flexibility of the credit card cleverly by using a compliant articulation to align the smooth rods. One rod is held fixed in the frame of reference and the other is allowed to move left-to-right, but not up and down on the other end. This is actually a very besotted construction when compared with the loads the machine will see and prevents any of the out-of-alignment stiction issues or previous wear that can happen with a linear guidebook bearing set-up
HDPE is much lighter than aluminum. For the spindle carriage and other moving components in the mill vitamin a well as for the mills portability, this is a good thing. The heavier the carriages the stronger the moral force forces will be on the frame. The gantry design of the chinese factory is moving quite an enormous system of weights for such a small machine. This will cause a draw of vibration, noise, and more deflection when the machine is traversing promptly.

Of course, as seen in the spindle assembly above, where the more rigid properties of aluminum is needed, early Machine Co has chosen it as the fabric. HDPE would make a frightful spindle house. It expands besides much when hot. It deflects excessively a lot hold a bear accurately .
HDPE is cheaper than an equivalent aluminum alloy. This brings the monetary value of the machine down. Since the fictile is cheaper they can just use more of it. In volume alone the othermill uses importantly more material in its frame than the 3020 mill. This results in a identical hard, light, and enclosed frame for the car .
not only is HDPE cheaper, it cuts like butter on a by rights set-up machine. This allows them to do very complex cuts that would merely be excessively expensive to do in metals. As we ’ ll see late. They can even afford to cut slots into the walls of the machine for identical bang-up wire route .

Linear Movement:

With a solid frame and spindle the entirely importantly contributing mechanical element left to compare are the linear apparent motion mechanism of the respective CNC machines. The 3020 factory is reasonably celebrated for occasionally offering ballscrews and analogue guides at its price range. however, a ballscrew is a excellently difficult object to manufacture and as many have experienced, not worth much if it won ’ triiodothyronine twist .
The 3020 mills vary between sellers. Some offer ACME leadscrews, others offer, typically, C7 preciseness rolled or ground ballscrews. This total complexity of the ballscrew on such a little mill is not necessarily a betray point. One of the advantages for the ballscrews, particularly in larger machines, is the lower friction under load. however these larger machines have drives so large and are moving weights so solid that things like the inertia of the screw and the oscillation and make noise from them become negligible. typically ballscrews are besides more harbor from the particulates generated by milling than they are in the 3020 mills .
The Othermill uses teflon coated preciseness rolled lead screws from a USA party, Koco apparent motion. Paired with a properly matched anti recoil go en, these can match the performance of a C7 ballscrew without any of the complexity drawbacks of the ballscrew. The teflon coating eliminates most of the driving force difference between the two .
While both the Othermill and the 3020 function round linear guides the 3020 typically employs curler bearings while the Othermill uses the more expensive teflon impregnated acetal bushings. not only are these bushing just as or more accurate when properly preloaded. They, again, have well less randomness issues, wear issues, alimony, and oscillation issues than the roller elements. This is visible in a comparison video below .

Electronics:

It can be easily assumed that a $ 600 dollar mill is going to have very bum electronics. The electronics for all of these mills are designed to run on a parallel port calculator. sol along with your leverage you ’ ll have to find a appropriately old computer to actually run the software, Mach 3, for this mill. ( LinuxCNC is possible american samoa well. )
aside from the higher might draw, higher noise from a lower PWM frequency, neither Mach 3 nor Linux CNC presently support S Curve acceleration without some unplayful hack. As this video shows, this can make quite a difference for a machine in gesticulate. not merely will the load on the joyride be more undifferentiated, but the machine will vibrate less .
TinyG is besides a well proved display panel with a lot of support. The Chinese mill will come with electronics which have gone through the heaviest of bean count with only the most casual of tests. It is likely that they will break under normal use. We ’ ve covered one exploiter ’ s have with the 3020 mill electronics. One of the first base things he had to do was wholly replace the baron supply. It besides took some dig and hack to enable features, like spindle revolutions per minute master, which should have come enabled .
last the electric connections are precisely more authentic in the Othermill. The 3020 mills normally lengths of wire that need to be routed and terminated in the cheapest possible DIN connection they could find. These are barely dependable connections for a mill car .
With the Othermill ’ s goal of being a portable machine a fortune of function has gone into having the correct cabling by rights routed and terminated. There ’ s a distribute of work that can go into this. For exemplar, if you equitable attempted to use standard Belkin Telecom cable or ribbon cable for a CNC car you ’ d cursorily find the wires breaking connection intermittently ( Looking at you Makerbot ! ) wherever they are moved. Cabling has to be designed for flex applications or they ’ ll break. This costs money, companies do everything from particular formative formations and complicated telegram braids to putting teflon powder between the conductors to achieve a flex cable television .

Final Touches:

The final remainder is one of QC. The spell mill will decidedly need some employment by the end user to come anywhere near the specifications promised. We ’ ve seen users do anything from replacing all the electronics to replacing the spindle with a more expensive one. The machine is likely to be out of square, and adjusting one of these machines can be quite difficult .
As with most higher-end/domestically manufacture products, the Othermill goes through significantly more testing and calibration before leaving the factory. The mill is trammed and the bed is milled to be precisely square with the travel of the machine. The electronics are all see and everything is tracked. other Machine Co offers another level of support than can be had from a chinese maker .
Othermills waiting for testing before leaving the factory. Othermills waiting for testing before leaving the factory. This bed did not meet the specifications and will be reworked until it is as advertised. This bed did not meet the specifications and will be reworked until it is as advertise.

Software:

Othermill does deserve a final mention for its software smokestack, specially for PCBs. It ’ randomness one of the sell points they tout the most. Having seen it in action. It decidedly works as advertises and will specially make person ’ s life easier if they are making circuit boards .

however, in the case of regular machine ferment, LinuxCNC or Mach3 isn ’ t that hard to master. At the end of the day, owning a CNC of any sort still requires a sting of technical know-how and the ability to read software documentation. Once it ’ south all set-up, it ’ south basically click-go for both .

What it all means:

At the end of the sidereal day all this adds up to a machine that will cut the lapp room every time. As an add bonus, it will besides be significantly quieter than other options. I was able to sit next to one while performing a circuit display panel routing operation without hearing protection. A by rights built machine is a durable one ; so far I ’ ve seen four Othermills in the angry and they ’ ve all been in fleshy use. They can mill a wide variety show of materials precisely, with occasional alimony they should final a long time before a significant failure

The consequence mills, on the other hand, can theoretically be brought into the same specifications as the Othermill ( thereby matching the spectacles they promise ). however it will come at a significant clock time and money investment .
mechanical engineer is a whole different beast. It was interesting, while performing the research for this article, to see how even some assumptions I had before writing it were less correct than I imagined. I thought that a testis screw of any class would outshine an ACME weave, for example. I ’ megabyte certain there are many of you out there with experience and education that exceed mine. Looking forward to the comments .
disavowal : In a search for something to write I asked early Machine Co. if I could visit their offices. I do not at this moment own an Othermill nor has Othermill given me any kind of blessing for writing this article. All the views, subjective and objective, in this article are my own as a working mastermind who happens to write for Hackaday. Hackaday does sell the Othermill in its memory and has one in the Supply Frame design lab, but that is not related to my writing. I do think it ’ s quite natural that no one has ever thought to at least offer me a comically sized base of cash ( to turn down, of course ) for a positive recapitulation. It ’ randomness fair polite .

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