PocketNC P5 takes desktop CNC to the 5th dimension

PocketNCp5

What do you get when you put together a husband/wife team of a machinist and mechanical engineer? If you’re [Matt and Michelle Hertel], you get a 5 axis CNC, which we think was one of the hidden gems at Maker Faire NY.

Hobby CNC machines have grown by leaps and bounds over the last few years. Nearly all these machines have been 3 axis (X,Y,Z). 5 (and more) axis machines have been around for years in the industrial world. These higher level machines never have made the jump to the hobby/home shop world.

The P5’s two extra axis allow for extremely complex parts to be created in one setup. A good example of this would be a turbine wheel. Compound curves on (and behind) each blade would make this an impossible job for a 3 axis CNC. The P5 was machining these parts all weekend at Maker Faire NY. Even more impressive is the fact that it was cutting Delrin, not wax.

The P5 uses a modified Synthetos TinyG board for stepper control. Every sliding axis is on a ball slide.

[Matt and Michelle] paid special attention to the spindle. Rather than attempt to reinvent the wheel and create a low runout spindle themselves, they went with a commercial unit. Considering the dynamic loads on a spindle when machining aluminum, we think this was a good idea.

Comments

  1. Galane says:

    Can this machine 7075 aluminum? That would make it a compact machine for milling compressor wheels for model jet engines.

    • andres says:

      could you mill it in wax and then use lost-wax casting to make the aluminum part?

      • wolfy02 says:

        That would defeat the purpose of milling it out of aluminum.

        • andres says:

          if it’s not strong enough to mill aluminum then this would be a viable alternative to get the same part.

          • wolfy02 says:

            casting a part out of aluminium is not the same thing as milling it out of aluminum. the casting process brings in other elements into the metal that normally are not there. Nitrogen and Oxygen from the atmosphere can hinder the structural integrity of the part if it were cast, where as a milled part is 100% solid aluminum(dependent on the type you choose).

            I used to work in an aluminum factory. Really awesome experience. Was awesome when I found some magnesium ingots once with the NASA emblem stamped on every one of them, probably could have walked away with $500k worth of the stuff before they shut the plant down. Then again, that’s another story.

          • andres says:

            well, i just learned something new today then, thanks wolfy02.

          • Hack Man says:

            Except magnesium spot is about the same as aluminum. Under $1 / lb.

          • mmhmm says:

            Indeed Hack Man. Makes me believe his other words are of equally little value.

            I will tell my little tale now:
            For some years I drove past a tiny little place on my way to work. I never really thought about it until they were moving passenger aircraft jet engines out of this building smaller than my house. Turns out they made and installed the blades. They used investment casting. Given that, I’d imagine lost wax method for model plane engines would work just fine.

          • wolfy02 says:

            @mmhmm
            You can choose to believe me or not, but facts are facts. Casting a part and milling a part will create two totally different internal structures, and thus a stark contrast in quality. While casting a part, you can run into porosity issues if it cools too fast or doesn’t have enough run-off vents. While a milled part will waste less material and is ultra rare to have porosity issues.

          • GrowAPear says:

            Mechanical engineer here. With proper design of your pour, (and maybe some heat treating) you can get similar properties with investment casting – the important part is knowing what properties you actually need to have. (On a model scale, I’ll hazard a guess that the material requirements are not as ridiculous as a full size turbofan.) Compressor wheels are often investment cast in the real world, with some finish machining for balancing and surface finish. All things being equal, if a part can be cast, a fully machined part uses significantly more material, and thus is significantly more expensive.

          • wolfy02 says:
          • pcf11 says:

            I view anyone touting billet parts with deep suspicion myself. They’re never telling the whole story. Porosity in casting can be overcome by using proper casting techniques. There is a method specific to aluminum called de-gassing in fact. Proper mold design reduces atmospheric air pockets in cast objects too. Vents, feeders, and risers have to be carefully designed to eliminate mold imperfections. For the record even billet stock is manufactured out of molten metal. Hopefully the folks making billet stock know what they’re doing though, so it is not really a factor. When superiority of one process over another is being judged all factors have to be taken into consideration. Things such as what alloy is being used, or grain flow as it relates to the finished part. The reality is often billet machined parts are produced because they are the cheapest overhead process available. “With technology as it is today, it costs the same to machine servos out of solid aluminum billet as it does to cast”, is telling there. Fact is they have to machine their castings anyways, so they decided to just cut out the process to save themselves a little money. Their entire explanation is an attempt to justify that decision in fact. One attribute often lost in machined billet parts is the skin effect. Other metal processes develop a hard outer skin on the resulting product. Machining cuts that skin away.

    • Mr Name Required says:

      Compressors can be made from other materials too. In one of the pioneering books on homebuilt model jet engines – can’t recall if it was Schreckling or Kamps – the plans show how to fabricate the compressor from thin plywood, which is then wound with carbon fiber to stop it flying apart at 100k rpm.

  2. yama says:

    wooow! what a crystal cutter/polisher!

  3. Julian says:

    Any videos of this working?

  4. John says:

    Is this going to be commercially available? Or just a prototype for now?

  5. lol says:

    Nice machine, if it could do aluminium it would be awesome.
    Also, worse possible font used in their site, what a POS..

  6. Yarr says:

    If you click the link, be prepared for your eyes to bleed from the font used on their website.

  7. RandyKC says:

    This is a thing of beauty.
    What kind of torque does it have?

  8. Thebes says:

    Do they plan to offer an affordable 5 axis continous CAM solution to go with it?
    If they can bring it to market at that price point they will sell many of them to jewelers for cutting waxes.

  9. Galane says:

    Just the table section would be very useful for easily adding 5 axis machining to any number of small to mid size CNC mills. Heck, it’d even be useful on larger mills for doing finicky small work that’s hard to fixture on a bigger table.

  10. What they dont mention is how much 5 axis CAM costs…

  11. Ryan Turner says:

    This mill looks flimsy. I highly doubt it can do a satisfactory job in metal, especially given that its maximum RPM is only 6K.

    • AMS says:

      .125″ 4-tooth end mill running 2thou tooth load at 165SFM only would need 5krpm and 40ipm feed.

      • t-bone says:

        Wow, you’re jumping right into steel!

        I think [Ryan Turner] (to do it the HAD way) is referring more to the stiffness. The spindle’s X and Z looks good, but the rest of the connection is more tenuous. The workpiece is on rotating plate on a single-ended trunnion all mounted on the Y-axis which itself might be cantilevered from the spindle’s X-Z box. And it’s all aluminum.

        Now, it’s super cool, but I think the further in -Z, +X, +Y, and the further from A0. you get, the more problems you might run into.

      • gyro john says:

        Are you really going to try to get .002 cpt out of a 1/8 end mill? (said the cnc machinist)

    • 0xfred says:

      I’ve got a small 3-axis mill (Proxxon MF70) that doesn’t look any sturdier than this and can happily mill aluminium – if you’re not in a hurry.

    • Steveo says:

      it’s all about speeds and feeds and chip load. The catch with aluminum is that you must cut it FAST. Too slow and it’ll gum up and ruin your expensive bits, too fast and the same shit happens. High chip load is REQUIRED with aluminum because the large chips allow the heat to be properly wicked away from the aluminum being milled.

      When machined at the proper speeds and feeds the aluminum and the bit should remain at ROOM TEMPERATURE. When your cut is done, stop the spindle and feel the bit, it should be cool and so should your workpiece.

      CAM software, ah the headache. I use linux so adding lots of axes are fine, but the cam side of things is tough. There is also solidCAM from solidworks, it can be easily pirated and supposedly can do up to 5 axes. Finding a tutorial would be nice.

  12. Joejoedancer says:

    I like it but what advantage does it have over a 3D printer?

    • Megol says:

      Precision, (production) material quality? 3D printers are still mostly toys producing parts with lousy precision in materials worse to much worse than traditional production processes does. E.g. delamination isn’t a problem in traditional cast plastic, for many 3D printed parts it can be a problem.

      • Cynyr says:

        why not use both? much like you might do for casted parts (like engine blocks usually). “Cast” the part and then mill to final dimensions for the critical areas. I see 3D printers as low temp, moldless casting machines.

        • pcf11 says:

          If you used both you’d be in a worst of both worlds scenario. You’d be using the output of a 3D printer, which is not as solid, or cohesive as billet, or cast stock, and you would have the added challenge of homing, and fixing the printed part too. Aligning, and holding (fixing) some cockeyed 3D print would be much more difficult than homing, and clamping a cube of plastic would be. By the time you’re done with all of that you might as well have just skipped the whole 3D printing process entirely for the time, and effort you’ve spent. All of that on top of the time, and effort expended printing the part to begin with.

          Congratulations, you’ve just removed the rapid from rapid prototyping.

          • Cynyr says:

            Sure if I wanted a part out of Al, but for a complex plastic parts I still think I could hand finish them to fairly high quality with a drill press, a file, and flat surface.

            Yes it removes the “rapid”, but I don’t have a way to cut complex shapes with high precision in plastic. a 3D printer is cheaper than a 3 axis mill, especially as the only way i could justify one of those would be if i could cut steel on it, thick hard steel.

          • pcf11 says:

            Get a mill. You may find that you use it differently than you imagine you would. I use mine for drilling a lot, squaring and dimensioning stock, and occasionally doing pockets. That CNC milling out complex shapes stuff really doesn’t come up a whole lot in practice.

  13. cyberteque says:

    Want!!!!

  14. tiberius says:

    I wonder how they modified the TinyG board. TinyG can handle up to 3 cathesian and up to 3 rotational axis but has only 4 stepper controllers. They must have added a fifth stepper controller on some kind of daughterboard.

    • Riley Porter says:

      tiberius,

      Hi I am a one of the 3 guys that make TinyG. We have been working with Pocket NC for awhile now. What we did was slave 2 TinyG boards via RS-485.

      Also to note. TinyG supports 6 axis not 3. However, we discovered some timing issues that popped up :) That being said we have some new stuff in the works that will make applications like this a breeze.

      https://github.com/Kinen/Kinen

      Enter Kinen. Its in the works. You can see our “4×2.5″ on that page. 4 axis 2 smart kinen slots and 1 “dumb” kinen slot. This is all in flux and we are working on getting it up asap. However feel free to read up and comment as you like!

      ril3y

  15. fartface says:

    This is where this stuff is headed….

  16. Nice machine that pocket cnc. Only the diagram shows y,a,c instead of y,a,b like in the description text apart from that I see most work went into the machine and that’s what matters, good job! Ditto on the font -> use verdana or something modern for a modern machine ;)

  17. SATovey says:

    >>>
    5 (and more) axis machines have been around for years in the industrial world. These higher level machines never have made the jump to the hobby/home shop world.
    >>>

    That’s not accurate.
    http://www.cnc-toolkit.com/ has been around a while and sells plans for a 5 axis cnc machine. You can see an animated gif of one at the bottom of their home page.

  18. MHertel says:

    Thanks for all your comments and for checking us out, interesting for us to read for sure! Just posted a blog post that might answer some of the questions you have, might not.

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