My review of building the KRMx02


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Thread: My review of building the KRMx02

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    Default My review of building the KRMx02

    I am really happy with my decision to build the 50" square KRMx02.

    I bought Michael's plans and was very skeptical. I figured I would be on my own because this clearly his hobby job (my going thoughts without experience). I have no experience in mechanical machining, CAD, or anything. I'm a computer engineer who is a living example of the blonde stereotype. But I have some really sharp friends, one is a PhD candidate in mechanical engineering and works at NASA. He's the long pony tail type who machinists are actually friends with because he's one of the few engineers that can bridge the gap between paper and real life.

    I give you you all this information just so you can truly understand how incredibly easy and well designed the KRMx02 is and how helpful Michael and his forums are.

    My Mechanical Engineering genius came over to check out the design and help me lift the X gantry onto the machine. This is a guy who has a 8'x24' water jet, some large 3 and 5 axis CNCs (watching the tool change on the 5 axis is crazy cool), and some huge 4 axis lathes. He was really impressed with the design, said that it was so over designed for rigidity and so many points for adjustments that he wasn't surprised when I said people in the forums were getting 3 thousandth repeatability.

    He and I volunteer on a high school robotics team and have access to 2 4' square CNC machines there that use the V groove system, mdf bed, and water cooled spindles. But he said there was no way he would try to cut aluminum on those. When he looked at mine, he said we have to get it done before the new year so we can use it to mill out our aluminum chassis.

    So in summary, the 50"x50" KRMx02 is a $15k machine for 1/3 the cost. The forums are tons of help with great people who won't make fun of your lack of knowledge, instead they teach you. There is only 1 time where I had to wait more than 12hrs for a response from Michael, and I'd bet money that he was on vacation or sick. He is dedicated to helping you be successful and full of wisdom and knowledge.

    If you don't like the 6" Z travel, like I initially did, I would encourage you to listen to Michael and others and build it stock first, then after all that, you can make an upgrade. There are so many factors to change, I am only now seeing what will need to be beefed up. But I can't see a need to do this now until I'm ready to add a rotary axis. But even then, I can get by with out more height unless I need to turn something bigger than 4" OD.

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  2. #2

    Default Re: My review of building the KRMx02

    Thanks for the endorsement. Be sure to add some pictures as you complete your build.

    Only one correction, The KronosRobotics web site is my full time job.

    Author of: The CNC Construction Set Books, the KRMx01, KRMx02, KRmc01, and KRmf70 CNC Books, the HANS Electric gear clock book. All available at www.kronosrobotics.com.


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    Default Re: My review of building the KRMx02

    Quote Originally Posted by msimpson99 View Post
    Thanks for the endorsement. Be sure to add some pictures as you complete your build.

    Only one correction, The KronosRobotics web site is my full time job.

    Yeah, I should have made that more clear. My initial thought was that Kronos was a side gig and that I would be alone, but with the time and effort you put into the forums, it would have to be a full time job or a politician (since they are the only profession that won't get fired for neglecting there duties), and your too competent to be a political figure.



  4. #4

    Default Re: My review of building the KRMx02

    Something to point out about the Z travel/ height on the KRMx02. There is a little over 7" travel. I'm just very conservative in my specs, as it has to do with how stock you build your table surface and where you mount the Z-plate in the Z-beam.

    There is exactly 10" of clearance between the stock clamp table and the bottom of the X-carriage. You can raise the Z-plate up so that you can utilize this clearance with a rotary. This is one of the reasons I ask folks to build the stock design first. In most cases it will work just fine with a rotary. You can still get 6" of travel over your rotary.

    In any case, I am very interested in what you come up with. Post lots of pics.

    Author of: The CNC Construction Set Books, the KRMx01, KRMx02, KRmc01, and KRmf70 CNC Books, the HANS Electric gear clock book. All available at www.kronosrobotics.com.


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    Default Re: My review of building the KRMx02

    Once I start deviating from stock, I will start a topic in the advanced build section.

    Your design is conservative, but that is what makes this the best build in its class, Rigidity. It's very solid, and any mods I do, I will strive to maintain that level of rigidity.

    My order of upgrades:
    3D printer add on - mid to late 2016
    Laser cutter - late 2016 - mid 2017
    Rotary lathe axis (parallel to X axis) - tbd
    5 axis mill - tbd
    Z travel



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    Default Re: My review of building the KRMx02

    Jimmarks, Thanks for your review. I've been looking at the KRMx02 and have visited the site to look around. Its well laid out and broken down by what tools are needed and how long each part of the build
    will take. I'm a little unsure if any special tools are needed to cut the extrusions and the steel to length? The build of the metal stand mentioned use of a reciprocating saw with a metal blade? is this the procedure you used? I'm just
    wondering if there are any special tools required to complete the build aside from ordinary tools? Sounds like once you buy the plans and get access to them, the forums are helpful to get advice if you are a first time builder. From your
    description of your experience level someone who isn't necessarily a mechanical wizard can still complete the project? thanks alot for any responses!

    Mark



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    Default Re: My review of building the KRMx02

    As far as special tools go, you will want to invest in a drill press. I built the 50x50. I calculated that I drilled over 700 holes. I bought a nice standing drill press with a light and laser sights. The real benefit of this DIY is I learned loads. Before this, my tool experience was working on a farm fixing tractors and building barns and fences. Not precise machine work. This taught me how to make accurate marks on metal and using cutting oil. I didn't cut any steel for my machine except the stand. The aluminum extrusion are cut to length and I recommend sourcing a good Steel vender who will also cut it for you. I had a HORRIBLE experience with the quality of the steel from "onlinemetals.com". A local vendor is recommended. The 2 main issues with the steel I had were my pieces weren't straight and the corners were nicked to hell. A friend and I spent 2 hours just filing the rough spots. If I were to do it again, I would have got a piece of steel plate water jetted (save on drilling too) for the rails.

    As for the steel stand, I followed his plan until my wife's uncle offered to weld it for me. How do you turn that down? And yes, I used a reciprocal saw to cut the unistrut. If you follow his guild to cutting it, you can get really accurate results.

    cutting aluminum is really easy. I have a miter saw, and if you get the Diablo 80t blade for wood and nonferrous metals, you will never have a problem. I cut a 1/2"x 5" aluminum flat bar for my Z plate. I recommend Aluminum Express, Inc. - Quality Aluminum Stock for aluminum stock. They send you 6063 aluminum, and its worlds better than the 6061 you get elsewhere. They also are wicked fast getting it out the door.

    My email is my user name with a gmail account. Feel free to email me and I can send you pics and videos.

    Jim



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    Default Re: My review of building the KRMx02

    Jim, thanks so much for the detailed reply. I appreciate it



  9. #9

    Default Re: My review of building the KRMx02

    I built my first two KRMx02 builds, using a small 10" bench top drill press. I might also add if you find a local steel suppler, while the steel may cost a little more, you will save on shipping.

    Author of: The CNC Construction Set Books, the KRMx01, KRMx02, KRmc01, and KRmf70 CNC Books, the HANS Electric gear clock book. All available at www.kronosrobotics.com.


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    Default Re: My review of building the KRMx02

    I built a 50X50 KRMX02 also and I am having trouble cutting a perfect circle when it is more than a foot in diameter. Are you having the same problem ?



  11. #11

    Default Re: My review of building the KRMx02

    How far out is the circle? Is it consistent? IE always out the same?
    If you are doing a climb cut what does it do when you do a conventional cut?

    If you cut a circle at different sizes does the error scale?


    You really need to log in to the KRMX02 forums on the KRonos robotics web site and post your problems there.

    Author of: The CNC Construction Set Books, the KRMx01, KRMx02, KRmc01, and KRmf70 CNC Books, the HANS Electric gear clock book. All available at www.kronosrobotics.com.


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    Default

    Quote Originally Posted by bogie58 View Post
    I built a 50X50 KRMX02 also and I am having trouble cutting a perfect circle when it is more than a foot in diameter. Are you having the same problem ?
    No, I made a wood ceiling medallion that's 23". It's a perfect.

    Check your belt tension on your rack and pinion drive. Also check your steps per inch are as specified in the book.

    Then check out your cam post processor. If you are manually writing your code, it could be an issue. If you analyze Goode from a tool like fusion 360, they don't use 2-4 lines of code for a circle, they use 100s. And I'm sure it's for accuracy.



  13. #13

    Default Re: My review of building the KRMx02

    Some CAM packages dont support Arc commands so they have to do very small cord changes to do a circle. A CAM package that supports the Arc command con do a circle with only a couple commands. The controller you are using has to support the Arc commands as well. The latest version of Mach 3 does.

    Author of: The CNC Construction Set Books, the KRMx01, KRMx02, KRmc01, and KRmf70 CNC Books, the HANS Electric gear clock book. All available at www.kronosrobotics.com.


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My review of building the KRMx02

My review of building the KRMx02