.0001" Accurate gantry CNC design suggestions?


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Thread: .0001" Accurate gantry CNC design suggestions?

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    Member Thunderskunk's Avatar
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    Default .0001" Accurate gantry CNC design suggestions?

    Hello gents,

    I am looking for a CNC router design that is really stinkin accurate, and I definitely need some help on this one.

    This forum is bloody huge! I drooled over CNC routers as a kid, but I ended up as a CNC machinist and then an engineer for an EDM shop. I have a fanuc robodrill in my basement, which somewhat dampens the desire to build a CNC router, haha. Still cool that folks make em themselves.

    I am on a different quest. I fully understand that a router with a .0001" resolution would be... well, fairly pointless. What I need is the base to build a Coordinate Measuring Machine (CMM). I haven't seen any cheap already-made machines that fit the description, and there's a lot of things I don't need for a CMM that a router has.

    Full-fledged CMMs are not cheap. With good reason, but there's definitely no low-end version. My idea is to take a gantry DIY CNC router minus the router, add a wired probe, use Mach3 with a probing routine, output the measurements in CSV, and use excel to generate a report. Heck, you can even use encoders for position.

    If I can build it cheap enough and make it WORK (key word), even if the results are garbage, I can build a platform that is more rigid and square using a surface plate and some granite straight edges.

    Anyways, let me know what you guys think. Thanks for the help!

    Matt

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    Default Re: .0001" Accurate gantry CNC design suggestions?

    I thin you will need to build a standards room to house it.In any other environment a draught through an open door will probably cause enough thermal movement to throw doubt on such desired levels of accuracy.



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    Default Re: .0001" Accurate gantry CNC design suggestions?

    Every motion component needs to be of the highest quality, if you need that kind of accuracy. Ultra precision linear bearings, precision ground screws. These parts will be extremely expensive, unless you can find a good deal on Ebay.
    And I would think that the frame needs to be precision ground as well?

    Gerry

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    Default Re: .0001" Accurate gantry CNC design suggestions?

    Quote Originally Posted by ger21 View Post
    Every motion component needs to be of the highest quality, if you need that kind of accuracy. Ultra precision linear bearings, precision ground screws. These parts will be extremely expensive, unless you can find a good deal on Ebay.
    And I would think that the frame needs to be precision ground as well?
    Gerry I think he also said "Cheap" so I guess he needs to decide. There was someone on here building on a granite plate perhaps he can help.

    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router


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    Default Re: .0001" Accurate gantry CNC design suggestions?

    Quote Originally Posted by wmgeorge View Post
    Gerry I think he also said "Cheap" so I guess he needs to decide. There was someone on here building on a granite plate perhaps he can help.
    And that's exactly it. If I had 10k to spend, I'd get a CMM and call it a day.

    Step 1 is getting a CNC router to output data like a CMM, regardless of accuracy. Step 2 is making said system more accurate. The easiest way I can think of is to use a surface plate as the base, granite parallels as the ways and gantry legs, possibly with home-made air bearings, and go from there.

    But as mentioned, if there's a design or even prebuilt router that claims to be the least bit accurate, it would be easier and faster for me than starting from scratch.



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    Default Re: .0001" Accurate gantry CNC design suggestions?

    even prebuilt router that claims to be the least bit accurate,
    A $150,000 router is not even close to being that accurate.

    Gerry

    UCCNC 2017 Screenset
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    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: .0001" Accurate gantry CNC design suggestions?

    Here are a couple of good starts, at least the base machines are there so the hard work is done.

    https://www.ebay.com/itm/Renishaw-Cy...O62:rk:47:pf:0

    https://www.ebay.com/itm/BENDIX-CORD....c100005.m1851

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: .0001" Accurate gantry CNC design suggestions?

    Quote Originally Posted by Jim Dawson View Post
    Here are a couple of good starts, at least the base machines are there so the hard work is done.

    https://www.ebay.com/itm/Renishaw-Cy...O62:rk:47:pf:0

    https://www.ebay.com/itm/BENDIX-CORD....c100005.m1851
    I agree you can find some good deals on Ebay for this kind of machine, even if it is not working the main building blocks are there

    Mactec54


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    Default Re: .0001" Accurate gantry CNC design suggestions?

    That's probably where I'll end up. Definitely going to buy the real thing, inspected and refurbished by someone who knows more about CMMs than I do. Alas, we need more $.

    Here's a specific question. I've been getting input from Jim on an older thread on a similar subject, but I'll focus it here.

    With the potential to end up using encoders, I'm steering away from Mach3 and toward KMotion. Is there a thread that breaks down the details of building a CNC router using a KFLOP board and KMotion software?

    I'd like to test the functionality before the accuracy, and the cheapest way I think would be to get the electronics and drivers plugged in to a cheapy-Chinese router with a cruddy spindle probe, then work my way up from there. I'd love to piggy-back on a design and parts list someone has already made work.



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    Default Re: .0001" Accurate gantry CNC design suggestions?

    This might be helpful https://www.cnczone.com/forums/dynom...int-cloud.html

    You should be able to buy any cheap router kit and hang the KFLOP on it for testing. The Dynomotion website has all of the setup documentation. You just need to decide on using steppers or servos for testing.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: .0001" Accurate gantry CNC design suggestions?

    The guy that made a granite CNC:



    So, I'm going to straight-up conclude: No. This doesn't work. At least not in my budget.

    My ultimate goal was to have parts inspected while I was away from the shop, or lights-out inspection. It's not that it can't be done, and that I won't do this at some point in time just to play around, but I'm going to join the many voices I've heard over a few forums and say this isn't the project I want to get in to right now. I'd love to toss a few K at the project and get something that's semi useful. At the very least, I need a surface plate, and I'm sure the components would sell after the fact if it didn't work, but I'll never get back the hours into programming something I'm not all that knowledgeable about. Hours better spent making money with my mill. A good few months with the mill might even pay for a CMM, and those dollars gone towards tools and holders will multiply faster than my home-grown CMM will.

    Maybe somebody like Tormach will see the niche market and make a $10,000 CMM for simple, low tolerance inspections. But maybe not.



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    Default Re: .0001" Accurate gantry CNC design suggestions?

    Quote Originally Posted by Thunderskunk View Post
    ......

    Maybe somebody like Tormach will see the niche market and make a $10,000 CMM for simple, low tolerance inspections. But maybe not.
    No reason you couldn't use a mill for a pretty good (not a great) CMM. Should be able to get into the +/- 0.0005 range depending on the resolution of the machine.

    I have thought about adding CMM capabilities to my mill. Not much of a step in my case, I already have 1 micron scales installed and run it with a Galil motion controller, so all I need to do is write the software and buy or build a decent probe. Maybe I'll get ambitious and write the software. Been thinking about ways to make a really accurate probe. It should be able to use the G code to compare the expected shape to the actual part and log any deviation. Not to difficult. The main problem is that my shop is not temperature controlled so real accuracy is not possible.

    Jim Dawson
    Sandy, Oregon, USA


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.0001" Accurate gantry CNC design suggestions?

.0001" Accurate gantry CNC design suggestions?