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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > partial 80/20 build using some easy to find parts
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  1. #1
    Join Date
    Nov 2012
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    59

    partial 80/20 build using some easy to find parts

    hello everyone, this is my first post on this site, ive been wanting to build a cnc for several years now and finally have some time n money to spare on it,

    little bit of background : NONE lol, im not a machinist or nothing like that actually an electrician, just always been facinated by them. im slowly trying to learn everything i can about machining tho if anyone know of some good reading material let me know.

    im also trying to learn solidworks slowly and mastercam along with mach3 cnc.

    here is a picture of my basic design with the exception that i have since redesigned the y axis using .25" x 4" steel plate and bearings and z axis from cncrouterparts.com and fineline automation. as soon as i get the changes made i will post them



    the rails are 20mm rails and two bearing blocks per side from qxb bearings.
    trucks were custom made, as well as the spacers for the acme nuts and acme bearing blocks. the whole reason i switched from my design to the finelineautomations design was to have less custom machined parts and less flex, oh and btw u cant see it but each rail is drilled and tapped every 10 inchs for a bolt so i can control downflex as the machine moves.

    also i dont have any brackets showing however there will be a buttload of them i want it as rigid as possible

    i got lucky and have access to a 5 x 10 cnc table that i will use to drill all my holes for my table.

    let me know what you think of my design, hopefully its not to god awful,

  2. #2
    Join Date
    Jan 2008
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    853
    Hi, and welcome to the Zone!

    I think that even with the rails supported on bolts every 10", there will be a lot of deflection, especially side-to-side. If you can't justify the cost of supported rails (I can't) then perhaps you can fab some with good ply on edge and side-to-side braces.
    The top plate (wood?) is also going to flex a lot unless it is very well supported at the edges and in the middle. Have you considered a torsion box?
    The X drive screws may pick up a lot of swarf where they are. If you went the torsion box route you could place some of the mechanicals on the sides to get them away from the cutting area.

    Cheers!
    Paul Rowntree
    Vectric Gadgets, WarpDriver, StandingWave and Topo available at PaulRowntree.weebly.com

  3. #3
    Join Date
    May 2012
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    231
    Also you might want to think about using a plate for the Z then 80/20. Every inch from Y you are out the more deflection you will have on the Gantry.

  4. #4
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    Nov 2012
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    Quote Originally Posted by PaulRowntree View Post
    Hi, and welcome to the Zone!

    I think that even with the rails supported on bolts every 10", there will be a lot of deflection, especially side-to-side. If you can't justify the cost of supported rails (I can't) then perhaps you can fab some with good ply on edge and side-to-side braces.
    The top plate (wood?) is also going to flex a lot unless it is very well supported at the edges and in the middle. Have you considered a torsion box?
    The X drive screws may pick up a lot of swarf where they are. If you went the torsion box route you could place some of the mechanicals on the sides to get them away from the cutting area.

    Cheers!
    This is a dumb question but what is swarf exactly. I may try to fab some sort of rail support. Didn't think of that. Was hoping that with driving from both sides would help keep deflectiondown.

  5. #5
    Join Date
    May 2012
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    231
    Swarf is the chips,dust either metal or wood that would get into or on the bearings or surface of guides. If you are planning to use the bearing guides has your support for the gantry. You are going to get a lot of defection in them unless you go with large harden guides (like in the 1 inch or larger) or go with a supported guide with and open bearing for support.

  6. #6
    Join Date
    Nov 2012
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    59
    They are supported rails. And the more I think about it the more I think I'm gonna make a Support instead of just using bolts.

  7. #7
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    Nov 2012
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    And the bearings are open face. As far as dust I think I'm gonna make some contraption to block the rails n leadscrews. Lol hopefully it don't suck to bad

  8. #8
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    Jan 2008
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    I suggested fabbing the supports without really thinking about the work involved. The openings in the bearing blocks will allow only relatively narrow supports like commercial Al ones. I am not sure if you can make them this narrow out of ply and still get the strength you need. If you try, it will take a lot of side supports (half-lap joints? barrel nuts?) to make the supports rigid.

    At the end of the day, you may want to look at buying supported systems or trying alternatives like V-groove bearings running on angle iron rails.
    Cheers!
    Paul Rowntree
    Vectric Gadgets, WarpDriver, StandingWave and Topo available at PaulRowntree.weebly.com

  9. #9
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    Nov 2012
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    yea just did some measuring and ur quite right about that not enough room for a easy wooden support, hmmmmmm, i could make some aluminum brackets but im trying to make this a simple build with not much custom made parts, do you think is possible to use the machine its self to cut out some softer aluminum brackets? or too much sideways play? hmmm i never even saw the side play problem glad i posted here and thanks for the help btw

  10. #10
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    I don't think it will be stiff enough to cut Al.

    Time to rethink.
    Paul Rowntree
    Vectric Gadgets, WarpDriver, StandingWave and Topo available at PaulRowntree.weebly.com

  11. #11
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    Nov 2012
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    well i got some parts in today from cncrouterparts.com, and mcmaster carr, got some things to work out but already in progress for some things. may just have to bite the bullet and have some custom parts made. idk yet





  12. #12
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    Apr 2009
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    5516
    Quote Originally Posted by RNation0001 View Post
    well i got some parts in today from cncrouterparts.com, and mcmaster carr, got some things to work out but already in progress for some things. may just have to bite the bullet and have some custom parts made. idk yet




    You can buy the rail supports very inexpensively on eBay if you look.... Makes things a bit easier too as all you have to do it bolt it down.

  13. #13
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    Nov 2012
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    so what would i type in to get these supports on ebay?? thanks for the info btw.

  14. #14
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    Apr 2009
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    Did you try "linear rail supports?"

  15. #15
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    Nov 2012
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    yea didnt see any for 20mm rail tho

  16. #16
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    Quote Originally Posted by PaulRowntree View Post
    I don't think it will be stiff enough to cut Al.

    Time to rethink.
    If all else is done in a respectable manner, it will definitely cut aluminum, but not very fast. The bridge on my machine is also very weak and slowing down my machine was the only way to get anything out of it.

    Your bridge design is very weak. The Z plate seems to be suspended on the 2 cross slides. That's not a good thing because of the vibration that will be produced. It will start with chatter and grow into bit-snapping followed by violent vibrations that will destroy your stock any semblance of smoothness.

    If you start with a stronger way to join your Z-plate to the bridge, you'll likely get 4 times the speed if not more.

    That's my "OPINION" !

  17. #17
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    Jan 2008
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    Ok, perhaps I should not say it won't work ... perhaps that it won't work well?

    It seems to me that building a seriously weak machine (that would be hard pressed to do light work in wood) with the expectation of slowly grinding through Al to make Mk2 is just a waste of time, and would probably require more iterations, cash and frustrations. I believe we should build to the best of abilities, budget and materials so the machine is useful, with the hope that the machine can do better next time around if improvements are required.

    YMMV
    Paul Rowntree
    Vectric Gadgets, WarpDriver, StandingWave and Topo available at PaulRowntree.weebly.com

  18. #18
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    Nov 2012
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    Quote Originally Posted by jsearles View Post
    If all else is done in a respectable manner, it will definitely cut aluminum, but not very fast. The bridge on my machine is also very weak and slowing down my machine was the only way to get anything out of it.

    Your bridge design is very weak. The Z plate seems to be suspended on the 2 cross slides. That's not a good thing because of the vibration that will be produced. It will start with chatter and grow into bit-snapping followed by violent vibrations that will destroy your stock any semblance of smoothness.

    If you start with a stronger way to join your Z-plate to the bridge, you'll likely get 4 times the speed if not more.

    That's my "OPINION" !

    Don't pay attention to the y and z axis in the pick they have been completely redesigned already. Instead of rails I'm using a 4 inch wide quarter inch thisvk steel plate that is used with Cnc router parts carriage bearings.

  19. #19
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    Aug 2008
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    Quote Originally Posted by PaulRowntree View Post
    Ok, perhaps I should not say it won't work ... perhaps that it won't work well?

    It seems to me that building a seriously weak machine ..................... is just a waste of time........... I believe we should build to the best of abilities, budget and materials so the machine is useful...........

    YMMV
    Hey Paul, forgive me for belaboring the point, but I completely understand your position on this. I checked your site out and seems you work in a world of very high precision. I don't....... and many of us beginning work on cnc projects have objectives that don't make extremely high precision necessary at first.

    I only take issue with words that would discourage anyone from any aspect of cnc building. "Won't work" probably should have been "will present some challenges and here are the challenges I would anticipate". Then guys like me are helped and not discouraged by the use of absolutes terms like "won't".

    In the end, you are right if we use your experience, background and environment as the context. But my context says that I have learned a lot with my admittedly imperfect machine that I will pour into my next build. Also, I need to mention that this less than perfect machine I call "Beast" is opening so many doors for me.

    I don't consider this as much a rebuttal as a clarification. I appreciate your insight.

  20. #20
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    Jan 2008
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    Hey Paul, forgive me for belaboring the point, but I completely understand your position on this. I checked your site out and seems you work in a world of very high precision.
    Are you sure you were on my site? I am still trying to beat my chains into submission (but there are good things on the horizon here) :cheers:

    I think we are all on the same page here, with no offence taken or implied. I probably should have expressed myself better (I hope that doesn't sound like Mitt Romney talking). The goal is to get it up and running, making parts and having fun ASAP. And always thinking of Mk2.
    Cheers!
    Paul Rowntree
    Vectric Gadgets, WarpDriver, StandingWave and Topo available at PaulRowntree.weebly.com

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