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Routy CNC Router (V-Slot Belt & Pinion)

Discussion in 'CNC Mills/Routers' started by Mark Carew, Nov 11, 2013.

  1. Richard

    Richard New
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    First of all thanks for developing a great DIY system and providing some great designs to start with.
    I am a complete newbie to CNC but I have allot of experience making stuff and can use all types of metalworking machines, hand tools etc. I have extensive electronics skills and 35 years experience with computers.
    Right I have a few questions! I want a machine to drill in thin 1.5mm aluminum extrusions and 4mm aluminum rectangular stock. drill sizes are 3.25mm, 4mm and 5 mm. Also 5mm holes in 3mm plexiglass. It would be nice to be able to mill alu as well.
    1) Will this machine do this - I am planning on using the Kress 850 or 1050 spindles.
    2) What accuracy can I get from this machine - I need 0.1mm or better
    3) Is it worthwhile (or will it cause problems) to upgrade all the motors to Nema 32? Budget isnt really a problem.
    4) Where can I get a mounting kit for the Kress spindles?

    I am sorry for all the questions but I work 80+ hours a week and dont have much time to try and work this out, I need to find the answers from people who know what they are talking about and dont want to make any expensive mistakes, like building this and finding out it wont do what I need! Thanks allot!

    richard
     
  2. Richard

    Richard New
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    Sorry, point 3) should be "upgrade all the motors to Nema 23"!
     
  3. David the swarfer

    David the swarfer OpenBuilds Team
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    accuracy,resolution,repeatability
    similar words that mean different things, particularly for CNC machines.
    so....
    accuracy DEPENDS on resolution and repeatability, and ultimately results from the accuracy of the leadscrew, roundness of pulleys for belts, etc
    resolution is a measurement of the size of a step
    repeatability is a measurement of how close it gets to the position you desired.

    At home I have a bunch of M14 allthread, which has 2mm pitch. If I attach a 200step per rev motor I get a resolution of 0.01mm per step (without any microstepping).
    If I use some sort of nice preloaded anti backlash nut I will get near 0.01mm repeatability.
    If I am seriously lucky to get an accurately rolled thread, I might get 0.05mm accuracy, but any wobble in the thread will mean that sometimes 100 steps moves 0.9mm and sometimes it moves 1.02 and sometimes it actually moves the desired 1mm. To get accuracy I'd need a precision ground ballscrew or similar high dollar hardware. To get repeatability I'll need a good antibacklash nut on that ballscrew.

    You may have a high resolution but low repeatability because something is loose or can bend/stretch, has backlash etc.
    you may have LOW resolution and high repeatability because everything is stiff, the leadscrew is precise, the bearing are preloaded, etc etc.

    There are the inevitable tradeoffs too, 'high' anything costs more money, but high resolution will come at the cost of speed and we must ask if we really need high resolution or is it high accuracy and repeatability that we need?

    How high a resolution do we need? I figure something to cut foam and balsa for model airplanes doesn't really need more than 0.1mm resolution (0.0039"). A machine for doing small 3D carvings may be much better with 0.01mm resolution, for big carvings working to 0.01mm may take a long time.

    How much repeatability do we need? as much as possible! (within budget of course).

    And then there is a question of how many decimal digits to output for Gcode.
    If the machine cannot do a step less than 0.01mm, is there any usefulness in feeding it Gcode to 4 decimal places? Intuitively I think it is a waste of time, but as a programmer I say it will depend on which processor is better at rounding while keeping track of real position, the Gcode creator or the machine controller?
    If the controller is LinuxCNC I say let it do the rounding as internal values are 8 byte floating point
    If the controller is GRBL, let the Gcode generator do the rounding since GRBL runs on an 8bit processor with no native floating point support, so any extra resolution will cost processor time, and then be lost anyway.

    this CNC thing is a bit of minefield eh?
     
    Robert Hummel likes this.
  4. mightyevo

    mightyevo New
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    How did you guys go about securing the spoil board?
    finishing up the build, seems a bit loose?
    cheers
    mevo
     
  5. mightyevo

    mightyevo New
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    this is gonna sound like im being difficult here, maybe im just dumb..
    no laughing :p
    here goes..
    screw it to what? im outta tnuts an dont know how else id get screws into the extrusion.
    if this is just me being stupid feel free to point it out.
    always wanted people to think i was special....
     
  6. Robert Hummel

    Robert Hummel Custom Builder
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    If your in a bind maybe measuring, then drill and tap the extrusion with an M5 tap and put your holes in the same places on the spoil board then sucure :)
     
  7. Ceiling Cat

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    Just curious but has anyone tried cutting thin gauge sheet metal with routy? (sheet metal made from steel).
     
  8. mightyevo

    mightyevo New
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    hey, all
    having a lil problem, wondering if anyone can help.
    my x axis has horizontal play in the y direction, it wiggles, even with both eccentric's tightened all the way(the eccentric's for this axis are one each side on the bottom with one normal and 2 normals each side on top right?
    how solid should i expect to get it?
    just now negative Y cuts are great, but positive seems to just skip around on top
    any help would be much appreciated
    mevo
     
  9. mightyevo

    mightyevo New
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    it appears to be the 2 plates connecting the wheels to the gantry, id suspect bad eccentrics but there is 100% no up down movment and eccentrics are fully tightened
    thank you for getting bk to me so quickly
     
  10. Robert Hummel

    Robert Hummel Custom Builder
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    Can you post a picture so I may see what it looks like
    I may be able to help in some way
     
  11. Brian Slee

    Brian Slee Well-Known
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    Mightyevo...I am new here and definitely no expert, but I believe all of your eccentrics should be on the same side and all wheels on the side with the eccentrics should have one. So you should have 3 on one side with eccentrics and 3 on the other without. Someone please correct me if I am wrong.
     
  12. mightyevo

    mightyevo New
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    no problem, here a few from different angles and how its effecting flattening the bed... snot pretty
    let me know if any more angles would be better
    thanks for the help
    mevo
     

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  13. Robert Hummel

    Robert Hummel Custom Builder
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    Your problem is most likely the v wheels, you should be using solid wheels
     
  14. mightyevo

    mightyevo New
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    i dont understand.
     
  15. Robert Hummel

    Robert Hummel Custom Builder
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    If you have no up and down play then it's flex.
    Putting force on the v allows flex

    ->v<-
    putting force in the direction the arrow is pointing at the v flex's the wheel

    I would also remove 2 of the essentrics as they are not needed
     
  16. mightyevo

    mightyevo New
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    the play is back and forth though(like side on for the wheels) which eccentrics are you talking about. i have followed the build pics pretty exact.
    im thinking the eccentrics dont adjust quite far in enough, allowing a little space inside the rail, so when its twisted, the lip of the wheel moves(talking tiny amounts here, but the drill can flex because of it)
    thank you, and hope im not asking too many questions
     
  17. Robert Hummel

    Robert Hummel Custom Builder
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    Your X axis plate looks like your using 4 essentrics 2 top 2 bottom
    Most plates are 2 solid mount with 1/4" spacers and 2 essentrics.
    Another thing could be the wheels are not in full contact on both sides of the groove

    I still think the solid wheels would help with better contact
     
  18. mightyevo

    mightyevo New
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    got er.. well i think i did.
    things got MUCH better when i tightened the belt. unsure if the belt is meant to assist in this maner though....
    thank you robert. took some spacers out(only had 2 eccentrics in) and got a lil play out. even the stuff i didnt use will be kept for later an it helped me having someone right here helping as i went
    cheers
    mevo
     
  19. Robert Hummel

    Robert Hummel Custom Builder
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    No prob, the belt being tighter put force on the wheels and seated them better onto the rail :)
    Good to hear it helped
    Anymore issues feel free to ask and someone if not me will chime in ;)
     
  20. mightyevo

    mightyevo New
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    ok well that lasted :p
    i now have a few mil(1 or 2) "play" on my x axis.
    it wobbles
    like left to right can wobble bout a mil or 2(making the bit able to flex more like a cm or so)
    any thoughts/fixes?
    or do i need more parts
    cheers
    mevo
     
  21. Greenman

    Greenman New
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    Well I finally got going on my Routy build and things are going together well. Impressed with the parts and the fit and finish. The place I feel there is a little room for improvement is in the parts lists and instructions. If I have time I may try to amend the one that is listed with any missing parts. Also with the way my brain works it would be easier to break things down to sub assembles. Robo cuter from the UK has some nice diagrams that helped. Just to let everyone know I am a new Open build parts distributor in New York State just got going and have a limited supply of V-rail. www.opensourceluthiersupply.com
     
  22. mightyevo

    mightyevo New
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    yeah the robocutters page really helped me understand the build so much. renders of the parts in stages and different angles
    and the guys there are really good for any help or questions you haveo
    cheers
    mev
     
  23. bit53b

    bit53b New
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    Just thinking about how I will wire up my own emergency stop.... if I choose to cut power to the drivers, could I damage them, or the motors?
    Don't get me wrong - I know that emergency means just that - no graceful shutdown, and I would rather have damaged motors than damaged limbs - I'm just thinking about how expensive testing might be ;)
     
  24. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    If you have limbs even close to being in harms way when the machine is running, you are doing something wrong.
     
  25. Tweakie

    Tweakie OpenBuilds Team
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    As Robert has said, the emergency stop button should cut all power to the machine and it's associated equipment (spindle etc.).

    From experience, cutting the incoming power to the drivers will not damage the drivers or the stepper motors (what you must never do is cut the power between the driver and the stepper).

    Just as an example, my machine and it's associated equipment is powered through a mains contactor - my emergency stop trips the contactor.

    Hope this helps,

    Tweakie.
     
  26. bit53b

    bit53b New
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    Thanks Tweakie, that helps - much appreciated.
     
  27. remco

    remco New
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    Hi, I am just getting started and read through this thread once. Some things sure did not register.
    For once, is the BOM currently close to reality? I think it does not jive with the sketchup drawing at all,
    but I am a sketchup newbie...

    Should the wheels not all be solid? The hollow v does not make sense to me, since I don't see them support
    the belt so well. What are the advantages of the hollow v?

    The BOM seems to list too few linear rails, and the wrong type? I already ordered according to the BOM,
    but think that I did order wrong stuff, and not enough of what is really used.

    The long dimension calls for a 1500mm length extrusion cut into two 750mm pieces. What kind of saw blade
    are you using? Or are the pieces 1500mm+ to make this possible? Or is it 748mm and nobody really cares?

    Luckily I am not in a great hurry, but I hate wasting money on shipping.

    Thanks to everybody here for their contribution which finally convinced me that it was time to get my feet wet.
    Without it I would have waited (wasted) another year or two...
     
  28. Tweakie

    Tweakie OpenBuilds Team
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  29. GrayUK

    GrayUK Openbuilds Team Elder
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    Hi Tweakie:

    (Just as an example, my machine and it's associated equipment is powered through a mains contactor - my emergency stop trips the contactor.)
    Do you mean you kill all the power to the whole thing? Any chance you could supply an idiots guide to this wiring? I'm reasonably sure I could work it out, but I'd like to be sure.

    Many Thanks
    Gray
     
  30. Tweakie

    Tweakie OpenBuilds Team
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    Hi Gray,


    Not enough time to draw a diagram just at the moment (perhaps next week) but basically it is as follows…

    The incoming mains goes to a contactor (a push button for ON and another push button for OFF) when the ON button is pushed the contactor latches ON and the mains output from the contactor then powers the machine (it is just a big, latching relay).

    My E-Stop is double pole (normally closed contacts) and one pole is connected in series with the contactor’s latching coil – pressing E-Stop breaks the circuit to the contactor’s latching coil, the contactor drops out and all mains power to the machine is removed.
    The other pole of the E-Stop is connected (through the break-out board) to the PC which tells Mach3 that E-Stop has been activated and the running GCode is halted.

    Obviously E-Stop is only used in an emergency (that’s exactly what it is for) as a lot of subsequent effort is required to synchronize G-Code and work position if the job is to be resumed.


    Tweakie.
     

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