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The Frog CNC Router

Discussion in 'CNC Mills/Routers' started by Neil Rosenberg, Jan 3, 2014.

  1. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Here's some photos of the leadscrew refit. It also updates various other aspects, such as the dust boot, vacuum table, cable runs and etc. The Z-axis is still rack and pinion, works fine. The last two photos show it with and without the dust boot. BTW the vacuum table works great as long as I block any un-used holes with plastic sheeting. All of the brackets are .1" thick steel, quite stiff enough for the job.

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    #121 Neil Rosenberg, Dec 14, 2014
    Last edited: Dec 14, 2014
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  2. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Hi Justin and thanks. I used 8-wire ethernet cable (24awg), with four pairs of two wires each doubled for increased current capacity. Never had a problem running about 3a max step motors, but of course the average current per motor is much less.
     
    #122 Neil Rosenberg, Dec 14, 2014
    Last edited: Dec 14, 2014
  3. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Not sure which parts are "wiggly", but I used standard modular RJ45 connectors which are gold plated and have spring loaded contacts. I've found them to be pretty vibration and tug tolerant, same as that used with Ethernet and phone jacks.

    My biggest concern was current capacity, but even after extended cutting my wires are still cold to the touch, unlike the motors.

    I did not invent this, it's what the (now defunct) maker used on my plasma cnc table. Works well there too, even with all of the sparks flying! (BTW he's defunct for other reasons.)
     
  4. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Starting the next aspect of this project, converting the z-axis to leadscrew as well. Will post photos soon as the project progresses. I'm also adding a carriage stiffener that does double-duty: reduces whatever racking the two-plate carriage exhibits, plus provides vertical support for the z-axis motor.

    You'll see it all in the photos, but here's a couple screen shots of the Solidworks model:

    Z-axis Update.JPG Z-axis Update 2.JPG
     
    #124 Neil Rosenberg, Dec 28, 2014
    Last edited: Dec 28, 2014
  5. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Z-Axis now leadscrew, please see YouTube video at:



    Enjoy!
     
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  6. Tweakie

    Tweakie OpenBuilds Team
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    Excellent :thumbsup:

    Tweakie.
     
  7. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Thanks Tweakie! Here's a photo of the "new" z-axis, now with a laser crosshair:

    2015-01-11 15.06.10.jpg

    Notice my very high tech Altoids can for the LED batteries and on/off switch :duh:

    OK I'm cheap.
     
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  8. Tweakie

    Tweakie OpenBuilds Team
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    That's neat - I like hi-tech solutions. :D

    Tweakie.
     
  9. Hytech2k

    Hytech2k Veteran
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    Nice idea !! I like the crosshairs, bet it helps alot setting 0,0...
     
  10. Neil Rosenberg

    Neil Rosenberg Journeyman
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    Thanks. It was a pretty easy update, good for basic alignment of the workpiece. Came in handy immediately. Lines are a bit wide but good for $6 emitters, particularly since my goal was to get within 1/8 inch or so.
     
    #130 Neil Rosenberg, Jan 12, 2015
    Last edited: Jan 13, 2015
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  11. Tweakie

    Tweakie OpenBuilds Team
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  12. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Neal, I have a couple of quick laser questions which show my level of ignorance. Are these lasers strong enough to require glasses? And any idea if the $1.99 bicycle lasers could be hacked into such a system?
     
  13. Neil Rosenberg

    Neil Rosenberg Journeyman
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    I'm not familiar with the bicycle lasers, not really sure what they're for, except to draw someone's attention.

    I wouldn't look directly into the light of any laser, even the low-power ones. I don't think there's any danger looking at the reflected light from these really little ones, as long it's not from a mirror.

    Here's a link to the Ebay auction that I bought them from:

    http://www.ebay.com/itm/150828205147
     
  14. Neil Rosenberg

    Neil Rosenberg Journeyman
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    No problem, and good question. There are two single-line emitters mounted at approximately 90 degrees separation around the spindle center. The most important aspect is that the leds are mounted in holes that are parallel to the motion of the z-axis so the intersection won't wander as you move up/down in the z-direction. After mounting, you rotate each led so they intersect as nearly as possible where the spindle center is located. It's easier than it sounds.
     
  15. sgspenceley

    sgspenceley Veteran
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    Hi Neil, I'm thinking about doing leadscrew mod similar, my machine will never be a long Y bed, so I think your approach is worth more investigation.

    The bearings on the end of the Y axis, as the screw turns what prevents the axial movement. I had always "assumed" end bearings would take the axial load not just the rotation. Did you just add a collar which is tightened down on the leadscrew to take the load like the openbuilds Z axis?

    I was thinking about mounting the lead screw much lower down. Any specific reason why yours is mounted high?
     
  16. Rhinofart

    Rhinofart New
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    Where did you get the lead screw stuff from? I'm looking to update my OX to lead screws as well.
     
  17. sgspenceley

    sgspenceley Veteran
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  18. Rhinofart

    Rhinofart New
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    Sadly mcmaster doesn't ship to Canada for some weird reason. :(
     
  19. sgspenceley

    sgspenceley Veteran
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    Ah... Same issue I also live in Canada. So I will have to find a workaround because I cannot find them easily in Canada. I found the bearings, and cncrouterparts does the lead screw nuts.
     
  20. Steve123

    Steve123 New
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    I purchased three 5 start 1/2" 6' long lead screws from McMaster last October. Our company orders from McMaster every couple of weeks and we are in Ontario. We have all our USA shipments freight forwarded across the boarder every few weeks, saves on brokerage and shipping. Are you guys in Ontario?
     
  21. Hytech2k

    Hytech2k Veteran
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  22. sgspenceley

    sgspenceley Veteran
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    Thank you Steve123 & Hytech2K.
    Steve123, yes I live in Ontario, near Parry Sound but down in Toronto every week.
     
  23. Neil Rosenberg

    Neil Rosenberg Journeyman
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    I saw Sgspencely's questions about my leadscrew retrofit.

    Yes, I do have lock collars in strategic locations on the leadscrews to prohibit axial motion, using the sides of the bearings as the limits. I can post pictures if requested.

    Since I capture chips and dust with the dust boot it has not been a problem to have the leadscrews up high and exposed, and doing so made it much easier to add to my design. It also puts the drive points closer to the center of mass, thus reducing the moment arms.
     
  24. sgspenceley

    sgspenceley Veteran
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    Hi Neil thank you for the quick reply and the explanation. I guessed you must have a good reason for this design decision.

    I had assumed centered in-between the wheels vertically on the y axis would be better for movement?

    How well do the anti backlash nuts work?

    It's a toss up between your mod vs hyteck2k

    If you had to do it again, what design changes would you make?
     
  25. Serge E.

    Serge E. Journeyman
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    Did you see the price of the matching nut ? Nearly twice that of the 6' length. Still, not that bad where one gets better precision and repeatability of movement.

    Man, myOX will never be done at this rate ... there always seem to be a better way just around the bend. :rolleyes: Stay on course, stay on course, stay on course, ...
     
  26. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    The nuts and collars from dumpsterCNC and Ebay are far more reasonable.
     
  27. Serge E.

    Serge E. Journeyman
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    Cost of shipping might make it near even (at least to my end of the world) ... not to forget it's brass vs delrin for the part. But definitely alternatives to consider.
     
  28. Rhinofart

    Rhinofart New
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    @Steve123
    I'm in British Columbia. Bout 4 hours North East of Vancouver. I won't do Ebay / Paypall for my stuff as I have an Anti-Fraud suit against them and a scumbag in Spain who ripped me off over $1200
    @Serge E.
    I know exactly what you mean! Just when I think I've completed the build, I come across something else shiny to add to it!
    @Rick 2.0
    Thanks for the tip on dumpsterCNC!
     
  29. Serge E.

    Serge E. Journeyman
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    I'm this close || to taking myOX completely apart to try anodizing given the recent info shared here. It looks so easy, aside from having to strip and rebuild the machine :duh: It might be easier just to get more parts and build a twin or baby myOX ... Maybe go broke and prep for myOX 2, the next generation ?
     
  30. Neil Rosenberg

    Neil Rosenberg Journeyman
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    I've been using the anti-backlash nuts from Dumpstercnc with very good results.

    For motor adapters however, I strongly prefer the flexible couplers -- search on Ebay or Amazon. The ones I am using have a 1/4" bore on one side and 1/2" on the other. They have a slight rotational springiness, I suppose it could introduce *very* small errors on harsh cuts, but they go a long way in protecting the motor bearings and smoothing out any misalignment.

    Thinking about your question, what would I do differently to the Frog ... here are a few things that come to mind:

    1. I would use a much stiffer cross arm for the gantry. I really thought a pair of 20x60 vslots (screwed together) would be stiffer than they are, rotationally. This is one of the biggest contributors on this machine to unwanted flex. I'd probably go to a pair of 20x80s or maybe three 20x60s. BTW it's REALLY important to tie them together along the length so that they act as one larger beam rather than 2 or 3 smaller ones. I drilled through laterally in the web and bolted them in a few places. Helped a bunch!
    2. As cheap as the Harbor Freight trim router is, it gets bogged down with any significant cuts. In actual fact, it's ok for this (currently) lightweight router system, but if was building a beefier unit I'd probably switch to a higher strength cutting motor.
    3. The vacuum table has been great, but I will likely add some threaded holes to it so I can use conventional clamps when desired, and leave the vacuum system off.
    4. Changing bits is a chore. I'd like to find a quicker way to swap in/out cutting bits, something that doesn't break the bank.
    5. I'd like to be able to visualize the cutting location with the vacuum boot in place. I'm thinking of mounting a very small video camera and led light near the cutter and inside the boot to display on a nearby mini TV. Hmmm, maybe I can use an old smartphone...
    6. The Openbuilds plastic wheels are OK, but not super. In retrospect for each movement I'd prefer to use steel V-rollers on steel rail(s), and have a self-aligning adjustable two-wheel rocker on one side. This would eliminate the need for all those small-motion eccentrics, be stiffer in operation, and end up much less finicky to adjust. In my current design there's always one or two wheels that aren't doing very much.

    That's it for now.
    Neil

    P.S. 1/2-10 5 start acme leadscrews are really cheap just now on McMaster, only $17 plus shipping for a 6 footer! I paid over $60 just a few weeks ago for the same thing.
     
    #150 Neil Rosenberg, Jan 22, 2015
    Last edited: Jan 22, 2015
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