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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 Veteran
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    Neil Rosenberg published a new build:

    Read more about this build...
     
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  2. Mark Carew

    Mark Carew OpenBuilds Team
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    @Neil Rosenberg this is a fantastic looking build and I look forward to your veneer and inlay projects. The inlay is something that has always interested me for arrowhead cases. So I will be subscribed for sure!
     
  3. Neil Rosenberg

    Neil Rosenberg Veteran
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    Thanks Mark. I placed a large order with OpenBuilds today. Only thing in short supply was the eccentrics, hopefully more on the way...

    TTYL!
     
  4. Nick Lancaster

    Nick Lancaster Journeyman
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    Neil, I too am working on a OX direved design. Need to figure out a few more things before I order parts. I do have a question and a concern about your built.

    Would love to know what exactly you are doing for the z-axis rack, where are you getting it?

    And the concernt I have. I think your machine is going to rock and roll, there is going to be alot of stress on those pieces of 2080 that act as the stand for your machine. They are going to cause alot of flexing back and forth the way it is built. I have not had a chance to look at the solidworks files yet, do you have some sort of beams running between them, like the Routy has?
     
  5. Neil Rosenberg

    Neil Rosenberg Veteran
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    Hi there Nick, thanks for the follow-up.

    The z-axis rack and spur gear are from SDP-SI.com, part numbers S1811Y-RC-1 and S1086Z-024S016, cost at single unit qyt is $57.44 and $18.57 respectively. They are both in stock. The spur gear is .25 bore, good for the NEMA 23 motors I chose.

    Also there are three full-length 20x40 vbeams running the long direction, mounted with angle brackets for stability. Here's a screen-shot of the underside (brackets are not yet shown in the model):

    [​IMG]
     
  6. Neil Rosenberg

    Neil Rosenberg Veteran
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    Oh another comment -- the "spoiler board" is going to become a vacuum table. There's a neat video on YouTube by Sean Martin of DonekTools:



    I don't think the vacuum table needs to be as thick as what he did -- there's really not much airflow, in fact almost NONE during operation, otherwise it won't draw down the parts. Mine will probably be about 1/2 as thick as his. I like his idea of putting a sacrificial layer on top, but I'd probably screw it down rather than glue it.

    Also, at about timestamp 6:58 there's great footage of (I assume) his kids helping him build a CNC Mogul CNC router. I almost bought one of those, but there was just too little information on the web page (http://cncmogul.com/) and besides, I really wanted to roll my own :D
     
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  7. Nick Lancaster

    Nick Lancaster Journeyman
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    The CNC Mogul appears dead. No one on CNCZone has recieved any info from them. And I even sent a few emails and got no response. Sad.

    As far as your build. Those ribs should be the same size as the 2080 on the ends. Or mount 2 of them at the bottom and the center one at the top to support the top surface. This would give you a much stiffer machine.
     
  8. CutAboveZ

    CutAboveZ Well-Known
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    Hey, how 'bout sandwiching in the middle 20 x 20 between to MDF sheets, only first cross route some dado channels to channel the air through? :) Then the 20 x 20 becomes the ribbing for the vacuum table.

    I've also read somewhere the shop vac does better, last longer, if you let some air always leak through. i.e. building in a little air leak valve at the far end of the table from the vacuum pickup.

    The Sean Martin, Donek video is great! I LOL when the kids were assembling the CNC Mogul. :D
     
  9. Nick Lancaster

    Nick Lancaster Journeyman
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    Sandwhiching the channel could work, but sealing the ends would be a PITA.
     
  10. Neil Rosenberg

    Neil Rosenberg Veteran
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    I'm playing with different ideas on the construction of the vacuum table, thanks for the suggestions. It may work to have the vacuum box provide most of the long-direction racking stiffness of the machine. Perhaps I'll remove the three lengthwise 20-40's, nestle the box in the open space, and attach to the end rails high and low. Just need to avoid the motors...

    As far as the vacuum itself, that's a good thought to add a "leak" hole at the end away from the hose (I may make it adjustable somehow) -- don't want to burn out too many shop vacs :(
     
  11. Neil Rosenberg

    Neil Rosenberg Veteran
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    Updated model available, now has a start at some of the ideas above.
     
  12. matt_o_70

    matt_o_70 Journeyman
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    Neil,
    Nice work.. I really like the vacuum table feature. Any chance of getting your plates as .STEP (or DWG) files for guys without SolidWorks?

    Or anybody else have experience with good way to convert SLD to IGES / STEP?
     
    #12 matt_o_70, Jan 4, 2014
    Last edited: Jan 4, 2014
  13. Neil Rosenberg

    Neil Rosenberg Veteran
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    I can provide any format that SolidWorks can export.

    I have a few more days of detailing, then I'll post them. Let me know your preferred format please. They will probably import as uneditable but you'll be able to get all the dimensions and details.

    Also FYI there's a free SolidWorks eDrawings Viewer that may allow you to view the models I've already posted. Here's the link: http://www.edrawingsviewer.com/ed/edrawings-viewer.htm

    Neil
     
  14. Mark Carew

    Mark Carew OpenBuilds Team
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    I like the idea of a vac table but I wonder what are you going to use as a spoiler so you do not cut into your table on through cuts? Maybe you could use the 'onion skin method' and leave a little material on the cut that gets trimmed after the cut. I have a large router that uses a vacuum hold down but it has 3 very powerful 3 phase blow motors to pull down with. The pull is so great it actually pulls though 3/4 MDF o_O and holds the sheet. So maybe there is a inexpensive porous sheet medium that will allow the same on a smaller scale.
     
  15. Neil Rosenberg

    Neil Rosenberg Veteran
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    Similar to how Sean Martin (Donek) did it -- drill the current (shown) permanent top with a matrix of holes, attach a sacrificial spoiler of MDF on top, glue and use vacuum as a hold-down. Once dry, re-drill the same set of holes, but this time through the MDF. Then surface skim the MDF in place to true it to the machine.

    The MDF spoiler can be skim machined as needed. When it gets really thin I'll replace it, re-drill and re-flatten to get started anew.
     
  16. Mark Carew

    Mark Carew OpenBuilds Team
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  17. Neil Rosenberg

    Neil Rosenberg Veteran
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    Good thought, thanks.
     
  18. John89702

    John89702 New
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    I have the eDrawings 2014 from Solidworks .. how do i get the dimensions out of the pictures ?? How do i display dimensions of say Gantry Slide Mount B. SLDPRT or the Side Plate<1>, Right SLDASM (read-Only) from the frog ?? i can isolate just the plate but haven't figured out how to get the Dimensions via the eDrawings 2014 software.
     
  19. Neil Rosenberg

    Neil Rosenberg Veteran
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    I am now building the Frog, going well so far. I plan to post some photos soon.

    BTW I have just posted an updated version (1.3), now includes provisions for a belt tensioner for the dual-motor X axis, plus holes in the end plates to allow the belt to "escape". Makes life a lot easier. I'll put up photos of that as well.

    As regards John89702's question, I've been trying to enable measurement in SolidWorks, but no matter what I do eDrawings doesn't seem to see it. I was however able to import the .sldprt files into Inventor 2013 and measure from there. Perhaps other packages can do the same?

    I will be happy to export any of the parts files in whatever format you need (iges, dxf, stl, etc.) -- just say the word.
     
  20. Neil Rosenberg

    Neil Rosenberg Veteran
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    Apparently I need to have SolidWorks Pro to enable measuring, sorry. I have the Standard version.

    In the meanwhile, my offer stands. If there's a request for an export of one or more parts, I'll be happy to provide.
     
  21. John89702

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    Without knowing much, purchased Turbocad Pro V19 it might be able to see .dxf ... google sketchup is free and then there's adobe's .PDF SolidWorks viewer doesn't do much for me.
     
  22. Mark Carew

    Mark Carew OpenBuilds Team
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    Looks great @Neil Rosenberg ! I really love the idea of the belt tensioner
    Great build keep up the good work
     
  23. Neil Rosenberg

    Neil Rosenberg Veteran
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    Thanks Mark :)

    It's coming together pretty fast now. I've already checked the electronics, time will tell if this $58 4-axis Chinese/Ebay driver board will be a boon or a headache. Seems ok for now, but the proof is in the cutting. I already fixed a tiny solder blob on it that prevented 2-directional travel on one of the axes. Mach3 is great with it, easy to set up.

    BTW I'd like to share a bit of feedback with whomever about a few of the OpenBuilds parts. Nothing earth shattering, but perhaps I can help improve things for others. We can take this offline if you like.

    Also I have concerns about the GT2 glass belt for my y-axis. Seems pretty lightweight, I wonder how stretchy it is. Do you have any data? I ordered a Gates polyamide (Kevlar) GT2 belt -- when I get an opportunity I'd like to do a bit of A-B testing vs the glass belt.

    Neil
     
  24. Mark Carew

    Mark Carew OpenBuilds Team
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    I had one of these boards (older blue board) and had problems with it as well. There was a thread over on cnczone where some of the guys went through and fixed the problems but it was pretty intense.
    On the part feedback, shoot me a message if you don't mind
    For the OX build I went to a GT2 (3mm) pitch seems to be a much better belt for cnc work due to its being thicker and the teeth are monster grabbers.
    Looking forward to your first cuts! :)
    DSC03329.JPG
     
  25. Neil Rosenberg

    Neil Rosenberg Veteran
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    Been looking for the 3mm pitch GT2 belts and pulleys, seem to be pretty rare. Do you have a good source?
     
  26. matt_o_70

    matt_o_70 Journeyman
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  27. Neil Rosenberg

    Neil Rosenberg Veteran
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    Thanks Matt, I'll have a look.

    I did my first cutting today, very exciting! Showed me all sorts of things that I need to do better, starting with the right speeds, depths of cut, material stabilizing. I also had to do some revisions in Mach3 to the acceleration ramps and maximum speeds of the various motors to eliminate a bit of jerky motion. I'm running 1/8 microstep on x and y, 1/16 on z. On paper this gives the system .001" granularity or better, but I'll be happy with .01" to .03" accuracy in actual use.

    The good news is that the electronics and software performed flawlessly, and after some fussing with the bit mount (kept wanting to loosen up) I was able to get clean repeatable lines. Every indication is that with good bits and proper speeds it will do quite nicely. However, this is no Bridgeport knee mill; the speed and depth of cut can't compare with an industrial strength machine with leadscrews everywhere and massive frame components. No surprise here.

    I do have some concerns about the lightweight trim router that I'm using, it's a new Horrible Freight model 44914, cost all of $30. It emitted a fairly strong burn smell, but in truth I did abuse it at the start, even stalled it once. I also had difficulty getting it to tighten on a few of my 1/4" shank bits. Cheap is cheap, I guess. It did work well eventually once I got my bit mount and speed/depth worked out.

    Onward!

    P.S. I also see that my grab bag of old routing bits will *never* do -- love the smell of burning wood (NOT!). Anyone have a favorite source for routing bits, good deals, etc?
     
  28. matt_o_70

    matt_o_70 Journeyman
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    Neil,
    I am looking at stepper options and I am curious what is the torque of the motors you are using? You mentioned that you stalled the router.. did you have any missed steps / are you happy so far with the stepper motors you have?

    If you can you post the files for your gantry plates as .STP or DXF. That will allow most anyone to Import them into 3rd party software and generate gcode etc.
     
    #28 matt_o_70, Jan 26, 2014
    Last edited: Jan 26, 2014
  29. Mark Carew

    Mark Carew OpenBuilds Team
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    Congratulations on your first cuts Neil! Always exciting to see a machine come to life for the first time, I never get tired of see it happen.
    BTW just noticed the screw tighten straps on your router mount, this is exactly what I am looking to do on the OX. I just need to find smaller versions (5mm width) to fit in the holes.
    We actually have GT2 3mm belt stock (still working on the pulleys) that needs to be added to the store it should be up there in a day or so :)
    The 20 tooth gt2 (3mm) pulleys we used for testing came from here:http://www.bbman.com/catalog/product/20-3P06-6FA3

    I always like the bits from these guys https://www.drillbitcity.com/

    Once again congrats my friend its all chips in the air from here :D
     
  30. Neil Rosenberg

    Neil Rosenberg Veteran
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    In response to Matt -- the motor I stalled was the router itself (the high speed cutting motor), not one of the steppers. As I mentioned, I had a bit wander out, and it started to gouge the material. It was too much for the weeny motor to handle.

    I haven't yet noticed dropped steps or accumulated error, but I do keep the belts tight and don't try to accelerate the steppers faster than they can handle. That being said, it's early yet. The Nema23's I got are 270 oz-inch, 200 steps/rev, 3 amp. I'm running them at 75% power. Plenty strong, any more than that and the machine would start to tear itself apart if it jammed.

    I'll post the gantry and side plates in DXF by tomorrow, thanks for asking. I will also post a few other custom parts that may be useful. I cut these out of aluminum on a CNC plasma table, then post-machined for accurate holes.

    Mark, thanks as always for the encouragement. Means a lot to know there are folks like yourself who have "been there" and are willing to lend an ear!

    The router mount (with hose clamps) is really rigid, that puppy's not going to move. It was nice that the particular router has a true cylindrical shape, fits into the middle groove of the V-Groove, keeps it aligned. The (4) brackets are plasma cut and bent up, one-screw mount to the extrusion with a Tee nut. I cut the straps into two pieces, looped the cut ends through the brackets, then back on themselves. I also cut off excess length and put electrical tape over the cut end, it's pretty sharp:

    [​IMG]

    For those who may be interested, the belt tensioner is similar in concept to strap tighteners that have been used on backpacks and etc for years. The belt exits from the chassis through a hole I milled into the support plate, once around the slots, and then I tuck a short end back into the chassis, locks on itself that way. The screw tip has been ground into a dull point, fits into the head of the nearby screw (to keep it in place). Here are better photos, one is a screen shot from SW (minus hardware and belt):

    [​IMG] [​IMG]

    Also, thought I'd post a photo of the "drag chain" that I used on the carriage (there are two more under the chassis). I've not used them before, I really like them for keeping the wires out of harm's way. Also, I used Cat6 24 awg cable for the step motors, with like-colored wires paralleled (4x2) for greater current capacity:

    [​IMG]

    Thanks for the leads on the 3mm belts/pulleys (and router bits). I will probably pick up some of the 3mm stuff soon, glad you're adding it to the store. I'll email you separately (as promised) with parts feedback and a few other items you may consider for the store.

    Be well
    N
     
    #30 Neil Rosenberg, Jan 26, 2014
    Last edited: Jan 26, 2014
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