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  1. #1

    Join Date
    Oct 2019
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    24

    Kim's - BTW 4x8 CNC Build

    Greetings from North Georgia! This is my first CNC Router build and like Jake I started off designing this in Fusion 360 around Jan 2019 and was the first of April when I pulled the trigger and began to purchase steel and components. This build is not as heavy duty as Jake's as I had some design limitations due to a number of things like garage door frame width is 6' in my basement shop and the landscape of my house is on a very steep hill (aka North Georgia mountains). If I every need to move this machine out of here, I needed to make sure I could dis-assemble it

    I wanted to be able to do cabinet panels, 3D and rotary work with 12" of bridge clearance and handle a 4'x8' sheet of plywood. So, I'll start off with some of the specs:

    All axis are 25mm guide rails
    X and Y axis are rack and pinion
    Z axis is 16mm rolled ball screw 5mm pitch

    X and Y axis are NEMA 34-12.5N closed loop stepper motors
    Z axis is NEMA 34-8.5 closed loop stepper motor
    Coming soon - Rotary axis is NEMA 34-8.5 closed loop stepper motor

    Spindle is 3.2kw ER20 water cooled spindle /w 4kw VFD

    UCCNC Controller Software
    AXBB-E Ethernet Motion Controller
    UCSB single port breakout board

    I completed my build minus a few minor details like nice cover for the ends of tubing, paint touch ups and locking the controller cabinet doors just before this last Christmas. I purchased Vectric v-Carve Pro to start with and they had the 12 days of Christmas designs and I did a few of these that happened to be the first real parts that I cut! I'll start my build log here first with some pictures of the finished CNC router and then continue with the progression of my build from start to finish.

    The last picture I had the whole family (grand kids too!) in the workshop to watch the first part being cut out.
    .

  2. #2

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    Oct 2019
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    24

    Re: Kim's - BTW 4x8 CNC Build

    It all started with me putting up my first drawing on the wall and on to the feet and legs. I used a pair a very large washers and grade 5 bolts and after welding, I chucked them up in a buddy's wood lathe and ground them flat and true. I used .5" plate and welded a nut on the back side and then welded the plate onto the legs. The legs are 3x3x.25 wall tubing.

  3. #3

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    Oct 2019
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    24

    Re: Kim's - BTW 4x8 CNC Build

    Next I laid out the sides, the top rail is 3x5x.25 wall tubing 11' long. I spent hours on the floor, leveling, squaring this out using chunks of 4x4 wood and door shims. You find out pretty quickly and it turns out my concrete floor has a slight slope Tack weld, check everything and weld segments, flip it over weld a segment on the other side just to keep the distortion limited. All my steel came from a steel yard that is packed away in the middle of the woods and it's pretty much what I would call over runs and maybe not quite perfect specs but not in a bad way. For example the 3x5 tubing had one corner radius that wasn't to spec and was slightly larger than spec. But it was straight as an arrow. I prepped all my steel with a flap disk as you can see.

  4. #4

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    Next I laid out the other side, then I tacked on some angle iron pieces to help support the cross bars. The last picture is were I stood the sides up and began placing the cross bars and the beginning of more hours of squaring and leveling. I continue with my build story in the coming days.

  5. #5
    Community Moderator ger21's Avatar
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    Mar 2003
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    34693

    Re: Kim's - BTW 4x8 CNC Build

    Really, really nice. :cheers:
    Gerry

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

    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)

  6. #6
    Member
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    Jul 2018
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    1063

    Re: Kim's - BTW 4x8 CNC Build

    Hi Beartooth - Very well executed build. Enjoy

  7. #7

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    Oct 2019
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    24

    Re: Kim's - BTW 4x8 CNC Build

    Thanks guys! Continuing my frame adding cross bars, tack weld first and make sure it's all squared. All this extra work making sure everything is level, squared up and flat paid off in the end as later in the build you will see when I put the first layer of 3/4" plywood for the table top and surfacing it I only had to take about .050 thousandths off and I got into the first glue line of the ply in a few places.
    Attached Thumbnails Attached Thumbnails IMG_20190405_223444_1.jpg   IMG_20190405_223458_1.jpg   IMG_20190406_195635_1.jpg   IMG_20190406_195647_1.jpg  

  8. #8

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    Oct 2019
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    24

    Re: Kim's - BTW 4x8 CNC Build

    So in my best effort I was hoping not to have to do the epoxy bed for the Y axis rail guides, but it was out about .010 thousandths in the 11' length and it was simply going to be very difficult to keep it flat enough for the rails and bearing blocks. It doesn't take much to put these rails into a bind. So I bit the bullet and put some 24 grit paper in the belt sander and roughed the top of the tubing for good adhesion of the epoxy.

    I found some of the "click and lock" cheap flooring, 8" wide at the big box store (HD) on sale for less than $9 a pack and bought 2 packs and split it in half. I used contact cement and glued it onto the sides to make a moat all around the frame. I also used a smaller piece to take up most of the radius of the tubing, that's why you see a double thickness of the flooring. Silicone sealed it up, then used water to check for leaks. Note, adding some Dawn dish soap to the water and it will flow very nicely, otherwise it will just bead up on the metal and not flow all the way around. Took about 3 times to get all the leaks fixed, but buy then I also knew exactly how much epoxy I needed to mix as I measure the water and measured the depth of the water to make sure I had enough thickness (1/4" thick or a little better is the recommended thickness). It poured beautifully, but I was a nervous wreck doing it and took about 10 days to setup completely, Oh, and you have to use a propane torch to get the bubbles out sparingly. I actually think it gets harder as time passed. The last picture is a shot looking all the way down the 11' with the moat removed and epoxy tapered to the tubing, not a single ripple in the reflection of the epoxy!

    One other thing I forgot to mention, before I did all this, I filled the rail tubing with High Density foam (the stuff they use for fence post and telephone pole now) and added a piece of PVC tubing inside the steel rail tubing for wire conduit.

  9. #9

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    I can't remember who it was that posted the same thing I'm about to here (I believe they were in SC), but here in the south, humidity is something we just have to live with. After about 2 weeks this little bit of cloudiness showed up on top of the epoxy in just a few places. It was not measurable and nor could you feel it, so no harm and carried on

  10. #10

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    Now the beginning of the hundreds and hundreds of holes to drill and tap. In the first and third picture you can see that I tacked on some angle iron on the ends of the right side and strung some music wire and tensioned it very, very tight with some threaded rod double nutted. This wire is what we always called it, but I bought a huge roll of it 25+ years ago that I used to cut windshield gaskets out with when I restored a few old Studebaker's and the countless cars I've painted. Used a feeler gauge as I clamped and drilled and tap the holes in place for the guide rails. Then I bolted a piece of angle iron to a bearing block across to the other side and used a dial indicator to place the guide rail perfectly parallel. I have a video that shows for the full 11' length I'm within .002 thousandths parallel.

  11. #11

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    Next up, I began to mock up the gantry uprights, the angle iron is 5x5x.312 wall, the main upright is 4x4.25 wall and the plate is .500 thick. Not show here but there is also a piece of angle iron that backs up to the gantry that is welded onto the large angle support web.

    Now I realize this design is front heavy, but I built it like this so I could eventually build a swinging angle table at the end so I could clamp/stand pieces on its end for machining, therefore I needed to forward mount the spindle a little. (This is a bit of a copied idea of the Legacy routers which I thought would be useful ). To compensate for this, I really beefed up the uprights, as well as I am using 3 bearing blocks on each side. I can tell you using 3 bearing blocks, the bottom has to be perfectly flat to not bind the bearing on the guide rails. Took hours to scrape and bluing to get this flat, when I welded this up I had it clamped to a large piece of 6x10 tubing and it still distorted some. The rack and pinion is drilled and tap and roll pinned in place. I had the reduction gear box in place to have a gear teeth meshed with a ever slight compression to make sure I had zero backlash.

    - - - Updated - - -

    To be continued.

  12. #12

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    Some how I think due to a planned vacation and not taking the time to takes photos (late nights) each step of the way I managed to only take 2 pictures of a finished gantry. It is made from 4x8x.25 wall tubing and each corner has 2x2x.188 angle iron welded onto the corners. Again this was filled with high density foam and a PVC tube for wiring and oil lines.
    Attached Thumbnails Attached Thumbnails IMG_20190826_232255_1.jpg   IMG_20190826_232309_1.jpg  

  13. #13

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    So my initial design for the Z axis was to use .500" aluminum plate, but that all changed when I was given approximately a 4' x 4' x .75 thick sheet of aluminum plate, so I had to go back to the drawing board.

    Here's the catch, I had to go find it in a field/woods patch of Kudzu (google it), that's right it had been in the shop "field" for gosh knows how many years under a bed of Kudzu. If you anything about the south, it's a good place for snakes as well . I found it though after about an hour and half! And it had very minimal corrosion spots, a few scratches and it was flat as well, I couldn't believe it!! I got it home and spent a couple of hours cleaning it up and in the photos you can see it turned out very well. I have enough left over that I will be building my rotary axis with it too. The last picture of the routing of oil lines actually isn't what it finally worked out to be as the ball screw was to close for comfort, but you get the idea of the oil lines.

  14. #14

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    Z axis assembly is complete here.

  15. #15

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    The painting begins, I really couldn't spray paint this as I would had to cover up my entire shop, so just did it the old fashion way and brushed on with a good oil based brush. I was initially going to use the "tractor" paint that Tractor supply carries as it's a pretty good quality paint, but the gray color they had was a little to dark for me. So I used Rustoleum Gloss white and mixed in some black and made a light gray color and added a little hardener. Then I started to assemble the gantry uprights.

  16. #16
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    Re: Kim's - BTW 4x8 CNC Build

    Hi BT - Earlier you say the epoxy beds are 1/4" thick? Will be interesting on how they pull down and stay down over time. Epoxy is not very stiff. Cheers Peter

  17. #17

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    I had one of my son in-laws come over to give me a hand to put the gantry and the the Z axis together as this was clearly a 2 man job. It was quite exciting as this was the first time to really see it come together as a near complete structure. I spent a lot of time aligning the beast up using all the typical ways to measure. In the end when I dialed in the spindle, I could swing what was about 4 feet piece of angle iron from left to right within .0005 and from front to back at .005 across the top of the guide rails. The full travel in the X axis was .004 using a straight edge across the top of the guide rails. You can't really see but, I used 7/16 grade 5 bolts, 8 on each side (6 in the bottom plate and 2 in the back) for mounting the x axis gantry to the uprights.

  18. #18

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    Quote Originally Posted by peteeng View Post
    Hi BT - Earlier you say the epoxy beds are 1/4" thick? Will be interesting on how they pull down and stay down over time. Epoxy is not very stiff. Cheers Peter
    Yep, I hear you. This stuff is supposed to be designed for machine tools and guide rails, but like you say, I am going to keep a careful eye on it. You'll note that I did the X axis entirely different (and was a design change) and if I have to go back and retro-fit the Y axis I'll do it similar to what I did the X axis.

  19. #19
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    Re: Kim's - BTW 4x8 CNC Build

    Hi BT - They may be designed for setting or grouting a rail but floating it 1/4" above the steel? What is the epoxy spec can you link to supplier? Cheers Peter

  20. #20

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    Oct 2019
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    Re: Kim's - BTW 4x8 CNC Build

    I swear at this point in the build I was wondering if the fabricating would never end. From here on out everything else was sort of designed and built by the seat of the pants as I did not go to the n'th degree for these details in Fusion 360, but was more in my head how I would approach it. Hence it took a little longer to and it was a lot of measuring twice, cut once and weld. Made a few mistakes were I had to make some changes and/or a do over but nothing earth shattering. Here you can see the cable chain trays I made along with attachment brackets for the cable chain.

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