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  1. #1
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    Jun 2010
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    First half-decent machine build attempt

    Ok, first a little background. I am in college, always get started on projects over breaks, then they fade out over the semester. Anyway, a couple years back, I bought some random linear bearings and some odd assemblies on ebay and threw them together on a wooden frame just to get some satisfaction of a 'cnc machine'. It's been sitting in my basement collecting dust ever since.....

    So, this winter, I got hooked on the idea again that I am going to make a mill that might actually be able to do some work.

    Goals:
    1) Design a small machine that can mill some small aluminum parts.
    2) Use what I have previously purchased, but let a little money out so I can actually build a decent machine.
    3) Try to keep cost low.


    Well, goal 3 is going to be an issue, since I'm already over $500 and don't even have a frame built (or a head assembly), but it could be worse. I've sold some things to offset the cost, anyway.

    In the spirit of keeping things cheap, I'm using SBR16 supported shaft rails for the X/Y table motion.
    For the Z, I had 17" long 5/8 thomson shaft with 2 precision steel bearings. I cut the shaft in half, bought two more bearings and 4 pillow blocks to press the bearings into. Not sure if this is going to be too small of travel yet.... I think I can only squeeze 2.5 to maybe 3" of travel out of it (thinking off the top of my head without the shafts in front of me).

    I scored a pair of 18" big ballscrews with timing pulleys on the end off ebay for a good price, and they seem in great condition, so I will use them for the X and Y table motion.

    Here is the current lot of parts, with the Y axis semi-assembled on 1/4" 8x18" aluminum plate. The 'saddle' plate is just a 1/4" 6x8" plate right now. I will probably beef up that saddle, just trying to decide if I need different dimensions. The X will be similar, except only 6" wide if I keep the current plan. This should allow a decent work area table for small stuff.



    You can see the screw and 6x18" plate on the right. On the far left, you can kindof see a small ballscrew assembly that I might use for the Z axis, the only problem I have is that it is, I think, 1 TPI, and I am not planning on using $200 stepper motors.

    I have received the second set of linear shaft bearings, so I will just set it together later and take a pic for you to see what my plans are. Currently I just want everything together so I can see how this will work out.

    I'm having trouble designing a frame though. Really can't decide which approach to take. I was inspired by Leeway's 8020 build. Steel tubing (possibly filled with something) may be a cheaper option though. I'd like to stay away from having things welded though...
    I was also looking at the possibility of purchasing the 'solid column' replacement from LMS to use, and possibly the mini mill head assembly to bastardize and try to put a makeshift belt-drive on until I could make brackets. I'd like some thoughts/suggestions on spindle and column ideas if you have any.

    Anyway, more to come...

  2. #2
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    Mini update: Received new dial indicators and new set of linear rails. Too much other stuff to do tonight, so I will update you with more visuals tomorrow afternoon.
    Still looking for suggestions on a mill head and column. I found sherline headstocks that are cheap, but aren't they for even lighter work than the x2 spindle? Pretty sure I'll just end up with an x2 head. Anyone happen to know the dimensions of the bolt pattern on the back of the x2 spindle housing?

  3. #3
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    Ok, laid out the X axis. Will drill and bolt together tomorrow for a test. I ordered a Chinese 800w water cooled spindle to start with. Still need a vfd though... Probably will pay more for a vfd than the spindle lol.

    Pics of x/y axis attached.
    Attached Thumbnails Attached Thumbnails C360_2013-01-17-17-30-07.jpg   C360_2013-01-17-17-29-51.jpg   C360_2013-01-17-17-29-35.jpg   C360_2013-01-17-17-29-26.jpg  

  4. #4
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    I've been delayed a bit with other responsibilities, and the fact that I've ordered more parts that I want to wait for. I've scored a large base with blanchard ground aluminum flat top from eBay that I will use to bolt the column to.

    I have purchased a piece of 3x6" 8020 extrusion for the column, as I've seen it work well in Leeway's build. I have also ordered 8 1/4-20 threaded rods to go through the extrusion holes into the base plate. I will probably also purchase an angle plate to square up and support the column as Leeway did. Then I can possibly fill it for additional rigidity in the future.

    I've also purchased a few pieces of aluminum plate to put together my z-axis. Currently, everything is ordered except for a VFD for the spindle. I'm thinking of going with a Teco EV series 1hp since it is affordable and can run on 110v. My panel is full and can't run another 220 line..

    Well, I'll have progress pictures sometime this weekend i'm sure.

  5. #5
    Looks good similar to what I have built. I used an X2 head, treadmill motor and KBMM controller.

    IMHO I would only use allen headscrews its easier to use and they tighten up well without stripping, unlike philips head screws. They are easier to remove in tighter places as well.

    Good luck with the build!
    www.VicRC.com

  6. #6
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    Thanks. Yeah, I'm going to buy some allen head screws. I have an 800W chinese spindle, but no VFD, so I might end up just getting an X2 head to start and wait for a good deal on a VFD to come along since for the price of a VFD I could almost buy the X2 head... What are the dimensions of the X2 head? I do have a treadmill motor too that I could probably do a belt drive.

    Anyway, I received everything I've currently had ordered now I think. More aluminum plate, 3x6 aluminum extrusion, and threaded rod to go through the extrusion. Here are some pics of the pieces that will become the Z assembly, the column, and overall how it will basically fit together.

    When I was putting the X axis on top of the Y I was thinking maybe it would be better to have the rails bolt to the saddle of the Y axis and have the table on the bearings on top, instead of upside down. Although I think it looks neater upside down (X axis bearing blocks bolted to saddle plate, rails upside down bolted to table). I have pics of both, What do you think?
    Attached Thumbnails Attached Thumbnails s3NZunJ.jpg   EMebtsL.jpg   WHXUrEI.jpg   AOwzuXh.jpg   XtonsaS.jpg  


  7. #7
    When I built mine, I opted for the first option because
    1 - you get larger table
    2 - the pillow blocks are always under the tool spindle head so its always supported
    3 - because of 2 you don't need to space the pillow blocks further apart and you will get more travel on the X.
    4 - if you went with the smaller top you will have to cover the ballscrew with some covers left and right of it.
    5 - you wont need a second aluminum plate as you can mount the pillow blocks directly on top of the Y platform ( you can use that top plate for the Z mount instead)

    I have seen many others try the smaller top option and I still dont know why.
    www.VicRC.com

  8. #8
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    Those were my thoughts as well, and probably what I will go with. I still plan on using the two 1/2 plates, that way each axis will be assembled and simply bolted together. It should allow for some adjustment/shimming if necessary to square the table up also. Unless I take a look at it again and think it will be easy to put it all on one plate and change my mind again. :P


    I'm looking more and more into using an X2 spindle assembly from littlemachineshop and running it with a treadmill motor. Any thoughts/suggestions for other cheap alternatives?

    Edit: In looking around, I'm thinking a Taig spindle would provide better precision than the X2 spindle, while still allowing tooling up to 3/8. It is also easy to mount and easy to mount a motor to. I think I can get the spindle, mount adapter, pulleys, belt, and motor mounting hardware for ~$160.

  9. #9
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    Smallish updates:

    Drilled holes in the base for the 8 threaded rods through the column. Drilled the large holes in the end plates for the Z axis assembly. Taig spindle has been ordered.
    Attached Thumbnails Attached Thumbnails I0Qwxw5.jpg   cxyWhSR.jpg  

  10. #10
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    Ok, weekend again, so I might work on a few things. Yesterday I put together the motor mount for the taig spindle and an old treadmill motor. I used a thick piece of sample 'plastic lumber' that has been laying around for years and a steel angle bracket to sturdily attach it to the taig spindle. The motor had a bracket that has an adjustment for belt tightness already, so that made things easier. I tested it out and it seems to run smoothly and quietly with quite a bit of torque on the low speed pulley! Should be good to start, anyway.
    Attached Thumbnails Attached Thumbnails spindle1.jpg   mchsMlC.jpg.jpg   sVXozhZ.jpg  

  11. #11
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    Another weekend, a little more progress.
    I've mostly assembled the Z-axis. Just needs a bit of tweaking and counterboring some of the holes for the screws. The rods are just a slip fit into the end plates so I put set screws in through the sides. It all feels pretty rigid.
    Attached Thumbnails Attached Thumbnails yz-front-top.jpg   yz-front-bottom.jpg   yz-side.jpg  

  12. #12
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    OK. Three axis are assembled. Just need to tweak the alignment and add the table top. I already fooled with it to elongate the ballscrew nut mount holes on the X axis saddle plate, and once it was all together I cut along the back edge of the top plate. Seems to cut well (for using a used endmill and moving the axis by hand).

    Next step is to mount the motors. I already have holes drilled and tapped in the top plate for the X axis motor. Just need to drill and tap the base for the Y motor mount also. The Z, I'm not really sure how I will end up mounting that motor. I would like to do a belt drive like the other axis since the Z screw is about 1 TPI.
    Attached Thumbnails Attached Thumbnails nRJ70U7.jpg   k9Zor21.jpg   m6zaW00.jpg  

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