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  1. #1
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    Jan 2015
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    36

    My 1st CNC build

    Hi guys,
    Thought it was about time that I put up some info on what I have been working on. I always wanted to build a mini CNC and fortunately I was able to start it not long ago.

    So far I'm really happy with how it is coming along. I have had a dial indicator mounted an X axis bearing and ran it across the surface plate. It barely moves by +-0.01mm, so it looks like the plate and everything is running very nicely.
    I had the z axis running just the other day and set the MPG to 1mm and 0.1mm movements, each step moved damn on exactly 1 and 0.1mm on the indicator, I have not even looked into backlash comp. yet too. Hopefully the X and Y are that good!

    Big thank you to the following people who have helped me along the way:

    - Dad, he is the guru when it comes to machining and has been a big help. We have made all the parts on his kingrich mill.
    - Mactec54
    - PeteEng
    - Fox (aka Fox3d on here), I've watched his videos on his granite CNC build about a million times. My machine is heavily based on his!
    - Everybody else on this forum who has taken the time and effort to reply to my questions!

    Here are some details on it:

    Approx. 425 x 425 x 215mm X-Y-Z travel and 250kg machine weight. The enclosure and frame that is sits on is around 150kg.


    Materials:
    - 900x600x100 cast iron surface plate base
    - 50x650x127mm alloy side/riser blocks, the Y axis bearings bolt on the top of these
    - 50mm thick plus 25mm alloy plate between the Y-axis bearings and the gantry.
    - 25mm thick plate for the X and Z axis plates, Z axis will be stiffened with ribs bolted to the edges down the track.
    - Mildsteel welded gantry, filled with epoxy and sand mixed at 25-30% by weight.

    Bearings:
    - THK SHS25 rails and blocks for the X and Y axis
    - THK SHS20 rails and bearings for the Z axis
    - THK BIF2005 ground ballscrews for the X and Y axis
    - THK DIK1605 ground ballscrew for the Z

    Spindle:
    - Jainken JGH-105-2.2 - 4 pole, 400-800Hz, 10,000-24,000 rpm, ER20 - we chose 4 pole unit for the extra torque.
    - Fuling 3.7kW DB600-3R6G-2 VFD

    Electronics:
    - OMC Stepper online, nema24, 24HP39-5004S, 495oz.in stepper motors for Z and X axis
    - 2 x 24HS32-4004S, 339oz.in, nema23 motors for the Y axis
    - DM556T drivers for all axis
    - Meanwell 48V, 24V,12V and 5V powersupplies
    - UCCNC + an AXBB-e controller
    - LAPP Kabel Olflex Classic 100CY shielded cable for the steppers and spindle. - 4x1.5mm2. I found some copper saddle clamps in the plumbing section of the local hardware store which clamp around the braided shield perfectly. Hopefully I don't get any inference issues!
    - BEST Tech. GPenny USB MPG wheel. This has worked with UCCNC really wel so far.
    https://www.aliexpress.com/item/4000288265160.html?spm=a2g0o.order_list.0.0.21ef18 021LoXxU

    Tooling:
    - GSTOOL, BAP400R 50mm cutter and carbide inserts. This works very well so far (in my dad Kingrich knee mill), will be interesting to see if it can run in the jainken spindle.
    https://www.aliexpress.com/item/1005001343354116.html?spm=a2g0o.order_list.0.0.21e f18021LoXxU
    - DGMZNC carbide 3 flute endmills. So far these have worked great. https://www.aliexpress.com/item/33009302932.html?spm=a2g0o.store_pc_allProduct.814 8356.1.13172f0camHre5


    The spindle was only dummy-assembled in this photo, hence the strange mounting arrangement.



    The gantry has a 75x50x6mm inner RHS tube which has 5 x 3mm laser-cut plates/ribs welded to it. I cut slots in the outer RHS so I could then weld the ribs to the outer tube in the hope that it would help to stiffen the whole assembly. I only really did this because I already had the material lying around and it was basically free. I welded 12x30mm bar to it for the X axis bearings to mount to, plus 12mm plates on the bottom which mount to the alloy Y axis bearing blocks. Then I drilled 25mm holes in the rear and filled it with the epoxy-sand mix as much as possible. Even though I used a round bar and hammered the mix into the voids, it still has some empty cavities in there which I found when drilling the holes. Overall it weighs not far off what I expected and sounds very damp when it tap it. The inside area of the 75x50 tube is still hollow, only the voids between the tubes were filled.
    After welding I had it surface ground to give us a nice flat surface for the X axis bearings, then finished it off on Dad's mill.
    The little sample of the mix was simply packed into a plastic spray can lid, no vibrating.


    The enclosure is made from a 9mm MDF inner layer, 30mm gap filled with wool insulation and a 6mm cement sheet outer layer. The doors are the same but with a 4.5mm and 6mm piece of perspex for the windows. Then the inside is painted with epoxy resin for waterproofing. So far it reduces noise quite a bit. I'll get some dB measurements when the spindle is running. I also have plans to tidy up the windows etc. The sealant underneath the windows looks terrible!



    We machined the alloy Y axis blocks together to get them exactly the same hieght, same as the larger 50x650x127 bars.







  2. #2
    Member
    Join Date
    Apr 2004
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    5539

    Re: My 1st CNC build

    Nice build, CR - it looks really solid. Have you run it yet? What are you planning to use it for?
    Andrew Werby
    Website

  3. #3
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    Jan 2015
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    36

    Re: My 1st CNC build

    Cheers!
    I've only had the spindle running on the bench (to run the bearings in) and the Z axis moving up-down a few days ago.

    I still need to machine the ballscrew nut blocks for the X and Y axis, then machine the spindle mount.

    My ultimate goal was to be able to close-deck subaru engine blocks. It'll be a stretch and will see how it goes. Otherwise I'll use it for a lot of car parts, then whatever else I can come up with. My old work has custom machines which require a lot of small alloy cnc machined parts so there is a possibility of some work there too.

    It won't be the fastest moving machine but if it's accurate then we'll be happy!

  4. #4
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    Jan 2008
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    1348

    Re: My 1st CNC build

    Nice build!
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  5. #5
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    Jan 2015
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    36

    Re: My 1st CNC build

    G'day guys, just wondering if I could get some feedback on these vibrations that I seem to get when cutting in a particular direction and area?

    My machine seems to get some vibrations when it passes (roughly) the centreline of the vice, climb milling from the RHS to LHS direction. I have also seen this when machining a fixture plate that was bolted directly to the surface plate/base of the machine. It always seems to happen on the front LHS area of the machine/part. BUT it does not seem to happen when milling from the LHS to RHS.

    Both videos were using the same 8mm carbide 3 flute, 0.8mm WoC x 16mm DoC (bordering on too much I know, any deeper WoC and it was bad).

    Good cut:
    https://youtube.com/shorts/cAslYM_2YnM

    Bad cut:
    https://youtube.com/shorts/RcD5OfxowLw

    Edit: Something that has been on my mind is how the gantry assembly's CoG is directly above the rear carriages and not centered between them. Thoughts?

  6. #6
    Member
    Join Date
    Jul 2018
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    4183

    Re: My 1st CNC build

    Hi CR - Your feed seems to be very slow, what is your feed rate? & your spindle speed? Do you have the recommended chip thickness from the cutter manufacturer? I don't think the GOG of the gantry assm affects this. Get a long steel rod and listen to different parts of the machine eg place the rod somewhere and place the other end to your ear or jaw. You will hear lots of interesting noises enabling location of the one of interest.... Does it do it if wet cut? Peter

  7. #7
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    Jan 2015
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    36

    Re: My 1st CNC build

    Hi Pete, both cuts were done at 1000mm/min (0.8thou chip per tooth but 4.8tenths corrected thickness), 16500rpm. No data from the tool supplier either (aliexpress). I was basically trying to replicate Poitr Fox's tests on youtube as we are using very similar spindles, though different machines.
    The entire machine and enclosure vibrate so I'm not sure i will be able to hear much?


    I am going to machine up a coolant manifold fairly soon so it will be intersting to see how that changes things.

  8. #8
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    Join Date
    Jul 2018
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    4183

    Re: My 1st CNC build

    Hi CR - The rod or long screwdriver will isolate noises and you will learn alot. Re: vibration I'm learning a bit about this at the moment. Your vib is when climbing so could be the tool rubbing vs cutting. chip thickness is equal to [ feed/rpm/N ] which in your case is 0.020mm . This is too thin and can't start the cut when climbing so then slides and rubs. Program your toolpath so you are always conventional milling.

    For a 3F 8mm tool guhrings chart (roughing) says chip to be 0.057mm or 0.057*25.4= 1.45 thou. Guhring has good charts and info on their tools.... Peter
    Attached Files Attached Files

  9. #9
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    Jan 2015
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    36

    Re: My 1st CNC build

    G'day guys,
    I think I have found the issue (or maybe part of it) with my strange chatter. I have noticed that the Y axis stepper motors are vibrating or humming quite a lot when the spindle is on, the Z and X stepper motors do not hum anywhere as much. Also when the spindle is off, there is no humming at all.

    Any suggestions? I've checked the shielding ground clamps on all the stepper cables and the motor, nothing looks out of the ordinary. I have the VFD carrier frequency (F00.17) on 8kHz, the vfd is supposed to go up 16kHz but will not let me go above 8 for some reason.

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