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  1. #1

    Scrap built cnc/manual surface grinder

    Hello,

    I am building a cnc surface grinder (very light duty) that I can also use as a manual machine. The goal is to finish my parts which come off the cnc mill and maybe do some experimenting. The goal of the machine is to take light finising passes and to smooth out the machining marks on the parts. Taking off 1-3 thousanths(0.0254 to 0.0762mm) per pass is what I'm looking for .
    I'm on a very strict budget and the machine frame is made from scrap material or material that I got for a very good price. After welding, I will also have it stress relieved (got a friend to do it).

    X-AXIS

    The X-axis is riding on MGN09 rails with MGN09CA carriages ( 6 of them). The rail length will total 990mm, the main mounting plate will be 1050x180x15mm, made from S355J steel.

    Y-AXIS

    The y-axis is riding on HGR15 rails with HGH15CA carriages (4 of them). The rail length will be 400mm. They will mount to the base frame.

    Z-AXIS

    The z-axis will be custom made and will essentially be a box-way(although very much flimsier compared to real ones). The z-axis spindle carriage will slide on a Teflon /PTFE surface, 2mm thick.

    SCREWS

    All screws are based on TR12x3, with anti-backlash nuts. Considering the light duty the machine is running I did not see it important to put ballscrews in there.

    ELECTRONICS and MOTORS

    Motors will be NEMA 23, probably 1.26 or 1.89NM ones, breakoutboard combatible with Mach 3.

    I'll post more pictures and stuff when it comes available

  2. #2

    Re: Scrap built cnc/manual surface grinder

    Found some more pictures and a video too - beware, a lot of rambling



    As you can see from the pictures, the design has changed quite a bit already.

  3. #3

    Re: Scrap built cnc/manual surface grinder

    Hello people, I've been working on the surface grinder and a bit more has been completed - the second video about the build is now ready and uploaded


  4. #4

    Re: Scrap built cnc/manual surface grinder

    Hello people - an update on the surface grinder build. I decided to tackle the biggest mill job first - since I'm only learning the machine and program (and the part was 2x the reach of the machine on the X axis). It turned out really nice and so far I''ve spent about 4-5 hours on the machining alone (i'm guessing another 3-4 to go). Enjoy the pictures - next video coming soon.
    Thanks for reading

  5. #5

    Re: Scrap built cnc/manual surface grinder

    More updates - things are moving along, although they are taking longer than expected. I'll try to post more updates soon

  6. #6
    Registered
    Join Date
    Jul 2005
    Posts
    161

    Re: Scrap built cnc/manual surface grinder

    Interesting build - don't see many people here making surface grinders! Best of luck with your build.

    I hope you have made provision to cover your rails thoroughly - grit getting on them will make them wear out very quickly, otherwise. We use surface grinders at work, and they are messy tools - lubricant mist mixed with abrasive from the wheels and very fine grindings from the part make an abrasive mud. You will also need to design a coolant return/filter.

    Another concern is the Z column. If you can, I'd suggest making it even more robust. The sturdier it is, the more it will resist vibration, so it will give a better surface finish.

    Just my $0.02.

  7. #7
    Gold Member
    Join Date
    Feb 2009
    Posts
    6021

    Re: Scrap built cnc/manual surface grinder

    Wow, too bad you weren't closer, we have an old Harrig surface grinder with magnetic chuck you could have had for cheap.

    Sent from my A3-A20FHD using Tapatalk

  8. #8
    Gold Member
    Join Date
    Feb 2007
    Posts
    4556

    Re: Scrap built cnc/manual surface grinder

    Where is the grinder located?

    Quote Originally Posted by underthetire View Post
    Wow, too bad you weren't closer, we have an old Harrig surface grinder with magnetic chuck you could have had for cheap.

    Sent from my A3-A20FHD using Tapatalk
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  9. #9
    *Registered User*
    Join Date
    Jul 2014
    Posts
    194

    Re: Scrap built cnc/manual surface grinder

    Quote Originally Posted by Roadsidejobshop View Post
    More updates - things are moving along, although they are taking longer than expected. I'll try to post more updates soon
    Good luck with this project. I find it interesting and I hope that you are able to obtain the tolerances you need with it. You can always fill the z column with rebar and EG and add additional external bracing to make it stiffer and more vibration resistant if you need to. I think that one of the greatest challenges will be to build an good low vibration spindle bearing for the grinding wheel and make it low enough in mass so that the vibrations are held in check by the Z column structure. Although mounting an inexpensive portable hand grinder is an option, I doubt that you will be able to get very good surface finish with that approach. If that is what is needed. Air bearings would probably be ideal for the grinding spindle if you have access to a lathe that can do pretty close tolerance work.

  10. #10

    Re: Scrap built cnc/manual surface grinder

    Hey DSpeck, all types of currency are accepted, even canadian 2 cent coins

    - I am planning on putting a pretty well sealed accordion types bellows on top (since I'm planning on using flood coolant). Coolant filter-separator I am going to buy off-the-shelf(reasonably priced).
    - the whole z-axis looked much much better in the model, not so good in real life. I'm planning on building a replacement z-axis tower assembly in the near future, but I will use the current version to make sure the machine works.The z-columns is pretty heavy though - about 25-30 kilograms and it will be filled with epoxy granite later on(so closer on 50kg for the column itself alone).

    The whole assembly weighs about 120 kilograms and while filling it with epoxy granite will increase the weight to almost 200kg, it's still pretty light. But I also watch a lot of guys on youtube who have huge heavy machines, yet take 1 thousands deep cuts per pass. I find it really strange that machines that handle easily 10-15 thou per pass are being so underused

  11. #11

    Re: Scrap built cnc/manual surface grinder

    I've currently spent less than 50 euros on the whole machine build ... being poor is not nice LOL. I find that building this machine is teaching me a lot of important things about machine design, parts selection etc. Also, since I'm moving back to my home country in about 4-5 months, I have to keep the machines in a manageable size - no 2 tonne machines allowed

  12. #12

    Re: Scrap built cnc/manual surface grinder

    Alright, some updates: the original frame was too difficult to work with and after running through simulations I decided to build a completely new machine frame for the surface grinder (which should be much easier to set up after mounting rails). The original frame will be repurposed as a small CNC mill frame, used to mill my aluminium pieces. So I'm including many many pictures here and a few videos as well. I'll do a more in-depth video in a few days.


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