Surface Grinder

Discussion in 'Knife Maker Shop Talk' started by KenH, Nov 30, 2017.

  1. currenthill

    currenthill Member

    Thanks!

    Do you strip the abrasives at the splice for the higher grit, which have thinner backing?

    I've seen the technique being mentioned a couple of times when using SGAs.
     
  2. KenH

    KenH Well-Known Member

    Never thought about that - seems like I did read something about that in trying to reduce the bump. That is something you'll just have to try for yourself to see your thoughts.
     
  3. currenthill

    currenthill Member

    I'm pretty new at this milling business. I saw your magnetic chuck which looks nice.

    How do you mill those slots so nicely? What kind of end mill would I use? Full width and several passes to get the depth? A pilot slot with a more narrow end mill and then finish with the correct width?

    Thanks!
     
  4. KenH

    KenH Well-Known Member

    It all depends on which milling machine you have and how much cut it can handle. I used a 3/8" endmill and took full depth each pass. If you're using a mini-mill I'd expect it to handle 3/8", but how deep each cut would be I don't know. If you're using the 10mm width, .375" works out about right - the magnets are not a full 10mm.
     
    Smallshop likes this.
  5. currenthill

    currenthill Member

    Thank you guys for the inspiration!

    I've been looking for a better way of surface grinding, my process today involves my belt grinder, disc grinder and surface plate. But it's time consuming and not really giving me the precision I'd like. So I came across One Armed's build, and then KenH's and knew I had to build one myself. I sourced the parts a while ago but haven't had the time to get it all together. But I managed to get it done today. It was a fun build with a lot of small challenges for a non machinist. I learned a lot making it. Thanks KenH for the tips about milling, I sourced a 10mm 3 flute 45 deg helix carbide end mill made for aluminium, it was like cutting hot butter, even with my mini mill.

    I'm also waiting for some 75x2000 mm (3" x 78") belts. I built the SGA with a 75x200 mm (3"x8") serrated wheel so I can take full advantage of the 60x400mm (2,36" x 15 3/4") magnetic chuck. A lot of my knives are 50-60mm wide. This means I don't have to track the belt up and down for full coverage.

    The components I sourced:

    Magnets
    https://www.aliexpress.com/item/15-...Rare-Earth-Neodymium-Magnets/32398053200.html

    Linear stage sliding table
    https://www.aliexpress.com/item/Man...al-Linear-Translation-Stages/32612615636.html

    Linear slide rail
    https://www.aliexpress.com/item/1pc...ulti-axis-core-linear-Motion/32842691822.html

    Contact wheel
    https://www.aliexpress.com/item/200...isher-Wheel-Sanding-Belt-Set/32381815454.html

    Chuck and plates
    The magnetic chuck is made from AW-2007 aluminium. The holding plate for the chuck and the mount plate for the slide rail is made from O1 tool steel.

    The linear stage sliding table was a little less precise than I wanted. If I were to build it again I would probably get this one instead:

    https://www.aliexpress.com/item/GGP...4-Ball-Screw-Linear-Rail-CNC/32806395029.html

    So I had to take it apart and lap the pieces for a tighter dovetail fit. I now have a runout of about 0.02mm (~0.0008") across the slide. And I decided to get a lot of magnets on the chuck since they're only 4mm. And it seem to have done the trick, the grip is fantastic.

    I also put the two stops at the correct distance for easy tapered tangs, just like Wuertz SGA.

    I decided to build the whole package on the same tooling arm for more rigidity.

    Now that everything seem to be in perfect working order, and with the precision I want. I'll probably make it a little prettier, round some corners, gun blue the O1 and so on.

    Edit: I did the finish work today, so I replaced the pictures with the updated ones.

    Here are some pictures.

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    Last edited: Jan 14, 2018 at 9:57 AM
    KenH and Johan Nel like this.
  6. JawJacker

    JawJacker Well-Known Member

  7. KenH

    KenH Well-Known Member

    You did exceptionally good with your build. Clean and works well I'm sure. Congrats on a job well done.
     
    currenthill likes this.
  8. currenthill

    currenthill Member

  9. currenthill

    currenthill Member

    I did the finish work today, so I updated the pictures. The only thing missing now is the 3 inch belts, they should arrive this week.
     
  10. KenH

    KenH Well-Known Member

    You did really good with that build, and good with the photos. I especially like the contact wheel mounted to the tooling arm. Since I saw OBG's setup with his contact wheel mounted to contact arm I've been thinking about doing the same thing. BUT - I'd have to resurface my magnetic chuck. Due to the slop in the tool arm holders when my system is mounted the magnetic chuck wasn't exactly square to the contact wheel. Once I surfaced the magnetic chuck it's now square, but I'm not sure the "slop" will come out to exactly the same every time. I might just move my contact wheel to the tool arm like you've got. I do think that's best.

    Again, GREAT JOB!

    Ken H>
     

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