9" Cutting Discs?

  1. Windy Miller Semi-Professional Potterer!

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    Evening all

    Can anyone recommend a 9" cutting disc for the angry grinder please?

    I've only ever used smaller grinders for steel, but I have some 20X200mm mild steel plate to cut into manageable sizes, so I'd rather use the bigger grinder.

    It's only ever been used to cut slabs previously, so I have no clue about discs for mild steel.

    What do you guys use?
     
  2. gaz1

    gaz1 Forum Supporter

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    big grinder might be too much to be honest more so with 3mm discs in them

    ive only attempted doing it with 5" 1mm discs on the smaller grinder as better control

    even with that said i will admit that metal got hot and then you have to be carefull that your blade isnt nipped between the thick pieces of metal it did with me onn the 5" discs and i was only cutting up 3/4" plate steel

    1hr to do it slow and steady to be honest that includes breaks for metal to cool down

    this was only 11" or 13" i cant remember but the smaller cuts didnt take as long

    20170803_170138.jpg
     
  3. grim_d

    grim_d Unlikeable idiot.

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    Plasma cutter and linisher. :D
     
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  4. gaz1

    gaz1 Forum Supporter

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    [​IMG]
     
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  5. grim_d

    grim_d Unlikeable idiot.

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    I don't mind, but my wife wont appreciate you kicking her handbag. :D
     
  6. gaz1

    gaz1 Forum Supporter

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    only because she has you by them all the time :D

    all it takes is a little squeeze and you jump to it :rolleyes:
     
  7. barking mat

    barking mat Barking at Pigeons

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    Any big disks will do the job.

    But if you're not used to a big grinder be careful.

    They bite.
     
  8. Windy Miller Semi-Professional Potterer!

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    Smart 4rse!
     
  9. Windy Miller Semi-Professional Potterer!

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    Yeah I know they do. I have an ancient 7” 110v Makita that is a beast, so I doubt the 9” will be any better! The only think that might tame it slightly is that it’s a Chinese no name so probably not such a powerful motor.

    I would use the old Makita, but the cutting discs that I have are well over 25 years old so probably past their best by now!
     
  10. Hood

    Hood If it walks like a duck....

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    I get Tyrolit discs for doing stainless from my local place and they are decent enough, last time I bought it was £30 for a box of 25.

    For Aluminium I buy ones from Wurth that are specifically for Aluminium and they are good but are quite a bit more expensive.

    Don't ever do steel but the Tyrolit ones are multi purpose so would be fine.
     
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  11. James1979 Member

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    476
    Location:
    Orkney
    Klingspor here. I get the thinnest possible in whatever size - less demand on the grinder, and they seem to last longer. Maybe because they stay cooler (?), dunno.

    Thinnest they do for 9" is 1.9mm so thats what I get. 0.8mm in 115mm (4 1/2")

    Tried SAIT ones the other day. Absolute *****
     
    Last edited by a moderator: Jul 30, 2020
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  12. premmington

    premmington Member

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    +1 for the above...
     
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  13. Hitch

    Hitch Moderator Staff Member

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    Somerset
    If you get the thin 9" one, they should be used with big flange adaptors, not just the normal nuts.
    Hardly ever see people using them, but then moaning the disc wont cut straight.
     
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  14. Windy Miller Semi-Professional Potterer!

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    Thats a very useful tip!
     
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  15. Pete.

    Pete. Member

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    When I was working in the Mersey Tunnel there were a couple of Geordies down under the road cutting out a redundant cast iron main. They were using those 9" thin disks and they were popping the centres all the time. I guess they didn't know you needed adapter flanges either.
     
  16. Hood

    Hood If it walks like a duck....

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    Never use adapter flanges and can count on a single hand the amount of times I have ripped the disc off the centre. I thought I was rough with a 9" grinder but obviously not.
     
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  17. mpats

    mpats Forum Supporter

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    1,120
    Aberdeen
    Must admit I didn't know about those adapters either, I've used a few of the thin disks on the 9inch, might have to get myself one just to be on the safe side.
     
  18. Pete.

    Pete. Member

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    Location:
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    I've blown a few normal 9" discs but usually it's because I'm cutting rebar under tension. These guys were using 9" discs about 1mm thick. I'd never seen them before (or since).
     
  19. Hitch

    Hitch Moderator Staff Member

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    Somerset
    More to keep the disc from wobbling than to stop the middle ripping out... athough the 2 go hand in hand to an extent.


    Flanges like this, I think it should be marked on the disc if they shoul be used.
    It is on Klingspor ones anyway.
     
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  20. Agroshield Member

    Messages:
    805
    How does the tension cause the disc to spoil? If the forces in the member are pulling it apart, the cut will widen as it deepens, helping your efforts.

    I think you mean compression, same as the cast iron main you mention earlier. That probably closed up on the cut, trapping the perimeter of the disc, which means the motor torque overcame the strength of the disc and it bust at the smallest shear perimeter (closest to the middle).

    To the OP. If you have a 7" machine, consider the Abracs Pheonix II extra thin in 7" as they are 1.6mm, thinner than the thinnest 9" disc you will buy*. Flanges also available in this size if desired.

    https://www.abracs.com/products/abr...hoenix-ii-extra-thin-cutting-discs-phoenix-ii

    * it does not seem much, but even on 0.9mm stainless sheet, a lot less than your 20mm thickness, you can tell the difference between a 0.8mm and 1.0mm 5" disk.
     
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