Drilling Holes In 3mm Galvanized Steel.

Discussion in 'Engineers' Talk' started by Johns1980, Nov 27, 2022.

  1. Johns1980

    Johns1980 Member

    I'm thinking hole sizes from around 8mm - 25mm. I have a decent quality, newish, floor standing pillar drill. What are the best type of drill bits to use and technique of drilling, speed to run bits, will steel heat up, deform? Cutting fluid type, using it, better to drill smaller hole first, then larger?
    " drill smaller hole first, then larger ", speed to drill at? This in relation to different drill sizes?
    Will I get a nice clean hole?
    I'm drilling a 300 x 300mm sheet.
    Any help advice appreciated.
  2. WillyEckerslike

    WillyEckerslike Screwfix Select

    I think my first choice would be a decent step drill.
    Abbadon2001 likes this.
  3. Muzungu

    Muzungu Screwfix Select

    The first formula I was taught when I started my City and Guilds was the cutting speed calculation; n=1000s/pi*d , stayed with me!

    Any way, for anything under 5 mm steel I would set the pillar drill at high speed, 2000 rpm or so. 25 mm you should be taking the speed right down, something around 400 rpm and use plenty of oil. This is for a standard HSS drill bit.

    Johns1980 likes this.
  4. arrow

    arrow Screwfix Select

    I would use a Starret cutter for the larger holes.
  5. Bob Rathbone

    Bob Rathbone Screwfix Select

    On low speed with plenty of coolant.
  6. Johns1980

    Johns1980 Member

    OK thanks for the replies.

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