How do I cut hole in stainless steel sink?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Randyj, Jul 18, 2009.

  1. Randyj

    Randyj Master Plumber

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    1,047
    Location:
    Alabama
    Problem: I've got to retrofit a new type of valve in a stainless steel sink in a jail. The old buttons that operate the valves will have to be replaced by new ones which require a bigger hole. So, I'll have to make the hole bigger.

    The only tool I can think of to do this is a knockout punch & die. However, the info says it's only useful on mild steel and aluminum. So, do I try it anyway? Is there a better way or better tool to use?
    [​IMG]
  2. hj

    hj Moderator & Master Plumber Staff Member

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    holes

    Some people use the "stepped" Uni-Bit, but I use those knockout punches you show. They will cut some very thick stainless steel.
  3. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    I doubt those "tornado" or stepped up bits will work... the hole has to be 1 1/4".... anyone else vote for the knockout punch and I'll go with it. I don't want to make a mess out of the sink!!! Even if I tear up the tool after this one job I'll still be happy.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
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    bit

    They make large UniBits which will drill the size you need. The advantage of using one is that they will be automatically centered on the existing hole.
  5. Herk

    Herk Plumber

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    I use a Lenox stepped bit all the time to cut holes in stainless sinks. I wouldn't have thought it would work either until I saw it being done at a trade show many years ago. Unless the jail sink is very heavy it shouldn't be a problem at all.
  6. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    Well, I've already got the knockout kit... so I probably should try that. Since the hole is "D" punched it might be a bit cantankerous with a drill bit but those things definitely do a good job. I guess I'm worried about it because the one I bought is the el-cheap-0 sold by Harbor Freight, carbon steel, not hardened steel like a better quality too might be. But, I have had some pretty good tools from there.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
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    hole

    If the hole is not round, then the KO punch will be better. Try to position it so that there is metal between the die and the mandrel at all points, otherwise it could jam or snap something.
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