Enlarging and re-aligning holes in stainless steel frame

Discussion in 'Engineers' Talk' started by BuildMore, Jul 7, 2021.

  1. BuildMore

    BuildMore New Member

    Problem: Have a frame made from 2.5 mm stainless steel sheet, with a small trough formed in it, 30 mm wide and 30 mm deep. At the bottom of this trough there are several holes 15 mm diameter. Need to make these holes 22 mm, but also offset them by 5 mm. Frame is fixed in place; work has to be done in situ, not in my workshop.

    - Can’t use a step bit as this wouldn’t move the centre by 5mm.

    - Difficult to use a hole saw as not easy to centre it given the hole is already 15mm wide - can’t clamp another piece of sheet metal underneath and drill a pilot hole into that, could drill some new holes through frame and bolt a strip of metal underneath to create new pilot hole in, but don’t really want two more holes for every hole I need to re-work.

    - Can’t use a Q-Max type punch as sheet material too thick.

    So currently thinking of using some kind of aggressive rotary file/reamer/de-burring bit to widen and re-position these holes. Could fit this into a cut-out tool (like a router, but set back from the workpiece so you can see what you are cutting into…).

    Can anyone recommend a particular bit?

    Can anyone suggest a better approach?
  2. Whitling2k

    Whitling2k Member

    start with a <4mm pilot, then widen it slowly - with 'disposable' bits that are going to get gnarlled?

    How neat and secure does it have to be? Can you just make the original hole even bigger, then hide it with large stainless penny washers or other offcuts? with enough overlap and thick enough to take the load it needs to take of course.
  3. BuildMore

    BuildMore New Member

    @Whitling2k - Do you mean use the <4 mm bit primarily to cut out a crescent shape?

    These are drainage holes with a stainless steel flush fitting outlet (a marine skin fitting) attached to each one, I can't raise (or lower) the frame surface which negates the penny washer approach.

    Making the holes bigger than 22mm isn't an option, the outlet wouldn't seal, plus I'd start getting close to the sides of the trough.

    There are so many rotary files, reamers and deburring bits out there. I am looking for one that is sharp enough to cut out some additional sheet material.

    Ot perhaps there is a tool (or a way) to realign holes easily.
    Last edited: Jul 7, 2021
  4. Abbadon2001

    Abbadon2001 Active Member

    Make a metal jig, that fits in to the trough. Put holes in it, in your desired locations, to act as guides to run a hole saw in without the pilot drill. (Also put holes in the plate it with threads so you can pull it back out again).

    Something like this concept shown by AVE here where he uses a jig to run a hole saw through two metal beams with howhere to put the pilot drill. :

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