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Hole saw for drilling through an RSJ?

  • 13-10-2010 8:07pm
    #1
    paddy147
    Banned (with Prison Access) Posts: 15,858 ✭✭✭✭


    Can anyone tell me what would be the best type of hole saw for drilling through an RSJ beam/girder.

    Need to get a 20-22mm hole drilled through an RSJ in order to get a power cable installed.

    Thanks.:)


Comments

  • #2
    Buford T Justice
    Registered Users, Registered Users 2 Posts: 6,262 ✭✭✭Buford T Justice


    paddy147 wrote: »
    Can anyone tell me what would be the best type of hole saw for drilling through an RSJ beam/girder.

    Need to get a 20-22mm hole drilled through an RSJ in order to get a power cable installed.

    Thanks.:)

    None, You'll need to hire a Mag Drill (Magnetic Drill) from a tool hire shop with the appropriate bit to broach the steel. Regular bits won't do it.


  • #3
    paddy147
    Banned (with Prison Access) Posts: 15,858 ✭✭✭✭paddy147


    Fingers McGee wrote: »
    None, You'll need to hire a Mag Drill (Magnetic Drill) from a tool hire shop with the appropriate bit to broach the steel. Regular bits won't do it.


    Problem is that the RSJ is allready in place and floor boards above it are lifted to run the power cable.

    the plumber put a 20mm hole through another RSJ in my extension a while ago,using a hole saw,but he went through 2 20mm holes saws to make the hole in the RSJ.


  • #4
    aujopimur
    Registered Users, Registered Users 2 Posts: 3,953 ✭✭✭aujopimur


    A 22mm hole is possible with a standard holesaw,drill a pilot hole first to match the holesaw bit, keep your drill speed reasonably slow and keep the saw well lubricated.


  • #5
    paddy147
    Banned (with Prison Access) Posts: 15,858 ✭✭✭✭paddy147


    aujopimur wrote: »
    A 22mm hole is possible with a standard holesaw,drill a pilot hole first to match the holesaw bit, keep your drill speed reasonably slow and keep the saw well lubricated.

    Thanks for that.So drill small pilot hole 1st.a HSS steel bit then?

    What type of lubrication?

    WD40 ok to use??


  • #6
    aujopimur
    Registered Users, Registered Users 2 Posts: 3,953 ✭✭✭aujopimur


    A holesaw usualy has a 6mm. bit, so pilot hole 6mm.
    Don't use the holesaw to drill the pilot hole as they tend to snap off when it breaks thru'
    Use engine oil (5/40 10/40 or similar) in one of those oil cans with a flexi neck, WD40 is too light it will just burn away.
    An assistant to do the oiling would make the job easier.


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  • #7
    gsxr1
    Closed Accounts Posts: 3,167 ✭✭✭gsxr1


    i would use a light oil or even water to pour on the drill. Lots and lots. We use a little bit of animal based oil mixed with a gallon of water to keep drills and cutters cool in engineering. use lots WD40. dont spare it.

    Its not for lubrication. Its to stop heat build up. A hot drill will lose its edge very quickly. Also a hot drill will harden the material being machined

    keep it cool and clear and it will last the job.;)


  • #8
    handydandy
    Closed Accounts Posts: 57 ✭✭handydandy


    +1 for standard hole saw, as above you could go through a couple of them but cheaper than renting large drill!!


  • #9
    paddy147
    Banned (with Prison Access) Posts: 15,858 ✭✭✭✭paddy147


    Sorted now.

    5mm HSS bit as a pilot hole,gear oil as lube.Cordless 18V drill set on low speed.And then a 22mm HSS steel hole saw.:)


  • #10
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Treflex for the conduid threading works well on that sort of thing, it melts and runs into the curcular groove the blade is making, i did a few that way before. Just keep dipping the hole saw into it.


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