Tapping a Hole in Laser Cut Sheet
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  1. #1
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    Default Tapping a Hole in Laser Cut Sheet

    Question,

    I've got a fabrication project coming up that will involve some tapped holes.

    Most all the material will be cut on a laser. Thickness will be 3/16 or 1/4. Hot roll steel sheet.

    My question is, can the laser cut out the holes so I can go back later and tap them?

    Hole size in question is 3/8-16. I'd have the laser burn them to around 5/16" dia and then tap them when I got them. Is there a hardened layer I'll have to tap through?

    Another thought I had was get the laser to cut a 1/4" hole for position, then I could drill a 5/16" hole and tap that hole I just drilled.

    Suffice to say that the laser bed has enough locating precision for this project.

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    laser, drill and then tap, but don't make the pilot that large with the laser, the drill will have hard time centering, make the pilot only as large as the web thickness of the drill you're going to use, that is, if you don't plan on doing that with hand tools (don't know how large the pieces are)

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    if you don't need the worlds most beautiful tapped hole ... it's no problem to tap 3/8"-16 in laser cut steel. Do you 5/16 hole size for 50% thread engagement. Use a decent quality tap. Go to town. We've tapped thousands of laser cut holes.

    Cut parameters such as laser power, gas used for assist, etc all will factor into how hard that edge is. I think the worst I've had was taping 5/8" fine thread into 3/4" laser cut steel. It was done on an older laser and has a super thick glassy cut edge. It would ruin a drill bit when I tried to open up the hole. And would only get a few holes with a new Widia tap. But switchced to a YMW tap and got a bunch of holes no problem.

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    Should be no problem to tap straight off the laser, we tap thousands of laser cut holes in mild steel and 304 stainless every day without a problem.

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    I used to do it all of the time with no issues. Typically 1/4-20 or 10-32 on 10 gauge to 1/4" steel.

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    Default Tapping a laser cut hole in hot rolled steel

    Quote Originally Posted by CatMan View Post
    Question,

    I've got a fabrication project coming up that will involve some tapped holes.

    Most all the material will be cut on a laser. Thickness will be 3/16 or 1/4. Hot roll steel sheet.

    My question is, can the laser cut out the holes so I can go back later and tap them?

    Hole size in question is 3/8-16. I'd have the laser burn them to around 5/16" dia and then tap them when I got them. Is there a hardened layer I'll have to tap through?

    Another thought I had was get the laser to cut a 1/4" hole for position, then I could drill a 5/16" hole and tap that hole I just drilled.

    Suffice to say that the laser bed has enough locating precision for this project.
    Double check the hole size at the top and bottom on the first parts off laser the assure you'll create a good thread. Hot rolled steel has a low carbon content so that tapping will be normal without problems from the heat off the laser. Hot rolled has carbon content of 10 to 18 percent carbon. This is to low to cause trouble.


    All the best,
    Roger

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    Quote Originally Posted by rogertoolmaker View Post
    Double check the hole size at the top and bottom on the first parts off laser the assure you'll create a good thread. Hot rolled steel has a low carbon content so that tapping will be normal without problems from the heat off the laser. Hot rolled has carbon content of 10 to 18 percent carbon. This is to low to cause trouble.

    All the best,
    Roger
    you left out a decimal point there, obviously! (.10-18)

    It does depend on the laser, the faster fiber lasers run so quickly that there is enough of a a "quench" to harden many steels in the "mild" range. it depends on a number of factors, including the thickness, particular alloy constituents of the melt in question, and the hole size for a few. depending on the above, you may want to figure a drilling op before tapping. test it, but you might want to laser it at 9/32 and drill to 5/16, then tap.

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    Quote Originally Posted by kb0thn View Post
    if you don't need the worlds most beautiful tapped hole ... it's no problem to tap 3/8"-16 in laser cut steel. Do you 5/16 hole size for 50% thread engagement. Use a decent quality tap. Go to town. We've tapped thousands of laser cut holes.

    Cut parameters such as laser power, gas used for assist, etc all will factor into how hard that edge is.
    5/16 is 75% thread on a 3/8-16. true dat on variables.

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    Quote Originally Posted by rogertoolmaker View Post
    Double check the hole size at the top and bottom on the first parts off laser the assure you'll create a good thread. Hot rolled steel has a low carbon content so that tapping will be normal without problems from the heat off the laser. Hot rolled has carbon content of 10 to 18 percent carbon. This is to low to cause trouble.


    All the best,
    Roger

    Carbon content should be ,10 to .18 percent carbon.

    Roger

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    The place I did stainless, they'd laser undersize and we would have to drill out in the mill(had other ops to do)never made much sense to laser then wreck drills(1/2 to 3/4 thick), why not just drill from the start. 1/4" was usually no problem, welders forced taps through small holes just fine not knowing any better. The new Cincinnati laser cut truer holes in thicker material.

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    One alternative is to use a riv nut. Easy cheap and you get a first class threaded hole

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    Quote Originally Posted by surplusjohn View Post
    One alternative is to use a riv nut. Easy cheap and you get a first class threaded hole
    If you want to go that route I would suggest self clinching hardware such as PEM nuts. They are much easier to install, lower profile, and possibly cheaper. You can also get studs and standoffs and various other odds and ends. We used to use those a lot at my old job and it was much faster than tapping a bunch of holes.

    Laser tolerances are no issue for them.

    Plasma can be made to work if you are careful and only using aluminum.

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    Quote Originally Posted by Strostkovy View Post
    If you want to go that route I would suggest self clinching hardware such as PEM nuts. They are much easier to install, lower profile, and possibly cheaper. You can also get studs and standoffs and various other odds and ends. We used to use those a lot at my old job and it was much faster than tapping a bunch of holes.

    Laser tolerances are no issue for them.

    Plasma can be made to work if you are careful and only using aluminum.
    I agree about the PEM nuts for flat or small work. we use riv nuts because they are mostly installed after fabrication and powder coating. so riv nuts and a pneumatic gun work very well. If we were only installing in small parts then PEMs win out. Either way 1 million users cant be wrong.

    another direction is to use thread forming screws

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    Quote Originally Posted by surplusjohn View Post
    I agree about the PEM nuts for flat or small work. we use riv nuts because they are mostly installed after fabrication and powder coating. so riv nuts and a pneumatic gun work very well. If we were only installing in small parts then PEMs win out. Either way 1 million users cant be wrong.

    another direction is to use thread forming screws
    Oh, yeah, we use riv nuts occasionally in similar situations. I hate them solely because we don't have a pneumatic tool.


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