Tapping a Square Hole (Square to Your Material That Is!)


Introduction: Tapping a Square Hole (Square to Your Material That Is!)

I have always been vexed by having to tap threads in a hole so that the threads are square to the top of the material I was tapping. I found a nice solution using a block with a groove in the side.

Step 1: Insert Tap Into Hole

Start by putting the tap in the hole. Notice the tap I am using has a somewhat flat profile on it’s side.

Step 2: Place Block So Tap Sits in Groove

Next, place the “jig” in place to align the tap. This jig is an old hydraulic valve with the right sized groove in the side of it. Start tapping the hole, while keeping the tap pressed against the inside edge of the groove.

Step 3: Remove Block to Finish the Threads

After you have the threads established, you can slide the jig out the side to run the tap down further.



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    add some tapping lubricant like break free they go a long way

    If you can get your work under a small drill press, then why not put the bit in the chuck, removed the drill press belt and turn the chuck manually?

    Would it be possible to use a same size die to guide the tap bit into the hole?

    1 reply

    That's the point of this, you can't always get the drill press where you need it ;)

    Great idea.

    What y'all need is a tapping block. Mine is about 1 1/4 tall and 3 x 3in on a side ot of steel . I've drilled in a drill press holes for every size tap from #6 - 1/2 in. This starts every tap in straight. You could make it out of plastic, al., wood. anything that is flat. For getting holes in straight by hand. I first pilot drill with a small bit. Small like 1/8 or 3/16 . Then I used a bigger dril and since The force to start drilling is so small I can concentrate on watching and making sure its square. I'm talking about drill in something relatively hard here like steel, al. ect.

    Cool instructable. I never seem to have a problem finding the vertical with drills and taps unless I'm working at an awkward angle. Something like this would be perfect for those situations.

    1 reply

    Also, you only need one or two such tools. As long as the hole is large enough to take the largest of your taps, you can pack out a selection of smaller taps with rubber sleeves or heat shrink over the shaft. Presto hey, one size fits many.

    Handy little tip, one other thing I can think of is to take a tapping tool and modify it in to a little jig frame to make it specifically for making nice square threads. By the way delete step four, it's empty. I added a few keywords to your 'ible to help with searches as well.

    4 replies

    Yes, my original idea was a tool with a spring loaded tube or something. But I have enough projects that I decided not to start making more tools just yet.

    Ah maybe one to put on hold until you're free of time or embarking on something that would really be helped by such a tool... So we're likely to see some more projects soon then?

    Impressive, I may have to have a look at that gantry system, it supports you pretty well and I have a little project I'm planning that could benefit from such a thing...

    DoomMeister hate's tapping holes too.
    This looks like a solution, however you would need one for each size of f tap you use. So perhaps it would be worth making the spring loaded tube or even investing in something like this.

    One tip I can offer is that if you use a drill press or miller to drip a hole that needs to be tapped then before you move the workpiece is place the tap in the drill chuck and start the tap by hand using the column to keep the tap square, this also works on lathes. Just be sure to knock the power off first (at the safety cut out preferably).

    1 reply

    Yes, it is definitely limited. I my case I had to tap about 60+ 1/4" holes, so finding a jig the perfect size was a blessing. I had tried the drill press trick on other projects, but my holes were in a table structure so I couldn't move it there.

    Good idea. For me, always this has been a problem.