Instructables

Tapping a straight hole with the aid of a drill press

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Picture of tapping a straight hole with the aid of a drill press
This is a description of a simple operation that might make tapping holes a little easier! Ever wondered why your taps have a little chamfered hole in the top? Read on and learn
 
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Step 1:

Picture of
tools and supplies:
material that needs a tapped hole
drill press
center punch
hammer
center drill
tap drill ( sized to tap )
chamfer
live or dead center
tap
tap handle or wrench
tapping fluid
safety glasses

Step 2: Center punch hole location and center drill

Picture of center punch hole location and center drill
Using your center punch and hammer locate where the hole is to be tapped. Centet drill hole location ( sorry forgot pic ) I cannot stress enough the importance of a centet drill when hole location has to be accurate!!

Step 3: Drill hole with appropriate drill size

Picture of Drill hole with appropriate drill size
Now drill your hole with the drill you selected. There are charts available for this. There is also a formula for this as well.

Step 4: Chamfer your hole

Picture of chamfer your hole
Using your chamfer tool, chamfer the hole. I like to go slightly larger than the major diamter of the thread to be tapped. This gives a nicer lead into the thread with no burrs. It also looks better.....

Step 5: Line up tap

Picture of line up tap
So at this point install your live/dead center in drill press. Install tap handle on tap. Line up your taper tap with drilled hole. Now the tricky part. Bring your live/dead center down on the little hole in the top of the tap. Now you should be lined up dead cenrer on your hole.

Step 6: Start to tap

Picture of start to tap
Ok now apply some cutting fluid. Apply pressure to drill press and rotate tap handle. If you dont have a tap handle any wrench will work with this method. For every rotation of 360°of cutting action rotate tap reverse 1/4 turn to break off chips. If this is not done broken taps may be in your future!!!
If you are tapping a blind hole start with a taper tap and once full thread engagement is achieved switch over to a bottoming tap.
TeleDex22 days ago

I also just put the tap directly in the chuck. On my el cheapo drill press, variable speed is achieved with a belt and two stepped pulley wheels. This allows me to just remove the belt and turn the shaft by hand (holding on to the chuck) when tapping. Consistent with my machinist skill and sophistication levels, I suppose I could grasp the tap shaft between the chuck and the tap threads with a needle-nosed Vice-Grip if necessary.

cutprogram1 (author)  TeleDex22 days ago
that is a great way as well. try leaving all belts in place and use your chuck key as leverage. this ible was meant for taps too large to fit into chuck.

Thanks for a great Instructable. After I have tapped the hole, what is a safe and easy way to remove the cutting oil from a thru hole? from a blind hole?

cutprogram1 (author)  2 left thumbs1 month ago
I just point hole away from me and blast with shop air.
That sounds good. Do I have to worry about loose chips flying about when I use air? Especially with a blind hole. I guess I could just put a rag over the hole and then blast away. Thanks.

The machinists that taught me would tell you to float it out with oil, never compressed air. In fact if they caught you with an airline next to a machine they would ask you if you were a machinist or an auto mechanic. You would get the day with a hand file to think about your answer. Never, ever, use compressed air in a blind hole. You know two things going in - one, there are razor sharp pieces of metal in there and two, the only way out for the air is back the way it came in. The one time you forget to have on your safety glasses is the one time you get a trip to the doc. Even if you always have them on you are still talking about spattering oil and metal everywhere under pressure. Personally, on large holes I take a bit of soft copper wire and bend it into a U and then bend the tips out and then chase the threads down with the bent out tips. On smaller holes I use a spray bottle filled with oil (But didn't you just say...) yeah, but you are talking a few psi vs whatever your compressor is set at (90?), it is a world of difference.

cutprogram1 (author)  seraphim_721 month ago
this is all true. there is a very good reason vintage machinist toolboxes have little mirrors in the lid.

I can see clearly, now. Thanks very much!

Ganhaar2 months ago

Once it's lined up, a battery drill on low gear is excellent for speeding up tapping.

mrademeyer12 months ago

great way to tap with drill press I do exact same but in the lathe have never tried the drill press for tapping holes thanks for some great advise. I use PS23 for tapping fluid and have never broken tap and it taps better than tap-matic in aliminuim

Even tho i have no use for this in my foreseeable future it was still interesting to read! great post.

Ditto. I own neither a drill press nor a tap set, but I was intrigued.

tuppence2 months ago

I have struggled with this problem on and off for years - A great solution, and clearly presented - Thanks for sharing your method.

Uitvindertje2 months ago

What a good idea. Thumbs upp for this one. !!!

cinpro2 months ago

you could do this on a lathe as well, good idea for doing it on a drill press!

anvil_man2 months ago

Nice instructions, may I make a safety comment.

Please grind off that mushroom on your center punch.

this is very dangerous, pieces can fly off and CUT you.

RE: The center, You can get a spring loaded center that keeps pressure on your tap. also if you have not used a spiral tap (through holes only), give one a try.

geoffball2 months ago
An old machinist taught me to lay a mirror on the flat surface and keep the tap and reflection lined up and your tap is straight. Great if you surface won't fit into a press
Kevanf12 months ago

I tend to just clamp my taps in the drill press chuck. I do not power the taps in rather I hand turn them. This way I can use any taps and just back off a turn every couple or so turns in to clear the swarf build up. I like your idea though, thank you. One small suggestion if I may? Before you do anything get a spirit level (builder's level) and check everything is to the same level, preferably true level. There can be differences in tolerance with drill presses and though it may look to be a nice 90 degree angle between bed of press and drill shaft there could be a significant outage.

sschoemann2 months ago

Ive found that the 360/90 forward reverse cutting method isn't optimum once you get past the lead in of the tap,(taper) at this point reduce to 180 degree forward rotation to 90 degree reverse to clear chips or you risk destroying your taps.

jakwagenaar2 months ago

Very good tip! Thank you. If I may add?

  1. There are taps available for continuous use in a machine. They are called "Machine taps". Hand taps will break very easily if used in a continuous run as the cuttings build up to a point where there just isn't enough space to accommodate any more waste metal.
  2. Especially on larger diameter holes and taps, I would strongly suggest the drilling of a pilot hole as a first step. This guides the bigger drill which otherwise might show a tendency to wander a bit resulting in a hole that is not acceptably round. This is another reason for broken taps.
  3. You did mention cutting fluid. This is crucial to the longevity of your taps, especially retaining a sharp cutting edge. Maybe as important is that the correct cutting fluid will prevent mechanical seizure of the tap in the hole, a situation where you can neither go forward or backward with your tap as the tap is truly stuck. Google what cutting fluid is perfect for the material you are working with.

Hope this help a little bit.

excelente idea muy facil y pratica

stephenfitton2 months ago

I like your idea! I use it all the time and especially handy when you have more than one matching hole to drill, Suggestion mark out top piece, super glue only on edges matching pieces, drill/ tap complete. then shock apart with a quick hammer blow to vertical edge. (Easy out) for a repetitive job

cutprogram1 (author) 2 months ago
I mainly use this method for very large taps that will not fit into my chuck. I have also turned drill on, let get to speed and shut down,While spinning start to tap. Not my preffered method though
Quesnelquack2 months ago

I routinely clamp the tap in the drill chuck and start it for 3 or 4 turns before switching to a wrench. Sometimes there just isn't enough space for both. The first few turns assure that the tap will follow in straight.

Ah, I see RWL1951 beat me to it :-)

RWL19512 months ago

Rather than switching over to the dead center, you can grasp the body of the tap in the drill chuck and turn the chuck with the long end of the chuck key inserted in one of the chuck's holes. When the tap begins to slip in the chuck or you can't turn the tap with the small leverage of the chuck key, it's time to attach the tap wrench to complete the job. By that time you usually don't need the alignment of a dead center - but not always.

snoopindaweb2 months ago

That's a bunch of great tips, the chamfering alone can make a better start.

andrea biffi2 months ago

thanks!

Stan1y2 months ago
so simple but if no one tells you you never know. Thanks
Kinnishian Stan1y2 months ago

exactly agreed :)

Void Schism2 months ago

When I worked in a workshop we tended to use the actual drill to tap due to speed. Owing to the increased speed of the cut the reverse cut is not needed as the material is removed in chips anyway. However this is not easy without an auto-reverse system to back it out at depth.

you also need high quality, high speed taps to do this. Your every day craftsman taps you get at sears suck and will break if using them at any higher speeds than hand speed.

jakeframe2 months ago
This is the same concept we use when tapping on the lathe. Thanks for sharing!
Pat Pending2 months ago
Clear and helpful - thank you
pdub772 months ago
Good info!
boatingman2 months ago
Good pictures with clear and concise instructions. Great job on your instructable. Great job on your tapping, too.
cutprogram1 (author)  boatingman2 months ago
Thank you. Glad you liked it!!
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