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Author Topic: HELP what tap to use for tapping steel with tapmatic tapping attachment  (Read 1035 times)

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HELP what tap to use for tapping steel with tapmatic tapping attachment
« on: October 27, 2019, 07:30:17 pm »
I have a large quantity of holes to tap 1/4-20 in 3/8 steel. I have a tapmatic type (off brand)  reversing tapping attachment for my drill press but have only used it with aluminum. Using a standard 4 flute hand tap in steel soon led to a broken tap, even though it worked in aluminum. I'm guessing there is a better suited tap for my steel project. The threads are through hole, so no bottoming tap needed, but a little research has led to several choices of taps to use, but I'm hoping someone with some experience can recommend the proper tap to use.
I have come up with 3 choices:
OSG form tap
spiral point plug tap
spiral fluted tap

Is one of these what I'm looking for or something else? Is there a type of tap that clears the chips better than others, and what type of material is best- HSS, cobalt, carbide?
I appreciate any help in this matter and thanks in advance.
crazydoug
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #1 on: October 27, 2019, 08:25:10 pm »
Hi Doug,
 No expert , but I have broken plenty of taps. I have least problems with quality taps, cutting fluid and backing out more often.
 I no longer use taps from a set only buy several  of  the size I need. Just curious what counts as a large number?

Len.

https://www.mcmaster.com/standard-taps
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #2 on: October 28, 2019, 01:05:05 am »
I'm with Len on this one: quality taps, back out a lot. Turn slow, too. I don't use tapping attachments, because they're just not sensitive enough for me.

Oddly enough, over the years I've found a lot of good taps at yard sales, often unused in little boxed sets of three....

I'd also like to know what a "large nunumber is.
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Bob

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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #3 on: October 28, 2019, 03:44:11 am »
I would back up the quality taps not sets unless high quality sets .
Also i only do manual tapping with regular reversing to break chip
Plenty of cutting fluid .
And also removing tap to clear threads .

Cheers
Dennis
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #4 on: October 28, 2019, 06:49:59 am »
300 holes to start-more in the future. I am not going to tap them by hand!
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #5 on: October 28, 2019, 07:44:38 am »
300 holes at 5 minutes a hole--that's some 25 hours. Many people watch more TV than that in a week, and maybe you could do both at once....🤔
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Bob

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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #6 on: October 28, 2019, 07:48:30 am »
Wow that's a lot!. Just some thoughts is your drill press on its slowest setting? Also not sure of application but do you need full 3/8 inch of thread to hold? Drilling a relief a few sizes up can help for reducing stress on tap as well a help in starting.
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #7 on: October 28, 2019, 11:36:42 am »
Yeah, you don't want to do 300 holes by hand.  :)

For machine tapping, you don't want to use a hand tap because you should break the chips by reversing the tap.  What you want is a HSS gun tap which will push the chips down through the hole.  Straight in and straight out.  You probably want to set the speed of your drill press to it's lowest setting and use plenty of cutting fluid.  The taps are not that expensive, MCM stocks one at $7.

If you had a blind hole, you can get taps that pull the chip upwards and out.  They look sorta like a cork screw.  Not necessary in your case.

For people unfamiliar with a tapping head, this video shows how they work.



For the record, I don't own a tapping head.  I just use my mill which has reverse and slower speeds.
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My Workshop Blog:  http://doug.sdf.org/

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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #8 on: October 29, 2019, 08:35:08 am »
Thanks everyone for all the info. Looks like my biggest problem was that i was using a hand tap. I have now ordered some proper taps for the job. I think with a little practice figuring out the proper torque setting on the tapping attachment, I should have it working well soon.
crazydoug
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #9 on: November 10, 2019, 05:17:48 am »
Doug,
 Saw this video of mag drill in action, not that it directly applies to project but made me curious as to how goes 300 holes?


Len.

 Drilling/tapping is at about 10 minutes, arm tapping installed in around 25.
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #10 on: November 10, 2019, 07:54:29 am »
There will be more to come, but for now I am caught up on this project. I ended up with a carbide spiral point "gun tap", appropriately named as it shoots the chips downward and out the bottom of the hole. Ran the speed at 350 rpm and some tapping paste , and never broke a tap. My "shars" tapmatic tool worked flawlessly, once i figured out the right torque setting.
crazydoug
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Re: HELP what tap to use for tapping steel with tapmatic tapping attachment
« Reply #11 on: November 11, 2019, 04:07:58 am »
Makes me dream I might need a tapmatic, glad it went well.

Len.
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