Using an impact to cut threads?

[Knotgoalie]

Yeah, I know, not a good idea but today I took a chance and won!

I was doing a parts drawer riv nut driver...and on an early attempt I snapped a 1/4-20/2 1/2" grade 2 bolt with my DeWalt 899 because I was stupid and had it set on 3 instead of 1! I fixed the tool and afterwards was looking at the bolt that lost 1/2" of thread and said "hey, why not?"

I locked a 1/4-20 die in the vise and cleaned up the bolt enough to get it into the die then applied gentle torque on low to start (0 to120~140Lb/Ft), moved up to mid torque (420Lb/Ft) and it worked nicely for what I was doing. I reversed every 1/2 turn, blew out the chips and added oil before each turn. I took it down to about a 1/8" shank and was rewarded with a 2" refugee from the scrap pile! The die survived perfectly as did the bolt but that bolt was "warm" when I finally backed it out!

As I stated, not the ideal way to do it but if you need a bolt right now it could work for you? I love the concept of "makin' do"

 

[Automag88]

I can honestly say that is not a thought that’s ever crossed my mind haha

 

[Knotgoalie]

I figured by now that someone would call me an idiot even though I was wearing safety glasses when I did it! Hard die+soft bolt+oil+strong impact=new, usable bolt if you exercise restraint in the process!

 

[plinker]

I've used an air ratchet to run a tap to clean/chase threads, larger tap though, 3/4-10. Not the preferred way by any means, but it went fairly quick on all 18 holes.

Not sure I'd use an impact in that fashion, but push can go to shove at times.

 

[619DioFan]

I do it all the time when I need to add threads to a long bolt. die in the vise , use lots of cutting oil and run the bolt thru the die with an impact. I do go easy , run it down then back out slightly then down.

 

[Knotgoalie]

I do it all the time when I need to add threads to a long bolt. die in the vise , use lots of cutting oil and run the bolt thru the die with an impact. I do go easy , run it down then back out slightly then down.

Air or cordless? I use cordless...stronger and consistent+no waiting for the compressor. I'll admit that cordless is something of a re-learn for an old dog but it works!

 

[619DioFan]

Air or cordless? I use cordless...stronger and consistent+no waiting for the compressor. I'll admit that cordless is something of a re-learn for an old dog but it works!

Either or. what ever I am using at the time. although I have to admit that since I invested in the milwaukee fuel impacts (3/8 and 1/2 inch ) my air impacts have not been used as much.

 

[strength_and_power]

My tap handle accepts a 3/8” ratchet on the back meaning it will also accept the 3/8” shank on my Dewalt 18v impact. Using a decent 3/8-16 tap from McMaster and cutting oil, I have probably tapped a thousand holes over the years with the same tap in 1/4” wall DOM. Works great and fast.


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[Provincial]

I would never try an impact on a 1/4-20 tap. Those taps have the least material supporting the teeth, so they are the easiest taps to break - even more fragile than much smaller taps! Your die has more beef to the teeth, and the geometry of the teeth provide more support, so it would survive better.

A high-speed steel (HSS) tap or die holds up to impact better than a carbon-steel tap or die because the carbon version is more brittle. Avoid using an impact with carbon-steel taps and dies.

 

[Wamsutta]

A high-speed steel (HSS) tap or die holds up to impact better than a carbon-steel tap or die because the carbon version is more brittle.

I thought it was the other way around. Thanks for the information!

 

[seber]

Charpy impact resistance of M2 steel is 22. Impact resistance of high carbon steel can range from 2 to 92. Toughness will depend entirely on how the manufacturer does the heat treat. About the only thing you can count on is that the more you pay the more likely it is to be tough.

 

[MagKarl]

Our mechanics at work don't tap anything by hand, they run taps with cordless impact guns. They have sockets that are sized to hold the taps.

 

[rlitman]

Charpy impact resistance of M2 steel is 22. Impact resistance of high carbon steel can range from 2 to 92. Toughness will depend entirely on how the manufacturer does the heat treat. About the only thing you can count on is that the more you pay the more likely it is to be tough.

i.e. cheap carbon steel taps will be unpredictable.

Anyway, I wouldn't try an impact on a small tap, but on a die, yeah, I guess it's not an awful idea.

 

[ihateminimumwage]

I worked for a heavy equipment manufacturer for a short stint, and they would "power tap" everything with 18v impacts. I was nervous after having to fight out taps and easy outs that snapped off, but it worked well with enough oil to keep the threads sharp.

That said, I get to spend tonight fighting out An M6 thread chaser I was using to clean out the remnants of a drilled out bolt in a turbo housing. Fun...

 

[6PTsocket]

Why would you want to impact a cutting tool. They are hard and therefore brittle. There is nothing wrong with power cutting with taps and dies that are designed for it but hammering it in on another story. I think you are lucky it worked but I will stick to manual.

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[PelicanPines]

Just because something worked once... based on doing something everyone knows is wrong... doesn't make it ok.

Cleaning threads is a HUGE difference from cutting threads... there's that too.

 

[CGT80]

My tap handle accepts a 3/8” ratchet on the back meaning it will also accept the 3/8” shank on my Dewalt 18v impact. Using a decent 3/8-16 tap from McMaster and cutting oil, I have probably tapped a thousand holes over the years with the same tap in 1/4” wall DOM. Works great and fast.


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Last night, I was tapping 1/4-20 holes in 3/16" steel and was considering a drill or impact. Often, I chuck the tap in a cordless drill, but it tends to slip-both a good and bad thing. I forgot that I have the gearwrench tap and die driver set that use ratchets and extensions.

What did work was to spin my V28 drill up to full speed before pushing the tap into the hole. It worked great, but the tap is a HSS 2 flute that is made for power tapping, from what I recall. This was with craftsman tapping oil. If I had used Norsman cutting lube (clear, thick, and sticky like honey) it would have worked much better, but that stuff is a bit of a pain to clean up.

The problem with running a die down the shank of a bolt is that the diameter can be too big on some. Sometimes it works fine, but often it takes a lot of force and I have stopped instead of taking the chance of breaking the die.

 

[Knotgoalie]

Either or. what ever I am using at the time. although I have to admit that since I invested in the milwaukee fuel impacts (3/8 and 1/2 inch ) my air impacts have not been used as much.

I went yellow/black, excellent pro grade on the top end and...my brother works for S/B&D. At his price, TOTL DeWalt all the way!

 

[skruft]

There are air powered tappers.

 

[pi_guy]

Just because something worked once... based on doing something everyone knows is wrong... doesn't make it ok.

Yes it does.
I read it on the internet that makes it true....

Not everybody knows that it is wrong and with the internet and reading comprehension not being a 100% accurate -- you get mixed results.

 

[6PTsocket]

There are air powered tappers.

But they are not inpactors. Power tapping is not the same as impact tapping. It is not a practice I have heard of before; maybe there is a reason.

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[customh]

https://www.dewalt.com/products/acc...s/tap-and-die/impact-ready-tap-and-drill-bits

These and competing products have sped up a number of different fab jobs for me.