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Tapping Handle vs Air Tapping Tool

11/15/2012 1:55 PM

This company I recently started working for designs, fabricates and assembles large textile related machines. The number of tapped holes is considerable. My issue is that they use a tap handle to tap all these holes. It sometimes takes up to two minutes for our assembly people to tap each hole. A guy can spend 2 or 3 hours on one large plate. In my years of contract R&D work I have always used a hand drill to tap large quantities of holes, if it didn't fit under a drill press with a proper tapping head. Granted, there was the occasional broken tap, but over the years I've become adept at this method.

I've suggested this method here, but I get a lot of backlash because they are sure that too many taps would get broken. I can somewhat see their point, as there is a learning curve involved in doing it this way. But I've done the math, and even the occasional broken tap vs the incredible amount of time and labor cost it takes to use a handle, the savings are considerable from my point of view. But still, management here is reluctant to try this.

So... alternatives. I know that there is an air powered tapping tool that can be used for this. But I've never seen one. As I understand it, it has some type of tapping head that both deals with torque, and assists in getting the tap started perfectly perpendicular to the surface. Does anyone have any experience with these tools? They are somewhat expensive, the cheapest being about $600, up to twice that. So for me to get budgeting for this would require my having good solid justification.

I'd like to hear your opinions on hand tapping, in various ways. The tap sizes we use are generally no bigger than 3/8", but more often in the M4 - M6 range, or 1/4-20. The material is both stainless sheet and carbon steel tubing and angles, 1/8" to 1/4" thick. These are all thru holes.

What have been your experiences? Suggestions?

Thank you for any input.

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#1

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:01 PM

How are the holes drilled? Could the tapping be done in the same setup with the drilling?

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#7
In reply to #1

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:25 PM

That is, of course, how it should be done. But due to a complicated set of circumstances, it's not. No, I just need to explore better alternatives to tapping in situ, than using tap handles and less than enthusiastic workers that can stretch out a tapping job into a half day.

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#2

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:04 PM

Try one of these:

http://www.flexarminc.com/index.html

We have used one for 15 years, woks great!

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#5
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Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:20 PM

Thanks, but no. If I could get the part under a flexarm, I would also be able to get it under a drill press with a tapping head.

These parts are too large. And the holes are tapped in situ.

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#3

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:17 PM

A pragmatic question (please, no offense is intended, it's just a question):

Does this fabrication shop operate under a collective bargaining agreement?

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#6
In reply to #3

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:23 PM

No.

Union-free zone. It's a medium sized company that still operates under mom n pop parameters.

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#8
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Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:28 PM

Then I'm with you.

Cordless drill/driver motor, clutch set low, dip the tap in lube every hole... I've done the same as you thousands of times and, as you say, an occasional tap gets sacrificed to the tool gods. This is the price of tapping 56 holes in 45 minutes versus two hours.

Battery drill/drive seems a no-brainer to me. Air tool... Meh... From Fargo I can't see any obvious advantages; might be some, I dunno.

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#4

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:17 PM

Tapmatic is your friend. It is fitted in the chuck of a drill press, and other tools and works very well.

Tapmatic

Not an endorsement, just a fact. I've used them. They are great of the pilot hole is the proper size and the tap is lubricated.

<Oh, never mind.>

You might find one that you can chuck into a hand drill.

Tap & Drill Combo - Hand Tools - Aubuchon HardwareElectricians Drill & Tap Bit, 12-24

GREENLEE TEXRON MODEL # DTAP12-24

$7.99/each

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#9
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Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:31 PM

I've used Tapmatics before... in drill presses. I can't get my parts into a drill press, or any machine. These holes are situated up on top of 15' tall structural frame assemblies where the guy must climb and straddle a 6x6 square tube, or on vertical surfaces. They are on semi-assembled large machines, not on pre-fab small parts.

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#10
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Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:37 PM

Ah... spiral tap. It's called an electricians tap? I'm curious why.

But I have heard that using spiral taps in the way I described does cut down on broken taps. I'll have to look into that... just chucking it into a regular battery powered drill, as Doorman mentioned. Battery drill is what I normally use, but have not tried to see what benefit a spiral tap might have.

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#11
In reply to #10

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:39 PM

They (spiral tap) clear the chips better, that's for sure. Can be run in a little faster.

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#24
In reply to #11

Re: Tapping Handle vs Air Tapping Tool

11/16/2012 4:26 AM

A roll tap does not produce chips-of course the drilled hole size must be adjusted.

Also depends on the material being tapped.

My experience has been excellent provided lube is used and material is compatible with the roll tap process.

DB

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#13
In reply to #10

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:46 PM

Never used one myself.

I'd think there'd be a learning curve and you'd need operators with some "feel".

Good luck.

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#28
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Re: Tapping Handle vs Air Tapping Tool

11/19/2012 1:15 PM

One of my duties when new equipment arrives is to mount equipment. Almost always it is in sheet aluminum, or stainless steel sheets. The Greenlee taps you show have saved me many hours of tapping. I find that they do tend to be brittle, but that with a can of lube in one hand, and the cordless drill in the other, I do real well.

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#12

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 2:45 PM

For the times whereI have built something of my own that needed a lot of tapped holes in it I go with a simple three step possess.

1. I drill the pilot hole. (Self explanatory.)

2. I chamfer the holes with a drill bit that is about 2x their diameter. (This gives the tap a good angled lip that helps center it when it first starts.)

3. I then use one of my air powered reversible drills to turn the tap and have its air pressure set at a level that keeps its peak torque below the breaking torque of the tap.

It makes for a quick easy and highly repeatable possess without needing extra jigging or setup work.

One thing I would recommend is that if you have a lot of stainless steel or thicker metal to go through custom grind a tap down to approximately 1/2 the thread cutting depth and use that as a pre tap between step 2 and 3. It's only cutting half the thread depth in its pass and thusly takes more stress off the taps as they cut.

Granted custom grinding a tap down does take a few practice runs before you find the right diameter and angles though. A small lathe with a tool grinding jig is the easiest and most accurate way to do it.

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#14

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 3:41 PM

Seen literally (actually) millions (that's aus with 6 "0's") of holes tapped using air driven tools. While it is possible with care to achieve a long life from the taps, there are a couple of issues that I see you would face.

My suggestion however is to either get the dedicated driver or something like a "Tech" driver where the clutch disengages instantly pressure is removed. Power drills tend to continue rotation due to gear and rotor inertia.

The first challenge is if the tap breaks 50' above ground level, the time and effort to remove the tap, remedy the hole and re-tap might not be worth the effort. Especially if there is even one reluctant operator who "chooses" to break a tap so the job still spans the whole day.

The second challenge is the operators themselves and the workplace described. We all know that it is easy to break a tap at any time. The operators, sitting on a beam, 50' up in the air, with the necessary safety equipment would have to add another few pound of equipment to their kit (The driver), compared to the few ounces for the hand tap. Moving around with the extra weight would be just that little bit more awkward.

Good luck.

Also, what will happen to the saved time? Will it actually mean less labour hours for the job, or will it mean that one operator is idle for hours while the others complete their tasks. This might make the one job seem favoured and create tension within the team.

Why can't they be tapped before erection? Are they pre-drilled?

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#15
In reply to #14

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 3:56 PM

No, not 50'... 15'. Our machine frames are generally 10' - 15' tall. The holes are not always on that top beam, I was just making the point that they are not small parts that can be put in a drill press. It's usually somewhere on an assembled frame, or wall of the machine cabinet; or the floor of the machine, for that matter.

I believe the tech driver you speak of is a version of the tap drivers that cost close to $1000. That is under consideration.

The labor situation here is very informal. Almost everyone is a welder/assembler, and everyone just does whatever needs to be done. The saved time would just help us to stay on schedule and get the machines finished and shipped that much quicker.

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#16

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 5:39 PM

I have to go with the consensus. I have tapped a lot of holes over the years using a hand drill, many of them in the days before drill motors had a clutch.

It does take a little touch and being sure that you are aiming the tap straight into the hole. Use spiral point taps in through holes.

If you are doing it on a production basis, make it a policy to replace the taps every 25 holes on SS and 50 holes on MS. Taps are cheap and sharp taps don't break as often as trying to muscle a dull tap through one more hole.

Also, the tool shown in #4 is a drill and a tap in one tool - a drap, if you will. They are good for emergencies in the field, but not for production IMHO.

Good luck

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#17
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Re: Tapping Handle vs Air Tapping Tool

11/15/2012 6:25 PM

Yeah, I'm going to have to agree. Although I was hoping to get some feedback on the hand tool that is specifically designed for tapping, I see that so far no one has had experience with that specialized tool, which leads me to believe that it isn't a very commonplace method, for whatever reason. I'm going to guess that reason is the seemingly disproportionately high price.

Also, given the fact that the consensus here generally has no basic problems with using a drill for this purpose, other than the need for developing a certain touch or knack for it... that gives me better confidence to press my case and try to convince the GM to try what I've suggested.

I appreciate everyone's input.

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#18

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 10:55 PM

There are special reversible dapping drills. Pushing forward engages CW rotation, driving the drill/tap inward. Pulling back reverses the motor to withdraw the tap/drill. This scheme works well for small holes in say, electrical backplanes. I haven't tried it in larger/deeper holes.

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#19

Re: Tapping Handle vs Air Tapping Tool

11/15/2012 11:27 PM

Why not do as the automotive manufacturers do:Use self tapping screws.Drill pilot hole, and it taps it's own hole as it is tightened.

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#20
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Re: Tapping Handle vs Air Tapping Tool

11/15/2012 11:43 PM

That explains things....such as Cavaliers....

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#21
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Re: Tapping Handle vs Air Tapping Tool

11/16/2012 12:07 AM

They all use them...Hondas,Toyotas,Mercedes,etc.

They are only used where the metal is thin and threads are fine as a result.

As for Caviliers, I had one..or rather it had me...sorriest piece of engineering that ever was excreted by Detroit.(IMHO). It broke me from all GM products.Any company that would sell that has very low standards of quality.Should have let it go bankrupt instead of letting it become Government Motors.

GM claims to have repaid the government bail out loans, but it borrowed money from another government fund to do it.Still running in our money.

RIP GM.

I now buy Accords exclusively.

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#25
In reply to #21

Re: Tapping Handle vs Air Tapping Tool

11/16/2012 6:30 AM

Yes, as you said, the metal must be very thin for self-tappers. That isn't the case here.

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#27
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Re: Tapping Handle vs Air Tapping Tool

11/16/2012 5:05 PM

OoBEx,

Actually, self-tapping screws are also available to drill and tap into steel as thick as 1/2". I know them under the type (brand?) name of TEK-7. When you drop one the "ping" sound it makes is very high-pitched, because of its being hardened. I've used them and they work well.

--JMM

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#22

Re: Tapping Handle vs Air Tapping Tool

11/16/2012 12:14 AM

I think it is odd that the management at your workplace are reluctant to user power tapping. The economies of it are glaringly attractive.

Even here, in Cambodia, where labour is very inexpensive we tap large ( even small or single) numbers of holes using a hand held drill to rotate it.

I even found that the breakage events were more frequent when hand tapping. It seems that it is easier to learn how to start a tap with a drill than with a tap wrench. The torque clutch on the drill saves taps that inexperienced workers would break by hand.

I expect that a proper tapping head would work even better.

Taps are also cheap here. A packet of three (taper/intermediate/plug), 1 set, of M4-M6 might cost as much as 1USD if the shop sees you coming. So, breakages are not a big deal and the tap is just another consumable.

The incentive to save time is more than a cost cutting measure. The sooner you can deliver the sooner you get paid, and that is really important, possibly even more so than the margin if breakages really started cutting into the bottom line.

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#23

Re: Tapping Handle vs Air Tapping Tool

11/16/2012 1:28 AM

Two suggestions:

1. Tapping in SS is relatively difficult, more chances of tap getting seized. If permissible, go for slightly larger pilot hole.

2. Taps mostly get broken when retracting. Wherever possible, try tapping all the way through and take out the tap from other side.

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#26

Re: Tapping Handle vs Air Tapping Tool

11/16/2012 6:34 AM

I may end up printing this out, or perhaps sending this link to a couple people here. It could sway their opinion.

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#29

Re: Tapping Handle vs Air Tapping Tool

11/19/2012 2:10 PM

how about one of these?

http://www.hougen.com/mag_drills/hmd904/hmd904.html

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