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Taps for a Porter Cable manual tapping drill

M

martin_05

Hot Rolled
Joined
Mar 11, 2009
Location
Valencia, CA, USA
I've had a Porter Cable 7520 EHD 3/8 Tapper for a while. Got it from a friend, never used it.

Now I have a pile of 8020 1x1 extrusions of different lengths I have to end-tap with a 1/4-20 thread. Wondering if there's a recommended kind of tap for this type of tool. On my Haas I use form taps exclusively. I have a handful of cheap Home Depot cutting taps in the toolbox but that's about it, so I likely have to buy something no matter what. I guess my primary concern is tap breakage. I'm thinking spiral tap or one of those combo drill-taps. I'm sure that latter doesn't necessarily make the best threads though.

Here's what the tapper looks like.

Porter Cable 7520 EHD 3/8" Tapper | eBay

It's supposed to auto reverse when you pull. This thing has been with me for at least five years. For a while I was thinking of ripping the motor out and rigging it to use on my Bridgeport...I guess I'm glad I didn't do that now.


Thanks,

-Martin
 
8020.... I think I'm going to be sick.

I like 3 flute gun taps they work great for through holes. I have never used a tapper but I have held many taps in an electric drill without problem.

Just watch out some of that 8020 crap doesn't have a round Center hole.
 
Limy Sami said:
if you can find a pistol drill stand to put that tapper in, …...with an angle plate etc end tapping becomes a doddle

Stand like this Single Hand Drill Stand Electric Drill Bench Clamp Drill Press Stand Workbench Repair Tool with Depth Gauge: Amazon.co.uk: DIY & Tools
Click to expand...

Interesting idea.

I don't have to do this until next week, so I have a little time to think. One thought was to setup clamping on the edge of the Bridgeport and get a tapping head for it. The 8020 pieces range from a few inches to about three feet, so it has to be done off the edge of the table or workbench.

The other crazy thought was to get a right angle head for my VF2 and just do it in the Haas with, maybe, manual pre-drilling to go from a 0.201 hole (which is already part of the extrusion) to a 0.227 hole for form tapping. A lot easier to clamp and push cycle start, even if one extrusion at a time. Trouble is the cost of the right angle head (haven't even looked and never used one).

Just looking for the most intelligent and painless way to get the job done. This is for an internal prototype so cost isn't really that important. In other words, I could probably buy a right angle head for the Haas because I know we might be able to use it for future work. We only use our machine shop for prototyping, we are not a job shop which means metrics and decision-making are a bit different.


Thanks,

-Martin
 
Hi Martin

About a month ago I had the same task. About 500 80 / 20 1"x1" bars of different lengths cut and tapped 1/4" 20 in the end hole. I have a porter cable, fein and drill attachment for power tapping by hand that I could have used but didn't. For the shorter bars (less that about ~36") I used a drill press with a Vertivise off the side of the table with a tapping head and a gun tap. For the longer bars I used the Deckel in horizontal configuration again with tapping head and gun tap. In addition to support the long bars on the mill I set up a lifter/stacker.
I still have the drill press set up if you need photos? I still have to make a few more but I have not been given the lengths yet.
The 80/20 post were used for corner vertical posts for plexi boxes.

Andy
 
FFS, its a 1/4-20 in aluminum. just stick the tap in a cordless drill and go!

since you have the P-C thing why not just use it? you can set up a stockrest or other reference for the up-down angle, and eyeball the left right. a couple of Destayco toggle hold downs, and you should get a 15 sec. or less cycle time.

(sorry, on edit i see you are intending to, I was reacting to some of the other posts!)

a top quality TIN coated gun tap. you don't need the spiral, thats for blind holes. as always inspect the cutting teeth even on new taps (preferably with a 10X loupe)
 
The .201 hole in the extrusion is already the right size for a 1/4-20, so no drilling is needed. I'd do them on the drill press with a tapmatic.

I do thousands of those type of tapped holes. I use a 3-flute Hy-Pro S/P Plug tap.
 
cyanidekid said:
FFS, its a 1/4-20 in aluminum. just stick the tap in a cordless drill and go!
Click to expand...

Sorry my question bothers you. I've tapped a bunch of these in the past using a 12V Milwaukee cordless drill. It's a pain in the ass. The tap jams and you have to be careful not to break things. It might very well be that we have crappy cutting taps (we only use form taps on the CNC). So I'm asking for help. Not a professional machinist. Thankful people are willing to help.
 
martin_05 said:
Sorry my question bothers you. I've tapped a bunch of these in the past using a 12V Milwaukee cordless drill. It's a pain in the ass. The tap jams and you have to be careful not to break things. It might very well be that we have crappy cutting taps (we only use form taps on the CNC). So I'm asking for help. Not a professional machinist. Thankful people are willing to help.
Click to expand...

please see my apology above.

the quality of the taps makes a huge difference, the ones you get at the hardware store, even the made in usa such as Irwin are usually not really sharp. a quality brand such as Hertel or Widia, a gun style tap that pushes the chip ahead of it and a TIN (gold titanium nitride) coating helps tremendously. also, what lube have you been using? I like a combo of Boelube stick and acculube 2000.
that extrusion may be anodized, it might not hurt to send in a #7 first even though it already has a hole, especially if it is out of round. hope that is of some help, :)
 
Andy St said:
About a month ago I had the same task. About 500 80 / 20 1"x1" bars of different lengths cut and tapped 1/4" 20 in the end hole.
Click to expand...

Ah, experience! Yeah, if you want to post pictures it'd be great. If someone else travels this path it would help them too.

At the moment I'm thinking of getting a set of these taps and setting-up to tap horizontally to facilitate chip evacuation (rather than taping vertically down).

McMaster-Carr

It'd be interesting to find out what 80/20 or Futura/T-Slots (same stuff, made in Utah) use in their factories since I am sure they process many thousands of these per week for customers. At those levels you have to optimize the operation and tool life. My guess is some kind of a horizontal setup with pneumatic clamping, etc.


Thanks,

-Martin
 
cyanidekid said:
please see my apology above.

the quality of the taps makes a huge difference, the ones you get at the hardware store, even the made in usa such as Irwin are usually not really sharp. a quality brand such as Hertel or Widia, a gun style tap that pushes the chip ahead of it and a TIN (gold titanium nitride) coating helps tremendously. also, what lube have you been using? I like a combo of Boelube stick and acculube 2000.
that extrusion may be anodized, it might not hurt to send in a #7 first even though it already has a hole, especially if it is out of round. hope that is of some help, :)
Click to expand...

No problem, thanks for the useful advice.

You are right, I forgot about the fact that these things are anodized.

So...

I've always been confused as to what really constitutes a gun tap. I've seen two types of taps called "gun taps", even cnccookbook does this. Well, they call one gun nose (spiral point) and the other gun tap (full spiral):

10 Different Types of Thread Taps [Definitive Guide]


EDIT: I'm using Tap Magic
 
the first one, "spiral point" is what we are referring to as a "gun tap"

the second one is a "spiral flute", and it's for tapping in a blind hole. it sends the chip back out behind as the tap goes in, Ideally in lovely little corkscrews (depending on the material you are tapping). they can be a little more fragile, and are more expensive, so I only use them on the blind holes.

I'm not sure why they are calling that a gun tap?

I get mine from MSC on sale, they usually have Hertel 1/4-20 TIN spiral points for about 5-6$ each. I'll take a look and see if they are on sale at the moment.
 
Hi there Limey, I was referring to the linked page where the "definitive guide" mis-identifies a spiral flute tap as a "gun tap"

just looked, and this month MSC has Kennametal 1/4-20 spiral point TiN coated taps for 7.99 each on sale, and I guess that makes them about "normal" priced, instead of the regular "overpriced" 15-16$ :D

(go to their site, on the top they have "sales and rebates", click , then select "metalworking", page 14 of that)
 
Limy Sami said:
Nor was I so I Googled it (cos I'm an impetuous fool) and lo and behold. ''They are called "Gun Taps" because they shoot the chips ahead of the tap. This also reduces loading and clogging in the flutes''


From Spiral Point Taps - ICS Cutting Tools
Click to expand...

So...with gun taps you actually want to tap the 80/20 pieces vertically rather than horizontally so the chips can fall through then.

Thanks.
 
cyanidekid said:
Hi there Limey, I was referring to the linked page where the "definitive guide" mis-identifies a spiral flute tap as a "gun tap"

just looked, and this month MSC has Kennametal 1/4-20 spiral point TiN coated taps for 7.99 each on sale, and I guess that makes them about "normal" priced, instead of the regular "overpriced" 15-16$ :D

(go to their site, on the top they have "sales and rebates", click , then select "metalworking", page 14 of that)
Click to expand...

Thanks for doing the research. I don't think I am genetically capable of leaving the MSC website with an $8 shopping cart. Same thing with Home Depot and Best Buy (not that I am complaining).
 
Here is a photo. This is on a med./Lg. gear head drill press. The same set on a #1 knee and turret mill would have about the same results and maybe a little more length especially with a riser block. As I was staging the photo I remembered I ran the first set in a small CNC lathe (manual would work also). 4 jaw universal with a bushing / cat head at the back of the spindle and a SPI tap head in the tool holder.

Andy
 

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Thanks. As they say, the second guy who saw the wheel said "That's obvious". And yet the first guy had to invent it for him to be able to say that.

I like the ruler clamped on the vise.

Just for the fun of it I tried one of my cheap hardware store taps with the Porter Cable tapper drill on the end of an 8020 extrusion. The thing snapped almost instantly. I wasn't going to keep that junk around much longer anyway. The evil part is that I had my son do it. I asked him to come help me with some work and didn't tell him the tap wasn't up to the task. I just told him to use facial protection. The expression on his face when he came over to tell me he just snapped a tap was priceless. Failure is the best teacher.

I have five good gun taps coming from MSC within the next coupe of days. Looking forward to getting this done with less pain and aggravation.
 
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