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View Full Version : Easy power tapping jig (warning: pic heavy)



lwalker
07-18-2012, 10:15 PM
I mentioned in this thread http://bbs.homeshopmachinist.net/showthread.php?t=55176 that I had an idea for an easy holder for a tap wrench that would allow power tapping without having to stop the spindle at the time. I made up a quick test of the idea and took photos along the way.

I don't have a lathe, so I use my HF mini-mill for turning by holding workpieces in R8 collets and a lathe tool in a vise or in a clamp I made out of a right angle plate.

Starting with a 3" length of 0.75" 6061-T6 bar (I didn't have any steel bar thick enough to contain the tap wrench) chucked in a 0.75" R8 collet

http://www.cedarlakeinstruments.com/SharedFiles/step2r.jpg

Lockup a massive Valenite 3/4" insert holder with a TPG322 insert in the vise and use a wiggler to align to center of spindle.

http://www.cedarlakeinstruments.com/SharedFiles/step3r.jpg

Workpiece in position. This is not the best way since the head is so far from the table rigidity is reduced. I have a fixture that lets me get the lathe bit only about 3" from the table, but this would have meant removing my vise and other stuff and I was in a hurry.

http://www.cedarlakeinstruments.com/SharedFiles/step4r.jpg

Continued...

lwalker
07-18-2012, 10:17 PM
Hit the 4 pic limit

Turning down the material to clean it up. I think this was a 0.003" cut. Couldn't get any pics of the facing cut. Who says light tools can't use carbide :-) My right angle lathe toolholder uses 1/4" tools and those inserts have chipbreakers so the long stringy swarf is avoided. But the TPG322 gives a better finish since the nose radius is larger. Besides, I love using that massive tool :-)

http://www.cedarlakeinstruments.com/SharedFiles/step5r.jpg

It looks like my column is out of tram since the top of the cut (at the step) is barely touched but the bottom has had about 0.006" reduced and it cut a taper.

http://www.cedarlakeinstruments.com/SharedFiles/step6r.jpg

Flipped the workpiece and turned the other end down to 0.5" diameter so it could be held in a collet or drill chuck. Also chamfered the ends. These steps aren't shown. Next pic has the turned down workpiece in a 5C collet fixture and drilling the center out 0.5" to take the tap wrench

http://www.cedarlakeinstruments.com/SharedFiles/step7r.jpg

Finished item (hard to get a good image with the flash since the outside is now shiny)

http://www.cedarlakeinstruments.com/SharedFiles/step8r.jpg

continued...

lwalker
07-18-2012, 10:23 PM
Demonstrating how it's used in a bit of brass scrap.

http://www.cedarlakeinstruments.com/SharedFiles/step9r.jpg

To use it, you set the tap wrench and tap in place and with the jig in the drill chuck, adjust its height so the tap wrench handle protrudes up the slot for the same depth you need to tap. When the mill/drill press turns and drives the tap, the threading action will pull it down the slot. When it drops out of the slot, it of course stops turning, giving you plenty of time to stop the drill press without breaking a tap.

One problem I noticed when making the jig is that in cutting the slots for the tap handles, I had a lot of burring at the edge. I think it may be due to my ball end mills being dull. I did a quick deburring job with a file, but as I mentioned, I was in a hurry (kids were getting hungry and wife was out) to finish. I also really need to tram my mill column!

I have never seen a tool like this described anywhere, but it's so simple that it must exist.

Dr Stan
07-18-2012, 10:50 PM
Interesting tapping jig. Think I'll have to make one.

BTW, when I was teaching at the vo-tech I had a CNC mill, but no CNC lathe. So I wrote a program to make chess pieces using the tool holder as the work holder and ground a 1/2" HSS cutting tool held in the vise. Worked out quite well if I say so myself.

tdmidget
07-18-2012, 11:04 PM
Demonstrating how it's used in a bit of brass scrap.

http://www.cedarlakeinstruments.com/SharedFiles/step9r.jpg

To use it, you set the tap wrench and tap in place and with the jig in the drill chuck, adjust its height so the tap wrench handle protrudes up the slot for the same depth you need to tap. When the mill/drill press turns and drives the tap, the threading action will pull it down the slot. When it drops out of the slot, it of course stops turning, giving you plenty of time to stop the drill press without breaking a tap.

One problem I noticed when making the jig is that in cutting the slots for the tap handles, I had a lot of burring at the edge. I think it may be due to my ball end mills being dull. I did a quick deburring job with a file, but as I mentioned, I was in a hurry (kids were getting hungry and wife was out) to finish. I also really need to tram my mill column!

I have never seen a tool like this described anywhere, but it's so simple that it must exist.

Never seen a tool like that? Of course not. While you typed that about a thousand holes were tapped with a drill chuck and no problem. you have reinvented the wheel, except that yours is square.

lane
07-18-2012, 11:24 PM
Just put the tap in the drill chuck . Key less chucks work great . center drill change to drill ,then to tap ,and be done with it.

firbikrhd1
07-18-2012, 11:31 PM
TD, you might be being a little tough on Iwalker. I've used my drill chick to hold taps but on my mill I don't have any way to stop the machine instantly when depth has been reached.

It appears that Iwalker's device will allow the tap wrench handle to slip out of the tool he made even though the machine spindle continues to turn. If I understand correctly, the spindle is locked at a particular height and the tap draws the tap wrench ever farther out of the his tool as the threading process continues until the tap wrench is drawn away from his tool releasing the wrench. Seems like it might work OK for someone without a tapping head or spindle that instantly stops using a brake or has the advantage of 3 phase.

lwalker
07-18-2012, 11:52 PM
Meh! I'm pretty thick skinned.

It works for me better than everything I tried before, and that's what matters. When I power-tap with taps in the chuck, I run the risk of breaking a tap if I don't react fast enough, or the tap chews up the hole because the mini-mill head doesn't move downward smoothly. Hence this solution.


TD, you might be being a little tough on Iwalker. I've used my drill chick to hold taps but on my mill I don't have any way to stop the machine instantly when depth has been reached.

danlb
07-19-2012, 03:00 AM
I like the idea.

Power tapping with a drill chuck has another problem. If (when) the tap spins in the chuck it tends to obliterate the markings on the tap. I now have a #12-24 tap and a 1/4 inch tap that have no markings. They always seem to be the first ones that I grab.

Yeah, I ought to toss one of them. :)

Dan

Black_Moons
07-19-2012, 03:45 AM
I like the idea.

problem with using a drill chuck is I really can't get enough torque on bigger taps. Maybe if I really crank that drill chuck down, but thats really not what they are for. I only use my drill chuck to start a tap, then put a handle on it to finish it

This would let me just retract the quill and finish it myself without puting the handle on since its already there. I don't want to put huge amounts ftlbs of torque on my drill chuck, or risk it getting stuck since I don't have spiral point taps.

loply
07-19-2012, 05:46 AM
I like this idea.

I have had a few problems tapping with the chuck which this would solve:

1- On big taps, it's hard to stop the tap slipping in the chuck

2- On small taps, the sheer weight of the return spring and the downward pressure you apply can strip the threads, because the whole set up lacks the sensitivity to drive the tap up or down at the right rate

3- It's a pain in the arse to unscrew a highly tightened jacobs chuck three times to do all three taps, or twice if I'm cutting the taper plug out, this looks quicker

Dan Dubeau
07-19-2012, 09:49 AM
I can see an application for this, Good idea.

I've done some turning in the VMC before. Took a bit of figuring on the programming side, but worked great. One shop I worked at rough turned all their pins (gauge pins for checking fixtures) in a mill, before hardening, and grinding in a harig on a surface grinder. They had a lathe, but it was so clapped out no one used it. Can't imagine why they went under.

tmc_31
07-19-2012, 11:39 AM
Iwalker,

Very nice, simple, elegant solution to power tapping in a mill. Well done.

I am going to build one of these. I think I will make it out of 1018 and I will also make the drill shank a hex. I also am going to build one for my lathe with a MT3 shank on it that will fit in my tailstock.

Using it on the mill, I can see following the tap down with the quill then when the proper depth is reached releasing the quill thereby instantly disengaging the drive. This approach will work fine on the lathe too if you just push or pull on the tailstock rather than moving the quill.

Thanks for a cool idea,

Tim

RWO
07-19-2012, 02:27 PM
I use these with a 3/8" sq.drive to 1/4" hex adapter in the drill chuck.
http://www.shopping.com/Irwin-Irwin-3095001-Tap-Socket-Adj-2PC-Kit/info

RWO

michigan doug
07-19-2012, 06:24 PM
Good solution to your particular setup. mr midget just likes to insult everyone at every opportunity. Pay him no mind.

I like the automatic disengagement feature especially.

Finest regards,

doug

H380
07-19-2012, 06:51 PM
I use these tap driver sockets. I think the set cost me about $20 from Sears years ago.

http://www.lislecorp.com/divisions/products/?product=398

lwalker
07-19-2012, 09:11 PM
Thank you for the kind words, I'm happy that my work might be useful to someone else. Hopefully as I use it, I can think of improvements over time.

platypus2020
07-20-2012, 12:38 PM
I use these tap driver sockets. I think the set cost me about $20 from Sears years ago.

http://www.lislecorp.com/divisions/products/?product=398


I also use the tap sockets in the drill chuck.

dp
07-20-2012, 01:39 PM
I like the simplicity of this. For blind holes you can set a quill stop on the drill or mill and follow the tap and then let it self-disengage after the stop is reached. Add a simple one-way clutch and you can back out without re-engaging.

J Tiers
07-20-2012, 05:05 PM
I've seen a similar idea (and made one for myself) in the "Toolmaking 1935" lindsay book.

That was for the lathe, and didn't use a standard tap handle. This is quite reasonable for Drill Press or Mill...... Just because the principle is not entirely new is no reason to jump on the OP..... This is a creative and different variation.