Need to thread an Automag bolt

[ScatterPlot]

I'm trying, for a little project of mine, to extend the Automag bolt some. To do this I was gonna tap the front end of one bolt and the back end of another and connect them with threaded rod, and see how that turned out. Well, 2 taps and 3 bolts later I have gotten the following:

• One bolt, threaded on the back
• 2 bolts with taps sheared off in the front of it
• 1 broken 6-32 tap from Home Depot
• 1 broken 6-32 tap from a cheapo combo kit I got at Harbor Freight (surprisingly, this one was stronger)

I wasn't tapping the whole bolt, just a 6-32 thread in the very center of the power piston. I keep shearing off the heads of the taps! Does anyone here know where I can get some taps that will tap into SS? I would just make a new bolt, but I don't have a lathe (yet ). I could also get someone online to do it, but that would cost more money than I really want to spend. I'd rather spend $20 on a really nice tap than $30 for one bolt. I can re-use the tap. So, any places I can get one of these? Or any better ideas on how I can extend the bolt? Thanks
Bert

[Chronobreak]

whats the purpose or objective of this? im sure you can find plenty of spare bolts around ehre on AO i have about 3 myself

[ScatterPlot]

I have plenty of bolts, just not the right taps. I'm trying to screw something into the tip of it.

[ShinyGuy]

You should be able to tap that. Good taps are worth the added expence and you'll want to use a good cutting fluid like Tapmatic #1 Gold. Take it slow and make sure to keep the tap straight.

[ScatterPlot]

Where can I get one of these "good taps"?


Oh btw- I broke another one (well my friend did). Any advice on getting them out? The drill bits wont stay centered and tapping it around with screwdrivers and all doesn't work.

[bjjb99]

You could try a tap extractor tool. Here is a set of them:

http://www.arizonatools.com/catalog/browse/3012-3634/detail/12054/

If you can't get the tap out with something like that, the only options are drilling (difficult) and after that fails you're probably into EDM and laser removal (expensive).

Any ideas why the taps are breaking so frequently? I have to ask since I don't know what metalworking skills you have... are you sure you're using the tap properly? At what point in the tapping process is the tap breaking (near the start, near the end, somewhere in the middle)?

BJJB

[Rick927]

www.use-enco.com for taps and broken tap remover, are you taping by hand or in a vise and drill press? Enco sells great tap holders for a drill press and they go in straight every time. If you are still breaking tap look for these things.

Tap not straight
Hole too small
Chips not clearing
Too much pressure on tap
Not enough taping fluid
Material too hard

Good luck getting out those little taps, you may want to try using a centerpunch to peen the end, the drill out with a solid carbide drill bit.

[ScatterPlot]

Sounds good, how hard are those tap removers to use? How do they work?

[Cristobal]

what Rick 927 said. Check everything on his list. That and make sure you're not bottoming out in hole you drilled Assuming you're hand tapping, you can clear chip build-up by backing (unscrewing) the tap a half-turn or so as needed.

[CoolHand]

What you want, for a hole that small, and a material that hard (but still quite ductile), is a thread rolling tap, not a cutter.

Look for them at McMaster Carr, under "thread forming taps".

For a #6-32, you will need to drill an 1/8" hole, that should give you about 85% thread engagement.

Go slow, and use plenty of Dark Thread Cutting Oil (also available at McMaster Carr).

Also, these taps do not require as much force to move as the cutters, so if it resists as much as a cutter, you know something is wrong. DO NOT try to force it, or you will end up breaking this one too.

Lastly, were you backing up the cutting tap every one or two turns to clear the chips? If not, then that's likely why they broke. When using a thread cutting tap, you must stop every one or two revs, and back it up a couple of turns, to clean the chips out of the flutes, and to break the ribbon of material you are removing (if the material is ductile).

Hope this helps.

[bjjb99]

CoolHand's got a good idea there to use a thread forming tap rather than a thread cutting tap. Thread forming taps with 6-32 threads are available from McMaster Carr as part numbers 2531A16 and 2531A27. The former is a plug tap and the latter is a bottoming tap... get both if you want the threads to go all the way to the bottom of the hole. Each one is under $9.00. If you need their website, here is is:

http://www.mcmaster.com

Verify those part numbers up there in case I fat-fingered something... otherwise you might end up getting a very interesting item that is completely useless for tapping holes.

BJJB

[ScatterPlot]

Wow, thanks for all the help. I didn't back it out right when I did it, but my friend did when he tried. I'll try some of those forming taps out and let you know how it goes. I am looking into getting a tap remover, but I'm not sure which to get. The sizes are kinda confusing, but I assume that for 6-32 threads I would need one with a tap size range of 0-6 (that's the only one with a 6 in it). Thanks again
Bert

[ScatterPlot]

Oh yeah, one more thing- What is the proper way to thread a hole with a drill press? Just go really slow, or what? I don't really understand the process.

[CoolHand]

Most drill presses are not made for tapping.

If yours does not have an instant reversing motor on it, then its not supposed to be used for tapping.

That said, I am the master of using things in a manner other that which they were designed for. You can use the press as a tapping fixture, to hold everything square while you do the tapping, and in some cases use the press to start the tap.

In this case, I wouldn't use the motor of the press to start it, as this is a tiny little tap. Just put the bolt in your vise, and the tap into the chuck of the drill press.

Now, run the tap down (with the quill feed) until it touches the face of the bolt, and hold it there with slight pressure. Now, turn the spindle (by hand, or with a strap wrench) in a CLOCKWISE direction. As soon as the tap starts in a couple of threads, you can let up off with the pressure. Continue like this until you bottom out in the hole, and then remove the tap (by going backwards). Bingo, one #6-32 threaded hole.

You don't have to back up thread rolling taps like you would cutters, as they don't make any chips. Also, be sure to fill the hole with dark thread cutting oil before you start to tap it.

One more thing, you want the extractor that works for 0-6 (that means #0-#6 taps).

Good luck.

[ScatterPlot]

OK thanks, I'll let you know how it goes.