I keep breaking taps

[Le Chuck]

I'm having to tap a bunch of teeny tiny ass holes I've drilled in some 1/2" nuts.  To mount things in a fixed manner to a round axle I'm adding set screws to bored out nuts.  I have one nut completed!  I have borked 3 others and have broken 3 taps.  I know what I'm doing wrong, I keep putting lateral tension on the tap when I'm turning it.  It doesn't help that the tap is about the size of a thick pencil lead. 

The really cool product that I ordered eons ago to avoid having to do this is not going to be made anymore it looks like (round holed hex bearings).  On the up side the taps are only $3 each and I'm only out 60 cents in nuts.  On the down side if I keep busting taps at this rate the costs will eventually add up. 

Anybody got some sage advice for tapping on a small scale?

[recklessindian]

Use lots of lube (oil) and keep backing it out every turn or so (to remove shavings that could bind).
Also make sure you are drilling a large enough hole for your tap. 

[Xiaou2]

Use lots of lube (oil) and keep backing it out every turn or so (to remove shavings that could bind).
Also make sure you are drilling a large enough hole for your tap.

  This. ^

   Additionally, you could probably hand turn a drill press (or tap thats mounted inside a drilled hole in wood) to keep the Tap steady, so as not to put lateral pressure and snap it.

 Frictional heat may also be an issue.  Heat causing the metal to expand, than as it cools, threads tighten up.  Quench the nut in icewater after drilling out the hole, and then every so often, as you tap.  Oil will help with friction, but it only goes so far.  Most industrial cutting machines stream cool cutting fluid constantly.

[Nephasth]

Paint thinner works great for keeping the tap cool and lubricated. Little secrect I learned manufacturing LBH drill rigs.

[lilshawn]

Use lots of lube (oil) and keep backing it out every turn or so (to remove shavings that could bind).
Also make sure you are drilling a large enough hole for your tap.

  This. ^

   Additionally, you could probably hand turn a drill press (or tap thats mounted inside a drilled hole in wood) to keep the Tap steady, so as not to put lateral pressure and snap it.

 Frictional heat may also be an issue.  Heat causing the metal to expand, than as it cools, threads tighten up.  Quench the nut in icewater after drilling out the hole, and then every so often, as you tap.  Oil will help with friction, but it only goes so far.  Most industrial cutting machines stream cool cutting fluid constantly.

sounds like your hole is too small.

http://www.thedirtforum.com/drilltapsizes.htm

also, try mounting the tap in a vise and using a deep socket to turn the nut...you can bottom out the socket on the vise and get it nice and straight the whole time.

[matt4949]

Paint thinner works great for keeping the tap cool and lubricated. Little secrect I learned manufacturing LBH drill rigs.

I will try this as I have a habit of working on junk and find myself tapping alot more than I should.

[DeLuSioNal29]

Using a drill:


and manually:


D

[Le Chuck]

All good advice guys, thanks. I'm using copious amounts of cutting oil and the drill size recommended by the manu of the tap but I think it may be a bit tight. I'm generating a lot of waste off the tap. I'm also going to try the power drill technique. I'll report back. Thanks again!

[johnm]

Drill size, correct lubricant and the correct size of dwang, too big and you wont feel the tap stress, do not use a shifting spanner or ratchet.. Also make sure you have the right tap, tapering taps cut less for the first few threads making it easier and causes less stress on the tap.

[RandyT]

Another thing to watch for is whether the tap is perfectly in-line with the hole.  If it goes in at the slightest angle, it can bind at some point and break.  A larger tap can handle more stress, and might be able to cut it's way through if it's off just a tiny bit, but a small one won't have a chance.  Also, smaller taps have less room for chips, so backing it out a couple of times to clean it off and blowing out the hole, might help.

The best approach would be to go with the drill press suggestion.  Lock the vice down, and the part in it.  Drill the hole, remove the bit from the chuck, chuck up the tap, and with the power off, turn the chuck by hand while putting light downward pressure on the handle.  This should help keep everything lined up.

[MonMotha]

You may have better luck starting with a taper tap rather than the (more common) plug tap.  This will have a much longer taper and tend to self-center better.  Depending on if you're going all the way through the material or not (and how much clearance there is on the back side, if you are) and how deep you need the hole tapped, you may have to finish with a plug tap or even bottoming tap.