View Full Version : OT: (*ON*) Topic: HF Emergency Tap Grinder

01-11-2009, 12:30 PM
I bought this little diamond grinding wheel set a while back. It was on sale then & cost me $3.99 though. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=32397

The flat one had about .010" runout so I chucked it up with a ring of brass shim stock around it to protect the jaws and bored out the hole true. Made a nice arbor for it and used it once in the mill to grind down some hardened T-nuts. I chucked it in a drawer and forgot about it 'til today when I needed to grind down the shank of an 8-32 tap to finish tapping a deep hole.

I chucked it in the lathe, cranked up the speed, chucked the tap in a cordless drill and bammo, ground down the shank in no time. Oh yeah, check out the custom chuck grit shield. Another use for a 2 liter soda bottle.;D


01-11-2009, 02:27 PM
Your diamond tools will last much, much longer on steel if you put a little lubrification on them. Just water will do.

01-11-2009, 02:40 PM
You're right David. I dipped the tap in a cup of water often while grinding which seemed to work OK. The relative speed was slow enough that weren't any sparks at all.

I dont have any type of coolant system on the lathe yet anyhoo...

01-11-2009, 02:43 PM
Just for reference, I did the same thing to a 1/4-20 tap that I needed to use to tap a very long deep hole (no clearance hole allowed). Only diff is that I used a dremel AO wheel of about the same aspect with the dremel in rubber jaws on a vise...

noah katz
01-11-2009, 03:01 PM
Unless it's a carbide tap, why not just use a regular grinding wheel?

I've done that to "make" bottoming taps.

01-11-2009, 04:08 PM
An A/O wheel would do fine; I just didn't have one small enough in the shop to cut the small area needed on the shank of an 8-32 tap. 1" wide, 8" wheel was the next step up and way too big.

I looked at my Dremel but didn't have a decent wheel or a way to hold it.