KeithB
Resident Half Fast Machinist
Never really had a good way to tap small holes on the manual lathe. A while back there was a thread posted by one of the members about making a hand tapper for a lathe. I followed that thread with interest, it was a nice project. We have picked up some business from a local company that needs small parts, mostly made from A2 tool steel or 4140. Most of the parts are lathe work and many require tapping small metric threads, i.e. M6 x 1 and M3 x .5. Many of the holes are blind. I was inspired by the hand tapper thread and decided I needed to make one for my own use.
I had made a tool years ago to thread rods using a die. It didn't work very well so I salvaged the #3 Morse taper shank and a 2" long section of the 1" diameter main shaft. I made an 8" long tube with a 1" bore out of a scrap piece of 1-3/4" aluminum round stock and clamped it to the Morse taper shank. We have several collet type toolholders with 1" shanks that could be used to hold a tap so all that was needed was a knurled friction collar to clamp to the toolholder. This was easily made from a 2-3/4" dia piece of scrap 1018 steel. After turning it down enough to get to clean steel I cut it to the closest calculated diameter for a clean knurl and got exactly that. (I used the spreadsheet I posted previously to do the calculations.)
I needed to use a Morse taper sleeve to step up the #3 shank to a #4 to fit my lathe's tailstock, but I keep a variety of adapters on hand so no worries there mate.
The tool works great. The video shows me tapping an M6 x 1 thread into a piece of A2; it's a through hole, but blind hole tapping is just as easy. I use spiral flute taps so it is no problem tapping all the way to the bottom of the hole, there is no chip buildup.
One of the reasons I asked for a machining section here was to share ideas and get inspiration and that is the case here. A previous thread has inspired me to make a useful tool, thanks!
Old tool for threading rods, only the Morse taper shank and part of main shaft were reused.
My hand tapper. The friction collar is clamped to the collet toolholder but is free to spin and slide in and out in the aluminum tube.
Here is a video of the tapper in action.
I had made a tool years ago to thread rods using a die. It didn't work very well so I salvaged the #3 Morse taper shank and a 2" long section of the 1" diameter main shaft. I made an 8" long tube with a 1" bore out of a scrap piece of 1-3/4" aluminum round stock and clamped it to the Morse taper shank. We have several collet type toolholders with 1" shanks that could be used to hold a tap so all that was needed was a knurled friction collar to clamp to the toolholder. This was easily made from a 2-3/4" dia piece of scrap 1018 steel. After turning it down enough to get to clean steel I cut it to the closest calculated diameter for a clean knurl and got exactly that. (I used the spreadsheet I posted previously to do the calculations.)
I needed to use a Morse taper sleeve to step up the #3 shank to a #4 to fit my lathe's tailstock, but I keep a variety of adapters on hand so no worries there mate.
The tool works great. The video shows me tapping an M6 x 1 thread into a piece of A2; it's a through hole, but blind hole tapping is just as easy. I use spiral flute taps so it is no problem tapping all the way to the bottom of the hole, there is no chip buildup.
One of the reasons I asked for a machining section here was to share ideas and get inspiration and that is the case here. A previous thread has inspired me to make a useful tool, thanks!
Old tool for threading rods, only the Morse taper shank and part of main shaft were reused.
My hand tapper. The friction collar is clamped to the collet toolholder but is free to spin and slide in and out in the aluminum tube.
Here is a video of the tapper in action.