Slip & Slide

So I chucked up a piece of 3/8" unthreaded brass pipe in the old lathe
and proceeded to thread it with a pipe die.
The die did a good job for about half the needed thread length. Then
the pipe workpiece stalled as the chuck spun on it.
I cinched it down and tried again. I got about a quarter turn more on
the threads only to have the chuck spin on the workpiece once again.
Well, ultimately I got the threads cut but the pipe was pretty much
galled.
The lathe seemed to have enough horse power to cut the threads - if I
could keep the chuck secured to the workpiece.
So what would you do (short of buying a new chuck) to keep the
workpiece and chuck acting as one?
Gary
Reply to
grice
Loading thread data ...
Use a collet. Much more surface bearing on the workpiece Simple solution for this project would be a Hex-shaped 5C collet holder in the 3-jaw, and 3/8 collet (assuming that dimension is the actual OD).
formatting link

Reply to
Rex
Perhaps a lathe dog and driver plate. Four jaws normally hold better than three. Was the die one that cuts a standard tapered pipe thread- and you wanted to cut longer thread than normal? Jim.
Reply to
JimL
Try putting some paper, only one layer, around the pipe before chucking it up. Use regular white printer paper, not shiny magazine stuff or thin newspaper. It's possible that when you chuck up on the part that the back of the jaws are the only jaw surfaces touching the part if the chuck is worn. If that's the case then the paper trick might work better with two layers. Of course the jaws should be repaired if worn but sometimes we can't do what we want.
Reply to
Eric R Snow
Oh yes, brass pipe is not very stiff.
You should not need that much HP. You need a sharp die and some cutting oil. Yes, cutting oil also helps on brass. Dies don't have a relief and brass is quite springy. The oil helps to reduce that friction.
HTH, Nick
Reply to
Nick Mueller
are you sure that your die isn't a rethreader type with no relief? That would make cutting threads much more difficult
tony
Reply to
Tony
collets have less holding power than a 3-jaw chuck, as chuck jaws bite into the work.
collets are good for precision work, rapid loading/unloading of the workpiece, or when you don't want the work marred
Reply to
Tony
can you do the job off the lathe, using a chain vise? I never had a pipe slip in a Rigid chain vise/tripod. Or just use a Rigid pipe threader.
Reply to
Tony
Sacrifice a bronze bushing. Find or size a bushing to the OD of the pipe. The longer the better. Saw cut through the wall. Now, chuck the assembly in the lathe with the saw cut between two jaws.
Reply to
Tom Gardner
| Try putting some paper, only one layer, around the pipe before | chucking it up. Use regular white printer paper, not shiny magazine | stuff or thin newspaper. It's possible that when you chuck up on the | part that the back of the jaws are the only jaw surfaces touching the | part if the chuck is worn. If that's the case then the paper trick | might work better with two layers. Of course the jaws should be | repaired if worn but sometimes we can't do what we want.
Better still is to use medium or course grit sand paper instead.
Reply to
Hunter
Answers to the questions: I was only cutting a standard length pipe tapered thread. The pipe was 3/8" pipe meaning it was 3/8" ID. The OD was whatever brass pipe is. The die was a Greenfield "little giant" 2 piece removable type - very old but seems to be sharp. I used steel tapping fluid as a lubricant. I don't have a chain vise or a traditional pipe threader.
Thanks for the sandpaper idea. I'll give it a try next time.
Gary
Reply to
grice
Don't know it this is true in your case, but I've sometimes had relatively thin walled tubing collapse slightly in a three-jaw chuck and then this collapsed area "rolls" as the work slips. The solution is to put a proper sized round pin inside the tubing so the jaws clamp the tube against the pin.
Jerry
Reply to
Jerry Foster
Sure, but that's part of the problem.
Reply to
Rex
The solution to this problem has already been posted. Turn a bushing as long as the chuck jaws. Turn its ID to slip over the pipe, then slit the bushing and use the chuck jaws to compress the bushing over the pipe. You ain't a'gonna do any better than that.
GWE
Reply to
Grant Erwin
I've yet to see a 3-jaw chuck that holds stock anywhere near as well as a 5C collet does in its diameter range. If the chuck jaws are biting into the work for solid pieces, the chuck is being abused. If the chuck jaws bite into the work for hollow pieces (as in this case) the work is scrap.
Mark Rand RTFM
Reply to
Mark Rand

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.