Avoiding Marring Of 1" Steel Pipe When Threading

[pollys1dad]

I'm threading 1" OD steel pipe. I attach some picture of the pipe vice I'm using and the jaws on it. How can I avoid the marring on the pipe when it is held in the jaws, see photo A.
Thank you,
Peter.

[warmstrong1955]

I'd suggest a chain vise, like a Rigid BC210.
Only vise I know that mars the pipe more than the style you have, is a bench vise with 'pipe jaws' in it.

https://www.ridgid.com/us/en/bench-chain-vises

Bill

[Carm]

Got a lathe? Get a piece of thinwall metal pipe and bore it a bit over the pipe OD, say 5-10 grand. Split lengthwise, slide over the pipe and put the split horizontal in the pipe jaws.
Heavy feed lines are to your advantage.

[boaterri]

How about using a piece of heavy leather (think old belt) around the pipe before you crank down on the vice?

Rick

[SteveM]

Maybe use Carm's suggestion and add a layer of thin double stick tape (not the foam kind) on the outside of the pipe to add to the grip.

Steve

[BadDog]

I've seen split sleeves used, copper/lead/leather/material-at-hand shims used to protect the surface. Not sure the origin, but a also saw one setup with something like a strap wrench, but the handle was the frame, and the strap was really heavy and composed of many layers.

[pollys1dad]

OK thanks everyone, will try the belt idea first, if no luck I know a guy with a lathe who has done couple of little jobs for me will see if he can help out.

[earlgo]

Once again I am going to fall back on my experience at Teledyne-Oster, the threading machine company. Tapered threading dies cut on all surfaces at once, not like a straight bolt die. Therefore for a 1 in pipe thread, which has a total length of thread, L4 dimension, of .984 in the total length of cut is about 3x that. Remember you are cutting on all the leading and trailing edges of the threading die segments. Imagine a single point tool cutting a single pass at about 2.75 in long. Yes the d.o.c. is much less for each die segment, but the overall result is as if 1 cut were being made. Imagine if you will, the amount of torque required to remove all that metal at one time. This is why pipe threaders use universal motors and multiple self locking chuck jaws. This is why manual threaders have 2 ft long handles and why the jaws on a pipe vise are serrated. They are not that way to aggravate the user, but because they have to apply and overcome a LOT of cutting torque.
You must also use a highly sulfurized oil to convert the pipe metal at the cut interface, to softer intermetallic compounds. If not, the torque requirement goes up even more.

--earlgo

[Carm]

Just a reference for future readers. The OP appears to be threading pipe for some Pony style bar clamps, WT wasn't mentioned.
I've found a better thing to do is get some Sch.80 nipples say 4" long, whack 'em in half and butt weld them to Sch.40 pipe. Sometimes the threads collapse/strip on standard wall pipe since a good bit of material is cut away and the use as a clamp is uneven loading.
I suppose if you aren't so handy with a welder you could lathe cut some sockets and braze together.

[warmstrong1955]

A couple other options.....

Buy a 21' piece of threaded pipe, or however many you may need, and cut off the lengths you need off both ends.
You'll have a piece or pieces left over, but it'll get used.
No such thing as scrap.

Most all places that sell pipe, will also cut it, and thread it, to what ever lengths you need.
I had a couple dozen threaded 3/4" NPT for the same clamps as Peter is making, for some set up tools for tanks.....back when people built their own tanks....
I don't remember the cost, but it wasn't much at the time. Would be worthy of asking your local pipe guys.

Bill

[SteveM]

Thanks for the education, Earlgo.

As someone here said, "Every day, I learn something. Problem is, I forget two"

Steve

[liveaboard]

I have some clamps like that; after cutting the threads, I cleaned up the burrs on the pipe with a big file.
It just took a minute.
I don't even have a pipe vice, I use a pipe wrench or my lathe chuck.
Yes, threading pipe by hand is a real pain!
Especially without a pipe vice...