I had a chance to thread some 1/2 NPT pipes. The threader worked,
however, the vise (Harbor Freight 4" vise) could not hold the pipe
well, so the pipe would slip. I tightened the vise rather well. This
is a vise with no special pipe holding provisions.
My question is, is the vise somenow not as good as it should be, or
was it simply a wrong tool for the job? Do vises with pipe "slots"
hold round objects better?
pipe threading requires an enormous amount of torque. Flat vice jaws
little surface contact.
Try making this tool I have several sizes of.
For 1/2" pipe (.840" OD) clamp two 3" pieces of 1" aluminum bar
together with .015"
shims between them. Drill thru the joint 27/32" long ways. With any
luck this with
make a saddle clamp with allmost 100% contact. Now put your pipe in
this tool and
into the 4" vise and try the threading die.
This tool is also great for screwing/unscrewing nipples without
I've threaded pipe hundreds of times.
Go to an auction of a closing electrical/plumbing contractor and get
yourself an American-made trivise made for the deed. Don't worry how
crappy and old it looks.
The seat for the pipe has got to have teeth on it and then chain that
you can then really crank tight.
Your vise can't hold 1/2"....hahahaha ! (not laughing at you)
I've threaded 2" ridgid conduit many times with these trivises.
One usually needs to use a cheater bar out the end of the hand
threader...and it helps to simply lay the weight of one's whole body
across the bar to offset the torque.
You have to tighten the vise as hard as you can but it, amazingly,
will hold even against those kinds of torques.
Ignoramus11107 wrote in
Flat jaws are not for pipe. You would have had much better luck if you had
clamped a set of v-blocks in the vice to hold the pipe.
Real pipe vices use a chain and serrated V's. (Rigid Industrial).
That will hold the pipe without marring it, but the surface area has
little to do with the friction. The friction equals the psi * area *
the coeficent of friction. If you double the area you halve the
A pipe vice is what you need. What you can do is to secure the pipe in
the vice you have and put a pipe wrench on it while you thread the other
end. An old three jaw chuck would hold the pipe too.
The jaws are supposed to dig into the pipe. If they are not sharp, or
heat treated well enough, they will slip.
I just got done hanging 1100' of black pipe air lines. I have both an
Oster pipe threader and the Rigid tripod vise for fitting work and so
forth, and had to regrind the jaws twice to keep them from slipping
There are two main types of pipe vise. The chain vise, and the clamp
vise. I actually prefer the clamp vise, given dull jaws in both.
I will be rigging up the KO Lee tool cutter grinder to recut all the
jaws now that the Project is winding down, in preperation for the next
Ive also learned to not skimp on pipe wrenches. While the $5 Harbor
Freight wrenches are inexpensive, they tend to have soft jaws and
after some use in a commercial application..dull quickly and stop
holding. For home use, they are fine.
So I scrounged up some beat up old Rigid pipe wrenches, and they, even
beat up, held better than some new HF wrenchs
I'd never try to use a machinist's vise for holding pipe for
threading. If you're doing a plumbing job, rent the right tool. I
happened to inherit my granddad's pipe vise, this wraps around a post
in the cellar and is tightened down with a wedge. The pipe holding
part uses a chain to hold the pipe against a serrated V, the chain is
tightened down with a jackscrew arrangement. There are free-standing
vises using a tripod stand which are probably more useful than my
vise, they can be used where there are no cellar posts. In either
case, the pipe has to be rather firmly wedged into a number of
serrations and they've got to bite into the surface or the torque of
the die is going to spin the pipe, no matter how small. Use proper
cutting oil and lots of it, too, the black stinky stuff, it reduces
the torque needed considerably although it makes for a mess. Just lay
a lot of newspapers down under the threading area.
My favorite emergency pipe vise is three pipe wrenches applied from
under the pipe - the outer two to oppose the threading torque and the
middle one opposed to them. The wrenches form a tripod, holding the
pipe above the work surface, then you sit a moderately heavy load
(child, wife,sack of potatoes) on top to hold the wrench handles in
contact with the work surface.
You needed the V blocks mounted below the jaws. Or use some others.
Typically only a single V block is enough.
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Life; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.