Picture of How to cut pipe threads without a pipe vise
First! i hope many to come.

well, the title says it all, i needed to cut some pipe threads for my new bed (yet another pipe bed) and i didn't wan't to invest money in a new vise with a pipe holding jaw, mainly because i alredy have a pretty heavy vise which suits most of my needs.

so, i proceded to find a way. tried pieces of cloth on the vise to have a better grip, then tried adding shellac to the cloth to make it 'stickier', then i made rubber jaws for my vise. none worked. finally i devised a simple method with tools most people alredy have lying around, and if they don't they really should make/buy (i often make even though it costs more, because it's fun!)

you'll need a heavy vise ideally, you could do around that using a fulcrum of some sort but if the pipe keeps sliping that will bother you to death, cutting threads is alredy hard enough.

the second tool is a pipe wrench. yes! a pipe wrench! turns out an instrument used to apply huge ammounts of torque is also the ideal instrument to resist applied torque. and really, the hard part of cutting pipe threads is the torque which causes the pipe to slip in the vise.

third tool is the threading die. this one is pretty straightforward, you need a die to cut the threads unless you want to file them (not since maudslay we don't!). you need to buy/make/rent a die and a threading kit (the turning thingy). mine is 1/2".

fourth tool is cutting oil. i use lard. that may sound retrograde but it actually has great adhering and lubricating properties. in fact, some machining oils still use lard in the mix even today. i advocate it's use because

1º it's enviromentaly friendly, lard is a byproduct and it is completely biodegradable and relatively non-toxic, unlike many cutting oils
2º it's cheap. the small cup you'll see me using in this instructable was made by myself and it cost me almost nothing
3º acessible to the hobbyist and still provides great, just as good, results as anything else.

well, let's get to it!
Ttalos4 months ago

When I took a machining class we used coconut oil as the cutting lube. It goes on semi-solid and melts as the parts heat. It's edible so if you get it in small cuts it its really an issue. Overall it works great and the machinists swear by it.

vtstruct8 months ago

Sure you can use bacon grease or other lard (animal fat). And rendering is just boiling the fat in a pot full of water and skimming it off the top, leaving the salt and other leftover bits behind. It also reduces odors.

Great Instructable.
One question.
Is lard the same as bacon grease?
My wife throws that out a lot.
enfieldbullet (author)  Ricardo Furioso2 years ago
lard is rendered pork fat. that can be done by wet or dry rendering, in dry rendering you heat the fat in heat without water, the resulting 'oil' is extracted. similar to what happens when you cook bacon.

so they're similar. but bacon is salted and smoked, so there will be some corrosive salts in the result as Iperkins said.

i'm thinking about putting up a ible on rendering lard. what do you guys think?
More or less. Bacon has a lot of extra salt though, so be sure to clean if off your tools when you're done though.
lperkins2 years ago
A good vise will have removable teeth in the jaws. You can use this to make all kinds of useful things for bending metal and holding oddly-shaped objects. If you ever find yourself bending enough pipe to be worth it, a set of pipe jaws is a relatively easy thing to make.
SwitchGear2 years ago
any hardware store can do this for you.
enfieldbullet (author)  SwitchGear2 years ago
yes, i heard that. but they don't do that where i live.
"Can" and "will" are two different things.
Many will thread when you buy the pipe.. not all.
mnwingnut2 years ago
You may know this, but not everyone does so I'll revel in redundancy.

Using a tap or die set to cut threads (taps cut threads on the inside, a die puts threads on the outside), it works well to go forward a half turn at a time, followed by a quarter turn backwards.

This helps by allowing the bits of cut metal to be drawn back into the recesses of the cutting tool and ease the binding that occurs. It also reduces heat a bit, which keeps the pipe from expanding and causing even more binding, and makes for more precisely-fitting threads.

Nice Instructable! I love the lard tip, that's awesome!
onemoroni12 years ago
More than one way to skin a cat, tap a thread. I worked as an elevator mechanic and had to improvise many methods to get the job done. Nice illustration of being creative and practical.
mr_bandit2 years ago
Not bad - but try using two pipe wrenches, one for each direction.

In general, one should cut about one turn, then back off a bit to break the cut bit off, then cut another turn. Use this time to put a bit more cutting oil on the threads - too much is much better than not enough (practice will tell you when you have enough but not too much).

You want to use about the same amount of force on each cutting turn. If it gets really hard to turn, you need to back off, apply oil, and start the next turn.

Any reasonably good oil will work - ie 30 weight engine oil. The oil lubes the cutting edge and keeps things cool. Higher speed (ie drilling into steel) needs oil. Cutting oil is specifically made for the high-speed cutting.

The poster uses lard - it will do in a pinch, although motor oil would be easier.

So - in general, a good idea. You can use two wrenches to create a "tripod" with the pipe, then lash/clamp the whole thing solid to a workbench.
dll9322 years ago
Lard oil is what machinists used to use-nothing wrong with it. In fact, I'd be real suprised if that wasn't what's in Tap Magic (tm).
kleinjahr2 years ago
Been there done that, all workable solutions though vise grip is probably best as it doesn't let go when you back off the die.
For cutting the pipe you can drill a pipe sized hole through a piece of wood, 4by probably best. Then rip down in line with that hole. Next drill a smaller hole below the first at 90 degrees and rip down to that. Slip the pipe through its hole and clamp across so it holds it tight, saw goes down the other rip which keeps it at 90 degrees. If you line the pipe hole with sand paper it will give a better grip and so use it as a pipe vise.
Good practice is to deburr the inside of the pipe after threading, a file tang works well enough as a reamer.
enfieldbullet (author)  kleinjahr2 years ago
thank you for the advice, it is indeed a good idea.

i didn't deburr because this was 'structural' pipes, nothing will pass inside them. but i did have to deburr and knock down the edges on some of them so they would thread onto the fittings easier.
Ob1zenobi2 years ago
Hi, good instructable! For the critics, there is such a valid thing as emergency & improvised methods: McGyverize. For many years have used this method out in the field when pipe vise not available etc. Just a note: when using any kind of tap/ die whether pipe or machine thread, it will be gentler on the life of the tool & easier to cut if you periodically back the tool off by 1/4 turn. I go forward maybe one turn or less then back 1/4 then repeat. Follow the increase in drag as a reference. This reduces the drag on the cutting teeth as you're allowing the cut filaments to break off instead of dragging all the cuttings around under the teeth.. You had mentioned a broken tooth, this may be what you were referring to ( instead of the pipe wrench popping loose in your face, lol. This method above will absolutely save your small 8/32 & smaller machine taps from breaking off in the work & they wont wear out as fast!
enfieldbullet (author)  Ob1zenobi2 years ago
actually my tooth indeed. not during this though, it was when i was unthreading a piece of pipe from a joint later and it hit my face. my profile pic shows it. i'm not negligent, but you know, accidents happen.

i certainly am right with you on backing out the tap/die so you can clear the chips but i didn't feel the need on this one, they were just curling out perfectly.
orator2 years ago
Not that it matters in this use, but are those threads actually 'conduit' threads instead of 'pipe' threads. May be just my eyesight.
enfieldbullet (author)  orator2 years ago
these are 1/2" USB tapered pipe threads.
hofy2 years ago
Wow, you need to think safety first. The very first photo you high light your feet and post "flip flops! no heavy machinery here so i can do that." . Then right next to that you high light the shavings and post "expect a lot of chips. a lot. these are like small razors and will cut your skin if you step on them. sweep as you go.
enfieldbullet (author)  hofy2 years ago
they won't cut through flip flops, they'll cut you barefoot though. and i wass sweeping the chips out of the way.

what i meant to say is that there aren't really any great dangers such as things falling and crushing my feet or splatter( as in welding). but you're right to point out safety is always welcome.
orator2 years ago
Forgot to say great idea!
Next time, cut two "V" block of wood for the vise jaws, instead of using fabric. That will allow you to hold the pipe in a stronger way, adding forces to the wrench.
By the way, nice work.
enfieldbullet (author)  charlycuervo2 years ago
i tried with rubber ones but that didn't work (hard industrial rubber, not the soft kind). i don't know if you can see but my vise will actually unscrew the jaws so you can substitute them.

i'll eventually make wooden jaws as well as soft metal ones(alu).
farmboy792 years ago
Pork chops for dinner honey, I need some lard for cutting threads! Seriously, as the author states lard is a good cutting lubricant. It has been used as a metal cutting lubricant for centuries and is probably as good and cheap as anything out there for the home hobbyist who doesn't need a gallon of cutting oil. It is obviously biodegradable as well so store it in the fridge or freezer long term or compost it when finished to avoid that rancid smell. Just have fried pork chops and save the grease but don't salt the chops until after you drain off the melted grease (lard). Lard in the grocery store has salt in it to prevent it becoming rancid and because it tastes good. Salt causes metal corrosion if left on metal and it is best it not be present in your cutting oil for sake of your cutting tools and the metal being cut.
Awesome! What did you need to thread a pipe for?
enfieldbullet (author)  audreyobscura2 years ago
thank you! i am making a nomad pipe bed.

so far i had 3 failures mid-project and managed to loose a tooth. does this mean i can apply for the redneck challenge? lol.

but it is coming along!
there's a redneck challenge???
jorricks2 years ago
Good Job well explained.
robots422 years ago
Glad someone else uses Lard. I bought a block from the grocery store, years later it still hasn't gone rancid or stink. If you back off the die - turn it back 1/2 a turn - when it gets tight you can avoid stripped threads.
lknowles2 years ago
Great idea! We sometimes don't think of things like this. A small chain tong would work well too.
pfred22 years ago
I did a project not too long ago where I had to thread 3/8" pipe but not mar it. It was pretty tricky. I did it by cutting open some copper tubing and putting the pipe I was tapping into it. Then I clamped that whole arrangement in a vise. It still slipped a little on me so I had to tap the pipe very slowly.