How to Cut Pipe Threads Without a Pipe Vise




About: not much really, i'm only building along as i go. i have an uncontro..incontro.. impossible to control urge to build things, and to disassemble others. i have been in college as a biochemist but dropped ou...

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!

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Step 1: Setting Things Up

First you'll need to measure, mark, and cut the pipe to lengh.

measure twice, cut once. (that saved me today while i was cutting these)

be sure you are cutting square, you don't have to be absolute about it but some care makes the threads come out better and makes work easier.

i like to lubricate the blade of the hacksaw (guess i didn't mention this tool, duh) it makes it MUCH easier to cut, the lard beatifully adheres and doesn't drip (try finding a cutting oil which will do that). also , the lard won't stay solid as people may think, it sort of liquefies on contact with metal (my guess is that the metal's ability to transfer heat fast is the responsible, but i digress)

after you cut, take down the edges with a file and make up for any imperfections in the cut.

i know most of you all know this, but bear with me, someone might not know that so i'm including every step except the stuff you can figure by yourself(not going to take all of the fun out).

lube it up and it is ready to tap!

Step 2: Actual Significant Part of All This

now the 'secret'.

with the pipe secure on the vise (not tight yet) put the pipe wrench on it as it is in the picture, move it around until you get that 'bite', then turn the pipe so that the handle of the pipe wrench rests on the table, this will ensure it keeps 'bit' and the torque will flow to the handle, which will keep things in place. then tighten the vise.

beware that there's a right way to put in the wrench(as if you were turning to the opposite direction that you are tapping), if you put it the wrong way there will be MAYHEM! (lol), actually, it'll just fall of because the rotating pressure will cause it to 'unbite' the pipe. but do beware there are extreme pressures going on as with any tapping and things can jump at you if you aren't careful.

lube things up. the pipe and the die. enough lube prevents wear on the die and these are expensive, lard is cheap.

proceed to tap. just turn ir clockwise while keep pressure forward on the first turns, then it'll become VERY hard to turn, this is a sign things are going well ( you're not striping the threads.). then keep going until your arms fall off, or until the thread protrudes just a bit out of the tap. you're done! turn things counter-clockwise until the tap slides off. you might have to replace the wrench the 'wrong way' because torque now is to the other side.

clean your threads and you're done. if you leave the lard in there it'll go rancid and stink. soap will take it right off.

Step 3: Ta-da!

Hope you enjoyed.

i had a lot of fun making this instructable and finally i feel a little useful doing something back for the community instead of just lurking.

i did this short instructable because i didn't find anything on google that was a good, cheap solution to this problem. so i thought other folks might see some use in it. if you have a better solution please share! if you like the article, please let me know!

Step 4: Addendum

Some afterthoughts and stuff that happened after.

firstly, you can also use locking pliers to resist the torque, perhaps that's a better alternative because it will stay still.

second, while 'cheating' i had some stripped threads, nothing that i couldn't chase back with the die but be warned it can happen.

third, when pushing forward on the first few turns on this kind of die you want to make pressure as in the picture, right on the die, with a cloth on your palm (it gets hot and can burn you).

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    33 Discussions


    4 years ago on Step 3

    Thanks a million for the tip! I been doing woodworking for a while, but I am a complete novice with iron pipes. Today I was trying my luck making an industrial coffee table. I bought a threading set that works beautifully, but the 1/2 inch steel pipe kept slepping in my Klutch vise. I look everywhere on the net and nothing. Until I found your post. Man, did it work for me! In less than an hour I threaded six pipes I had already cut to size. Again, thanks a lot!!!


    4 years ago on Introduction

    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.


    4 years ago on Introduction

    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.

    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.


    6 years ago on Step 3

    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.


    6 years ago on Step 4

    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!


    6 years ago on Step 2

    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.


    6 years ago on Step 3

    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.


    6 years ago on Step 2

    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).


    6 years ago on Step 4

    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.

    1 reply

    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.


    6 years ago on Introduction

    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!

    1 reply

    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.


    6 years ago on Introduction

    Not that it matters in this use, but are those threads actually 'conduit' threads instead of 'pipe' threads. May be just my eyesight.

    1 reply