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Thread: Need help on Pipe Threading
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21st Feb 2018, 04:31 AM #1New Member
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Need help on Pipe Threading
Hello, I'm Tiriaq from The Netherlands and a complete newbie in the metalworking world making a large wall mounted lamp from 1/2" pipes etc
After preparing a lot and putting myself to finally continue the project I'm at a halt, again... What happens now is that they start moving and damaging the pipe while trying to turn the die. Even if I clamp the pipe so hard that it deforms, it's still turning when I try to thread the pipe.
The pipes are 21.3mm outside diameter, the walls seem to be 2mm. I'm using drill/cutting oil and turn back every now and then breaking the chips, when I start I try to build up the force instead of yanking it in but it still moves.
-I need to know tricks or an affordable alternative to be able to clamp pipes in my vise that keeps them there without damaging them too much.
Solutions I've tried are what we call anti-slip mat, buying speeddrill and cut a hole inside a wooden block and cut that in half, also again with and without anti-slip mat, tried to clamp it horizontally, used only one block of wood and the other side agains the metal of the vise.
(The original set I bought was sold as DN15 and measures 20mm outside. When I read some of the Internet sites DN15 should be 15mm but that isn't 1/2" either, tried to measure outsides and insides... I don't get it. At first I thought when I bought the 6meter 1/2" pipe that was 21.3mm was the wrong one but when I browse the Internet again 21.3 seems to be a standard. Very confusing......)
Thank you in advance.
Kind regards,
Tiriaq
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21st Feb 2018, 07:54 AM #2Mechanical Butcher
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For galvanised water pipes, pipe vices with teeth on V shaped jaws are used. They do mark the pipe too, but stop it from turning.
Just an idea: Can you start with a longer pipe, weld a plate to one end, thread the other, then remove the plated end? Then use the other end with a fitting screwed to it, to prevent the pipe turning when it is threaded?
Another thought: As the threads are tapered, maybe tapering the pipe ends a little before threading will make it easier?
I was told that animal fat works better than mineral based cutting compound, because it melts at lower temperature and keeps the job cooler. I've used butter.
Jordan
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21st Feb 2018, 08:05 AM #3Golden Member
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As far as I am aware, the original pipe vice was a a toothed V base with a chain clamp over the top. Little to no damage; and if needed the correct old pipe threading stocks and dies can be adjusted for depth of cut on the 4 cutters.
I could thread them for you; but could be a bit pricey with the airfare to Australia etc. Then there would be the problem of metal pieces in the carry on luggage.
Have you considered approaching an old style plumber who may still have the tools for working pipe.
Ken
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21st Feb 2018, 09:47 AM #4Diamond Member
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Hi Tiriaq and welcome to the forum. You have received some good advice already. Not knowing what tools you have at your disposal doesn't help me much to give you advice on how to do it, but going to a plumber is probably the direction I would go because they are likely to have the correct tools to do the job, and probably the tools to do it quickly, like a pipe threading machine.
Your confusion about pipe sizes is quite understandable. British Standard Pipe (BSP) is denoted as having a nominal bore, so 1/2" pipe won't have a bore of exactly 1/2 of an inch, but it will be somewhere about that size, but it will vary with differing types of pipe. Galvanised pipe will presumably be a bit smaller due to the zinc coating, and heavier wall sections will also have smaller bores, so steam pipe or scaffold tube will have smaller bores than black (non galvanised) pipe of the same nominal bore. The reasons for this I think, was that the same threading tools would work with the various pipe types, with the outside diameters for a given pipe size being pretty close. If you are unsure what anyone talking of pipe vices or threading machines are talking about, Google Rigid pipe threading tools, and you should get a pretty good idea of the Rigid range of pipe tooling, HTH,
Rob.
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21st Feb 2018, 09:54 AM #5Most Valued Member
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The fact that the pipe is turning suggests the die is blunt or the wrong size, or you have the lead in taper facing the wrong way.
As stated the best way to grip pipe is with a toothed two piece bolt up clamp specifically made for the job. Some have two serrated angular sections and some have one and a chain.
Plain vise jaws are not going to grip well, particularly on galvanized as it is soft. A set of steel "V" blocks will help it grip a lot better.The worst that can happen is you will fail.
But at least you tried.
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21st Feb 2018, 10:10 AM #6Pink 10EE owner
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You will struggle to hold pipe for tapered threading without marking it in some way. Reason being you are cutting a tapered thread so the further you thread the greater the force required as the whole length of the die is cutting not just the leading edge.
What you could do is get a BSPP die and use it. The ISO designation is G. So something like this https://www.ebay.com.au/itm/G-1-2-14...-/270857117225
BSPT and BSPP are similar just one is tapered and one is parallel (like a normal thread), but the TPI and is the same.Gold, the colour of choice for the discerning person.
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21st Feb 2018, 10:40 AM #7Member: Blue and white apron brigade
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As others have said, vices will inevitably mark pipe. I have a set of notched pipe vice jaws and they make a real mess as well.
I have found holding pipes in a Collet jawed chuck in a lathe produces minimal marking but you will need to have access to all this gear to do that.
One problem with this is room to rotate the die.
Seeing as you don't need it to be water tight and the load does not seem to great you could also try removing some of the wall thickness off the ends of the pipe pipe which will substantially reduce the load. A lathe is the easiest way to do this.
Another tip is to use an adjustable die - these dies have screws in slots in the side of the die that allow the die to be slightly expanded.
Typically you can expand the die with the die screw and cut a thread and then loosen the screw till the thread fits.
I use Trefolex as the thread cutting lube - its heaps better than anything else. My BSP dies are all fixed size dies and the Trefolex makes it possible otherwise its impossible.
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21st Feb 2018, 03:51 PM #8Member
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If the wall thickness is about 2mm as described in the original post, that is a light pipe and I doubt you will get a thread cut on it and leave any metal behind to screw on to.
Hooroo.
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21st Feb 2018, 08:40 PM #9New Member
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Thanks everyone!
- I did grind the top and bottom a bit to make it easier for the die to grip.
- It's gripped the right way and cutting the thread. The problem is more that the pipe is turning while I'm doing this. Clamping it harder squeezed the pipe thinner
- I don't even remember how I got this vise, I only have a minimum social security so I try to pick up stuff from the garbage and recycle or keep it as cheap as possible while still being on the safe side. I have no clue if I can still buy stuff for this vise or if it has universal attachments.
- welding can't be done in my house (small 3-room apartment 1st floor) but I was thinking of hard-soldering a little something on the side to keep i from turning when I discovered that the oxygen tank was empty........... sigh cheap set, cheap valve on the burner. Should have disconnected the bottle every time.
- Someone finally found a store with the threaded nipples but it's too late now. I've already bought 6 meters and the threader wrench. Made way too much costs 90 euro or so on all the stuff, d*mnit. The good thing is that I'm learning something new, again. Though I'm choking from too many projects. Going to the plumber in The Netherlands will cost me a small fortune. If they want to bother for that at all. Then again I didn't buy all this stuff to hand it out to someone else.
I guess the only thing for now is to buy an oxygen bottle and solder something to the side a little bump or something bigger that can be sanded or grinded off easily so that the pipe won't turn and I don't have to squeeze it so hard that the pipe will be deformed.
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21st Feb 2018, 09:08 PM #10
A simpler cheaper solution to try might be to get some rough sandpaper-#60 or #80 grit and cut a length ways strip as wide as your wooden vice block.
Fold in half with the paper inside and glue-say hot melt glue if you don't have any contact cement or basically whatever you have around the place.
Wrap the sandpaper friction strip around the pipe and clamp up.
With luck, there will be enough friction to stop the pipe slipping in the clamp block.
Make sure the open side taper of the die is outwards and don't forget the lube on the die.Ensure that the thread die starts square to the pipe.
Best of luck
Grahame
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21st Feb 2018, 09:55 PM #11Member: Blue and white apron brigade
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22nd Feb 2018, 08:40 AM #12Most Valued Member
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As it is just going to be a non liquid carrying object, you can easily stop it from turning by cross drilling through the pipe and putting a bolt/piece of rod through to act as a stop in the vice. Just remove it after. You will have a few holes in the pipe after and if this matters just fill them with bondo and sand level, coat of paint and all good.
EDIT: I see something similar has already been suggested.
Cheers RobThe worst that can happen is you will fail.
But at least you tried.
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22nd Feb 2018, 10:22 AM #13Most Valued Member
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You coud slide a a length of bar the right diameter inside the tube to stop it crushing in the vise.
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22nd Feb 2018, 09:52 PM #14
I have done this BSP threading job quite a few times, I built a sprinkler system around the house ( bush fire ) using 3/4 pipe gal , the pipe is I used is around 1 and 1/16" OD . I just clamp the pipe in the standard vice . I have a Warragul 3/4 BSP die. Anybody remember the old square shaped Warragul dies ? I use a stihlson wrench on the die . I know that plumbers used to use the proper die holder and a chain lock device but I don't have that stuff.
On a few attempts the pipe slipped in the vice - this was due to the pipe OD being slightly oversize , the die would grab and stall and the pipe would then turn. BTW these gal pipes come in different wall thickness , I think there are three sizes of wall available in 3/4 gal.
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23rd Feb 2018, 03:07 AM #15
THAT is the way I do it (with my less than pristine pipe dies). I've had a Dicken's of a time holding 1" pipe still for threading and found a round bar turned to fit neatly inside the pipe allowed me to clamp it as hard as I needed to without deforming the pipe. On a couple of occasions, the bar was difficult to remove, but clamping it rotated by 90 degrees "re-formed" the pipe sufficiently to remove the bar (as I was tightening the vice).
I usually used Lard (pig fat) for threading pipe. It works MUCH better than anything ele I've tried - I must try Trefolex one day.
@Tiriaq: please post a photo of your threading die and holder - and maybe your vice and work bench. That might help us help you more.Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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