| Archive for The Unofficial Mamod and Other Steam Forum The Original Unofficial Toy Steam Forum Established 2006 The biggest, most popular global steam forum around! Accept NO imitations! We have a growing community of regular posting members who chat about all aspects of toy and model steam. |
| Michael |
Connecting ¼ pipe & fittingsHi,I am looking to use this type of globe valve with similar type “T” connectors also with ¼ x 40 female thread. http://cgi.ebay.com/Globe-Valve-B...faultDomain_0?hash=item5180ea8acc If I thread a ¼ copper tube with a ¼ x 40mm die can I screw it into this valve and get a proper fitting or do I need anything else? Thanks for any advice. Cheers Mick |
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| STEAMPROPULSION |
If the threads on the copper pipe are properly sealed your set up is correct but a coned union is advisable if the copper pipe needs to be removed. | ||
| xlchainsaw |
i cant see a problem.  i dont know about this valve but a pm research valve has a taper thread which helps it seal.
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| Michael |
I would agree that the coned union would be better from a practical standpoint but I think that a direct thread would be less bulky and therefore look better. I am enjoying playing around with a thread and die set at the moment so I think I will give this a go.
The supplier recommends using a rigged brass pipe as supplied with the fittings but copper is available here without postage costs and I do not see to much of a disadvantage using copper. Before ordering I will get a die and test it on my copper tube to make sure there is enough meat on the tuber to take the thread. Cheers Mick |
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| metalhead100 |
There is a model pipe standard that some (PM I'm sure) use ...were the pipe nipples and fittings are tapered for a tight seal...just like real plumbing parts....
The fittings and nipples on my PM boiler are that way. And they seal well . Might run into taper/non taper issues .... of course they sell taper cutting dies and taps... Just making sure you are aware of this... Jim |
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| xlchainsaw |
another problem you might run into is putting the thread on square. it can be done with patience and a willingness to stuff up!! in other words... you start the thread on a peice of thin walled tubing... all is going fine ... but if the thread has been started crooked!!!.... you end up with "cutting " the pipe into a hole say 10mm from the start. this renders the thread as useless. there are ways of putting the thread on via a lathe or drill press which help solve this problem.
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| Michael |
Ok I will check on the tapered thread isues and practice first with my tapping OD ¼ copper tubing. I have tried this with smaller bore copper tube and had sucess so far actually making a straigh threadded coupler for a 3/16 tube using a pice of ¼ tube and it has held pressure under steam so far.
Cheers Mick |
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| ozsteamdemon |
Speaking as a fitter and turner , i would say that cutting a thread on any pipe or tube reduces the effective diameter of that pipe or tube to to the minor diameter of the particular thread chosen , so in fact , you will be weakening your tube strength by the depth of thread cut , especially on soft and ductile material like copper , or hard and brittle material like brass .
Then you must take into account , engine vibration , heat and pressure issues . " Not good practice " Its not something i would think about doing . For good reliability and safety , use the proper unions . Whats easier is not allways best . |
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| xlchainsaw |
ive done it many times without a lathe or drill press. but ive also stuffed a few up. i think its a homemade device ???? but ive seen a collar attached to a die holder which helps starts the thread straight. different size collars would be needed for each size of pipe. you see this feature on old plumbers pipe threaders ... the collar that is.... the place i saw it was at a retired plumbers place who now is involved with plumbing in model boilers and is threading heaps of 1/4 me thread onto brass tubing. when i asked about it he was very vague and wouldnt talk about it. but i have a keen eye!!!! for these things . he just said oh that ..i had it made up! so i dont know if they are available to buy.?????? did i stumble on his secret tool??? or are they readily available.?????
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| xlchainsaw |
excellent point geoff!!! on thin walled tubing its vital to know all about the application you are submitting the "joint" too. at the end of the thread (next is plain pipe) due the thread actually cutting into the tubing makes it very thin and weak at this point. i have some very thick walled pipe here in 1/4 and 3/16 (not k&s)so thicker pipe is available and being thicker is easier to thread. my 3/16 tubing only has a 1.5mm bore. found it at the scrapmans.
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