Some Random Questions

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Postby Velocity » Fri Nov 24, 2006 5:53 pm

At my hardware store, the black iron fittings have a slightly shallower socket depth than the pipe nipples, and therefore, if I try to get two fittings flushly together, there will be a small, annoying gap. Would it be possibly to lathe-down a tiny portion of the threads on each side of the iron pipe nipple, in order to give it an overall shorter appearance? I would be building a pneumatic, which would hold 100 PSI or less.

Right now, doing this would be impossible. But this christmas, there is really nothing I want, and I realized this may be my only chance to get a lathe. So, I can only hope :)
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Postby c0mpl3x » Fri Nov 24, 2006 5:59 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Rmich732
[br]At my hardware store, the black iron fittings have a slightly shallower socket depth than the pipe nipples, and therefore, if I try to get two fittings flushly together, there will be a small, annoying gap. Would it be possibly to lathe-down a tiny portion of the threads on each side of the iron pipe nipple, in order to give it an overall shorter appearance? I would be building a pneumatic, which would hold 100 PSI or less.

Right now, doing this would be impossible. But this christmas, there is really nothing I want, and I realized this may be my only chance to get a lathe. So, I can only hope :)

<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">no, because the large ID taper is still there. why not just fill the gap in or weld the gap in? you'd have to either re-tap the fittings larger (the easier) or re-die the pipe thread with an internally gripping vice (the harder)
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Postby Navigator7 » Fri Nov 24, 2006 6:53 pm

If the fittings hold air......why not Bondo and paint?
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Postby Velocity » Sat Dec 02, 2006 6:28 pm

Ok thanks for the replies. I have a few more questions now...
1) When making an o-ring groove, how does one tell what size to make the groove and what size of oring to use in the groove?

2) Is there anything that is used to seal an oring into a groove, or does it just remain in the groove without any adhesive?

3) Say I want to make NPT threads on a lathe. How would I go about making the threads so that they are properly sized? I know it is possible to do this (looked it up online), but am just not sure how to do it precisely enough so that it is compatible with other NPT fittings that are not made by me, on a lathe (in other words, npt threads that are the right size and such)

4) If PVC rod is machined down properly, to have the correct OD, is it possible to glue it into a fitting or to glue it into the inside of a length of PVC pipe?

Thanks
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Postby SpudStuff » Sat Dec 02, 2006 8:08 pm

I don't believe you can get the taper on a lathe. Posibly but I would think it would take alot of skill.
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Postby Drew Rowland » Sat Dec 02, 2006 11:01 pm

A taper is easy on a lathe.
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Postby Velocity » Sun Dec 03, 2006 12:23 am

I am sure it is possible, and that many people do it to get threads that fit together even better than those which are produced on PVC fittings and such. I have read some websites about them, yet due to my limited knowledge of lathes (having not owned one...yet) I cannot comprehend all of the information.
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Postby clide » Sun Dec 03, 2006 12:34 am

He means tapered threads I believe. If your using it in a fitting with a taper then it won't really matter much that the other piece is not tapered. The only threads I've really done on my lathe were for the slide valve on the slider and it worked fine with no taper. You just have to have the right threads per inch and a piece with the right OD then just cut into it until the threads form a complete V

1)Personally I use a mixture of estimating and trial and error most of the time. http://www.sealseastern.com/OringDesign.asp has some design guidlines for several types of seals, can't vouch for how well they work though.

2) No adhesive neccessary. The only time I have had problems with o-rings leaving the groove is when I use an o-ring for the seat seal of a piston valve. The quickly moving air after the valve opens can suck the o-ring right out, a tighter o-ring can usually fix that though. A good lubricant is a must though.

4) Yep, just make sure it is a firm fit.
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