| Gallery, Projects and General > How do I?? |
| Cutting a taper thread... |
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| AdeV:
TTA (gah, of course!). I still haven't made the hangy-ony-bit for mine yet (oops)... Rob: 11TPI on a 60.3mm OD pipe. It's going to be an exhaust heat exchanger; once I've wrapped it in (or wrapped into it) a bunch of copper piping... I've cut the threads straight, and I can screw the pipe about 1/4" into the elbow; going to skim a tiny bit off the top of the outer threads (at a taper) until I can get at least 1/2" screwed in. :thumbup: |
| Jasonb:
Sounds like 2" BSP in which case the OD of the thread should be 59.614 not 60.3mm that may give a better fit. Pipe (male thread ) is usually cut parallel BSPP and the female fittings tapered BSPT Jason |
| AdeV:
--- Quote from: Jasonb on November 12, 2010, 03:35:19 PM ---Sounds like 2" BSP in which case the OD of the thread should be 59.614 not 60.3mm that may give a better fit. Pipe (male thread ) is usually cut parallel BSPP and the female fittings tapered BSPT --- End quote --- Interesting.... The original pipe is clearly tapered (male thread), it's not obvious which the female fitting is, I'd have to get the yardstick out for that. Anyway... I cut the thread straight, then skimmed a few thou off it to make it "tapered" (sort of). In the pic, I'm about to start skimming: For this test version, it works a treat. I screwed it into the engine & fired her up (NOISY), the ali got toasty warm in no time at all.... There was no sign of any blow-by around the threads, so - in best West Country voice - praaahper jaahb!. |
| Pete.:
Using your fixed steady (or set-over the tailstock) you could have set the tube over a bit to produce a tapered thread. Might have to take measures to stop it walking out of the chuck though. |
| Ned Ludd:
Another way to cut tapered threads would be with a hand held thread chaser, an under used bit of kit but useful all the same. They give a full form thread, that is to say they cut peaks and troughs, and they are good for making fine adjustments to machine cut threads as well. Thread chasers, for those who don't know them, are the opposite of "single point threading" in that they cut several threads at once. They are available in machine and hand held varieties. A certain amount of practise is need to cut a completely new thread but if wood turners can do it, so can we. Ned |
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