Even with bigger fittings though, keep in mind that these were all intended to be Production Machined after casting to drill and champher the holes along with running the pipe tap into them. Internal pipe threads are generally drilled to the minor diameter of the small end of the thread, meaning that by the time the tap gets in to the right depth the tap is removing quite a bit of material due to the taper, cutting nearly double the depth of the thread by the time it goes in all the way. Running Production, you can't afford to be breaking tooling due to bad castings. If your drill breaks, then the tap breaks. If you're lucky it only breaks the tooling and not the holders. They're not going to put up with crappy material wiping out tooling on a regular basis, and once it gets to the hardware store for you to buy, if it got through their machines at high speed, it should be easy to work with at home at lower speeds with watchful operator control. If you were to hear a clicking noise indicating a hard spot, you can stop feeding before your drill snaps off. If youre drill goes through OK, your reamer should go through OK.
Window weights or other castings that were never intended to be machined would be wise to avoid, or at least know the risk involved, but any casting that was designed to be machined, should be safe. I would agree with one of the other posts above that wheel cylinders would be another , maybe even better, choice for some projects, but I still like the look of pipe couplings for small steam cylinders, and have never had a problem with one yet. You may want to avoid an old rusty one with a hard layer of scale buildup in and on it, but clean castings, should be easily machinable.
I haven't worked with any cast iron pipe so I can't say much about that, other than what I pointed out above, if it's already been machined, it may be safe to use with caution, if it is the type that slips together with out being threaded, then you might want to avoid it.
Even with bigger fittings though, keep in mind that these were all intended to be Production Machined after casting to drill and champher the holes along with running the pipe tap into them. Internal pipe threads are generally drilled to the minor diameter of the small end of the thread, meaning that by the time the tap gets in to the right depth the tap is removing quite a bit of material due to the taper, cutting nearly double the depth of the thread by the time it goes in all the way. Running Production, you can't afford to be breaking tooling due to bad castings. If your drill breaks, then the tap breaks. If you're lucky it only breaks the tooling and not the holders. They're not going to put up with crappy material wiping out tooling on a regular basis, and once it gets to the hardware store for you to buy, if it got through their machines at high speed, it should be easy to work with at home at lower speeds with watchful operator control. If you were to hear a clicking noise indicating a hard spot, you can stop feeding before your drill snaps off. If youre drill goes through OK, your reamer should go through OK.
ReplyDeleteWindow weights or other castings that were never intended to be machined would be wise to avoid, or at least know the risk involved, but any casting that was designed to be machined, should be safe. I would agree with one of the other posts above that wheel cylinders would be another , maybe even better, choice for some projects, but I still like the look of pipe couplings for small steam cylinders, and have never had a problem with one yet. You may want to avoid an old rusty one with a hard layer of scale buildup in and on it, but clean castings, should be easily machinable.
I haven't worked with any cast iron pipe so I can't say much about that, other than what I pointed out above, if it's already been machined, it may be safe to use with caution, if it is the type that slips together with out being threaded, then you might want to avoid it.