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Hi Jon, I suspect a 3 axis machine that can tilt the head as the part is cut to deal, with a known tapper angle using a specific tip, cut rate, garnet feed rate, and material thickness might be available. But I don't currently know of a specific machine. I'll have to search a bit. If one needs a perfect 90 degree cut so you can machine it with a lathe, CNC router, or rotary table mounted on a drill mill, a aqua jet machine can rough cut your acrylic at a much faster feed rate, which would be much cheaper. But for that one can simply rough cut them out with a band saw, or jig saw. Which would be cheaper. You can also cut metal parts out this way, but it nice to just have them water jet, laser cut, or plasma cut out on a CNC machine if you have the CAD drawings, funds, and local shop that can do it for you. Also in some areas it may be hard to find a large enough lathe or rotary table drill mill set up to machine are larger windows, so that could be a important factor in deciding to have them water jet cut. When I get home I'll have to look thru that Stachiw book and PVHO data I have more and see what I can learn about side wall issues. I see so many flat windows and domes that don't touch the side walls, so I figured they were mostly for centering and extra strength for the welded in supports. If you do a window like some plate thru hulls that have no side walls, that are designed with enough strength to deal with the load, that is what I was thinking of. I like the side walls in many applications. But as we know there are many aps and PVHO configs. to choose from. Regards, Szybowski > Date: Mon, 20 Jul 2009 21:09:57 -0400 > From: jonw@psubs.org > To: personal_submersibles@psubs.org > Subject: Re: [PSUBS-MAILIST] Aqua Jet Cutting My 2" Acrylic Viewport > > > Brent, > > Remember that the high conversion factor addresses all potential short > comings of the window. If you have weaknesses in multiple areas you may > find that your safety factor isn't really quite as high as the raw > numbers would suggest. The dimensions of the taper you provided do seem > small, however you didn't answer whether the water jet machine can cut > true without any taper at all. However slight, I'm not sure I > understand why anyone would accept a taper if indeed the machine can cut > a 90 degree edge. Especially when paying $90/cut. > > In reference to not having side walls on the viewport seat, I can only > say that Stachiw makes no mention of such in his book and all the > recommended seating arrangements he provides for flat disc viewports > include appropriate dimensioned side support. Do you know if a seat > without side walls and simply using a retaining ring to maintain > centering has been adopted by ASME PVHO specifications? > > Jon > > > > Brent Hartwig wrote: > > > > > > *Hi Jon,* > > ** > > *I would just cut the window a small amount over size to make sure > > that there is at least enough material for the window specks with a > > little more, then make your metal seat accordingly. that way you have > > the full spec seating surface and acrylic disk size. How far away the > > side walls are is not really a concern to me, as long as the seat is > > designed to handle the load required of it. Since most the higher > > stress area is transferred to the inner area of the seating > > ring. Besides so many of are windows have a FOS of 8 so we are covered.* > > ** > > *For example, my original forward viewport had a OD of 16", and it's > > seating area had a OD of 16 3/16", giving 3/32" of room to play with. > > That is more then enough room to deal with a very small tapper I have > > of 0.012" / 0.31 mm in a 2" thick cut.* > > ** > > *You don't even need the side walls on the seat as long as the > > retaining ring can keep the viewport centered. For example, Idabel's > > lower forward flat viewport.* > > * > > Regards,* > > *Szybowski* > > > > > ************************************************************************ > ************************************************************************ > ************************************************************************ > The personal submersibles mailing list complies with the US Federal > CAN-SPAM Act of 2003. Your email address appears in our database > because either you, or someone you know, requested you receive messages > from our organization. > > If you want to be removed from this mailing list simply click on the > link below or send a blank email message to: > removeme-personal_submersibles@psubs.org > > Removal of your email address from this mailing list occurs by an > automated process and should be complete within five minutes of > our server receiving your request. > > PSUBS.ORG > PO Box 53 > Weare, NH 03281 > 603-529-1100 > ************************************************************************ > ************************************************************************ > ************************************************************************ > |