Yup.If a 60 is cut to take an MRod .25 mag, it can be used for .22 (wheel change), .25, and with Lloyds' mags, .30 cal. With the impending single shot tray, we can keep going up, until the barrels are too thin to mount.johninthecamper has .30 BTs that work well. I don't know the specifics, though.
The threaded portion is NOT pressurized and sees no radial forces.... That calculation was for the TENSION load in the thinner portion that is threaded, between where the thread is engaged and the full diameter section of the tube.... It is something people often forget to calculate....I will not discuss what other's have done, only what Eric has asked me to assess....Bob
If you increase the wall thickness, you will have to turn down the valve, backer block, hammer, and fill plug.... You would have to ask QVTom if making the hole in the retaining nut flange smaller and moving the point where the force is applied further in from the thread causes more stress on the corner from leverage.... The smaller diameter would decrease the area and increase the stress on the shear planes in the nut and the plug as well, but not by a lot (~5%).... Just changing to 4130 on the 0.065" wall would increase the yield strength from the 44K I used to 68K, which would increase the safety margin on "stretching" that thin portion of the tube wall axially from 3:1 to 4.6:1, making it no longer the weak link.... It would also increase the yield and burst pressure of the tubing by the same margin.... Here are the calculated yield and burst pressures of a couple of materials for the tube, and the safety margin at 3000 psi, using 0.875" OD x 0.065" wall tubing.... Note that the original XS-60C uses 22 mm x 1.5 mm tubing, which isn't as strong....Mild Steel (1010) - Tensile 53K, Yield 44K:Pressure at yield: 7678 psi.... Safety margin 2.6:1.... Pressure at burst: 9248 psi.... Safety margin 3.1:1....Low Carbon Steel (1021) - Tensile 70K, Yield 52K:Pressure at yield: 9074 psi.... Safety margin 3.0:1....Pressure at burst: 12215 psi.... Safety margin 4.1:1....Normalized CrMoly (4130) - Tensile 97K, Yield 68K:Pressure at yield: 11866 psi.... Safety Margin 4.0:1....Pressure at burst: 16926 psi.... Safety Margin 5.6:1.... Note if the tube is threaded and that threaded portion is exposed to the pressure, these numbers do not apply as the wall thickness is reduced to only 0.0365".... That is why Eric is planning on using a through tube on his 3K conversions, with the only portions exposed to pressure the full 0.065" wall thickness....Bob
Just as an aside.... I looked up the tap drill size for a 13/16-16 tpi thread and it looks like 19mm or 3/4".... Shouldn't that start right into a 7/8" OD x 0.065" wall tube (0.745" ID).... The OD is still 0.8125 regardless of the pitch, so why couldn't you use a thread that coarse on an end plug?.... Anybody?.... The minor diameter of that thread is 0.745"....Bob
I don't know why you are worried about the threads, be the material brass, aluminum, steel, or 4130.... with 1/4" engagement or more they are the strongest part of the plug.... and IIRC, the engagement is more like 3/8".... Now you are suggesting a 3mm wall?.... with a burst pressure of over 17,300 psi in mild steel?.... Oh, right, I keep forgetting you want to add more weight.... I'm not interested in continuing to run numbers that have nothing to do with the project Eric and I are working on.... I'm sure you know how to do that yourself....Bob
Couple questions, quite likely rather uninformed on the topic, but that is why I am asking the experts.Could the assumed weak section be lined to strengthen it? Is that what through tube basically does, by not stopping at the receiver?Is there any concern of galvanic corrosion between the aluminum receiver and ferrous airtube?
My question is can a tank block be used like the Mrod mod? If the receiver was to be drilled or machined out from the front short of the hammer striker block. Can the tube be expoxied in? Being that the valve fits into the tube. Predrilling for valve screw and transfer port would be also necessary. Anyways its was something rattling in my head.
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