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Post by kvom on Sept 18, 2011 10:53:32 GMT -5
A3 in 1.5" scale: regarding the reverse lever, fig. 18-7, p. 113.
If you double the hole diameter for mounting the latch lever (fig. 18-8) to .146, then you will need to use a 6-32 screw. To use a smaller screw, then plan ahead before machining, or else the latch lever will fit too loosely on the reverse lever. Regardless of the thread size chosen, the holes drilled in the latch lever will need to be chosen to match.
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Post by kvom on Sept 18, 2011 10:59:42 GMT -5
Minor drawing error: fig 18-20, p. 114, shows reach rod arm on the outside of the bearing rather than inside.
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Post by kvom on Oct 6, 2011 21:03:53 GMT -5
I went looking for o-rings for the piston and valve rods today, but find that Viton rings, specified by Kozo, are not recommended for steam. One vendor recommends EPDM. PTFE seems likely to be better than either.
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Post by kenrinc on Nov 21, 2011 19:04:38 GMT -5
Kozo wrote a very detailed article in LS magazine with his reasons for selecting Viton. It is reproduced in the "New Shay" book. He mentions that the mfg do not recommend Viton for steam service but he asserts that Viton is more than adequate for steam service.
I'm curious about the expansion links and trunnions. Kozo insinuates that the jig that is made for making the expansion link is again used for making the trunnions yet the holes drilled to hold the workpieces to the jig are 1-5/8 not 1-13/16 as are the holes in the links. This means that the jig can't be used to also make the trunnions. I guess you can drill another set of holes but thought I'd bring it up.
Ken-
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Post by kvom on Nov 22, 2011 10:38:01 GMT -5
The jig holes in the trunions (1-5/8 spacing) are milled off after the trunions are shaped. When I overlay the expansion link and trunions in CAD, the lower jig hole is too close to the bottom of the link. However, fig 17-21 shows that for the expansion link the lower hole is 1" from center.
So a single fixture for both expansion link and trunions requires three mounting holes, as Ken says.
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Post by kenrinc on Nov 22, 2011 13:46:24 GMT -5
Arghh!! OK, it's no mistake. Kozo is the master of showing huge amounts of detail in a single drawing. Pays to study it carefully or later on you might end up asking a question such as I did. If you look at the jig there are two sets of holes... (duh). 1-5/8 and 1-13/16 spacing. It's all good. No error.
I'm not too good at drilling jig holes and having things "magically" line up. I guess it would make sense to use the jig to drill all the workpieces first.?
Ken ken-
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Post by kenrinc on Dec 4, 2011 19:08:27 GMT -5
I had to remake my main crankpins. In viewing the dimension from the front face of the driver to the end of the crankpin, Kozo shows 2 different values and the calculated value is different still. The calculated value I come up with is .715"
.200 side rod .075 for spacer .040 for main rod bushing .200 for main rod .200 for return crank Total = .715
On page 78 Fig 13-1 he shows the distance from the drive face to the center of the main rod as .422 (27/64) . I get .415" for this dimension. If you add half the main rod plus the return crank you get .722" for the total length.
If you go to pg 74 Fig 12-1, Kozo shows the entire dimension as .728" Have no idea what the actual dimension should be at this point. Obviously knowing the center of the main rod is critical.
ken-
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Post by kvom on Dec 4, 2011 23:07:24 GMT -5
Fig. 12-14 p. 76 shows it as .744. Lots of numbers to choose from.
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Post by kvom on Dec 29, 2011 14:42:29 GMT -5
For anyone like me who's hunting for the front handholds on the pilot beam, they are the same as those on the tender, shown on p. 50.
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Post by kvom on Feb 16, 2012 17:32:06 GMT -5
For A3 in 1.5" scale, the boiler fire hole is likely too high. For the smaller scale, the bottom of the fire hole will lie ~ 2" above the grate, and 2" is a good thickness for a bed of coal. At double scale the bottom of the hole will be ~4" above the grate. Along with the size of the opening, this could make raking the fire difficult.
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Post by kvom on Feb 19, 2012 17:06:37 GMT -5
For A3 in 1.5 scale, I have been advised by experienced builders not to connect either the water gauge or the pressure gauge to the turret, but rather to have separate connections to the boiler. The reason for this is that anytime a valve is opened in the turret, there are resulting pressure fluctuations that will cause both gauges to register incorrectly.
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Post by kenrinc on Mar 8, 2012 12:07:31 GMT -5
It's typical to have the water gauge glass have a separate connection directly to the boiler but nearly all of the engines at our club have the pressure gauge on the turret. Of the people I've asked about it, all have said it doesn't make difference and they see no pressure drop when it's on the turret.
Ken-
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Post by kvom on May 18, 2012 17:48:54 GMT -5
Ken and I recently discovered that the boiler drawing for 1.5 scale has the steam dome too far forward. The separation from the sand dome needs to be doubled from the 3/4 scale.
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Post by Ed Hume on Aug 23, 2013 14:43:15 GMT -5
Here is a minor change for the New Shay.
In, Fig 13-1, page 133, part (27) shows flat head screws are used to attach the engine cover to the running board. Therefore, Figure 2-33, page 27 should show the leftmost 2.1 diameter holes as countersunk on the underside of the Right Running Board.
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Post by Patrik on Sept 1, 2013 18:31:15 GMT -5
Think i found one for the K27
The text about the eccentric 2.7 part 12 and FIG 2-22 text specifies offset of 5 mm while the two drawings specify 7 mm offset.
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