Kozo"s k 27

[hoppercar]

If a guy wanted to build kozos k 27 in 1 1/2 scale..7 1/2 gauge, has anyone figured out the conversion factor to scale it up ?

[SZuiderveen]

The K-27 in 7.5” gage would be 2.5”/ft. scale.

Steve

[Marty_Knox]

Actually, for modeling 3' gauge equipment on 7 1/4" and 7 1/2" gauge I use 1/5 actually size.
The math becomes real easy - just divide the prototype dimension by 5.

[jcbrock]

That's an interesting fudge Marty, it really works well. The equipment ends up very slightly smaller but who cares, the stuff is too durn big anyway and the error is less than 1.5" scale on 7.5" gauge. It's not mathematically correct but I'd call it 'live steamer correct'.

[jeffsmith]

Don't use Kozo's drawings, there's to many things wrong with them....

Jeff

[makinsmoke]

Of course a 1-1/2” scale K27 would be 4-1/2” gauge. 4-3/4” practical gauge as that is a common gauge.

A K27 gauged to 7-1/2” gauge would be 2-1/2” scale.

Two different things you are asking.

[AnthonyDuarte]

If I remember correctly, kozo explicitly recommended not scaling up the K-27 due to design considerations that were specifically for its size in 3.5” gauge.

[daveb]

In Kozo's New Shay book there is a section to build the shay in 1.5" scale at either 7.25 or 7.5. In the section he redesigns most of the running parts because the 3/4" design did not scale up. for other parts his comment was to just double the measurements

[FLSTEAM]

I believe the original question was a multiplier for the drawings made in 3/4" scale. If my math is somewhat correct then to get to 2.5" scale you would just need to divide the 2.5 by .75 and get the 3.33 multiplier you are looking for. I have never looked at Kozo's drawings in 3/4" but I assume they are for Narrow gauge.

JB

[jeffsmith]

Here is a K-27 in 1.5" scale built by Jim Schmidt. You can get an idea of the size.

[AnthonyDuarte]

The Kozo K-27 is 1.16" scale on 3.5" gauge track. To get from 1.16" scale to 2.5" scale just divide the larger by the smaller. 2.5/1.166 = 2.1428. this would be your multiplier (7.5/3.5 gives you the same number). If you're building to 7.25 gauge and wanted to scale the locomotive to the gauge, you could also just use 7.25/3.5 as your ratio, which would give you 2.0714.

I believe Alco West has Rich Ulin's K-27 in 2.5" scale 7.5" gauge. Might be easier and safer to just use an existing design.

[makinsmoke]

Jeff,
Please confirm. Is the K27 in your photo 1-1/2” scale? Because it looks like 1-1/2” scale narrow gauge. On 4-3/4” track, right?

It’s pretty awesome, because it fits right in with standard gauge 1-1/2” scale equipment. Few people actually do this, sadly because the need for narrow gauge (and some three rail) track.

FYI, Jeff sells plans and parts for this equipment and it is beautiful stuff!

Brian