I’m starting the very early work on my next monster project for the Battleship New Jersey. This will be Engine Room #3 with cutaways of some of the more interesting machines contained within. One such machine is the Main Reduction Gear. These $20 miillion / 60,000 pound works of mechanical art contain a double reduction chain of herringbone gears. I would like to open this up since visitors can not see inside other than through tiny viewports.
I’ve been able to draft a passible bull gear. It’s not to scale since I don’t know it’s specifications yet. I’m going to visit the National Archives in October to examine the original engineeering drawings of this particular ship and hope that will provide me with the specifics. Meanwhile, I’d like to master what I need to know to draw the component parts. The bull gear is split so I can 3D print it with all the gear teeth not having to recieve any supports which would destroy them.
While the large gear will work, I’m having trouble creating the thick (long) mating helical pinion gears. When I rotate the face to create the helix after pulling the gear to the correct length, the waist pulls in. I need the sides to be parallel. I can fake it by stacking narrow helical gears, but I’m sure there’s someone out in SU Forum World (#DaveR) who could tell me the secret. Once I’m able to create one gear, I’ll be able to create the rest. The other challenge for me is determining the meshing helix angles. I rotated the bull gear 10º. For the pinion that was too steep.
Thanks guys. There’s always a way in SU, you just have to find the right folks to tell you how. Very interesting making it with native tools. Since I have Pro, I’m going to get Fredo Box Twisting. Nice to know that if it doesn’t work I can still pull it off. I love the Forum!
Box Twisting did the trick. Here’s the 2nd pinion set. I had no idea how to set the twist on the pinions to match that of the bull gear. The rotation I used on the bull gear (10º) was too shallow to mesh with the smaller gear. I ended up viewing through the Xray and twisting until the teeth were parallel in the mesh zone. There must be an engineering way to figure this out. The guys that designed these things in the 1930s didn’t have “Box Twist” with Xray views on a computer.
It’s going to be a thing of beauty when modeled in 1:48 scale.
Modeling the housings in SU will also be a challenge since it’s all compound curves.
When I perfect the main reduction year, it will be on to making a respectible steam turbine with some blading. Again, it will be artisitic license to figure out just how much should be exposed.
Although not as simple as just using Box Twist, if I wanted to model gears that work together physically, as in 3D printed ones, I would use the same basic technique I’ve shown for modeling screw threads for 3D printing.
Dave, do have a link to that thread? This model will be static so actual meshing gears doesn’t matter as long as it looks convincing. I’m not showing the entire arrangement, only a view from the top. Most of it is for my enjoyment and to learn some new things to do in SU.
My exuberance about finding original Battleship NJ BB61 engineering drawings was premature. After going into the Archives note in more detail in planning for our visit in October, I find to my horror that the plans to which they are referring are for the Battleship New Jersey BB16 dated 1905! Who knew there were two of them! My ADD was in overdrive when I saw they had the plans that I ignored the date of publication. After reviewing an index card list of vast proportions (1,900+) I was seeing descriptions of guns in sizes not on the modern version. Then I saw the date… Needless to say, I won’t be going to the Archives unless they can find drawings of the modern iteration. There are drawings on microfilm, and I may have another source of them besides a visit to DC. Meanwhile, if I could just get the overall diameter of the bull gear in the main reduction gear, I could at least get started on drawing that in correct proportions.
Bummer! I know how frustrating it is to be sure that somewhere in the world there are original plans for an object of keen interest, but not knowing where.
