Great to hear
@OhioFlyer, thanks!
The bulb of the nosecone should be essentially flush with the outer wall. The shoulder has a bit of play by design. If you put the nosecone on and then rotate the tube to point downward, it should rotate past 135° before falling out. If there's a noticeable gap between the bulb and outer wall or if the shoulder doesn't stay in at all, then there might be an issue with that specific print; please let me know if so. Otherwise, referring to the shoulder not being especially snug, as you seem to be, long story short, that's intentional. They're just a touch looser than I personally prefer for display purposes. But for flight purposes I think the slight looseness aids successful ejection. I definitely understand shimming it with tape though. I personally would use Tamiya masking tape or Scotch tape rather than typical painter's masking tape; they're thinner, smoother, and cleaner. The plug is 6mm tall, so a Tamiya 6mm roll fits just right.
Long story (much) longer, the nosecone sizing is intentional within a set of goals & constraints. My line of thought went as follows below, for anyone interested in some rambling about kit design, which in many ways differs from and even competes with rocket design. I of course don't have a huge depth of experience in model rocket kit design, but a lot of this is partly coming from the same kinds of considerations and tradeoffs in similar hobby-level business designing models for tabletop wargaming (mostly terrain; think model train layouts, but shuffling soldiers and tanks around on it and going "PEW PEW PEW!").
Foremost is my belief that getting a proper recovery ejection on MicroMaxx motors is a bit tricky. T-MM sized minimal diameter rockets are real easy to overstuff and the streamer or whatnot just gets stuck. BT-5 rockets like the
HoneyBee have more space so the packing isn't as difficult, but it's a lot more volume as well as a bit more nose weight that the charge has to overcome. Objectively it doesn't matter, the rockets will usually be fine even if they lawn dart. But my friends & I find launches a lot more satisfying when the streamer does pop out and flutter down in the wind properly. That's a big motivator behind some of my design decisions, in this case pushing toward looser rather than tighter.
With these kits I'm also trying to minimize the amount of prep needed and make them more accessible to young kids and new rocketeers. That also encourages leaning toward looseness that can be tolerated vs tightness that has to be reduced. As a reasonably experienced modeler, I can appreciate a somewhat oversized nosecone shoulder that has to be sanded down to slide into the tube but results in a perfect fit. When I give a kit to my 5-year old though, the first thing they're going to do is try to put the nosecone onto the tube. Ideally that just works and they can start swooshing it around right away without it having to be sanded and so on.
So, in one approach to making the nosecone sit tighter, the plug could be longer such that it has less freedom to cant. I was worried though that additional length, as well as the consequent additional weight, would decrease the likelihood of the nosecone ejecting. More testing of different length plugs is an experiment I'd like to do at some point. But by the time I got everything else squared away on this design & kits I felt like I had to make a decision and end development, so I erred toward shorter/looser.
The plug could of course also be bigger in diameter. But I find sanding resin and plastic to be very unpleasant, not at all satisfying like sanding balsa can be. For a wood nosecone, especially balsa, I'd perhaps err toward too big and possibly having to sand it down. But for resin and plastic, given the choice I err toward taping if necessary. This is especially so for casual, beginner & youth friendly models.
Feeding into that point, model rockets are funny. On the one hand, they don't need tight dimensioning at all. Tape an engine to a spool or stick a nosecone & some hastily cut fins on a paper towel roll and those rockets will probably fly just fine. On the other hand, the dimensionsing is fairly tight compared to a lot of hobby activities, in particular woodworking and 3D printing.
My take on the general consensus in FDM printing (common filament based printing) is that dimensional precision & accuracy of 0.5mm is about what you can hope for and 0.25mm is well tuned. Somewhat unexpectedly, resin printing arguably has even worse expectations in general because it's more affected by variations in resins and curing. But in rocketry, the walls of BT-50 and smaller tubes are all 0.3--0.35mm thick, and you can tell if a part is too thick or too thin by a wall's width. The resin & ABS 3D printed parts in these kits have been modeled with a 0.25mm tolerance. For the resin parts in particular I was worried that going tighter would risk variances yielding parts that required sanding, which for these purposes I see/saw as worse than looseness. Now I think I could go a touch tighter and stay in tolerance, but at the time it was again a question of diminishing returns in the pursuit of perfection versus getting something good out the door and I erred toward looseness.
Beyond all that are calculations of cost and efficiency. E.g., much fancier printers or outsourcing the printing could permit tighter tolerances but would also raise the costs and required capital outlay quite a bit.
All that said, for the
HoneyBees and our next two similar kits in preparation I'm kind of committed for the time being to these decisions about looseness and so on (most of the parts are already made). But one nice thing about this kind of low overhead, semi on-demand light production is the ability to adapt easily compared to full scale production and traditional manufacturing. For example, the cutting alignment and variance on the
HoneyBee decals has already improved from the first batch as I continue to refine tools & processes. As a particular opportunity to adapt, I do have another somewhat more intricate and less beginner friendly model in the early stages of design. Especially in light of this kind of productive input, it might be reasonable to make the nosecones for that kit a bit tighter even if that meant they might require light sanding.
So, I can't say the choices were definitively correct, but that was the whole line of thinking and history behind the nosecone sizing. I do appreciate the question,
@OhioFlyer, it's a totally reasonable one that a lot of thought had gone into.
As some small reward for anybody that read to the end of this, and because I'm dying to share, here is a render of the sim'd and partially prototyped but not yet flown MicroMaxx design referred to toward the end there,
Obsidian.