Designed some handrails the other day. Well parts of a handrail to see what I wanted to do for the whole handrails I'll need on my kitbashed DDA35 loco I'm trying to build. Above is the first attempt (ignore the curve as it is quite flexible). This was designed with Fusion 360 after looking at a number of pictures of UP handrails from that time period (they still look pretty much the same). Can't believe the detail possible with the resin printer but in all truth you can't see the bolts and the channel in the upright or the wrap around the handrail with the naked eye at normal viewing distances. Even at a couple inches it is hard to see that detail. I'm going to exaggerate it a little for the next print and maybe painted it might show up better. I decided to print the exact same file with the Ender 3 Pro filament printer and actually it doesn't look all that bad and I doubt you would pay much notice to the difference seeing a loco on a layout and not right in front of your nose. I'll stay with the resin print for this go around but think if you want really good handrails true 'wire' for the handrails would look best but I've got way too much time into this project so doubt I'll go that way. Interested in anyone's thoughts on this and what some of the rest of you that are designing and printing hand rails do. Sumner
Interesting how you can print flexible handrails that small. Are they uncured? Curing usually makes them more brittle. If they are already cured, that's a big win.
I washed them for 4 minutes in the wash/cure station with pretty well used denatured alcohol and then 3 minutes in really clean alcohol (I bought a second but for the wash/cure station to make this easy to do). Then I cured in the Elegoo wash/cure station and no more. I'm really liking the Siraya Tech 'Build' sonic grey resin but haven't use anything else at this point. I've been curing 3-4 minutes with it and so far so good but this is all new to me. Oh, have I mentioned how much I like the Wash/n/Cure station . I don't think I would of enjoyed hand washing much. I did over-cure some things and they were more brittle. I'm wondering if this will continue to cure? Right now I can hold the railing (3 uprights) on the end and bend it almost 90 degrees with a toothpick without it breaking It just broke at 90 degrees but that is a really sharp bend for something this short (under an inch). Sumner
Another in the items to learn in resin printing--curing times. There's testing you can do to determine the proper settings for the printing, but I don't think the curing side is as cut and dry. It's kinda trial and error.
I've minorly exaggerated some parts on my project to get some definition, as well as gain a bit of structural integrity. In the latter category, I'm printing the handrail stanchions with the boiler; first iterations at exact dimensions were too fragile. Increasing the dimensions about a thou seemed to make them sturdy enough for careful handling: The handrail is 24 gauge piano wire; I'm going to use various wires for handrails and piping (geesh, I need to break out the macro lens...). Generally, I've found that, with the Elegoo plant-based resin, structures less than 0.02" in some dimension are not sound, subject to warping and breaking. Don't have much data on this yet, but I'm also worried about continued curing under various lighting, particularly fluorescent, which has a small bit of energy at 400nm. Haven't painted anything yet, hoping that'll provide both some structural integrity as well as UV protection.
Looking really good. Over the last few years I've designed handrails for five or six diesel locomotive shells, mainly U-Boat variants and a CF-7. My designs have evolved over lessons learned. First lesson is resin properties. Your resin has to be able to remain pliable for the long term, full stop. Whether that means a special flexible resin, or a normal resin that you haven't fully cured is up to the designer. I choose a flexible resin exclusively now, but I have a regular Anycubic grey handrail set that I took out of the printer, cleaned up, dried then painted (to prevent further UV curing) that is still flexible from a couple years ago. Second lesson is geometry. First designs used right angles where the stanchion meets the base (or mounting pin.) A perfect "L" shaped joint is easy to break at the joint. So I've given to designing very small buttress structures on the inside of the stanchions at the base that you can't really see but it eases that harsh 90 degree turn and distributes the forces better when any pressure is applied, lessening the chance of breakage. The last lesson isn't really a lesson but more of a preference on how to mount railing. My first designs used pins to push into the side of the shell. That was just difficult to apply with a floppy railing piece, and securing them more often than not would require glue, which I like to be able to pull shells apart like a Kato or Atlas. So my current design preference is to print the railing with the adjacent walkway so the piece has more structural stability and the walkway can handle the forces of clipping the part into place better than a squirrely stanchion. I'm actually considering re-designing my U-Boats with that style of railing after I clear a few projects off my to-do list. -Mike
Thanks Mike I appreciate the feedback and info. Is the above what you are talking about on the stanchion? Also on the one that stayed flexible did you not cure it at all? Just washed and painted it? Does the resin cure under normal shop lighting? Florescent lights? Thanks, Sumner
Oh, plenty of good advice and insight here. Particularly the last, I've probably spent twice the time on how parts integrate than on actually designing them. My cab was a wavy mess until I combined it with the floor/frame piece, a bit of "monoque" thinking. Integrated the floorboards with the boiler assembly for printing, as I couldn't envision a good outcome with gluing. Same with some of the top-line parts; domes just look nice glommed on the boiler in CAD vice gluing, but the headlamp and generator needed a different printing orientation and their spindly attachment points did okay with glue. Resin printing is definitely it's own medium.
Yep - here's a segment of my CF-7 railing, little force dispersing bits in red similar to what you did: On the "no cure" bit, I think I exposed them for a few seconds, like - less than 10 seconds, directly in front of a UV source. They were incredibly floppy still, but I was experimenting and trying anything. I've had uncured resin pieces in my workspace for months with ambient outside light through shutters and they did not appear to be affected as far as continued curing goes but I didn't want to take chances with my experiment so I sprayed them with primer. -Mike
