Evening all, I have a couple questions on how to build brass/plastic motorized structures. For reference, the structure in question is the Walthers Cornerstone Overhead Traveling Crane kit, part number 933-3102. The model train club i belong to has a different version, but I'm not sure of the part number.
Just the other night i had the idea to build a motorized version of this that would add a rather interesting operational structure, but I'm not really sure on what material to use. What i was envisioning was using 4 motors, two moving the crane up and down the length of the steel beams. A third would move the crane cab itself back and forth between the two support girders, and a fourth would raise and lower the cargo using a block and tackle setup. Adding to all this would be the usage of either DCC or wireless DCC transmitters to control movement. As for lifting weight, I would be aiming for the capacity to lift a NMRA standard weight freight car, disregarding car type.
Whats the best or most cost effective material and construction method to use for a project such as this?
First of all I have never attempted such a project so I have no practical tips to give you. But I have attempted some limited animation so I offer the following.
It is likely quite possible to add each of the movements/actions you list to this otherwise static model. Each would come at some cost to realistic appearance I think, as the various small threads or cables, pulleys and such are added to it. But when I think about trying to combine all of them: lifting things up and down (vertical) PLUS horizontal-plane motion back and forth, PLUS horizontal-plane motion from side to side, I cannot even envision the system of pulleys and threads/cables, and the various small motors or servos that would power all of them, with the flexibility to do all that AND still look reasonably realistic. I think the little crane would end up looking goofy. Try to envision and think about what you are really expecting out of this.
My advice would be to think of just one of the types of animation you seek and focus on accomplishing that. I do not want to quash a dream here but I think you need to take this one step at a time.
It is not like any one of those animation steps is all that easy after all.
One added thought. Certain types of motion can be simulated with creative cheating. For example, lifting the freight car. If the hook on the freight car (on the coupler?) was attached to the crane with elastic thread, it would be possible to put a small servo UNDER the (permanently placed) freight car and simulate the car being slowly lifted slightly without the cable going slack. That would avoid adding possibly unsightly cables and pulleys to the overhead crane itself.
Dave Nelson
First off, to the MR Forums, WesternRailfan5101
WesternRailfan5101...What i was envisioning was using 4 motors, two moving the crane up and down the length of the steel beams. A third would move the crane cab itself back and forth between the two support girders, and a fourth would raise and lower the cargo using a block and tackle setup....
What you're proposing certainly is do-able, but as Dave notes, it would be difficult (not impossible, though) to have it function properly and still not look toy-like.
Most of the overhead cranes with which I'm familiar had the bridge wheels on only one side powered, so you'd not necessarily need two motors for that function. I'd see getting power to the motors as one of the difficulties. Real cranes generally use pick-up shoes which slide on multiple rails - constructing those shoes in HO scale would be a nightmare, and getting them to work reliably even worse. An alternative would be powered rails, like our trains, but you'd end up with the trolley motion dependent upon contact with both its own rails and those of the bridge, and the hoist motor would be dependent on both, too. DCC control would certainly help, but I'd guess that the electrical path would be a problem. Large-span overhead cranes, because the wheels are not all powered, do get out-of-square, and the usual solution is to run them into the stopblocks at the end of the runway. A one-motor model would likely have the same problem, and with a two-motor version, it would be difficult, even using DCC, to syncronise them well enough to avoid that condition.The hoist presents its own problems: without a load (weight), it won't look very realistic, as the "cable" needs to be flexible enough to hang in a realistic manner and be easily taken-up on the hoist drum.
I scratchbuilt a model of an overhead crane (originally intended to be one of two in a blast furnace casthouse), but that project outgrew the available space and I ended up making just one crane. The blast furnace itself, along with the casthouse, was dismantled. The crane is a composite of several with which I was familiar. The crane's bridge can be manually positioned on the runway, and the trolley likewise atop the bridge, but the hoist is non-functioning.
The pick-up rails for the bridge can be seen in this photo, immediately below the near-side runway girders:
...and here also:
The pick-up rails for the trolley are just visible, at left, in this overhead shot:
And a couple of other views...
While this could be done in a realistic manner, it would be a project better-suited to a stand-alone diorama, as it could be a much more complicated build than you imagine. A layout version could be somewhat simpler, but in my opinion, this wanders into the realm of giraffe cars and the like, and is one of those things that often ends up looking out of place.At one time, I envisioned a fully functional wreck crane, self-powered, and with two working hoists, moveable boom, and rotating cab. The outriggers probably would have been manually positioned.
I certainly wouldn't want to discourage anyone's dream, but this one looks bigger to me than you're imagining it to be. If you do build it, we'll want to see lots of pictures.
Wayne
Just a question to the OP - why the phrase "scratchbuilding Brass structures" in the thread title? The Walthers crane is a plastic kit.Was this thread meant to cover something else, and you ended up redirecting to animating a traveling crane kit?
chutton01Just a question to the OP - why the phrase "scratchbuilding Brass structures" in the thread title?
Good point, and one which I neglected to address. My thoughts are that the OP figured that scratchbuilding such a model would require brass construction (for strength, I'd guess) but styrene would be plenty strong enough for anything in HO, and a lot easier with which to work.
aside from other posts a crane with a dead lift of 30 tons would be minium to dead lift most fright cars as with a safety factor of if i remember correctly would be 10% added to it making it a 35 ton aside from the fact it would be a 4 or 6 line setup, meaning it would a heavy duty.the walthers model is of a 25 ton unit .sounds to me like more of a headache than it would be worth unless you are building a meseum display
I would suggest using 3D printer parts. The technology has become cheper though there are many parts out there to build your own printer. I would either scratchbuild a crane using threaded rods, belts, worm gears, and servos from 3D printers for the motorized mechanism, or get a set up and then build a shell around it. It might help to look at things like laser cutters that just move in the x and y directions. 3D printers and laser cutters are highly accurate ans reliable, so they would work fine in you situation if you can get them to look like a model crane.
You hit the nail on the head with that. Yes, i was referring to the strength of the material being used, as I had thought of several scenarios that this could be used in. I do realize its a bit complex for what i was envisioning, but I have to say I'm not always thrown off by a complex build. And if i do build this i will definitely provide pictures.
As for the use of the two motors on either side of the girders to move it along the top rails, I had envisioned them wired to one decoder, seeing as this would have been a semi-stationary model, and wouldn't have required much more than a single number to run them by. I was thinking about this last night and come up with several ideas, which i think might figure out some of what I'm stuck on.
doctorwayne At one time, I envisioned a fully functional wreck crane, self-powered, and with two working hoists, moveable boom, and rotating cab. The outriggers probably would have been manually positioned.
At one time, I envisioned a fully functional wreck crane, self-powered, and with two working hoists, moveable boom, and rotating cab. The outriggers probably would have been manually positioned.
Thanks for the welcome, and on the subject of wreck cranes i think i got the answer for you. You'd have to contact the person through youtube, but I think he does do custom orders of these. At any rate they are rather impressive.
https://www.youtube.com/watch?v=RnUt1FgVcJo