So what's the deal with this porter? I get asked that a lot. First and foremost, nobody (except me) has received a kit yet! There are a lot of reasons the kits havent' shipped yet. Some personal, some business related and mostly because I want to make the kits build into a very reliable, good running, good looking locomotive! I wont bore you with the unrelated issues I've dealt with over the past year and a half, but let me elaborate on where I'm at with the design and production.
One major point of constant revision with regard to the design is the drivers. Initially, the idea was (stolen from our friends in the UK) to use simple spoked wheels with a photo etched counterweight and some creative epoxy use. That didn't cut it. Next was the idea to use rapid prototyped centers on nickel silver tires. This seemed promising. I found a good, strong RP material at an extremely high resolution that would've put the cost of each center at about $3.00 each. I went through a few iterations of sizing to get them to the point where they would fit perfectly. They even ran well, for a while, which segways to the issue; they just didn't hold up after extended periods of use.
This brings up a major point that has influence on many of the components to the model. First, I don't want to ship something that is only "so-so" in terms of either performance, reliability or longevity. Second, I don't want to spend all my coming days shipping replacement parts! So the solution was really simple, and one that I've pretty much known in the back of my mind since I embarked on this adventure. That is that the centers have to be brass. There's a reason the "good stuff" has brass centers. Sure some companies have made injection molded centers work, but only for so long before they either wear out or crack. So there would be none of this for these little porters.
Of course, if you've even looked into brass casting before you'll know that it's not necessarily a simple procedure, and the results are anything but consistent. Fearing a complete waste of time and money, I set out to find someone to cast these centers for me. It turned out to be a bigger waste of time and money! The casting shops either wouldn't touch the project because of the size, or they wanted a mint to do it. So I had to do it myself!
So here's the results of thousands of dollars in equipment (thank God my "real" business has a use for this tooling too!) and months and months of learning, trial and error, blood, sweat.... you get the idea.
Here's a sampling of some of the brass parts. Note that the boilers shown here may or may not make the cut for production kits. They pose a bit of a problem as far a spruing them to the tree and filling properly. I can iron that out, but my fear is they'll have too many sprue points to be cleaned up. A few more casting runs will tell.
The drivers are obviously the most important part of the equation. The master is a modified version of the original RP concept altered for casting and then machining. Headlamps are self explanitory. They were originally white metal (I'll offer them up for sale or as extras later) but I now have more than enough for the kits. The boiler is based on a new master pattern, but again, there are some fill issues due to the volume and me trying to limit the sprue size. A larger sprue seems to solve the problems, so a brass boiler will be included regardless. The tank at this point hasn't been molded for brass, but I have more than enough of the white metal versions for kits too.
The drivers are a major part of the time in processing for eventually shipping the kits. Below is a summary of the process that goes into each driver. Hopefully you can understand that with the number of kits offered/reserved, this process takes a LOT of time.
First, the rough driver casting is chucked in the lathe and the axle hole drilled. Next the crank pin hole is drilled off the lathe in a special fixture I made to facilitate location of the crankpin hole. Next the back is cleaned up to remove any flash from casting so that the pins on the turning fixture can pass through the crank pin hole and the spoke holes. The center is then fixed face out in the turning fixture and trued up so that it's perfectly square in the lathe. Pictures of the first stage in the fixture below:
The aluminum fixture serves 2 purposes. The smaller diameter is used to true the rough casting in the lathe when it's first mounted on the spur where the axle goes. It's also used later to press the tire on the center. The jig/fixture on the left is the turning fixture. It has a center stub that is .001 under the axle bore and is also drilled and tapped for a 1.5 hex nut. There are 2 locating pins pressed into the fixture for the crank pin hole and a gap to the right of the crank hole. The hex nut is tightended down to secure the center and the pins keep it from turning when the outer diameter is turned to the correct size to allow for insulating tape and the tire.
Finally, the finished driver with the insulating tape and the tire pressed on. All of this work is done on the lathe, or in another fixture (not shown) which is configured to work with a special program on the CNC mill. This ensures the crankpin hole is correctly located. As of now, the crankpin hole will need to be tapped by the builder. I may do that, if time permits, to save everyone from having to get the correct tap.
The next big "time sink" on the project is the gearbox. This has gone through numerous revisions. The first incarnation was a series of idenitcal spur gears driven directly via a vertically mounted motor ala Minitrains etc. This didn't have the right slow speed that I was looking for and was a bit "wonky" in terms of appearance. The next concept was a backwards "L" shaped gearbox configuration and specialty tiny gearing. This "L" box was very difficult to get seated properly in the frame. It also relied on the cab floor orientation being dead on, and the only way to tweak the geometry was to tilt the cab floor which obviously causes a visual problem. One thing the "L" gearbox revealed was that the rear driver was the wrong place to have power originate. This model has a nice big heavy tank and boiler up on the front of the engine. Along w/ the smokestack etc., the front has much more weight. So the current configuration is as follows. It still has a compound gearbox to get the gear reduction, but the gearbox is a much simpler design. Right now, the gearbox is a functional prototype. It works very well. How it's produced is the current challenge. They will either be directly machined on a CNC mill in delrin or brass or some combination of the two materials.
This new configuration solves several issues. It also generated a few new ones! One of which is that it must be fixed to the front axle and this can't be done in situ. In other words, the axle gear has to be pressed onto the axle in between the drivers (obviously) and that just can't be done into holes in the frame. So the final version will have axle journals in brass or delrin which will slide into slots in the frame. Traditional engine building here. Then there is a bottom plate to secure the journals in the frame slots. Whether I can squeeze equalization into the equation or not is yet to be seen. With a compound gearbox, there isn't much room for rotation of the gearbox. The rear axle could be sprung using traditional methods, but the front axle must maintain it's vertical alignmetn with the motor/shaft. Unless I put a universal on the motor shaft (this stuff is SUPER TINY!).
So this is a much overdue public update on this project. What does this all mean? I'm down to a few more hurdles. I have to manufacturer a metric ton of gearboxes (might as well be) and process a bazillion drivers. BTW, I'm not outsourcing this stuff. This is me working in my shop to get this off the ground. Add in to that a "real" business I run, along with 2 kids and a wife, and I think it becomes clear what's going on here. The good news is, once I decide on the gearbox fabrication process and I actually process all the drivers, and I get the revised etchings back (they aren't finished being drawn yet because of the casting changes) they're ready to go. I know, I know. Really though, I don't foresee any other setbacks.
So all of this has been a fun, but stressful adventure. The good thing is, I've now got a lot more tooling at my disposal to expand into producing other crazy little detailed monsters. I've learned a boatload about the difference between one-offs and production runs. There's about 3.6 million things I would do differently now knowing what I know now. Now to apply this knowledge to the future is exciting to me.
BTW, I still have all my own little railroad projects going on! More than I will admit knowing I have to get these porter parts in boxes. I also am up to my earballs in oddball model railroad engineering projects for others. I like doing the custom work for you guys!
I hope this helps explain the situation here. Please don't hesitate to contact me if you have any questions etc. Understand, however, that I am ridiculously busy right now and I may not respond quickly.