I changed the subject line here because this is shop talk and a little off topic but is in response to LJ’s question and something I am still passionate about.
I don’t believe a run of the mill (FDM) 3D printer that squirts molten plastic out of a heated nozzle can work for this. The features on the couplers are very small and they have to be produced accurately. Think about the diameter of the little hinge pin that the knuckle swings on. Its diameter is 0.0130 inches. My original 3D wax printer acquired in 2009 (for about $17k and probably never actually paid for itself) had a drop size of 0.0010” meaning it could squirt a single drop of wax 0.0010” in diameter. That was good enough to form an HO scale coupler than would work. My current printer acquired in 2013 (for about $24k that paid for itself in 3 years) has a “voxel size” of 0.0016”. That works too. My newest not yet in service printer acquired just this week (for less than $1000) has a voxel size of 0.0019” which I think will be fine as well. What’s the smallest drop of plastic a typical 3D printer can squirt out? About 0.01 inches in diameter which just doesn’t cut it. Its not the right tool for the job.
I put the pay off times in there for anybody that is thinking about jumping in. Those are based on profit from items sold that were 3D printed. They don’t take into account the fact that I sell many more diecast couplers just because I can offer the specialty couplers. You can see that my new printer will pay for itself in less than 2 months at the same rate.
For this work you need a printer targeted at the jewelry and dental markets. There have been some major advances that have occurred here recently that has allowed the price of these very high resolution printers to drop like a rock. Older designs use a UV laser or projector (like the one in a conference room) to selectively solidify liquid resin one layer at time to create a 3D object. The laser hardens one pixel at a time and is slower because the laser has to “draw” each layer. The projector projects the complete image for the layer at once, so its faster. Newer designs are actually much simpler. Rip the LCD display off your fancy new phone and put a few UV LED’s behind it. Now the pattern of UV light image that gets through the LCD can be directed at some UV sensitive resin. Add a computer to control the image on the LCD and some mechanics to advance the 3D object a little after each layer hardens and you have the world’s cheapest 3D printer. Fancy phones with fancy super high resolution screens have enabled this technology leap in 3D printers. As long as what you need to print is smaller than the display on typical phone, your all set. Imagine what happens if you have a 11” 4K LCD for a tablet computer. Hmmm. Most HO locomotives and rolling stock many structures are small enough to fit in that area. Trackwork components could fit in that area too if you don’t mind plastic track (Unprototypical shiny nickel silver railheads on passing tracks and sidings irk me anyway – why is that acceptable – dead rail is coming). See where this is all going. These are exciting times in the model railroading world and things are about to get crazy.
Also regarding 3D CAD. Check out Fusion 360. Free for a year for hobbyist and small businesses. I have historically used Solidworks, but Fusion 360 is about to eat its lunch. Fusion 360 plus a new ~$500 printer and a website can make you a model railroad entrepreneur. You still need to be able to turn those plastic parts into metal to make couplers, but maybe you have other ideas.
Finally in my opinion, the plastic parts created by any of these fancy new printers I’ve described is hard and too brittle for items that will take constant abuse like a coupler.
interesting question regarding the 3d printing. what is the problem so far with people printing in 3d? tolerance, or material strength. I know there are some metal filaments available with different metal types in 'suspension' with the PLA or whatever. Has that been tried? perhaps that has no more inherent strength than straight PLA or whatever. I also doubt it allows any finer tolerances. Just wondering aloud. I have a mostly put together home 3d printer, but haven't learned any CAD yet. I would assume that a typical home 3d printer has insufficient precision to allow the tolerances needed amongst the parts, but would love to hear what you(Mr Sergent) has to say on the issue.
who is still only a dabbler as the railroad is not running yet.
On Wed, Jul 11, 2018 at 1:21 PM, Frank Sergent <fsergent@...> wrote: