Passenger car coupler length and car gap.

Hours later and I’m finally learning to spell CAD and making progress.

No real measurements, just trial and error, but I finally got two couplers to mate and not bind. I printed with a brim which makes it a little bit of a pain post production. Might skip the brim in the future and see how it goes. Also had a lot of problems with supports as the part where the pin goes is the only part that touched the bed of the printer. Experimented a little and added to the bottom of the drawbar so it touches the bed as well. Not accurate, but also hard to see so I’ll take a cleaner part over absolute accuracy.

Proof of concept…

Long way to go and lots of work to do, but I’m happy with the preliminary results. When “finished” I will print them in black.

The diaphragms fit together pretty snugly. Around 0-72 curves they slide and gap on the outside, but come right back together on the straights.

I’m pretty happy so far. Here’s a before and after shot.

I think its a problem for all of us that want the diaphragms to be closer. I have experimented with a number of things but to no real avail.  Your work on this looks excellent and these kinds of projects take so much patience.  Great Job.  Bill

Absolutely great!

You've done a fantastic job not only bringing the cars closer together but shrinking the head of the coupler. Well done.

Thanks!

- Mario

Did you look at the possibility of a hybrid approach?  Merging 3d printer and parts of the existing couplers?

@A. Wells posted:

Did you look at the possibility of a hybrid approach?  Merging 3d printer and parts of the existing couplers?

No I did not. I’m not nearly good enough in any CAD programs.

Taking baby steps it feels like. Been tweaking this since 9 this morning and getting closer to something I can live with. Hoping to be ready to print black by tonight.

Hmm...  I might take a few of those.

Well, I spent the entire day printing failures. Finally gave up, and while laying in bed, remembered I turned the adhesion setting off that morning as a test and never turned it back on.

Oops.

Back at it this evening I hope…

I’m finally happy with the design. It’s taken 10x the work and time I originally anticipated but well worth it. I spent 2 days just trying to get the bottom portion to look right and in the end, it’s way too much post print work to be worth it. Cutting away supports just to have the ultimate detail is for the birds. The drawbar in particular is what I’m talking about. To have it elevated 1mm is a nightmare. I figure the only way you’ll ever really see it is if the cars crash off the rails and down to the ground, in which case I have bigger things to worry about.

The software fought me, the printer fought me, my fantastic eye condition (optic neuritis) fought me, the dogs wanting attention fought me, my ape brain fought me, but I won a small battle tonight. Funny how these things work, because I already have another betterer idea in mind after this is finalized.

Need to walk away from it for the moment, but will print them in black next and then fit them to my Amfleet cars. Had to use gray for testing as the print bed is black and I struggle enough as it is to see the details without having them blend in and fade away.

Again, thank you to CentralFan1976 for the original STL I used to make these work.

10 at once in black. This should cover my 5 Amfleet cars. The adhesion brim makes for a lot more post print cleanup, but I just can’t get them to print consistently without it.

Looking fantastic I think! Not sure if it’s just the different PLA or the way I modified my start and base layer sequence, but these are much smoother than all of my “test mules”. My biggest issue has been base layer adhesion but I think I have it figured out. Just got the printer for Christmas so overall I think I’m not doing too bad.

Well, they finished printing and then a family emergency happened and we had to leave town for a free days. Got back home tonight and cut a few out.

Overall I’m pretty darn happy with them. They do exactly what I wanted and look plenty good. Here’s a finished pic along with a few comparing the coupler head to the stock lobster claw.

Those are perfect!

I love how they’re short and soooo much smaller than the lobster claw!  Can’t wait to see a whole train of them!

- Mario

Problem solved, just want the Dr. ordered.

@gunrunnerjohn posted:

Problem solved, just want the Dr. ordered.

The next chapter will be shortening them even more and then using only 1 diaphragm between 2 cars. Curves will be greatly limited but with 0-72 minimum I think it will be ok. I’ll convert the 5 Amfleet cars as above first and run them for a while first though.

Often, problems lead to solutions.

I said my next venture would be bringing them closer and only using one diaphragm per car. Well that came quicker than expected.

I got all 5 cars converted and the diaphragms between the cars fit pretty snugly. Still bothered me how much space was between the bodies though. Started running them and at nearly every single curve there was enough pressure to either lift the inside wheels slightly or make the car derail. The obvious answer was to slightly lengthen them and free up that pressure, but that is moving in the opposite direction of where I want to be, so I decided to pull a diaphragm from between each pair and go the direction I wanted, which is closer.

I also spent some time and experimented with the printer and some of its deeper settings. I can now print them without the adhesion brim which makes them useable right off the printer instead of cutting them (and my fingers) for an annoying amount of time.

Pics above are where I left off and below is todays progress. The first “cut” was arbitrary in size and just done by eye. The next 2 we’re done 1mm at a time. The final is as close to perfect as I dare to get. The diaphragm just slightly touches the other car in straights and in curves just slides on the end of the car. No binding, no pushing, no issues.

GREAT WORK!!

I believe the issue is MTH wanted all their cars to go around at least O42 or less curves? Amazing that K-Line 21" cars are closer coupled than these. I have some Lionel F units where the gap must be 1" or more.

@BobbyD posted:

GREAT WORK!!

I believe the issue is MTH wanted all their cars to go around at least O42 or less curves? Amazing that K-Line 21" cars are closer coupled than these. I have some Lionel F units where the gap must be 1" or more.

Thanks.

I would agree that they were built to be able to negotiate much tighter curves so spacing sacrifices had to be made.

These results look amazing! Great work, engineer.
The progression of this thread was quite encouraging too!

@CharmCityAirLine posted:

These results look amazing! Great work, engineer.
The progression of this thread was quite encouraging too!

Thank you. CentralFan1976 provided the base file and inspiration, I just refused to let it not work.

@David K. Simpson posted:

Thank you. CentralFan1976 provided the base file and inspiration, I just refused to let it not work.

How strong are the printed couplers?

@BobbyD posted:

How strong are the printed couplers?

I have to believe more than strong enough for the task.

@BobbyD posted:

How strong are the printed couplers?

I would say the cars will probably break before the couplers. They are quite dense. If i had some cars I didn't care about i would test them, but I don't.

@gunrunnerjohn posted:

I have to believe more than strong enough for the task.

@David K. Simpson posted:

I would say the cars will probably break before the couplers. They are quite dense. If i had some cars I didn't care about i would test them, but I don't.

Thanks guys. Have a coupler ruined by Zinc Pest that is unobtainable and hoped this may be the salvation. 

@BobbyD posted:

Thanks guys. Have a coupler ruined by Zinc Pest that is unobtainable and hoped this may be the salvation.

That’s how we started down this path; my couplers for these cars broke.
thanks!

-Mario

@CentralFan1976 posted:

That’s how we started down this path; my couplers for these cars broke.
thanks!

-Mario

Just installed some more of your fuel tank spacers in a friends older F units. 🙂