Best Of Notes on body-mount couplers (work-in-progress)

[Sokramiketes]

- The two screw holes ended up being slightly larger than drawn.  The lid hole was supposed to be a .055 clearance hole for a 00-90 screw and it's a bit larger, but it still holds the screw head, so it's not really an issue.  The top hole in the channel was supposed to be a .040 tap hole for a 00-90, but it ended up almost as a clearance hole, so the threads are barely biting in the top hole.  I'll shrink the holes in the drawing for the next run, and I'll work around it for these samples.

Seems like you would want both holes to be clearance holes... I know you're thinking that the screw could hold the box together, but if that top hole is threaded it's going to be that much more difficult to use that screw to snug the coupler box to the underframe without a gap allowing the box to rotate.  Perhaps using a drop of glue (canopy cement? goo?) would be more appropriate to hold the box together and keep a full clearance hole.

[GaryHinshaw]

Here's my first test install - a BNSF trinity hopper, compared to a stock model with MTs:



The installation was very simple, just drill and tap one hole for the mounting screw:



I trimmed the channel by one dimple to fit here.  I'll probably add a second screw in the back for rotational stability.  Here's a side view showing how much the BLMA trucks lower the car, and how these low profile boxes still give the right coupler height:



The couplers operate silky smooth in this box.  More soon.

Cheers,
Gary

[ednadolski]

Here's my first test install - a BNSF trinity hopper, compared to a stock model with MTs:

WOW, fabulous work, Gary!!!  I am totally blown away!!!   Makes the old couplers look almost  like Lionels by comparison!

Just a few comments:

 -  Have you noticed any droop?  From the pics there doesn't seem to be any.

 - Have you run these on any tight-radius curves?

 - From looking at this it seems that one could use a dab of 5-minute epoxy to cement the pocket into place where a screw would not be workable.   

 - On the hopper, the only change for the ride height is the BLMA truck?

Can't wait to see what these look like on the Athearn Tank car and as an extended draft gear box!   

Ed

[GaryHinshaw]

Thanks for the feedback guys.  A few more comments now that I'm more awake:

- Mike, you're definitely correct that two clearance holes are best for cases where the box mounts directly to an under-frame.  My thinking was that I could start with a tap hole and ream it to a clearance hole for those situations (which are probably the vast majority).  A tap hole potentially gave me options for other applications like extended gear or maybe tank cars where the box is under a flimsy platform.  But that may not be true in practice, we'll see.

- Ed, the droop is minimal - the box dimensions seem to be just right.  I haven't run these on any curves yet, but I'm planning to saw a lot of roadbed for them this afternoon.     I think you could use epoxy for these just fine, but you'd still need a screw to hold the coupler, so maybe I'm missing your point.  RE the ride height: yes, the only change there was BLMA trucks.  But to be fair, the hoppers are shipped with an MT washer installed (even though it's not needed for coupler clearance), so part of the difference just comes from removing the washer.

- James, I can hook you up with a few FT couplers and boxes (see next post) if you're interested.

-gfh

[GaryHinshaw]

Future plans:

I have about 60 pair of FT couplers from Uncle Will's 'Naked Talgo' offering last year.  My plan is to try out a few more installs with the current set of box samples (and send some to Ed N for testing), tweak the details of the design, then order enough boxes to get me through the stock I have. 

If anyone else has some FT's and would like to try these boxes, send me a PM or email and I can order enough to cover the demand.  I don't know the price yet, but based on the sample, I'm guessing it will be ~$1.50 per pair.  I'd be able to give you an exact cost before any order was placed.  I'm thinking I'd like to get the next order in some time in January.

By the time I deplete my current FT stock, I'm hopeful that there will be a new N scale coupler on the scene.  If not, I'll probably go back to the FT trough.

Cheers,
Gary

P.S. The best thing to come out of this so far is the etching experience, as it opens up so many new doors.  I highly recommend it.

[Chris333]

Nothing like the smell of a freshly etched brass sheet first thing in the morning. 

Too modern for me, but they do look great!

[sizemore]

Gary! That's haut!

The S.

[Ian MacMillan]

Any updates? I want to start converting my cars over shortly.

[GaryHinshaw]

Sadly, only limited progress, as I've been somewhat obsessed with bench-work lately.  Let me see if I can wrap up the drawing mods this week.  PPD was pretty quick to turn around the etchings once I got the file to them, so hopefully it won't be too much longer.

-gfh

[ednadolski]

Here are a few recent pics with an FVM Boxcar:






I'm playing around with some ideas for a 'next gen' of the coupler box, and I'd like to solicit ideas from folks.  Here were a few thoughts I had:

 - Make a 'regular length' and 'extended length'  (any suggestions on dimensions?)
 - Add an air hose as an etched-on part of the lid.
 - Add some way to fit in a second mounting screw, to prevent pivoting and reduce the need to over-tighten the primary screw.

Any other comments?  I'll see if I can work in all the ideas and post a pic of the artwork before sending to PPD.

Thanks,
Ed

[Zox]

- Add some way to fit in a second mounting screw, to prevent pivoting and reduce the need to over-tighten the primary screw.

Have you considered having adding a narrow tab to the back of the unit, that could be bent upwards to stick into a dimple drilled in the bottom of the car floor?

The dimple would only have to be drilled deep enough to hold the tab--it wouldn't have to go all the way through the floor, thus avoiding appearance issues. And people who didn't want to use the tab could either leave it flat (so it lays against the bottom of the floor) or cut it off.

_{(edit--typo fix)}

[Philip H]

Um , Ed . . . . .

Seriously cool dude.  I'll take a couple dozen when you are ready for production.

Zox's idea about a tab and dimple seem right to me, and way easier then doing a second drilling.  I also like the added air hose idea - I keep having a devil of a time figuring out where to mount the great BLMA ones I have on hand.  And the extended draft gear version would be cool, but then I'd need a website with the appropriate draft gear boxes listed for all my rolling stock so I mount the right ones.

But again, well done.

[jagged ben]

Have you considered having adding a narrow tab to the back of the unit, that could be bent upwards to stick into a dimple drilled in the bottom of the car floor?

I second the idea.  Micro-trains cars, and some others, already have a second hole for this.  It's used for the little post that comes on the 1027 and is used for precisely the same purpose.  Make it the same spacing and it will work for a lot  cars without even drilling the dimple.

[GaryHinshaw]

Ed, I tried to go back and look at the v2 file you sent me (months ago!) and my copy of DraftSight had expired, so I'll try and download a new copy soon and help you get another version of these done.  I personally have a moratorium on all loco and rolling stock projects until I get the upper deck of TBC running.  But this this project - and etched loco handrails - are still of great interest.

-gfh

P.S. Love that Railbox.

[Ike the BN Freak]

I really like how this is going. Just does anyone know how well the FTs hold up under long trains? Say 100+ cars?