Adventures in prototypical True-Scale coupler pockets.

[wcfn100]

I got a Shapeways package today with my first try at a True-Scale coupler pocket.  The design is pretty simple.  I'm using the long shank coupler with the screw through the coupler hole and a floating wedge at the springs.  There is no provision for centering, and I went as narrow as I could for a one piece design.



The design works as intended although it does need some clean up to do so.  He it is on an Atlas PS-1.





There are a couple big downsides however.  First, there's too much coupler swing, but that could be addressed.  More importantly, using the coupler hole for the mounting screw has two big issues.  First, it's a poor place to have to tighten down a screw without some sort of bushing.  It just squeezes the coupler halves together effecting operation.  Second, in order for the the long shank coupler to stick out form the body a prototypical distance, it needs to have a hole drilled about .0828" back from the sill.  But many models already have some sort of hole designed into the floor in that area so it can be difficult to drill a clean hole.  In the CNW example, the coupler and pocket should actually extend out farther than they do to be prototypical but the factory hole prevents doing this so I just used what was there.

Rev B is already in the works and should go to the printer in the next couple days after I make some adjustments based on these samples.  THis will be a two piece design with a lid and hopefully a more universal way to mount it at the correct depth.


Jason

[wcfn100]

So I think I have my next incarnation.





You may notice there isn't room for the springs.  I think for my purposes, simply welding the back of the shanks is where I'd like to start.  It's an easy procedure to do and saves a ton of room.  The coupler hole is now a pin and the screw hole won't effect operation no matter how hard you tighten it plus it's out of the way for drilling a new hole on most cars. 

Hopefully I can get these back in a week to test out.


Jason

[ednadolski]

The Rev B looks pretty good.  Is that the FUD?  Does that material seem strong enough?

simply welding the back of the shanks is where I'd like to start.

So just clip off the whiskers and 'weld' with the tip of a soldering iron?

Looking forward to seeing more.

Ed

[wcfn100]

The Rev B looks pretty good.  Is that the FUD?  Does that material seem strong enough?

So just clip off the whiskers and 'weld' with the tip of a soldering iron?

Yep.  Hold the coupler closed with your fingers and put a 00-90 screw in the coupler hole and touch the back with the iron.  The soldering iron can be clumsy and if you hold too long, the coupler can get stiff but will still function. I'm hoping to find a better process but this works for now.

I'm printing in FXD.  I'm not sure of the strength of the pocket.  I just ordered a bunch, when they get here and I get one installed, I can try and do some sort of test.

Jason

[Sokramiketes]

This looks awesome.

[wcfn100]

This looks awesome.

Thanks Mike.  I'm really hoping to find a solution that will cover the majority of the the rolling stock out there but it's a mine field of surprises when you start turning over the different cars.  I'm waiting for a while to tackle the Train-Worx cars that have the blind coupler pocket screw. 

If this design works, it wil lend itself to extended coupler boxes too. I'd just leave the air line off so the buldge can be sanded flat.  A future version may also try and include coupler slack.

Jason

[Sokramiketes]

Yeah, I like the overall size of the MTL brake line hose, but I'm having trouble with the upturned connection.  I suppose the decision was made to make it look like they were connected when coupled, but then it looks funny uncoupled, when you get your best view of it.  So leaving it off isn't a big deal for your coupler box. 

[chessie system fan]

Looks good.   If it helps anyone, I took these pictures at the local rail museum last month in my own quest for a better coupler pocket.

[wcfn100]

Thx for those.  At this point a lot of what I'm dealing with are the minimum dimensions of FXD and the dimensions of the MTL coupler shank and how much swing they should have.  I should have the next pockets tomorrow and we can see how they compare to those pics.


Jason

[wcfn100]

The parts are in and I'm going to try and get some shots later if I can setup my photo rig with my Marco lens.

In the meantime this is what it looks like.



So overall it works.  I'm way too tight on all tolerances which I sort of knew would happen.  Basically everything needs a .005" bump to make more space.  The width of the pocket looks okay as far as coupler swing so that was good.

The biggest issue is the depth from the striker plate (the flange on the coupler end) to the post.  It looks like I got overzealous with prototype numbers and the pocket ends up hitting the back of the coupler knuckle which is a little bit larger than proto.  Another big issue is the bottom plate is too flimsy.  That was a wait and see for me.  I'm going to have to bulk it up somehow without loosing too much fidelity. 

New revisions are mostly complete.  Still working on a bottom plate solution.

Jason

[learmoia]

Is the flimsiness of the lid due to the two holes? or thickness?.. or both?

you could put the coupler center post on the lid instead of the box to help firm it up.

PM me your address, and I'll send some more box detail photos I took at Boone Scenic Valley.. (including CGW specific pockets..)

~Ian

[wcfn100]

Is the flimsiness of the lid due to the two holes? or thickness?.. or both?

you could put the coupler center post on the lid instead of the box to help firm it up.

PM me your address, and I'll send some more box detail photos I took at Boone Scenic Valley.. (including CGW specific pockets..)

~Ian

Thickness, but that's a good point about the two holes, maybe no hole in the lid at the post would work.  Putting the post on the lid is an interesting idea.  Not sure I trust that design when thinking about the lateral force on it.  If the pin popped out of the hole, the lid could easily just break.  I'm going to fatten up the bottom and the lid a bit and put more lid where the screw goes through and see what I get from that.  It may just be that these will require a touch of glue at the pin and at the flange.

Thx for the offer on the pics.  I've been to the museum there a couple times and have a ton.


Jason

[learmoia]

Thickness, but that's a good point about the two holes, maybe no hole in the lid at the post would work.  Putting the post on the lid is an interesting idea.  Not sure I trust that design when thinking about the lateral force on it.  If the pin popped out of the hole, the lid could easily just break.  I'm going to fatten up the bottom and the lid a bit and put more lid where the screw goes through and see what I get from that.  It may just be that these will require a touch of glue at the pin and at the flange.

Thx for the offer on the pics.  I've been to the museum there a couple times and have a ton.


Jason

Extrude the post from the lid to be flush to the top of the box so it never slips out.. (Assuming you have a post hole in the box instead of the lid)..

You could also put .012 worth of the screw post into the lid too and have those meet in the middle inside the box.

(I've been working on the same thing you are.. but for normal MT Couplers instead of True Scales.)

Another detail you seem to be omiting that may help strengthen the lid is the lower L bracket on each side of the pocket..  (I'm assuming your rib in the box is an air pipe)

Widen your lid out about 3" (scale) on each side from the box.

You can see the detail I'm discussing in this photo..


BTW those aren't approved footwear for railroading

~Ian

[soo]

Yup....wrong footwear.. Oh well I guess he does not his toes..lol

I noticed the welds on the pocket. Looks like might have been shop added. All of the ones I have seen have been cast.

Nice researching.

Cya Y-it

[wcfn100]

So I think the next revision is ready to print.  I went and placed it into my NP flat car file to see what it looks like.




Hopefully this will be the final version and I can start making different conversions for various cars.

Jason