Adventures in prototypical True-Scale coupler pockets.

[C855B]

IMHO, the biggest secret to tapping the FUD or FXD is running, by hand, the tap drill to ensure the hole is perfectly sized for the tap.

Good advice. I thought about doing that after noticing how much material I was removing, but pressed on - so to speak - anyway.

[C855B]

I did a little more testing with coupling/uncoupling. A sharp dental pick worked pretty well for uncoupling. I tried a round toothpick like I normally use for regular MTLs, and it is too blunt for the tight knuckle fit. Coupling with the modded coupler? Strictly manual, even more so than stock. I couldn't slam into the 16-car cut hard enough for engagement. I like the decisive "CLICK!" when coupling, but I'm still tempted to experiment with possible hands-off coupling by milling weak spots in the drawbar near the pivot to reduce the spring force.

[wcfn100]

Coupling with the modded coupler? Strictly manual, even more so than stock. I couldn't slam into the 16-car cut hard enough for engagement. I like the decisive "CLICK!" when coupling, but I'm still tempted to experiment with possible hands-off coupling by milling weak spots in the drawbar near the pivot to reduce the spring force.

Mike, I'm able to coupler just two cars together without a lot of force.  I'll try and get a video later.  I wanted to check that you did everything in the coupler mod?  And something I don't remember if I included was to polish off all the faces that could come into contact.  I think alignment is a issue as well because of the small coupler head.

I think as you do more, you'll get a feel for it and you'll start getting better results.  At least I hope so, because what you're describing isn't acceptable in my book.

Jason

[C855B]

I didn't cut the gap in the ring, and I welded the rings solid, relying on only the drawbar halves to define the spring rate. Oops.

Since I'm committed on the welds, it's an opportunity to try something different - thinning the drawbars near the pivot. Let's see what that yields.

[wcfn100]

I didn't cut the gap in the ring, and I welded the rings solid, relying on only the drawbar halves to define the spring rate. Oops.

Okay, that's more than oops.  That's the main modification.   

Here's a video of just coupling one car.

It didn't seem that fast when I was doing it.  I may try again at a much lower speed.

If you get a chance, please try the mod as written  and let me know how it goes.


Jason

[C855B]

OK... redid the couplers, per instructions. Yes, it makes a big difference relative to what I had (mistakenly) originally done.

One useful procedure tip - I leave the coupler halves on the sprue until the final steps. Makes handling much, much easier for the cut and trim operations. Next to last step is to cut the gathering arm from the sprue, still holding the assembly with the sprue attached to the knuckle half during staking with the iron. Then cut off the sprue, trim any flash, and install in the box. Disassembly and reassembly happened to result in height mismatches, so I have to see where that issue lies. One of the four still couples hard, and I suspect I bobbled with the iron and welded across the gap. To be totally frank, I think the staking operation is probably going to introduce more variability than desirable.

I ran for a few minutes testing coupling effort, and it turns out the area of the layout where I was testing was on a slight grade. So given the super-easy rollers these cars are, I was doing little more than pushing them down the hill. So... still testing, and will report on operating results possibly later tonight.

[wcfn100]

One of the four still couples hard, and I suspect I bobbled with the iron and welded across the gap. To be totally frank, I think the staking operation is probably going to introduce more variability than desirable.

I think it's just practice and getting a feel for how much of a weld you need.  After 10-15 of these, now I barely touch it with a 25w iron.  Ideally, the only force the weld has is the coupler opening which between the long shank and ring modification, is very little movement.

With that said, I'm certainly open to any other ideas.

Jason

[C855B]

Bugs debugged, retest done, and good news all around.

Height problems were burrs on the bolsters. There was also one bit of sprue on the back of the box lid I overlooked, it was impinging on a bolster. Everything seats nicely now. The remaining stiff coupler was a workbench mistake - I picked-up and reinstalled one of the original bad ones. Found the correctly mod'ed coupler, installed, and all is right with the world.

Now here's what you really want to hear. I ran multiple tests against single ore cars, quantizing the relative coupler forces with throttle setting:

• "Regular" MTL Magne-Matics - 5
• Stock MTL TSC Short Shank - 50 (!!!! - something like 60 SMPH)
• Your mod - 15

Impressive. Maybe not quite as "kiss touch" as the old reliables, but very, very good. Perfectly reasonable coupling speed with a single very free-rolling car. Even better, force was the same, at 15, for both pairs. Consistency is a good thing here.

The most significant issue I encountered was simple alignment. If the couplers aren't aimed well enough, it pushes away. Not unexpected.

[wcfn100]

Thanks for the follow up Mike.  All of that is much closer to what I was hoping to hear.    I agree that alignment is going to be something to watch going forward especially as the pockets get wider to accommodate longer cars on smaller radii.

Jason

[robert3985]

While modifying BROWN TRUE-SCALE LONG SHANK COUPLERs for my Bestine-ized new Jason coupler pockets for my extensively kit-bashed UP CA-1 cabooses, I found I needed to drill new holes in the caboose platforms to get the coupler pockets to protrude at a prototype length from the ends of the caboose platforms.

All well and good, until I read the instructions provided with the couplers by Micro-Trains.  Here's the quote "Use a #56 bit and 00-90 tap."  WRONG!!!  A 00-90 screw has an o.d. of .044" and a #56 drill is .0465" in diameter, meaning if you need to drill a hole to thread with a 00-90 tap and follow Micro-Trains' instructions to use a #56 bit, there won't be any material to cut threads into!!

The correct bit to use is a #65 with an o.d. of .035"

Looks like a transposition of numbers, but it will cause some big headaches if followed....


Cheerio!
Bob Gilmore

[peteski]

For taping 00-90 thread I use #60 or #61 drills. #65 is too small.  #55 is drill size for clearance.  At least that is what I do (I did see some online charts mentioning using #65 bit for taping)

Here is a site recommending using #61.
http://www.richardspens.com/ref/repair/drills.htm

[wcfn100]

While modifying BROWN TRUE-SCALE LONG SHANK COUPLERs for my Bestine-ized new Jason coupler pockets for my extensively kit-bashed UP CA-1 cabooses, I found I needed to drill new holes in the caboose platforms to get the coupler pockets to protrude at a prototype length from the ends of the caboose platforms.

Hi Bob, I meant to put this out before you and the others who ordered got your couplers boxes but forgot.  The distance from the striker to the center of the mounting hole is .206".


Jason

[robert3985]

For taping 00-90 thread I use #60 or #61 drills. #65 is too small.  #55 is drill size for clearance.  At least that is what I do (I did see some online charts mentioning using #65 bit for taping)

Here is a site recommending using #61.
http://www.richardspens.com/ref/repair/drills.htm

For tapping in plastic, a #65 bit is perfect.  For tapping in metal, use a tapping lube and it'll be perfect too.

Cheerio!
Bob Gilmore

[peteski]

For tapping in plastic, a #65 bit is perfect.  For tapping in metal, use a tapping lube and it'll be perfect too.

Cheerio!
Bob Gilmore

But with smaller hole you will put much more stress on the 3D-part being taped. There might be a chance that it will split.  Using #61 would still produce useful threads with less stress.

[wcfn100]

But with smaller hole you will put much more stress on the 3D-part being taped. There might be a chance that it will split.  Using #61 would still produce useful threads with less stress.

Fortunately the boxes Bob has don't require any drilling or tapping themselves just the body of the car.  The ore car adapter needs it as there is nothing to mount to with the given screw location.  I am surprised Mike was able to tap the part without drilling first.  I just assumed that he would drill, I should have said something.  Tapping FXD is more like breaking off little bits as you go.  It doesn't seem to work well when you're doing it but the screw holds as a result so just go with it I guess.  Ideally I could design the ore car adapter without the screw since it only holds the lid, but no good design came to mind for the test.


Jason