Coupler heights

[bbussey]

... The issue is with how the defacto standard is these ridiculous bulky coupler boxes on locomotives. Absolutely no need for them. Over the weekend I redesigned them and redesigned them to be manufacturable. I would be more than happy to show them how to do a pilot plate if they would ask. But I know that will never happen. Insert Fringe manufacturing 

Not true!  If the design doesn't impede current functionality and will interface with other motive power and rolling stock, and doesn't require any additional tooling, then it qualifies as mainstream.  It may not be retrofitted into existing models, but it certainly could be incorporated into future models.  I would approach Atlas.
 

[6axlepwr]

It would require them to retool the existing mold. Or make additional tooling to incorporate the new feature. They would not need that blocky coupler box anymore. It would though GREATLY improve teh look of their models. In the next couple weeks or so I hope to show what it would look like for real on my models. I am having some samples made to test out the design.

I tried contacting Atlas yesterday, but the email addresses on their web site do not work. I really do not think they would be interested though. Their standard coupler would not work anymore because of the offset shank. It would put the center of their coupler to high. They would need to use a straight even shank coupler. An MT 1015 would work though.

[GaryHinshaw]

Because millimeters is a smaller unit of measure than inches, and metric is easier to work with than imperial.

Ok, I have to be pedantic here.    The precision of a measurement depends on the tick spacing on your ruler (or the number of decimal places in your micrometer, etc.), not whether it's metric or imperial.  Bob's point is that 1 mil is a shorter distance than 1 mm (and implicitly, that it's possible to make an imperial ruler as precise as a metric ruler).

It's true that metric rulers typically have finer tick spacing, and it's also true that the metric system is generally superior. 

-gfh

[ednadolski]

It's true that metric rulers typically have finer tick spacing, and it's also true that the metric system is generally superior. 

Personally, I prefer working in Planck lengths 

Ed

[bbussey]

Ok, I have to be pedantic here.    The precision of a measurement depends on the tick spacing on your ruler (or the number of decimal places in your micrometer, etc.), not whether it's metric or imperial.  Bob's point is that 1 mil is a shorter distance than 1 mm (and implicitly, that it's possible to make an imperial ruler as precise as a metric ruler).

It's true that metric rulers typically have finer tick spacing, and it's also true that the metric system is generally superior. 

To be equally pedantic ... I don't use physical rulers.  I'm virtual the majority of the time.   And while it's theoretically possible to make a physical mil ruler, in reality you can't because the ticks would be too closely packed.  And since a mil is a fraction of an inch, I can be more precise in mm since I can go to eight decimal positions on both (more precise than any affordable digital micrometer) and a mm is a much smaller uom than an inch.  (.001" = .254mm)

Also, when I have to perform physical measurements with the digital micrometer, I use mm.  My micrometer in inches goes to three decimal places (mils), but goes to two decimal places in mm which is more precise.

Admittedly it took some getting used to, but the pluses of moving to metric far outweigh the learning curve.

[skm]

I believe the US, Myanmar and Libya are the only countries still firmly entrenched in the Imperial system.
The UK and several other fairly recent converts are still ambivalent.

As a native 'metric' person, I still have difficulty with fractions when measuring (think 27/32nds) not forgetting volume or weight. 

[havingfuntoo]

In Myanmar they have right hand drive vehicles and drive on the right hand side of the road, it is an interesting experience. There is one big intersection where the traffic controller sat in a box and pressed the buttons to change the traffic lights ….. beside him was a soldier with a rifle, amazing compliance to traffic signals. We have a mixture of imperial and metric still happening here, my preference is to work in decimals, calculating to factors of 12 is harder.   

[Ike the BN Freak]

A #2004 coupler is never the answer for a prototype modeler.  The head is even worse than a standard MTL coupler. 

However when one has a fleet of Kato SD40/40-2s, there seems to be no way around it...unless I stick with the Kato couplers, which I am not a fan of.

[robert3985]

Having been a precision machinist since I was 14, starting out manufacturing standards for ultrasonic and eddy current probes used for non destructive testing in the aerospace and nuclear industries, using imperial measurements didn't seem to inhibit accuracy.

It also didn't inhibit accuracy when I was in the business of designing and prototyping weapons-mountable night vision and surveillance devices for international SWAT and SPECOP counter-sniper use with customers in Canada, England, Mexico, Germany, Austria and Italy.  There was no objection from my customers that my instruments were built using imperial measurements.

I agree that metric is a whole lot easier to use because of the division protocol for dividing up a meter, but the base measurement (the meter) is still arbitrarily derived, just as imperial measurements were derived from the king's forearm, or mailed foot or whatever.

Since I grew up with yards, feet, inches and mils, I don't have any difficulty whatsoever with using them for whatever I need be it a quick dismount Gen3 gated NVD for a Schmidt & Bender scope, or hogging Zamac on my Kato E's for speakers.

I rarely use a rule, in my model work other than when constructing benchwork.  The rest of the time a trio of progressively larger Starrett digital calipers does the job, allowing easy switching back and forth between metric and imperial if I wish or have a need.

For actual model work, I find mils are more than sufficient for everything I'm working on. 

If I need even more accuracy, I automatically switch to RCH's...the finest measurement known to man.   

[GaryHinshaw]

...using imperial measurements didn't seem to inhibit accuracy.

Oh good, another chance for me to be a pedantic jerk.   

In measurement theory there is a difference between accuracy and precision, but it only makes sense if you speak about repeated measurements of something, each of which has an intrinsic error.  This chart illustrates the difference quite nicely:



The bullseye of the target represents the true value you are trying to measure (never mind how you ever know what that is).  Panel A shows a measurement with high accuracy but low precision: the individual measurements (darts) are randomly scattered about the bullseye, but the scatter is large.  The average of the dart positions would converge on the bullseye with more measurements.  Panel D shows a measurement with high precision but low accuracy: there is very little scatter, but the darts are systematically away from the bullseye.  One of the great challenges in any scientific measurement is determining what your uncertainty actually is, and what fraction of it comes from systematic errors in your measurement process (which reduce accuracy), and what fraction comes from random errors in your instruments, such as electronic noise (which reduce precision). 

I wonder if we've answered the OP's question by now?   

-gfh

P.S. Not trying to suggest there was anything incorrect in the quote from Bob that I pasted, it was just a springboard.

[pedro]

Yeah, first his thread about stripping shells breaks down into debating the MSDS, now his thread about coupler height breaks down into debating the evils of the Imperial system.

Keep up the good work, 6axlepwr!

At least we recognize the 2-liter soda bottle.... You can keep everything else!

[Sokramiketes]

To be equally pedantic ... I don't use physical rulers.  I'm virtual the majority of the time.   And while it's theoretically possible to make a physical mil ruler, in reality you can't because the ticks would be too closely packed.  And since a mil is a fraction of an inch, I can be more precise in mm since I can go to eight decimal positions on both (more precise than any affordable digital micrometer) and a mm is a much smaller uom than an inch.  (.001" = .254mm)

Also, when I have to perform physical measurements with the digital micrometer, I use mm.  My micrometer in inches goes to three decimal places (mils), but goes to two decimal places in mm which is more precise.

Admittedly it took some getting used to, but the pluses of moving to metric far outweigh the learning curve.

Yeah, I want to see an ESM product tooled to eight decimal precision...   

[bbussey]

Yeah, I want to see an ESM product tooled to eight decimal precision...   

All three models are!   Well, the solid models are submitted to the contractor in eight decimal precision millimeters anyway.  I can't speak to what precision is used when the tooling is cut.

[6axlepwr]

I'll bring this back on subject.

last night I made my own height gauge. I have a block of aluminum that is 8" long x 2" wide x 3/8" tall. I milled two rails down the center. Now I can sit my models on it and the top surface represents the top of the rail head. I then milled a smaller block of aluminum about the size of an MT gauge to fit the rails I milled in the larger block. I cut the smaller block to exactly 0.216". According to my calipers, the needle is dead on 0.216". Now I have a solid surface to measure from as well as an accurate height gauge. Set an unabused Atlas GP38 (early version) with improved deck (deck has been retooled to remove the walkway/handrail combination). This model still has the factory installed Atlas coupler and box. The center line of the coupler lined up exactly with the top of my gauge. It was perfect.

So now for some testing. I took out an ESM X58 boxcar and tested it. Perfect alignment of the coupler as well. Center line of coupler dead on with top of gauge. Took out an MT car. Again, perfect alignment. Put on the Atlas C628. Again perfect alignment. So I know my gauge is correct and all the test equipment lines up.

Using the Atlas GP38 as my test subject. I took out the coupler and inserted my "special" coupler into the pocket. This is where I found out what where I went wrong. I put the "special" coupler in the box and lined it up to the gauge. It was about 0.010" lower than the gauge. When I saw this, the light bulb went off. looking at the coupler in the box closely I noticed it dropped. After investigating, I found there was 0.010" worth of play inside the coupler draft gear box. This combined with the wrong height on the MT coupler gauge is what gave me the impression over the weekend that the coupler was off by 0.020". I made a 0.010" shim from sheet styrene. I sanded the surface to make sure it was right on at 0.010". I placed this UNDER the coupler. The lid fir perfectly and the coupler was snug inside the draft gear box. I reinserted the draft gear box into the locomotive and placed the model on the gauge block. The coupler lined up PERFECTLY with the gauge. The center line of the coupler was dead on with the top of the gauge. this was great news to me, but now I had to go and edit my 3D drawings of the draft gear box/coupler pocket which in turn gave me another very pleasant surprise. Before I go onto that, I then put the "special" coupler in the C628 test model. no such luck with it lining up. The C628/C630 definitely uses a slight offset shank coupler. The "special" coupler was low by about 0.010"/0.015". So the Alco models are going to be a bit of work still to get a good draft gear box setup.

Onto the pleasant surprise. I made all the necessary edits to the drawings to change the coupler location. Back when I lived in Illinois, I would take a lot of weekend trips out to the Illinois Railway Museum. During these trips I would take all my measuring tools. Same goes for when I lived in Arizona. Whenever I would go visit the local sidings, I would take all my measuring stuff and record all sorts of things. During a few of these trips i documented the coupler pockets and draft gear boxes. Measured them up. I took those measurements and built the parts in N-Scale in my 3D software. I use a program called Alibre. OK, so enough on the background.

So I mentioned I drew the coupler pocket and draft gear box in N-Scale. I had to make some slight sizing changes so the parts could be manufactured. Mostly for wall thicknesses. The coupler pocket or what some call the buffer plate is scale height and depth. The width is 0.014" wider than prototype. This is because of the coupler shank pin hole.  The draft gear box is also just slightly wider that prototype, but not by much. Mostly due to the fact that it would be near impossible to cast 1" wall thickness in N-Scale. That would be 0.00625" thick. So after building these parts, I then built the Atlas GP38 pilot plate and deck in my 3D program. I meticulously measured the Atlas part and then measured it again and again to make sure I was getting the same readings. After building the deck I assembled the draft gear box and coupler pocket. Before I go further I must add that when I built the draft gear and coupler pocket, I built them around a drawing of the Atlas pilot. Not a detailed drawing, but enough to get the location of the rectangular coupler opening. This may not seem like much to many, but to me it was great! When I assembled the parts on the Atlas pilot, it just so happens that the drawings and the prototype measurement from the top of the pilot plate to the bottom of the coupler pocket (buffer plate) were dead on. Atlas built their EMD pilot correctly. I was to say the least, pleasantly surprised. Can't wait to get my parts in to see how it all fits together and looks.

[6axlepwr]

All my stuff is drawn to 6 decimals and then is written out in millimeters. I then check the accuracy of it in an stl viewer before submitting.