BLI N-Scale Announcements

[arbomambo]

This is interesting.  The BLI loco is significantly shorter.  Comparison with Hallmark brass 3751 and 3765.  After a quick check of Worley's Iron Horses of the Santa Fe Trail, I think they may have used dimensions from the original build of the 3751 class, but the rebuilt versions had larger wheels and boilers.  The Bachmann Northern is also longer.
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The 3751 class Heavy Mountains were not rebuilt with larger boilers during their rebuild… they did receive 80” drivers, frame updates, and roller bearings, but their boliers remained shorter and more narrow than the 3765-2900 Northerns that followed.

[mike_lawyer]

What a strange design.  Only the 3rd driver is gear driven and yet the traction tire is on the 4th driver, driven purely by the siderods.  It is a really bad design to have the driver which pretty much provides most traction in the model to be driven by siderods while the actual driven driver just sits there over the rail looking pretty. Even if all the wheels were on the rails, that is still not an optimal design.  They should have placed the traction tire on the gear driven driver and had the fourth driver be strictly cosmetic. Kato did that on their 4-8-4 locos, but they gave it soft springy suspension so it actually rode on the rails (and also picked up power), not hover above.  Model mechanism designers should pay more attention to Kato's designs - they are quite clever.

Pete, I am with you that the traction tire should be on a geared driver.  However, my BLI 4-8-2 M1s have the exact same design, and they are my best pulling locos - easily pulling 50 cars.  They outpull my Kato Mikados with GHQ boilers.

So whatever BLI is doing seems to be working.

[thomasjmdavis]

The Warbonnet, 2nd. quarter, 2026, in the article on 'Santa Fe's Super Steam' (auth: Rob Ray) has diagrams of 3751 class in original configuration (p. 15),  3751 as modified with 80" drivers  and 3765 class (both on p. 21).

The major 'spotting features' of the modified 3751 are a larger cab and greater overall length.  It also indicates the feedwater tank (sorry, not an expert on steam loco terminology) atop the front of the boiler.

The BLI model has the larger cab, and tank, of the modified 3751.

Original overall length was 104' 9".  The modified length was 107' 6 3/4".  Only about 5 mm in N scale , but measurable if someone has one.

The 3765 class, as Bruce said, have somewhat larger boilers, and an overall length of 112' 1 1/4".

* on the drawings the overall length is shown as tip of the pilot to the face of the coupler.

[peteski]

Pete, I am with you that the traction tire should be on a geared driver.  However, my BLI 4-8-2 M1s have the exact same design, and they are my best pulling locos - easily pulling 50 cars.  They outpull my Kato Mikados with GHQ boilers.g.

Pulling ability is not the reason TT should be on the geared driver. As it is now only the sideroads are transferring the rotary motion to the TT driver. That is not an optimal solution as it puts a lot of stress on the sideroads and crankpins. Plus, in N scale the inherent slop in the siderods results in slight hitch in rotation, especially under strain.

[Chris333]

In the top view what are the 2 pipes running from the steam dome to the cab?  The BLI model doesn't have those.

[spookshow]

A little more info on those ala carte MU hoses. According to BLI tech support, the reason they don't come preinstalled is that they interfere with the play of the couplers and drastically limit the radius of curves the engine can handle. Thus, they are included for static display purposes only.



-Mark

[robert3985]

A little more info on those ala carte MU hoses. According to BLI tech support, the reason they don't come preinstalled is that they interfere with the play of the couplers and drastically limit the radius of curves the engine can handle. Thus, they are included for static display purposes only.



-Mark

That explanation maybe works for the brake & steam lines on the rear of the tender, but, if no helper is ever going to be used (or if the engine isn't going to push, or pull a train in reverse with the train coupled to the pilot), mounting them on the pilot, and mounting an N-Possible Coupler in the pilot's coupler pocket isn't going to limit anything.

And, if the buyer's layout has larger radius minimum mainline curves, such as 18" or larger, maybe they won't interfere either. 

I would be informative to know the minimum radius at which they won't interfere.

Just sayin'...


Perhaps one day, manufacturers of N-scale "scale" train models will make brake hoses and steam lines out of a flexible, durable material, such as rubber or neoprene...or a super flexible black 3D resin.

Seems like I remember a rumor that one manufacturer (Atlas maybe??) had promised rubber brake hoses a few years ago...which would make them extremely durable as well as flexible enough so that interference with coupler swing would be minimized, maybe eliminated.

Would be a good detail part to make if an appropriate 3D resin could be found, since, with a 10" printer, at least a couple of thousand N-scale brake lines could be printed in a single one hour-long print session...which makes material cost per hose almost irrelevant.

Cheerio!
Bob Gilmore

[peteski]

Many types of flexible materials don't age well. They seem to get stiffer, or crack.  Some soft vinyl materials also ooze out plasticizer so they get sticky and that plasticizer can damage plastic materials shells are made of. Not familiar with 3d printing resins so I can't comment on those.  Silicone seems to be the one metarial I know which remains flexible and nothing leaches out of it.  But will we ever see N scale silicone hoses? 

[arbomambo]

In the top view what are the 2 pipes running from the steam dome to the cab?  The BLI model doesn't have those.

Those  are the external throttle rigging rods (or throttle operating rods)
The boilers on the 3765 through 2900 class 4-8-4s had larger diameter boilers that didn’t have room inside the boiler jacket for the throttle and secondary throttle rods.
They’re not in the BLi model because the real 3751 class 4-8-4s didn’t have them mounted on top of the boiler.
Again, the bolier on the 3751 class was shorter in length and diameter than on the 3765-2900 classes

[robert3985]

Many types of flexible materials don't age well. They seem to get stiffer, or crack.  Some soft vinyl materials also ooze out plasticizer so they get sticky and that plasticizer can damage plastic materials shells are made of. Not familiar with 3d printing resins so I can't comment on those.  Silicone seems to be the one metarial I know which remains flexible and nothing leaches out of it.  But will we ever see N scale silicone hoses?

I am aware that some vinyl materials don't age well, BUT, some rubber materials, such as those used for automotive hoses, belts etc., DO age well, and I've got an old neoprene wetsuit that I used when I was a teenager (and I'm 77), that is still flexible as well as a small 1/4" thick sheet of neoprene that I use on my workbench that I've had for over 40 years.

However, I don't know the processes these materials go through in order to manufacture the parts they are part of, so I don't know if they'd be appropriate for tiny N-scale hoses.

I am aware of several (advertised) super flexible black 3D resins that are used for model car parts, particularly tires, that might be usable, but...they are much thicker than the usual 3D resins that we use for very fine details in N-scale, and, IIRC, they also require a much higher vat temperature to print properly.

As far as durability is concerned, being super-flexible isn't necessary, but, to not interfere with coupler and/or truck movements, I would assume that being super flexible, such as being made of Silicone, would be necessary.

Cheerio!
Bob Gilmore

[squirrelhunter]

Has anyone laid the loco next to a scale drawing?

I suspect a major issue here is the proto loco as rebuilt with 80" drivers had the drivers too close to be modeled at scale in N due to oversize flanges- so I bet the brass 3751 makers went with scale 80" drivers and stretched the boiler to make things fit and BLI chose to use underscale drivers on a correct length boiler. But someone would need to put the loco next to a correct scale drawing to confirm.

[nstars]

Based on Spookshow the brass ATSF northerns don’t seem to be 3751 class locomotives. The Key loco is described as a 3776 class northern and on the page of the Hallmark unit #3773 is shown.

Marc