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Customizing MTH HO PRR K4s with Disc Drivers!

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  • Member since
    May 2014
  • From: Pennsylvania
  • 1,154 posts
Customizing MTH HO PRR K4s with Disc Drivers!
Posted by Trainman440 on Wednesday, May 15, 2024 6:33 PM

Hello all, I havent shared a project on here in a while, but I figured Id share this one, cause I spent 80 hours on this project and figured this particular project was worthy of sharing. This is a project LONG in the making. I think everyone knows how many different configurations the PRR had in their fleet of 475 K4s. As someone who models the PRR and loves the K4, it was a lifetime dream of mine to own models of two K4 variants, one with the center Boxpok disc driver, and one with PRR's homemade welded disc drivers.

I've spent many many hours brainstorming ways of obtaining such models. NJCB made a welded disc driver #3770 before but its very rare and $$$ and has many dimensional inconsistencies which makes it look rather strange. I considered buying BLI K4s and attempting to find a suitable wheelset of the same size to swap in, such as their 844 or Niagara models. But the main crankpin and rods are not swappable, and the hole pattern on the discs are off.

Alas, I had noticed that my MTH K4s had wheelsets which were different than those made by Bachmann, BLI, PFM. Their spokes were inset, relative to the tires/counterweights. That eventually lead to the idea of creating very thing disc "facades" to be glued ontop the wheelset. Thin enough to be placed over the MTH drivers without rubbing the backsides of the rods. 

That idea eventually lead to me spending around 13 hours CADing and 3D printing various iterations of my idea. I experimented with different ideas, and thicknesses. My first idea was to have the part be able to slot in between the existing spokes on the wheel to better hold it in place (which ended up not working). The final result was a very thin disc, which still had enough thickness to convey the arc-ed nature of the boxpok driver, yet thin enough to be fit over the spokes...and still printable with my cheap $100 Ender 3 Pro PLA FDM printer. (I dont have fancy resin printers)

On the boxpok, I wanted to make sure I modeled the partially filled-in inset holes seen on every other hole. That was a particularly challenging aspect, modeling that detail while also keeping the overall disc thin. Those particular holes resulted in a 3D printing piece with just 0.3mm layer of plastic. So thin its totally see-through!




The final print was made on black plastic. It was then very carefully sanded smooth (PLA prints usually result in a textured surface). The drivers were then taken out of the loco, cleaned. The spokes which would have been visible behind certain holes on the disc were very carefully broken off (to avoid cracking other areas), and the surface of the wheel was filed down to give the discs a flat even surface to rest on. Discs were then superglued, primed, painted and installed! 





Seperately, I also painted the tires and axles on the remaining wheels black, the cab roof the correct 50/50 mix "oxide red" and black (I use Tamiya Lacquer paints, my replacement for SCII), and added a few more details here and there. In total I spent over 80 hours on these two locos. Here are the final results!




*Note: Discs were a one time creation, think of it like my method of scratchbuilding. They are NOT for sale.

Thanks for reading!
Charles

---------------------------------------------------------------------------------------------------------------

Modeling the PRR & NYC in HO

Youtube Channel: www.youtube.com/@trainman440

Instagram (where I share projects!): https://www.instagram.com/trainman440

  • Member since
    March 2012
  • 1,162 posts
Posted by PC101 on Wednesday, May 15, 2024 7:11 PM

WOW! The fruits of your labor. That is good, you are good. Nice work.

Your one time creation is like making lost wax castings. 

  • Member since
    July 2010
  • From: Kyoto, JPN
  • 250 posts
Posted by BN7150 on Wednesday, May 15, 2024 8:11 PM

It's amazingly cool!!!

I tried editing three photos using the "Microsoft Photo" app that comes pre-installed in Windows 11, knowing that you might not like it. Since you have advanced craftsmanship and an expensive camera, next time please use a tripod and set the lens aperture to its maximum value.

  • Member since
    May 2014
  • From: Pennsylvania
  • 1,154 posts
Posted by Trainman440 on Wednesday, May 15, 2024 9:51 PM

BN7150

I tried editing three photos using the "Microsoft Photo" app that comes pre-installed in Windows 11, knowing that you might not like it. Since you have advanced craftsmanship and an expensive camera, next time please use a tripod and set the lens aperture to its maximum value.

The photos were taken at F/5.6 at 35 or 50mm focal length, from my F/2.8 24-70mm lens on a tripod. The RAW files were then transfered and edited to Adobe lightroom and adjusted to my taste.  I prefer not overexposing my photos to not lose detail on the high end, and dont like oversaturating photos either. I guess you can call that my "style".

As you probably know, bringing the F stop down to its maximum at F/22 brings the background also into focus. I prefer shooting at a lower F stop so the viewer focuses more on the foreground, at whatever part of the model I choose to pull focus toward. (in this case the wheels)

I understand my photography taste isnt for everyone, so thanks for sharing your edits on my pics!

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the PRR & NYC in HO

Youtube Channel: www.youtube.com/@trainman440

Instagram (where I share projects!): https://www.instagram.com/trainman440

  • Member since
    March 2011
  • From: Westford MA
  • 560 posts
Posted by Tophias on Thursday, May 16, 2024 8:38 AM

Charles, while I don't model steam (I have but one steam engine, a BLI Hudson for "excursion trips" on my layout) I am very much impressed with your project. The time, planning, effort and detail is way above my skill level. True craftmanship.  We'll done indeed.

Regards, Chris 

  • Member since
    February 2020
  • 24 posts
Posted by Col Bob on Thursday, May 16, 2024 9:21 AM

The Other Railroad liked Disc Drivers. That is the reason all true SPF's shoukld hate them. And while I appreciate your work, a K$s with sisc drivers is FUGLY.

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