4-8-8-4 Big Boy Tender 1:20,3

by Benoff, published

4-8-8-4 Big Boy Tender 1:20,3 by Benoff Apr 19, 2017



Design Tools


Liked By

View All

Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag.

Print Thing Tag


Thing Statistics

1090Views 918Downloads Found in Vehicles


2017_05_14: Added the lettering for side and rear as the rough surface of prints is rather hard to label otherwise.
Also .. built one ;)

Printed myself the BigBoy some weeks ago and started assembling. As no tender seems to be available I drew one. I have no original plans at hand so most measurements are literally taken by eye and internet image search and I am not an CAD-professional either....
The wheels were taken from the original project (not re-inventing the wheels...), the rest was drawn by me.

The scale is ap. 1:20,3 fitting to my printed locomotive, the whole frame and underfloor is for a static modell only and not modelled (no pictures found) but I think the tender should fit to the BigBoy that can be found on this site.

I want to finish that loco and just started printing parts for the tender. So I have no real idea how well they will fit and look like in reality.

Some proportions (lower bulge) are way off from reality, sadly only realized that when I found a decent picture from the rear, to late to throw away all the parts already made.

Also only some rivets are on the parts, no idea how those will come out of the printer yet so I left most of them away.

Meanwhile I will upload the files.
This is my first upload so I stil have to figure some things out.

Thanks to the original creator of the BigBoy and my boss who lent me a company notebook with Inventor over the easter holidays.

More from Vehicles

view more

File Name



All Apps

Upgrade this Thing with Thingiverse Apps


Edit, personalize, or revise this Thing

With 3D Slash, you can edit 3d models like a stonecutter. A unique interface: as fun as a building game! The perfect tool for non-designers and children to create in 3D.

App Info Launch App

Thanks for posting this. I appreciate it a lot.
You say you didn't know where to get plans. The Union Pacific Historical Society (http://www.uphs.org/CDdrawings.html) sells drawings of the 4000 4-8-8-4, the 4400 0-6-0 (a switch engine) and a bunch of shop drawings. Each of the 3 sets is about $30 for a CD. They're fairly complete. Some of the scans are from rather worn shop drawings, but they're generally quite good. I've been making CAD drawings of the 0-6-0.
Reading the original drawings is an interesting exercise itself. The 0-6-0 in particular is interesting because the drawings were done I believe in the 1920s, so the drawing standards were much different than current standards. Lots of fun to interpret design intent on some of them. The big boy drawings are much more current, and are more readily interpreted.
Again, thanks for posting this. Making the CAD drawings is a fair amount of work.

I am happy to see the tender of the BigBoy now being drawn and presented.
In June 2014 I used Paul Fischers STL-files from Thingiverse to print this impressive model and waited a too long time for the tender files.
P. Fischer (alias Forscape1) commented in Jan 2016 that the files for the tender were almost ready and were expected to be published likely a month later. Sadly that did not happen, Forscape1 is still invited to publish all the work done on his tender so far.
That would be appreciated very much as I like to continue printing the tender in his scale. How much should your files being up-scaled to come to the previous one?
Are you going to publish any construction drawings in the near future?

Regards Wim de Groot, The Netherlands

I scaled my BigBoy print down to 74% of it´s original file size of 1:15 so it fits my other (bought) 1:20,3 rolling stock.
The tender is in ap. 1:20,3 scale so multiplying the measurements times 1,35 should lead to a tender in 1:15 scale.

I drew another small and rather unfinished original locomotive in the past to test my printer and get used to 3D printing. Maybe I will upload that one in the future.

It also is an rather loose recreation of an interesting machine I found some pictures on the internet (compressed steam mining locomotive)

Else I already started drawing on another rail-based oddity, so more should come as work, life and software availability allow.