Over the last few weeks I’ve been toying with the idea of making my own archbar trucks. So I sat down at the puter, fired up Fusion 360 and started drawing. After several iterations, I’ve come up with a prototype. They are printed in 3 parts and then put together with the wheel sets to make a complete truck.

The bolster is inserted in the pocket of the side frames and then it is screwed in at the top. Here is the first print.

I’ve since added the spring detail to the ends of the bolster. Not sure how it will turn out but it is on the printer now.

You can just see the scalloping on the ends of the bolster that I hope will resemble a spring. I will continue to add detail as I fine tune the design. There will be a model with bearings. I’ve ordered some 3x6x2 and 3x10x4 bearings and once they arrive where I can get the exact measurements, I will modify the design to accept the them. Don’t pay any attention to the colors. Since these are prototypes and don’t take much filament, I am just using up whatever small rolls I have lying around. I am using PLA for the prototypes but will use PETG for the production models. Let me know if you see any issues or details that I need to add. When I am comfortable with a production model, I will be glad to share the STL file with any of you that would like them.

Here is a comparison with Bachmann trucks. Again, I don’t have the detail, yet, but they are functional.

That’s cool. And how much would these cost to make?

The 3D printed parts are less than a quarter for the 3 pieces that make up one truck. Of course you still have to add the wheelsets which is the bulk of the cost for commercial trucks. Bearings will add about $4 per truck. Not sure they are needed for most cars.

Bearings help, but aren’t really needed in the commercially available trucks.

So the truck, after R&D, costs about a quarter. Ya know, if you start making trucks that aren’t commercially available, you might have a market. Trucks like the Andrews truck, “T” section Bettendorf, even arch-bar trucks of different design/wheelbases.

I would think that these trucks need at least some equalization, they look rigid right now.

Greg

Cool stuff Dan.

Here is my contribution to the idea pile…

Two different Fox pressed steel trucks (pre 1900):

The second version is the design used on the Leslie Snow Plows in the early 1900s. They were adjustable for both NG and SG.

This is a different style used under rotary OY:

Chrysler:

Civil war era…

Disclaimer: No Roosters were harmed in the making of this post.

And that is all I have to say about that.

Greg, can you elaborate on “equalization”?

David, most any design is possible. The issue comes in the details. Small details are difficult with an FDM style printer, not possible but the printer must be dialed in. Creating the design files are straight forward but what you see in the design doesn’t always translate to the printed product. At least with my printer. With all that said, I am working on a Bettendorf now and should have it ready in a couple days. Looking at Boomer’s requests, I may be busy for a while (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif).

Ok, here is a rough draft of a Bettendorf T Truck side frame. I haven’t printed this one yet. I still have to design the bolster.

Fox Pressed Steel truck.^

Have fun…

Dan Hilyer said:

Greg, can you elaborate on “equalization”?

All you ever wanted to kmow about “equalization”.

The principles of model locomotive suspension

Basically, it’s about making the frame handle uneven track by allowing the axles/wheels to lift independently. On an archbar model, you usually allow the sides to rock about the bolster - Bachmann does this with their loose screw.

Thanks, Pete. I understand now. Great resource. I can provide for the equalization now that I know what it is. Just a small tweak to the design.

Dan,

What type of filament are you printing these with? I an running three boxcars with PLA printed trucks for the last 3 months. They are rigid and have been doing great. I use Bachmann 31mm metal wheels in them.

Joe, right now I’m doing all the prototype printing with PLA. My plan is to use petg for the final prints. The only reason I’m considering petg is it’s ability to withstand higher temps. My concern is that I’ve had some PLA prints that were exposed to the summertime temps we get here deform somewhat. The most severe is a threaded container that was left in the direct sunlight. The threads actually melted together to the point that when I did get the top off the threads came apart. Now, we don’t have any threads on the trucks so I may be overreacting. I think PLA is plenty strong enough for the intended use for the trucks and any small details will print better with PLA than PETG. PETG, IMO, will just be more stable. I’m using the same Bachmann wheelsets. I’ve also printed journal boxes and supports for single axles And I will probably use the Bachmann 24mm wheelsets for those.

I am working on several different designs … primarily because I like the design process, I guess it’s the engineer in me… so I will be glad to share the stl or Fusion files with you. Just let me know if you see something you like.

Dan,

am not familiar with PETG is it similar to ABS? I tried a FDM printer several years ago and sent it back, I was looking to print some bigger parts and the machine although size compatible would not make a good large print. fast forward to today I have a form 2 sitting on my desktop, and will not look back. what is you long term desire with these trucks. are you going to print dozens or just a pair or two? if you are going to make dozens, then it would be worth while to get an STA print and have someone cast up them in white metal. much more durable in the long run, regardless of the detail level, and not that all expensive. if interested pm me for details.

Al P.

OK now we know … why the oven isn’t finished …it’s held up in design …

Sean McGillicuddy said:

OK now we know … why the oven isn’t finished …it’s held up in design …

I suspect there is no desire to mess with the insulation, that’s grunt work, not engineering!(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Dan Hilyer said:

Joe, right now I’m doing all the prototype printing with PLA. My plan is to use petg for the final prints. The only reason I’m considering petg is it’s ability to withstand higher temps. My concern is that I’ve had some PLA prints that were exposed to the summertime temps we get here deform somewhat. The most severe is a threaded container that was left in the direct sunlight. The threads actually melted together to the point that when I did get the top off the threads came apart. Now, we don’t have any threads on the trucks so I may be overreacting. I think PLA is plenty strong enough for the intended use for the trucks and any small details will print better with PLA than PETG. PETG, IMO, will just be more stable. I’m using the same Bachmann wheelsets. I’ve also printed journal boxes and supports for single axles And I will probably use the Bachmann 24mm wheelsets for those.

I am working on several different designs … primarily because I like the design process, I guess it’s the engineer in me… so I will be glad to share the stl or Fusion files with you. Just let me know if you see something you like.

Dan,

Like I already said, I printed mine in PLA. I tried the PETG but the details weren’t good. I think I should have used a smaller nozzle (.2mm) instead of the .4mm I used. Any way I’m in the Jacksonville area of Florida. The trucks have been on three box cars for about three months with no problems. They are under the car so I guess they are shaded enough. So far so good on that count with PLA. As far as equalization goes, most of my locos don’t have any and they do just fine, so why shouldn’t a car? The answer is “they do”! I like your screwed bolster attachment. Mine are glued. Would you consider sending me your STL file so I can print out a set for evaluation? Are you using a Prusa printer? That’s what I am using.

I have been using ProPLA, made by 3D-Fuel. It can withstand high temps, and you can anneal it in the oven for even higher temperature tolerance. It is very easy to work with, and I have no trouble printing at the highest resolution my printer can handle (0.05 mm). It’s much more expensive than regular PLA, but I’ve found it to be much easier to deal with than PTEG or ABS.