Brio-Lego-compatible Carriage Wideload with Tack Axles

This is a ground-up remodel of the carriage from https://www.thingiverse.com/thing:4199752 and the wheels from that design's predecessor.

I loved the wider carriage deck, but I didn't want to deal with printed and glued axles. Since I ended up with 200 tacks from Amazon, I just subbed those in as the axles. This is pretty much how Brio used to do it, at least in the cars I still have from the 80s (see photos). I also simplified the carriage by removing the notch in the belly. More plastic means more weight, so I figured it might be an improvement.

As with the source model, 70% infill added a decent amount of weight and 10mm magnets were all I could find.

SAFETY AND FIT

Tacks: The holes in the model hold the tacks really well. It took a lot of pushing force from my thumb to get them in and vice-grips or a lever to get them out. Having said that, your printer will surely vary and you may need to tweak things to get a snug fit.No matter what, I don't recommend giving these carriages to kids who can't handle it if a tack comes out somehow.

Studs: The studs are modeled at the size that worked well for me at .2 layer height. Some lego pieces fit quite tightly and some fit a little more loosely, but everything seems to stay on. Even factory legos have some variation in their grab. I would say this is not a factory fit, but it's good enough.

If the tack holes or the studs don't work on your print, try adjusting XY compensation (aka "horizontal size compensation" or "horizontal size expansion"). Just adding or subtracting .1 should hopefully help!

This is not an official LEGO product, nor is it affiliated with the brand in any way.

Post-Printing

METAL PARTS

Make sure you insert the magnets with opposite poles facing out! Everything should press in well. A few times the magnets loved the tacks so much, I needed a small screwdriver to pin the magnet while I pushed in the tack.

Products like these are always changing on [Amazon](https://www.amazon.com?linkCode=ll2&tag=thingiverse09-20&linkId=e4759bff1fa9a55a0f897d801ce2d765&language=en_US&ref_=as_li_ss_tl), but for what it's worth these are the items I used:

WOTOY 25 Pieces 10x3mm DIY Multi-Use Refrigerators Magnets with 3MM Hole for Fridge Door Whiteboard Map Round Hole Magnet

Hilitchi 200-Pieces 7/16''(11mm) Silver Antique Tacks Nail Pins Upholstery Nail Tacks Furniture Thumb Tack Pins Assortment Kit (Silver)

How I Designed This

Initially, I modeled the studs as perfectly round, but my printer had a hard time accurately landing small circle layer on top of small circle layer with the precision necessary for legos. There was just enough slop that nothing fit. The solution was to replicate the source design's studs and use a 20-sided polygon, which effectively printed circular.

Switching to tacks for axles meant that I needed a new wheel design, too. The predecessor had low-poly wheel treads that I found to be a unnecessarily complex. For this model I just made them round with a fillet along the edges. In the future, it might be worth splitting the difference and doing something like a simpler many-faced polygon that's almost circular, but these wheels work for now.

Category: Toy & Game Accessories