Rolling resistance: Plastic vs Metal axles

[dr_spock]

Has anyone tried 85zz bearings with Technic axles?  Looks like the Technic brick holes need to be enlarged to 8mm?  Or 3D print a compatible holder?

[zephyr1934]

On 9/4/2022 at 12:50 AM, dr_spock said:

Has anyone tried 85zz bearings with Technic axles?  Looks like the Technic brick holes need to be enlarged to 8mm?  Or 3D print a compatible holder? 

A long time ago Andy from OKBrickworks had a 1x2x? holder for ball bearings on Shapeways. When I asked him about it at brickworld this year, I think he said it was not great. It would be great if someone came up with a good solution...

[Toastie]

36 minutes ago, zephyr1934 said:

I think he said it was not great.

Would be good to know what exactly wasn't great: The rolling resistance of the wheel set or the clutch (or whatever else) of the printed pieces? 

On 9/4/2022 at 6:50 AM, dr_spock said:

Looks like the Technic brick holes need to be enlarged to 8mm?

That would leave only a tiny - if any - material left on the studded side of the beam, wouldn't it?

Another question: When working with these bearings, they are usually rather intolerant when the axle is not aligned more or less exactly at 90° with regard to the face/open part of the bearing - at least this is what we see in the lab: Rolling friction goes up significantly. When there are two bearings sitting in two individual holders connected to one (stiff) axle, then any lateral/height tolerances of the bearings regarding their hole alignment across the wheel set would lead to deviations from 90° - could that lead to a performance issue as well?

Best,
Thorsten

Edited September 5, 2022 by Toastie

[Vilhelm22]

Are the HA Bricks roller bearings good quality?  In Britain obtaining the BrickTracks and BMR ones are pretty expensive to obtain and HA Bricks is closer to home.

[Moz]

4 hours ago, Vilhelm22 said:

HA Bricks roller bearings good quality?

I ordered their ball bearings in Technic bricks and one arrived disintegrated. The balls are tiny (as expected). Definitely not roller bearings. Tiny ball races like that are relatively fragile, I expected that, and when I was shoving axles through them I was appropriately careful. But still applied axial loads, especially because the tolerances on Lego axles and the bearings themselves meant that some combinations were too tight to fit together. Which makes it all the more surprising that one bearing fell apart in transit. I have emailed them but not heard back et (it's the middle of the night in Europe)

https://ibb.co/JygMbpV  the black blob is a Technic 1x2 brick with two holes, and part of the bearing race in it. Note 2mm hole through washer and tiny ball next to it.

Edited September 5, 2022 by Moz

[dtomsen]

On 9/3/2022 at 9:04 AM, Moz said:

I got the HDBricks ball bearing bricks, and I'm a bit unimpressed. One bearing arrived in pieces, and just generally the Lego axles+wheels I have don't stick together very well so picking up a model generally means half the wheels fall off. I suspect I need to 3D print some holders that have an exterior section like the Lego wheel holders do. It makes testing rolling resistance very tedious as I have to find all the wheels and washers then reassemble the test vehicle after every test.

Does anyone have advice?

I use BrickTracks own train wheels with their ball bearings bricks (HA bricks is just their European reseller) and those fit perfectly.

Unfortunately genuine LEGO train wheels are just that tiny bit too loose without any holder. Genuine LEGO metal axles work fine with BrickTrack wheels without any holder.

I find the rolling resistance much much lower than any solution without ball bearings so I'm rather perplexed why you aren't that impressed.

Lubrication is nessesary in the medium and long term though. I use a bit of teflon spray myself.

Edited September 6, 2022 by dtomsen

[Moz]

So the solution is to buy the BrickTracks wheels and axles, rather than using Lego ones. I will have to order some and wait.   For me HABricks postage is half what BrickTracks charge (USA postage is more than the cost of whatever I'm ordering).

[zephyr1934]

On 9/5/2022 at 11:34 AM, Toastie said:

Would be good to know what exactly wasn't great: The rolling resistance of the wheel set or the clutch (or whatever else) of the printed pieces? 

I think it was the clutch of the printed pieces. Might have been alignment too.

[Moz]

I got some more parts yesterday, including some old Lego metal axles and some really old red wheels with metal stub axles that go into the black 2x4 bricks. I made my test track a bit steeper but the really old wheels still only just barely managed to roll on straight track. So I didn't include them in my tests. Likewise I now have 8 wheels that take cross axles, so I put those on a test wagon and was equally disappointed (as expected). Those are really only good for fitting to motors, since I don't have ball bearing races that fit them. The older metal Lego axles appear to be very slightly larger diameter, only one of them fitted through the BrickTracks ball bearings so I haven't managed to test them at all.

I did a bunch more tests and by repeating some I've established that the variation between tests is larger than the variation between some setups. Specifically, adding graphite to the metal axles doesn't do anything useful (either in the wheels or the holders). With R40 curves I struggled to get consistent results, so I gave up after about 20 trials.

Conclusion: even on R40 curves the ball bearing races are significantly better for rolling resistance. They're a huge PITA to work with as the wheels fall off very easily (by design, they're supposed to have Lego wheel holders). Pic below shows the abomination I used for testing just so I didn't have to go chasing M2 washers out of the carpet after every run.

The next best option is the old metal axles, with graphite, IMO.

 

 

Edited September 30, 2022 by Moz
look at actual results :)

[zephyr1934]

Fascinating. Summing it up:

If one only considers the options available directly from Lego (red and yellow): the metal axles (just discontinued, molded plastic needle bearings) do better on the straights, things swap and the new split plastic axles do a lot better on R40, might be better on R88 but very close and worse on R104 but very close.

With graphite, the the metal axles perform better than the plastic on R40

Throughout ball bearings beat them all

Adding personal experience, on the straights the ball bearings do not look much better than the metal axles in your tests, but in my personal experience they make a huge difference even on straight track (cars roll away on their own to find the low point in the track)

[Feuer Zug]

Thank you for the data on the various radii of curves and straights. As @zephyr1934 mentioned and your data shows, ball bearings are the way to go for real train use. I've converted much of my rolling stock over to ball bearings and axle/wheel assemblies from Brick Tracks. Keep up the good science.

[ejayb]

As mentioned in the Community BlueBrixxs thread, I’m planning to switch from my ballbearing wheel sets to Lego holders. 
 

I decided to order Chinese axles and bearings and BB train wheels and technic bricks after reading the negative opinions regarding Lego’s switch to all-plastic wheel sets. 
 

My choice now is between metal axle and all plastic wheel holders. It seems like Moz’s testing shows that the all-plastic design isn’t as bad as originally assumed, particularly with curvy layouts, which is what I run my short wheelbase wagons on.
 

Unfortunately I have no way to source a set locally for testing so I’ll need to order online and it makes sense to order a batch. Is anyone else happy with the all-plastic design? Even better, is anyone running them over a trixbrix triple switch?  

[dtomsen]

In my opinion the all-plastic design is barely "just good enough" and far from the motto "the best is not good enough"
Why settle for an obviously inferior solution with all the many and better options available?
Mind you, metal axles don't cut it either without ball bearings (and teflon spray) for most of my long and heavy wagons especially the passenger ones close to 1 kg 

Edited April 8, 2023 by dtomsen

[ejayb]

Mine are 14 long, 6 wide and maybe 150g each. My layout has lots of back and forth, slow shunting over R40 an crossover and switches. 

The cheapest option would be to replace the BB wheels with Lego wheels on the existing ballbearing wheel sets. On the downside they are noisy and I never settled on any detailing to go around them.

[Elphiel]

First sorry for resurrecting an older Thread but does someone ever tried out the new all plastic wheels but with a short metal axle inside each separate wheel replacing the plastic part. Like, taking an old wheel, drill out the hole to the diameter of the new plastic bar and fit in a short metal axle.
Idea is to combine the advantages of both worlds. Independent movement of each wheels for better transition in curves (especially R40 curves and switches) combined with lower friction between axle and plastic wheel holder like in the old train wheels.
I don't want to delve into the ball bearing area and actually do like the new wheels, because of the many R40 curves in my layouts I build in my living room from time to time. And now with the Orient Express on the horizon and the official 'wont run well in our tracks' thing, I gave it some new thoughts because I really would love to have this train with multiple wagons driving around in circles :)

[Lyichir]

To be honest I kind of doubt the plastic wheels were the main reason why Lego couldn't find an adequate solution for motorizing the Orient Express—as the results in this thread seem to show, the efficiency improvement of the metal axles is not that extreme (much smaller than the improvement from third-party bearings and such) and would be a much smaller factor than the overall increased weight of the train.

[PopsicleLEGO]

The bearing on axles upgrade is a must do is your are serious about your Lego trains.

Over 100 axles got this treatment recently and what a difference to the running time of the train.

Because the carriages are heavy - 800ish grams - and up to 8 carriages per trains, the rolling resistance is an important factor to battery life. 

The pleasing side effect to bearings and heavy trains, is the more natural stopping speed of the train. When you slow down, the trains continues to roll like a real train would - not a sudden stop.

So here's the kicker - Buy the bearings and axles from AliExpress - mine cost very little and now the trains run smoother and quieter, have a longer runtime and the axles won't wear out over time.