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So I am a 3 rail guy, toy train, type of guy, with a two rail question.  I am looking for some axle sets to build a project car for three rail but I intent to start from the ground up.  Can someone tell me where to find wheel/axle sets that have solid end axles instead of the needle point design used in most 3 rail offerings?

I actually intend to build the car out of lego brick and have some pretty nice looking plans to work from, courtesy of  The problem is that Lego L gauge is wider than O and the axles don't re-gauge without breaking things.  Also, lego train wheels are very skinny ( despite having huge flanges!) The wheels mgith work on gargaves or ross track, but never on tubular rail.

Brick model railroader actually sells kadee couplers built into lego bricks and axle sets with brass bearings in the bricks, but again both the gauge and the profile won't work.

But if I had some axle sets with plain ends I could get bearings(bushings) made that would press into the bricks and slip of the axle ends with out a problem.  Can someone point in the right direction?

(My apologies in advance if the lego freight car concept hurts the heads of this group, just seriously looking for some advice.)

Last edited by jhz563
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Look at the NWSL offerings (North West Short Line).     They have a wide assortment of for O Scale wheelsets with both needle  point and square axles, and some variety of axle lengths.    My LHS stocks a bunch of them.    P&D Hobbies, which also has a website.

If the train shows were still allowed, I would suggest attending a 2 rail one and looking for some old Walthers wheelsets.    They used to make them with blunt ends also, but not anymore in O scale.

@Johnbeere posted:

Very interesting concept, hope it goes well. I've actually built Lego trains before ( ), but I've never heard of anyone trying this - wish you luck. I expect you'll have to rebuild the trucks completely, since they're normally designed for L gauge. You might be able to carefully shorten the Lego axles by cutting them/filing them?

Okay,  I checked out your Flickr link,  simply saying you have built lego trains before is a glorious understatement.   That 4-6-4 is beautiful!  I have plans for a Switcher very similar to that B6.  I don't know if I will be able to adapt a power train from lego to O gauge,  so a few cars need to get built first.

I thought about cutting the axles,  slipping a sleeve over the two ends and soldering them together at the right width.   This still results in the wheels in wheels with a profile that just doesn't make sense for O gauge.  I did some experimentation.  I can make outside bearing trucks at 7 wide width. I might be able to get down to 6 and a plate using some snot techniques and technique pieces.

If I could come up with a way to mount the bearing on the inside of the axle without taking things apart that would be better,  but most of the wheel sets have the axle knurled somehow to help how the wheels in position.   The knurling would interfere with the bearings. 

Thanks for the complements, glad you like the Hudson.

I think your best bet might be to 3D print new wheels, but I'm not sure. This is new territory, so it'll be pretty tricky to get it all working right.

I wonder if you could find any bushings or bearings that have the right sizes to fit inside Lego technic bricks while allowing some sort of O gauge axle to slip through. It will probably be tough.

I don't think there's any knurling on Lego axles/BMR wheelsets, pretty sure the wheels are just glued onto the axles.

A locomotive will be comparatively easy to gauge correctly, but with less room for gearing, driving it will be more difficult. There's definitely techniques to do it out there though, considering people have managed to make Lego narrow gauge locomotives.

@Johnbeere posted:

Overall, your best route will probably be to cut the axles to length, and fit new 3D printed wheels onto them, using the standard Lego axles. You might be able to contact Cale or Glenn at BMR to buy wheelsets without wheels fitted to them, I think they'll probably help you out.

That's an interesting thought!  BMR is already putting bushings in technic bricks,  but their axle diameter is much smaller.   The are set up for 4 wide between the wheels.   If I change the width that no longer works.   I would have to come up with a new brick spacing that does not result in excessive lateral play.

Also, I talked to the good folks at Kadee this afternoon.   I got a nice education that the 805 or 806 is the coupler that I want for the best chance of coupling with existing o gauge lobster claws.  Kadee even recommended playing with 1 gauge 821 couplers since the toy train couplers are so big.  I should be able to take the BMR coupling boxes and switch the 743 size they came with to the 806.  Then I can build truck assemblies that will interchange with traditional toy o gauge.   

This is shaping up to be quite the interesting challenge.

You can just slide the bearings closer to the center of the axle, making it 3 wide between the wheels. There will be some lateral play in your axles, but after cutting the axles down and fitting new wheels I think it will be fine. Hmm, if you 3D print new wheels cutting the axle may not even be necessary, since you could just make the hole in the wheels a through hole. May make gauging more difficult though.

Yep, I built and designed all of those things just out of Legos (except the O gauge stuff up there, of course) - It can be quite fun working with Legos, but you can never get the detail and quality you can with proper models. There's a community of people who design trains out of Legos, they can be quite neat.

I build my Lego trains in what is known as "8-wide" scale, meaning 8 Lego studs wide. It actually works out to be 1:47.63 scale, extremely close to O scale.

@jhz563 posted:

So I am a 3 rail guy, toy train, type of guy, with a two rail question.  I am looking for some axle sets to build a project car for three rail but I intent to start from the ground up.  Can someone tell me where to find wheel/axle sets that have solid end axles instead of the needle point design used in most 3 rail offerings?

Unless I'm reading your question wrong, it seems that pretty much any postwar or pre MPC wheelset will serve your needs...


Unless I'm mistaken, Lego trains run on plastic rails, so short circuits aren't an issue. 

Hope this helps!



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Last edited by M. Mitchell Marmel
@Johnbeere posted:

I think the issue with using standard Lionel axles is that there isn't an easy way to adapt from Lego to those axles - maybe a bushing with the right inner and outer diameter could work.

That's my overall idea, but all the axle sets I had ready access to are needle point style ends.  Based on this thread though,  I need to dig through my parts and see if I can find something in the parts bin that I can rob, or acquire axle sets elsewhere.   The bushings will need to be custom.



I think I found a likely solution. I bought a pile of these two rail trucks years ago and they have been sitting in the bottom of a box ever since.  I don't even remember what brand they are.

It turns out the ends of the axle sets are the same diameter,  0.076", as the diameter of the lego axles.   I think I will be able to snip the axle on a BMR wheel set and use the bearings on a new outside frame truck arrangement.  A between the wheels bearing arrangement would still be better in opinion, but at 3 studs wide probably not that stable. The outside the wheels bearing arrangement will still likely be 7 wide.

I hate to waste a set of BMR wheels but this is for a prototype, so I might have to break a few eggs to get the omelet.  Anyway I thought you guys would like to know what I found so far.


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You should be able to simply pull the wheels off the BMR wheelsets - the wheels are just glued on. Try twisting the wheels opposite each other and the glue should fail.

Maybe you can pull a wheel off of that O gauge wheelset? If you can, it would be preferable just to slip the BMR bearings onto the axle and refit the wheel. You can probably just use a vice plus a block of wood with a hole as a press for those wheels. I wouldn't expect any instability from just a 3 stud wide frame that the axles go through.

I am going to play with this alot more before it's done. 

I agree that inside bearings would be better.   I will need to get the studs offset by 1/2 pretty quickly since I am looking at a 3 wide inside base.

I am going to further sacrifice the old plastic truck axle sets to see what I can get.   The thicker portion around the metal axle is molded 1/2 and 1/2 to the back of the wheels.  If I can get the wheels off, I can cut that axle covering section off.

I would still rather use metal wheels.   I am a 3 rail guy so a short from one wheel to the other doesn't bother me, and the rolling resistance of metal on metal is much lower than plastic on metal.

O well,  several iterations to go, we will see what happens.

@Sarah posted:

Why don't you modify the lego car bolster and use the unaltered 3-rail truck? I mean it work's for the knuckle couplers - just trying to understand your motivation :-)

Well,  I have already done a little bit of that.


The objective is simply to build a fully interchangeable (o gauge) car as much out of Lego as possible.


This hopper will be my next adventure.

Brick Model Railroader has made a huge leap by offering coupler assemblies with Kadee couplers.


They did this to improve on the magnetic couplers used on standard lego trains.

But to me it's an invitation to step things up and make a full brick built car,  including the trucks.  This just combines several things I enjoy.

Now that I have a source for the axles/ wheels worked out, I am studying how to modify the 4 wide truck plans into 3 wide, and ordering parts.  I have plenty of lego bricks,  but the cleanest way to do this involves some relatively newer bricks that I don't have. 

Once I get past the truck assemblies I will probably start a new thread for the rest of the build in the 3 rail sub forum.   When complete though,  this car should be able to run on 2 rail or 3 rail tracks.


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Okay I have been playing with parts on hand until my brick link and Kadee orders show up.

The 3 wide truck is okay but not great.  There is about an 1/8" or more gap when the wheels are all the way to on side.  Fortunately I can leave more of that pipe portion on the donor wheels. 

That will work for now but only until I run out of donors.


The 2x1 offset tiles were just for mockup until my bricklink orders come arrive.  The whole thing is currently too high.  The new parts will allow me to come down 1 plate.  ( For those who don't speak lego, 3 plates =the height of one brick. )

I was able to mock up the lowered arrangement with a 3×4, 4 stud tile that comes with minifigure packages.


Another height check now shows the top of the couplers lined up.


This might be good enough.

I can show the height of the coupler box mounted directly to the minifigure tile, and it looks better.


The Kadee arm can be bent up if needed.  The problem I see is that center of the assembly is now below the top of the wheels.   

I think this is about as far as I can go without the 800 series kadee couplers and the rest of the lego parts. 

I think I will stick with the inside the wheels 3 wide truck assy for now,  but I am not ruling out using outside bearings and more readily available toy train axles for future assemblies.


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Still waiting for the rest of my bricklink parts to come in.  In the meantime I found enough parts to make a decent one sided mock up.


I still need to add some type of detail parts at an angle to emulate something closer to an arch bar design,  but the basic premise works.  The design above uses inverted studs to hold the cross bar with the journal boxes.

The design below forgoes the snot technique (studs not on top) but allows for round tiles at the same height as the top of the rest of the assembly.  The gray technic pieces would not be sticking out, and of course the crossbar will be black.


I like both options,  and will probably try for something more like the lower picture for the final product.

Also I was able to install the Kadee 806 couplers in the lego coupler boxes.  They roll freely and couple well enough to lobster claws.


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Last edited by jhz563

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