Legopold

Improved method to equip LEGO train wheel holders with ball bearings (no cutting of the wheel holder required)

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Hello,

last year I presented here on Eurobricks a method to equip the LEGO train wheel holder with ball bearings. A disadvantage of that method (see here) was that it required to cut a small part of the wheel holder, thus you had to damage the rather expensive wheel holder. Even worse, removing the ball bearings after modification left you with a more or less useless LEGO piece, thus making it very difficult to sell these LEGO pieces in the future. Furthermore, the modification slightly added to the height of the wheel holder, i.e. the resulting holder was approximately half a plate higher than without modification.

I came up with an improvement that does not require cutting the wheel holder and does not notably add to the height of the holder. It does require cutting of a 2L technic axle though, which I do not consider a big thing since these axles are really cheap:  

49049266901_38a4329696_c.jpg

 

When inserting the red axle pieces into the holder, it is important to align them exactly as shown in the picture. When the assembly is complete, it is crucial to prevent the axle from touching the two clamps in the center of the holder.

For some additional information, click on the picture above . For a comparison of the wheel holder with and without modification, see this video:

26206035258_a0c0b6a716_c.jpg

 

 

 

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On 11/11/2019 at 1:06 PM, Legopold said:

 

49049266901_38a4329696_c.jpg

This look like a great idea! I'm going to give it a try. 

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Wow! This is really great! I have been meaning to find a solution to bearings in the wheel holders but now you have saved me a ton of time! Thank you!

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Finally, I found the ball bearings on AliExpress. But is it needed to buy also the steel rods/axles ? Or can we use the original axles ?

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11 hours ago, RayZZoo28 said:

Finally, I found the ball bearings on AliExpress. But is it needed to buy also the steel rods/axles ? Or can we use the original axles ?

Hi Ray,

you can use the original axles but you may have a hard time fitting them into the the ball bearings from Aliexpress as they will fit very tightly. The inner diameter of the bearings has some variance and some of them can be applied with little effort. Others require a lot of force, e.g. by using a hammer (see this thread). The steel rods from aliexpress are a fraction of a millimeter thinner than the LEGO axles and fit into the bearings easily.

I use both types of axles with the ball bearings but mostly the ones from aliexpress.

I'd like to add that on flickr someone commented that the bearings may move towards the center of the wheel holder after prolonged use, e.g. if used for several hours at an exhibition. If this happens, you lose the power of the bearing and end up with the friction of the standard wheel holder. This behaviour was noted when the old type of modification was applied, i.e. the one that required cutting of the clamps in the center of the wheel holder. I expect that movement of the bearings inside ot the wheel holder will be less of a problem with the new type of modification. It certainly will not be a problem, if you hammer the bearings onto the axle as shown in the thread mentioned above. :laugh:

 

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Thank you for all those informations Legopold. It's very useful ;-)

When I see the new Lego Disney train and Hidden Side train set, the future will be more complex to have quality wheels 

lego-_38339_wheel-Red-38340__Train-wheel_Black-6253473_Red-6255082.jpg.1a2b50373563cc9001b73941ac607242.jpg

 

A video for train wheel comparison between the old one and the new full plastic one : 

 

 

 

Edited by RayZZoo28

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A couple large groups are working with BrickTracks to injection mold original style wheels that press fit on to the end of the BT axles. I believe they are fairly close to launch, they've had a few prototypes runs come off already.

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@legoman666 I tried this mod but the axle was still rubbing the two tabs in the middle. I made sure the cross-axle parts were all the way in the 3x6 bearing element and seated as indicated in your OP. Any thoughts?

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14 hours ago, ALCO said:

@legoman666 I tried this mod but the axle was still rubbing the two tabs in the middle. I made sure the cross-axle parts were all the way in the 3x6 bearing element and seated as indicated in your OP. Any thoughts?

Did you make sure that the red axle pieces are rotated into the right position as indicated in the picture? Once they are seated in the holder, you usually need to rotate them inside the holder (!) to reach their final orientation as depicted. If orientated correctly, the 2L axle is a fraction of a millimeter thinner than in the wrong orientation and this does the trick. You might need a tool for rotating the axle. Afterwards, place the assembled bearings with axle and wheels on top and press on the bearings firmly.

If this does not work, then obviously there is something wrong. Maybe there are different kinds of 2L axles or bearings with slightly different widths available? It might help to test some more 2L axles and bearings.

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On 12/15/2019 at 12:19 AM, ALCO said:

@legoman666 I tried this mod but the axle was still rubbing the two tabs in the middle. I made sure the cross-axle parts were all the way in the 3x6 bearing element and seated as indicated in your OP. Any thoughts?

I am not the OP and I have never made wheelsets using this method. All of mine are bearings pressed in to Technic bricks.

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Merry Christmas to everybody!

This morning I have the time to test Legopolds version of train axles with ball bearings.

I'm using the type MR52ZZ from a chinese dealer on Ebay. I combine them with metal rods from steel type 1.2210 called "silver steel" which comes with low tolerances and fit without force to the ball bearings. Please do not use force or hammering or something else, ball bearings even from China are precision products and can fail by deforming them by unneccessary force. I have to fix the ball bearings with a tiny speck of two component glue to the axle holders and remove the central clips.

The comparison with original steel axles on a shallow rail ramp is overwhelming: even lubricated the original axles performed 60% less the ball bearing axles. For the comparison test I used the rather massive hopper car from set 60051. Here the exact description:

Testramp consisting of 20 straight rails (new) on the flat floor. The fist three rails have a gradient of 1 plate, so the start is at 1 brick height above the horizontal floor plane. 

1) Axles with new style plastic wheels: The test car does not move after relase.

2) Original unlubricated metal axles: 34.5 cm (13.5 inches)

3) Metal axles lubricated with lithium grease: 54 cm (21.3 inches)

4) Ball bearing axles à la Legopold: 140,5 cm (55.3 inches)

I am aware that the drastic differences are caused by the very low gradient of the start slope which overemphasize the tiny friction differences at very low drag levels. The next test will be a comparison of a real train comparable to the original LEGO test.

Addenum I:  Wheels 57878 and axle holders 2878 are still available at the LEGO bricks & pieces service, somewhat expensive but still ok.

Addenum II: Do not buy ready made "silver steel" rods from chinese sources. They are zinc plated with too large diameter and do not fit to the ball bearings. Look instead for the steel type 1.2210 oder 115CrV3: Theese rods have a tolerance of h9 and fit perfectly to the ball bearings without any further machining. This material is too strong to be cutted with a saw but can be put to length with a long bolt cutter. Then you can grind the raw axle pieces to the exact length with a carborundum abrasive wheel.

Edited by Giottist
Addenums

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Hi Giottist,

thank you very much for your feedback and for sharing your rest results.

On 12/25/2019 at 11:52 AM, Giottist said:

Addenum II: Do not buy ready made "silver steel" rods from chinese sources. They are zinc plated with too large diameter and do not fit to the ball bearings. Look instead for the steel type 1.2210 oder 115CrV3: Theese rods have a tolerance of h9 and fit perfectly to the ball bearings without any further machining. This material is too strong to be cutted with a saw but can be put to length with a long bolt cutter. Then you can grind the raw axle pieces to the exact length with a carborundum abrasive wheel.

I bought ready made steel rods from Aliexpress and had no problems fitting them into the MR52ZZ bearings at all. The axles were advertised as "RC Toy Car Model Part Stainless Steel Round Rods Axles 40mm x 2mm ". Those had the right diameter and length. I can recommend them.

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Hi Legopold, we have to thank you for sharing your idea :classic: It's a nice feeling to reproduce your results.

I've bought my steel rods on Ebay but it seems it is the same source: My lot does not fit anyway and I do not know any usable method to grind them down to a matching diameter without removing the zinc plating. If I would do so the remaining cheap steel will rust away ... It seems there are large manufacturing tolerances, to big not to be a matter of risk. If we like to avoid any risk and do not hesitate to have some work, the steel 1.2210 aka 115CrV3 is the better choice since the rods made of this material have the tolerance h9, an international norm.

I used the calm holidays to test all my axles and all yet existing rods made of 1.2210 fitted perfect with my ball bearings, most of the original LEGO rods did so (about 10% not!) and none of the plated chinese rods.  It seems it is a matter of luck, which lot of the cheap plated chinese rod will fit or not.

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On 12/15/2019 at 6:19 AM, ALCO said:

@legoman666 I tried this mod but the axle was still rubbing the two tabs in the middle. I made sure the cross-axle parts were all the way in the 3x6 bearing element and seated as indicated in your OP. Any thoughts?

@ALCO: I modified some more wheel holders today and noticed that the modification (using the "2L axle method" described in the original post of this topic) failed to work on a few of the wheel holders. Those were somewhat older wheel holders that I bought second hand. Obviously, LEGO has used different types of moulds for the wheel holder over time. On the older wheel holder, the cavity where you put the 2L axle piece had a different depth which resulted in friction between the metal axle and the two clips in the center of the holder.

While both types of wheel holders look very similar, you can distinguish the old and the new mould by the style of the part number "2878". The number is notably bigger on the older inompatible mould:

49300819611_eca24f7cd8_b.jpg

 

I assume that you tried the modification on an older type of wheel holder which looks like the one in the bottom picture. If this is not case, please let me know. Maybe even a third kind of mould exists.

@Giottist: Apparently, there are different kinds of 3rd party metal axles available. I have bought axles here on four different occasions between 2016 and 2019, so it seems to be a reliable source to me.

 

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2 hours ago, Giottist said:

Hi Legopold, we have to thank you for sharing your idea :classic: It's a nice feeling to reproduce your results.

I've bought my steel rods on Ebay but it seems it is the same source: My lot does not fit anyway and I do not know any usable method to grind them down to a matching diameter without removing the zinc plating. If I would do so the remaining cheap steel will rust away ... It seems there are large manufacturing tolerances, to big not to be a matter of risk. If we like to avoid any risk and do not hesitate to have some work, the steel 1.2210 aka 115CrV3 is the better choice since the rods made of this material have the tolerance h9, an international norm.

I used the calm holidays to test all my axles and all yet existing rods made of 1.2210 fitted perfect with my ball bearings, most of the original LEGO rods did so (about 10% not!) and none of the plated chinese rods.  It seems it is a matter of luck, which lot of the cheap plated chinese rod will fit or not.

If it is of any help, I manufacture replacement axles that are ground undersized to fit perfectly with bearings.  They're held much tighter than h9 tolerances.

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On 12/30/2019 at 1:31 PM, coaster said:

If it is of any help, I manufacture replacement axles that are ground undersized to fit perfectly with bearings.  They're held much tighter than h9 tolerances.

I'm testing @coaster's axles with the generic MR52ZZ bearings and find that they seem to fit too easily in the bearings, e.g. put them on an axle, and if you turn the axle upright, the bearings will begin to slide off. Have others experienced good results without "tightening" up the BrickTracks axle-to-bearing-inner-ring connection? Maybe a loop or two of thin transparent tape to would help the bearings fit "tighter"?

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40 minutes ago, izx said:

I'm testing @coaster's axles with the generic MR52ZZ bearings and find that they seem to fit too easily in the bearings, e.g. put them on an axle, and if you turn the axle upright, the bearings will begin to slide off. Have others experienced good results without "tightening" up the BrickTracks axle-to-bearing-inner-ring connection? Maybe a loop or two of thin transparent tape to would help the bearings fit "tighter"?

They should slide easily on.  You aren't going to get a slight interference fit in stainless to feel like putting a bushing or gear on a technic axle.  It's going to either slide nicely or require significant force to assemble.

Now, if they wobble in the bearing, that's a different story, but they are held pretty tightly, so that shouldn't be the case.

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43 minutes ago, coaster said:

They should slide easily on.  You aren't going to get a slight interference fit in stainless to feel like putting a bushing or gear on a technic axle.  It's going to either slide nicely or require significant force to assemble.

Now, if they wobble in the bearing, that's a different story, but they are held pretty tightly, so that shouldn't be the case.

Thank you for the quick response and the material science tidbit. They do slide very nicely with no wobble (definitely a finger saver). A slight downside of this is it's no longer possible to quickly test the bearings by holding the axle, giving the bearing a spin and holding it close to the ear to see if it spins smoothly.

On to more testing!

Has anyone tried (supposedly) higher quality bearings (~$1/bearing, e.g. Avid), or is it best to keep playing the AliExpress 50-for-$10 lottery?

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16 minutes ago, izx said:

Thank you for the quick response and the material science tidbit. They do slide very nicely with no wobble (definitely a finger saver). A slight downside of this is it's no longer possible to quickly test the bearings by holding the axle, giving the bearing a spin and holding it close to the ear to see if it spins smoothly.

On to more testing!

Has anyone tried (supposedly) higher quality bearings (~$1/bearing, e.g. Avid), or is it best to keep playing the AliExpress 50-for-$10 lottery?

Of course!

Generally, the friction between the axle and the bearing is going to be much higher than the internal friction of the bearing.  Especially under load, it is highly unlikely the axle will slip before the bearing.  You'll see this in testing for sure.  The car should glide nicely along the track if everything is working properly.  If a bearing is seized, you'll definitely notice the drag, and you may be able to hear it, too.

Even the cheap bearings from China are sufficient for our purposes.  I wouldn't waste your money on more expensive ones.   

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