Ball bearings!

[ukewarrior]

If the axle is that tight, I think I would chuck it in a drill and use some steel wool on it to shine it up and that may be all you need to have a nice fit. Given the fact the lego parts are for toys afterall, I wouldn't always expect exacting tolerances with a part like the axle.

[ukewarrior]

Can someone identify the bricklink numbers for the axle and wheel? 

I would want the version with the through hole wheel and matching axle.

Thanks in advance.

[legoman666]

9 hours ago, ukewarrior said:

Can someone identify the bricklink numbers for the axle and wheel? 

I would want the version with the through hole wheel and matching axle.

Thanks in advance.

http://www.bricklink.com/v2/catalog/catalogitem.page?P=2878c01&idColor=11#T=C&C=11

[ukewarrior]

Are their part numbers for just the axle and wheel?

[Lego Dino 500]

I believe so, I ordered several pairs before and they were the complete assemblies. Try and get the 2878c02, the axles and wheels are removable, and will make for much easier modification. So we've all seen the video of the world's fastest Lego train, right?

With these bearings, and some ingenuity, we could potentially surpass this. I lack resources and parts, but do you think we could do a volunteer group build, to see if we can build something to beat it? I can help design trucks and cars in LDD. 

[ukewarrior]

So, I'm confused.  I thought the c01 variant was the one to get instead of 2878c02.   Doesn't the c02 varient require the side pieces to keep the wheels on the shaft?

[legoman666]

1 hour ago, ukewarrior said:

So, I'm confused.  I thought the c01 variant was the one to get instead of 2878c02.   Doesn't the c02 varient require the side pieces to keep the wheels on the shaft?

Correct. The wheels like to fall off of the c02 variant. The c01 is what you want and are in every 9v era train set. There are no separate part numbers listed for the axle or wheels. 

 

If it's any consolation, the c02 wheels and axle will fit in the c01 axle holder. 

[Lazlo]

Hello!

I am also experimenting on this great idea. I have found cheap bearings on ebay:

https://www.ebay.com/itm/50PCS-MR52-ZZ-2x5x2-5mm-Miniature-Model-Bearing-MR52ZZ-Ball-Bearings-2-5-2-5mm/361922341317?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

I am struggling to find a method not to "melt" technic bricks, but if I won't find any other easier solution, my last option will be that. I have found out that the bearing fits in to a 1 x 1 brick, with stud and hole on sides. It forces a little, so it might crack. I will make a prototype and run it some time, let's see what happens.

Thank you!

[Jeffinslaw]

4 hours ago, Lazlo said:

I am struggling to find a method not to "melt" technic bricks, but if I won't find any other easier solution, my last option will be that. I have found out that the bearing fits in to a 1 x 1 brick, with stud and hole on sides. It forces a little, so it might crack. I will make a prototype and run it some time, let's see what happens.

The bearings fit easily into the technic bricks without having to heat them up. Just line the bearing up with the hole and hit it into place with a hammer. Doesn't use much force and doesn't destroy the brick.

-Jeffinslaw

[dr_spock]

You could also try to press them in with a press or vise.  The opening could be enlarged with a drill so that the bearing doesn't put the plastic under more stress than necessary to hold the bearing in place.

 

 

[Lazlo]

Thank you all! I will try both methods. Looks like many of you have tried this technique out ;-)

[Lazlo]

The hammer worked well :-) I am looking for ideas to build a one axle fixed bogie for smaller wagons for now.

[Selander]

Sorry for bumping an old topic. In my decoupling bogie, I replaced technic axles with ball bearings and old 9v-era steel axle + wheels. It runs really smooth, with very low rolling resistance. 

 

 

Edited August 26, 2019 by Selander
Changed link

[Roadmonkeytj]

17 hours ago, Selander said:

In my decoupling bogie, I replaced technic axles with ball bearings and old 9v-era steel axle + wheels. It runs really smooth, with very low rolling resistance

Did you cut the axel for the wheels where the actuator runs through?

[Selander]

Yes, and for each cut axle I use 2x ball bearings to give it that extra stability, as one in each 3702 and one in each 32017.

Edited August 27, 2019 by Selander

[Ludo]

Hi,

I know, I'm late on this toppic, but my ball bearings arrived today, so I will give it a try.

I have some mechanical background, and was thinking to use a 5mm HSS reamer to enlarge the Technic hole. @coaster 

see picture: HSS reamer for those who don't know what it is.

It's not cheap, I can use one from my company. 

I can also use a milling machine to cut a part of the supports on the original wheel holder, as you can see in this picture.

https://www.flickr.com/photos/162569845@N05/25210157997

then i can place the axle deeper into the wheel holder to reduce the added height due to the ball bearing at a minimum.

Cross my fingers and hope it works.

I noticed also a difference in bore diameter, some axles fit perfect on the bearing, others do not fit.

I'm almost convinced that this 'problem' is on the bearing side, not on the axle.

I guess that the used axles are of the type G7/h6 according to the ISO fitting system (loose fit).

the mating hole need to be a H7/g6

Loose fit: combination of axis and a hole, whereby the largest possible axis (according to the given tolerance of that axis) will always fit into the smallest possible hole (according to the given tolerance of that hole)

 

[coaster]

@Ludo You don't need to ream it.  The ball bearing has an OD of 5mm, a Technic hole is 4.85mm, so it will press in quite nicely with a little bit of force.

[ALCO]

@Ludo I have also noticed that some axles fit in the bearings and some don't. All the axles I got from @coaster fit great and I do recall seeing somewhere maybe even in this same topic that older axles...I believe from the 9v era don't fit. But all the RC axles do. 

[Ludo]

@ALCO

The 'problem' i'll noticed is that some bearings dont fit the axle while others do fit on the same axle,

So I guess it has to do with the inner diameter of the bearing, perhaps little deformation or a blurr.

Putting the axle in a drilling machine or lathe, and use some sandpaper or Schotch Brite to polish will solve the problem.

Provided now 4 LEGO wheel holders with ball bearings.

Due to the fact I can still use a milling machine, I removed 1mm from the 4 supports.

This means that the bearings are 1mm deeper into the wheel holder, and the outher diameter of the bearing makes now one plane with the long sides where the bearings are fitted.

This 'trick' ensures that the height of the wagon with or without bearings is the same.

To be sure i'll don't loose them, i'll used a drop of hard PVC glue.

 

 

[MAB]

16 hours ago, coaster said:

@Ludo You don't need to ream it.  The ball bearing has an OD of 5mm, a Technic hole is 4.85mm, so it will press in quite nicely with a little bit of force.

The good thing about the hole being a bit small is that the bearing stays in place well too.

[Ludo]

On 10/25/2019 at 9:10 PM, MAB said:

The good thing about the hole being a bit small is that the bearing stays in place well too.

Thanks both for this information.

Next time I'll place bearings into Technic bricks, I'll press them into the brick.

Unfortunately, not every Technic piece will withstand the extra pressure. 

Can't find the picture now, but I've seen a picture with a cracked 18677 plate 1x2 with offset peghole on underside, due to the extra pressure of the bearing.

update:

found the picture of the cracked plate.

https://www.flickr.com/photos/162569845@N05/48568121336/

see:

 

Edited October 27, 2019 by Ludo
found picture