[TIP] Reduce slack on custom wheel hub with axle

[Didumos69]

When you have ever built wheel hubs that use an axle to attach the wheel to - typically a 5.5L axle with end stop - then you must be familiar with the substantial slack such a connection is suffering from.

If your wheel hubs have a more or less flat surface facing the wheel, like the wheel hub shown below, then it helps to fill the inside of the rim with 3 2L half beams, each attached to 2 3L axles, which are in turn inserted into the 6 pin holes of the rim. When the half beams are lowered deap enough into the wheel - you have to push them slidely away from the center of the rim to get them into place - and the 3L axles are inserted all the way into the half beams, the whole thing does not only make a tight fit, but also makes a nice flat surface together with the outer end of the axle hole of the rim. See images below.

Now when you slide a belt wheel over the 3L axles on the other side of the rim, the whole thing is ready to slide over the axle coming out of the wheel hub. While doing so, make sure the 6 3L axles are not inserted further into the rim, as that would disturb the flat surface on the inside of the wheel. Slide the rim over the axle all the way.

Finally, slide two extra half bushes to avoid the rim from sliding off the axle. Now the slack of the rim-axle-connection should be reduced by about 50%, while the rim rotates as smoothly as before.

EDIT:

I found out that using half bushes on the inside of the wheel makes an even better surface and reduces the chances on stuttering even further (I haven't experienced any stuttering sofar). The edges of the half bushes are slightly more smooth than the edges of the 2L thin liftarms that I used before. To anchor the setup I placed the three 2L liftarms on the outiside of the wheel. To finish the whole thing there are 2 options:

Option 1 - For the ones living on the edge: Before sliding the rim onto the 5.5L axle, place a half bush right between the 3 short liftarms. You can't just push it into place; use an auxiliary axle to align the half bush with the rim and make sure the last part you put in place is one of the 6 3L axles. That should do the trick. This makes a tight finish (2nd image below).

Option 2 - For the LEGO purists: After sliding the rim onto the 5.5L axle, place a half bush on the axle to lock up the 3 short lift arms. This makes a legal finish (3rd image below).

Edited March 28, 2016 by Didumos69

[JJ2]

Great idea but also like you last one you made it could be considered an "Illegal" build because it relies on the slack in parts, but heck I am going to use it on my builds

[Didumos69]

Great idea but also like you last one you made it could be considered an "Illegal" build because it relies on the slack in parts, but heck I am going to use it on my builds

Then luckily the 'illegal' part of the design is hidden behind the rim, so you might just get away with it ;-)

Edited March 20, 2016 by Didumos69

[JJ2]

Then luckily the 'illegal' part of the design is hidden behind the rim, so you might just get away with it ;-)

Exactly

[grum64]

First off let me make clear, I'm no expert builder nor do I profess to be but I'm at a loss to understand all this legal and illegal building technique malarky. Surely if something you build necessitates you going about it in a different way to what's perceived as 'the norm' and it works that's fine.

Edited March 21, 2016 by grum64

[Didumos69]

First off let me make clear, I'm no expert builder nor do I profess to be but I'm at a loss to understand all this legal and illegal building technique malarky. Surely if something you build necessitates you going about it in a different way to what's perceived as 'the norm' and it works that's fine.

Agree.

Sometimes it's a pitty that the discussion is about legality rather than applicability of an idea. On the other hand I realize that when I put this kind of ideas out in the open, I should be prepared for any kind of reply.

In this case, I think JJ2's first reply has put exactly the right degree of relativity to legality.

[grum64]

Agree.

Sometimes it's a pitty that the discussion is about legality rather than applicability of an idea...

...In this case, I think JJ2's first reply has put exactly the right degree of relativity to legality.

Agreed

Edited March 21, 2016 by grum64

[Didumos69]

I found out that using half bushes on the inside of the wheel makes an even better surface and reduces the chances on stuttering even further (I haven't experienced any stuttering sofar). The edges of the half bushes are slightly more smooth than the edges of the 2L thin liftarms that I used before. To anchor the setup I placed the three 2L liftarms on the outiside of the wheel. To finish the whole thing there are 2 options:

Option 1 - For the ones living on the edge: Before sliding the rim onto the 5.5L axle, place a half bush right between the 3 short liftarms. You can't just push it into place; use an auxiliary axle to align the half bush with the rim and make sure the last part you put in place is one of the 6 3L axles. That should do the trick. This makes a tight finish (2nd image below).

Option 2 - For the LEGO purists: After sliding the rim onto the 5.5L axle, place a half bush on the axle to lock up the 3 short lift arms. This makes a legal finish (3rd image below).

Edited March 28, 2016 by Didumos69