1) yes

2) Polishing has a disadvantage: they use small stones to polish the parts and this put a lot of force onto the parts. a set of parts which is connected together is not really safe to polish without breaking the connection. in the eyes of shapeways this makes the part unprintable.

3) maybe the hole was not oriented vertical and the gravity makes it oval.

@efferman

1) How do you know which way up Shapeways will print an item? I had the impression that they rotated parts to optimise use of the printer's material box, i.e. packing as many parts in as possible with no guaranteed orientation...?

2) I have found the test part that I printed at Shapeways!:

It is a 1M long version of the standard 2M Tube Coupler ( http://brickset.com/parts/4526985 ) and probably similar to the 1x1 Beam ( http://brickset.com/parts/6100030 ).

The part's cylindrical axis is parallel to the z-axis in the stl file and it was printed in unpolished strong & flexible. LEGO axles will fit in the bore, but rotate with some friction. LEGO friction connector peg's will also go in, but are very tight.

The dimensions compare as follows:

[mm] CAD Actual

Outside Diameter 7.80 7.76

Bore Diameter 4.90 4.75

Overall Length 7.80 7.96

Any thoughts on why the bore & overall length are not closer to the CAD dimensions?

Thanks.

Edited January 25, 20169 yr by PlanetaryHub

when shapeways change the orientation this is bad luck. the only thing i can do is to set the orientation in a optimal way, everything else is fate. your description of your dimension sounds like wrong orientation.

1) Is my CAD orientation correct: hole axis = z-axis?

2) I assume my CAD dimensions are OK...?

My design cannot be submitted through the LEGO Ideas web site, because new part designs are specifically excluded. However if I can get to at least 10,000 views on YouTube (the LEGO Ideas review threshold), I think LEGO Group may be prepared to give serious consideration to producing these new parts. If you like the idea please help by sharing this video on social media, in forums and with friends.

Thank you for your help.

Waste of time. TLG will not do this and this comes straight from one of their designers ;)

But I can see you've found the light, I mean efferman

Cheers,

Ole

1) Is my CAD orientation correct: hole axis = z-axis?

2) I assume my CAD dimensions are OK...?

1) i never look which axis is vertikal, so i dont know. important is the view on the shapeways product page. is the hole on this picture vertical, it will be nearly 100% sure printe3d in this orientation.

2) i have no doubt they are correct, or do you draw oval holes?

1) i never look which axis is vertikal, so i dont know. important is the view on the shapeways product page. is the hole on this picture vertical, it will be nearly 100% sure printe3d in this orientation.

2) i have no doubt they are correct, or do you draw oval holes?

Thanks for the information efferman!

No, my CAD holes are circular

Just for fun, while Shapewaiting, I have uploaded a short animated video of a track loop running on two planetary hubs:

https://www.youtube.com/channel/UCRxfS08NGOt0pCMtIKLkLXg

A new video for your delectation...

Seem to work great but something just seems really weird when the hub is not rotating when driving.

Yes, on real world parts the hub internals are hidden by a cover that forms part of the rim assembly.

However with these parts I was keen to maximise their educational value and therefore decided to leave the planet carrier exposed and also provide a good view of the gears in action by peppering it with holes! Nonetheless they are close in design to real world parts and work in an authentic way, this allows realistic functional models to be built.

If it works, I'll definitely will be interested.

And it has to be affordable to use.

@Dafgek81 Thanks for your interest, I will keep you posted - another video is on the way and will be uploaded shortly...

@JJ2 Thanks for your feedback, one solution is to add a hub cover:

New track test rig video just uploaded to YouTube:

This would give a tremendous amount of torque on a bulldozer in that size.

Driving the planetary hub directly with an XL motor does give a lot of torque due to the 3:1 step down. As you suggest a slightly larger scale model (longer track) would probably be better - the video was just intended to be fun.

I can see the benifits of this sort of wheel hub

Looking at the all that go's into produsting it.

it would almost cost as much as a PF motor and the metal bearing would be another problem.

I love the idea of the rime where you could have track or tyre.

Edited March 28, 20168 yr by Phantom59

With a planetary drive the drivetrain is rocksolid because the torque is splitted over 4 gears which reduces the stress on the gears

Last "Easter Holidays" video just posted on YouTube - enjoy:

On one like this would be very cool.