Ball shifter assembly
 

We had trouble assembling our 3 stage Vex ball shifters yesterday.
The washer spacers under the hex standoffs didn't support them properly on the narrow shoulder above the 7/16 hex recess.
When tightened, the standoffs were not square the the face of the gearbox, and were not tall enough to allow the front plate to mount properly.

The kids machined some 7/16 OD x .220" long spacers with a 1/4 hole to seat in the bottom of the 7/16 hex recess and reassembled the gearbox and we are functional now.

Watch out for this.

Re: Ball shifter assembly
 

We are (hopefully, if they come in) going to be assembling ours today, but I am a bit confused, which step in this guide did the problem occur? http://content.vexrobotics.com/vexpr...Instr-Rev1.pdf

Re: Ball shifter assembly
 

Martin,

I got your email, and you are correct, we need to update page 9 of This instruction manual To show the washers on the correct side of the standoff. They should be between the standoff and plate.

Thank you for bringing this to my attention.

-Aren

Re: Ball shifter assembly
 

I didn't want to create a new thread, but we ran into problems today with the assembly of the new 3 CIM ball gearboxes.

The bearing that supports the output side of the output shaft does not fully seat into the plastic housing.

The bearing flange is about .01" bigger in diameter than the bore in the plastic housing. When installed the bearing seems as if it is seated properly, but it is not and you will not be able to assemble the housings together due to this.

We simply carved away some material from the plastic with an Xacto blade to fix the issue.

I've attached photos for reference.

http://www.flickr.com/photos/72773803@N00/12141880874
http://www.flickr.com/photos/72773803@N00/12141888644/
http://www.flickr.com/photos/72773803@N00/12141487335/

Bearing not seated into bore.
http://www.flickr.com/photos/72773803@N00/12142132676/

Bearing seated into bore after carving away some plastic.
http://www.flickr.com/photos/72773803@N00/12141727993/

Re: Ball shifter assembly
 

After assembly, one of our gearboxes seemed to be binding pretty badly. I took it back apart and found that the problem was with the Encoder Gear Assembly.

The little plastic gear with bearing and rod that sits on the outside (back of the gearbox) was bent so that every revolution of the gearbox would cause it to bind on it's housing.

Vex is sending us a new part to replace it.

See the photo attachment if you don't understand what part I am talking about.

Re: Ball shifter assembly
 

Brad,

With a bit more press the bearing should pop right in, it will be updated for the future as that feature does not have a need to be tight on the bearing flange.

-Aren

Re: Ball shifter assembly
 

I'm sure it could be pressed in, but I don't feel a .007" or so press fit would be a wise idea especially into plastic. I would not want to see a crack develop especially in that area of the housing. The other bearings fall into place so it was abnormal to have to press in only one of the four internal bearings. This bearing does fall into place like the others until it gets to the flange and on the first attempt of assembling them it seemed right until the housings didn't fit together without a gap since the bearing wasn't fully seated.

Re: Ball shifter assembly
 

We used are manually press and with little effort it pressed right in.

Re: Ball shifter assembly
 

We ran into a problem that when we went to mount the gearbox utilizing the 1/4-20 nylocks on one of the sides onto our test base, the bolt cracked the plastic behind the nut. When we went to investigate the nut fell out of place. We aren't sure if this has compromised the gearbox housing or not. For other reasons we have switched gearboxes and have not taken them apart to look into it more.

Re: Ball shifter assembly
 

Jimmy,

If you use screws that are too long that would happen, The integrity of the case itself is still intact.

-Aren

Re: Ball shifter assembly
 

We thought we had the right length.

Thanks