[FTC]: Two different Tetrix servo bracket screws

[Joachim]

My local FTC team has Tetrix servo bracket screws of two types on hand.

Both are Phillips drive pan heads, but one has a small head with longer shaft, and the other has a larger head with a shorter shaft.

The one with longer shaft is much easier to use, and allows the servo bracket bearing to be mounted on a variety of Tetrix parts. The shorter one is so short that it is difficult to mount the bearing in the servo bracket (you have to compress the washer some before the threads will even catch in the nut) and impossible to use the bearing with some other Tetrix parts.

Anyone else notice this?

[Joachim]

Apparently the longer screws are first-year or first- and second-year Tetrix parts, and the shorter ones came later.

The bags the long ones come out of have "made in USA" on the label. The thread length measures almost 9mm. The shorter screws have "made in China" on the bag label, and the thread length measures about 8mm, which is the length given in the CAD models. These shorter ones are what LEGO Education currently stocks.

Tetrix / LEGO Education should maybe look at whether the 8mm screws are a little short for their intended use. Most of our FTC team members cannot get them to work in the servo bracket, since it takes a lot of compression on the split washer before the threads of the screw will reach those of the nut.

[pend]

Because the rules allow "compatible fasteners" we've been switching these out with #4 pan head screws a little longer, and we've been using #4 nylox nuts instead of the split washer. Works far better.

[Joachim]

Our team got an answer in this year's official forum to the effect that "compatible fasteners" could not be used as axles (which they are, essentially, when they are in the center of the bearing).

[Bea_Candy]

Originally Posted by Joachim

My local FTC team has Tetrix servo bracket screws of two types on hand.

Both are Phillips drive pan heads, but one has a small head with longer shaft, and the other has a larger head with a shorter shaft.

The one with longer shaft is much easier to use, and allows the servo bracket bearing to be mounted on a variety of Tetrix parts. The shorter one is so short that it is difficult to mount the bearing in the servo bracket (you have to compress the washer some before the threads will even catch in the nut) and impossible to use the bearing with some other Tetrix parts.

Anyone else notice this?

Are you using a servo for your minibot? If so, do you count it against the two motor limit?

[Joachim]

Originally Posted by Bea_Candy

Are you using a servo for your minibot? If so, do you count it against the two motor limit?

No, my local team is FTC and not building a minibot.

[JB987]

Originally Posted by Joachim

No, my local team is FTC and not building a minibot.

Check Update #3...servos ok now in addition to two dc motors (relevent info for FRC makers of minibots of course;-)