Sally Port is a bumper destroyer

FIRST General Forum
1

I’ve fount that our bumper corners are getting destroyed by the threaded ends of the screws that stick out on the back of the sally port. The worst part is that it is right in the middle of the bumper zone!

Can the GDC just turn the screws around? Robots contact the back of the door much more often than the front, so why don’t we put the bumper friendly head of the screw on the side that touches bumpers?

Alternate solution: Drill a 7/8" dia hole where the nut and washer currently sit. This allows the nut and washer to sit on the back of the tube wall that is touching the polycarbonate panel (which I would say is generally a better way to attach things to tubes). The screw could be shorter, so it won’t impale our beautiful bumpers!

Other solutions include: rivet nuts or Barrel nuts paired with nylon patch screws.

Otherwise, has anyone found fabrics that can deal with the screws?

2

Thanks for the feedback. Is it a wood screw or machine screw? I did not pay close attention to that and won’t see the defenses until Friday.

If it is a machine screw, I will suggest adding acorn nuts.

3

It’s a machine screw cutoff.
It can still protrude an eighth of an inch past the nut and may have a slightly ragged cutoff.

You can bring it to the attention of the field supervisor and ask for any sharp parts to be filed back.

Here’s a photo of the Kickoff field before the bolt excess was cut back:
http://www.chiefdelphi.com/forums/attachment.php?attachmentid=19957&d=1454516334

4

Pretty sure it’s just a large-ish machine screw… something like 3/8" diameter.

5

My team actually asked a question related to this on the Q & A:

Q854
Q: The official field drawing of the Sally Port (GE-16035) shows 1/4 bolts attaching the door panel to the reinforcing structure. These bolts protrude 1/2" beyond the nut and are right in the middle of the robot bumper zone. While this may have been intended as an additional challenge, we are concerned many teams practicing with the flat-faced plywood SD depicted in the team version drawings will be ripped apart when driving through for the first time at competition. Will these bolts be shortened?

A: Thank you for pointing this out. The bolts used on the assemblies are 2.25 in. long and sit flush with the nut, and the drawing will be corrected as soon as possible.

So theoretically it should be cut off flush with the nut. If it is not, I’d suggest pointing it out to the field staff so that they can correct the issue.

6

Perhaps if there is enough threads they can put on an acorn nut.

7

I didn’t notice any bumpers getting torn at Lake Superior last weekend. I wonder if there was a difference in the fields between that event and yours.

8

Here’s a photo of one sally port at LSR that shows how the hardware is installed on that unit. I don’t see any bolt sticking through the nut.

http://1drv.ms/1LOZgsF

9

An acorn nut is a good idea. Even with the bolt cut flush there is a potential to get caught, but with an acorn nut you could just slide through.