Bumper Attachment for Rapid Removal

[Dale]

I know the rules could change for the 2010 game but I'd be interested in what systems teams have used to facilitate rapid attachment and removal of bumpers.

We've always put threaded inserts inside the bumper and then bolted them onto brackets on the frame. This seems simple enough but given the cramped quarters inside the robot and subtle alignment issues it can be a tedious 30 minute job to take the bumpers on and off for weighing.

There has to be a better way? Care to share pictures or descriptions?

[MrForbes]

We had a nice setup in 2008 using fanged elevator bolts (from McMaster Carr) in the bumpers, and coupling nuts to hold them on. And we even made the bumpers well enough that we can use either side bumper on either side, and either end bumper on either end. Too bad we couldn't make it work so well on the 2009 robot. And too bad I didn't get good pictures of it.

[Stephen of REX]

Our team's 2009 robot used sheet metal plates on the corners with appropriate holes for the bumpers to attach. The bumpers had 1/4 20 thread sticking out of their backs, which went through the holes. Inside the plated, we used nuts in conjunction with these knobs to facilitate easy removal by hand.

[Joe Ross]

There's some good ideas in this thread: http://www.chiefdelphi.com/forums/sh...ad.php?t=73127

[Ryan Foley]

Dale,

Here is what FRC1995 used last year. There were two of these mechanisms at the top of each bumper. There was also another piece of aluminum-angle mounted on the bottom of the bumper. This lower piece has holes at either end, which would slip over fixed-mounted bolts on the lower side of the drive frame.

The upper mechanisms were activated by hand. By pushing down (1st picture) the white block with bolts would lower, leaving room for the bumper's aluminum angle to be inserted so it is just below the upper lip of the drive frame. By releasing the mechanism, the spring will push the assembly up, inserting the two locking bolts through the bumper aluminum angle and through holes in the drive frame. This locks the bumper in place. You can see the mechanism closed in the 2nd picture. Sorry, I don't have a good closeup of the lower aluminum angle.

These mechanisms worked fairly well for us in the 2009 season. Unfortunately we were behind schedule, so the mechanisms, while planned from mid-season, were built last minute. Better fabrication would help these perform better.

[jamie_1930]

Originally Posted by Ryan Foley

Dale,

Here is what FRC1995 used last year. There were two of these mechanisms at the top of each bumper. There was also another piece of aluminum-angle mounted on the bottom of the bumper. This lower piece has holes at either end, which would slip over fixed-mounted bolts on the lower side of the drive frame.

The upper mechanisms were activated by hand. By pushing down (1st picture) the white block with bolts would lower, leaving room for the bumper's aluminum angle to be inserted so it is just below the upper lip of the drive frame. By releasing the mechanism, the spring will push the assembly up, inserting the two locking bolts through the bumper aluminum angle and through holes in the drive frame. This locks the bumper in place. You can see the mechanism closed in the 2nd picture. Sorry, I don't have a good closeup of the lower aluminum angle.

These mechanisms worked fairly well for us in the 2009 season. Unfortunately we were behind schedule, so the mechanisms, while planned from mid-season, were built last minute. Better fabrication would help these perform better.

Ok I think I'll say it first, is it ok with you guys if every single team in FRC takes this idea?

[Trent B]

RC gave me this idea.

this is your frame []

This is your bumper |[ with the [ being two pieces of aluminum angle spaced as far apart as your frame is tall.

You line it up like this |[[]

The aluminum angle slides over the frame.

Drill holes in both at regular intervals and tap the holes in the frame, should make it easy enough to attach with a screwdriver.

[sanddrag]

We took some 3/8" 7075 aluminum rod and drilled and tapped one end. Then we put a chamfer on the other end and drilled a transverse through hole. These became our "bumper pins" these were screwed to a 1/8" metal plate, abut 1/2" wide and 2" long with three holes, one for the pin, and two to screw it to the wood in the bumper. We 4 of these sticking out of the bumpers on either side of the robot. They would go through 7/16" holes in the frame, and then hitch pin clips were placed through the transverse holes to secure it. Then we used a tee nut in each end bumper piece (the small front and back bumpers) with a 3/8-16 knob bolt to secure it. The end bumper pieces were attatched internally to the sides, with aluminum angle.

[Tom Line]

Originally Posted by Trent B

RC gave me this idea.

this is your frame []

This is your bumper |[ with the [ being two pieces of aluminum angle spaced as far apart as your frame is tall.

You line it up like this |[[]

The aluminum angle slides over the frame.

Drill holes in both at regular intervals and tap the holes in the frame, should make it easy enough to attach with a screwdriver.

This is what we did - purchased steel U channel that fit over our frame (perfectly). Then we drilled holes vertically with the bumpers on and dropped 3/16" quick pins in (bolts work fine - no need to thread or put a nut on, friction will keep them in just fine). This got us our "backing member", and got us within a 1/2 pound of max bumper weight which is where we wanted to be.

[R.C.]

Originally Posted by Trent B

RC gave me this idea.

this is your frame []

This is your bumper |[ with the [ being two pieces of aluminum angle spaced as far apart as your frame is tall.

You line it up like this |[[]

The aluminum angle slides over the frame.

Drill holes in both at regular intervals and tap the holes in the frame, should make it easy enough to attach with a screwdriver.

Thanks Trent,

Here's an image that shows the holes made out, the piece of aluminum angle sits on top and you can either bolt or rivet

http://picasaweb.google.com/rcthekid...26173247025970

-RC

[skimoose]

Team 228 turned aluminum pins which were inserted into holes in the frame and held to the frame with hairpin cotter pins from McMaster. The bumpers were held onto the pins with larger hairpin cotter pins as can be seen in this photo:



The bumper brackets were 0.125" aluminum angle bored to the OD of the pins on one flange and bored for deckmate screws into the bumper plywood. This system only required the pulling of 14 cotter pins to remove the bumpers and reinstall. We averaged under 5 minutes to remove/install all the bumpers.

We were fairly happy with this first generation design and had no failures in any component. We will probably change the design slightly so that instead of holding the pins to the frame with cotter pins, the base of the pins will be bored and tapped and bolted to the frame. This will remove the play that can be seen in the photo. We will also design a new bumper bracket to hopefully be produced in CNC sheet metal, like our frame, improving tolerances. These brackets will also hopefully incorporate wrapping the corners of the plywood with aluminum angle.

[Jared Russell]

We usually build our chassis with Bosch-Rexroth aluminum extrusion (20mm profile in recent years), so we outfit our bumpers to take advantage of the T slots in the extrusion.

The bumpers have bolts put into them (head side out). We usually mill out the sides of the channel at the top of vertical members (in the corners of the chassis) so that there's a place to insert and remove the bolt heads. All you have to do to add or remove a bumper is to put the bolt heads through the hole and slide them down into place.

[Akash Rastogi]

If we need to attach bumpers to any sort of round standoffs on our frame, we use the same method shown here by Brandon Holley.

http://www.chiefdelphi.com/media/photos/32788

[Foster]

Our bumpers had two fanged head bolts that came out of them and went through matching holes in the frame. Wingnuts held the bumpers onto the frame. We could mount/dismount the bumpers in a few minutes.

If you look at the picture you can see the bolts on the back of these partially assembled bumpers.

There was lots of hand clearance to get the wingnuts on and off.

[Jeff Pahl]

If you are using the kit frame, AndyMark sells a bracket that fits over the frame rails: http://store.andymark.biz/am-0317.html. Last year we had one of our sponsors bend up some channel for us that fit over the frame, and I found out about these later... although getting them donated by a sponsor is cheaper

We secured them with 1/4" hitch pins through the vertical holes. Carrying the robot by the bumpers was no problem. I was able to remove a bumper in less than 30 seconds when smoke started coming out of the robot while doing some testing.

If the GDC goes back to requiring "bolted fasteners" (or whatever the wording was in 2008), then a 1/4" bolt can replace the hitch pin, but that takes a little longer. As a robot inspector, I really (really, really) hope that they do not go back to the 2008 requirement. Being able to remove and install the bumpers quickly has a significant impact on both how smoothly your inspection goes, and also on the ability to perform maintenance and repairs on your robot.

Ok, let me say that again: whatever method your team uses to attach the bumpers to the robot, you should be able to remove and install them quickly. In fact, the rules last year recommended that you should be able to complete the process in less than 10 minutes. I have seen teams that it takes an hour, and they are still not what I would call "solidly attached".

There are several excellent ideas presented so far in this thread, and I hope to see even more. The biggest thing that I see in the good ideas vs the bad ideas that I see every year, is that the good ideas take bumper attachment into account during the design process, and the bad ones treat it as an afterthought.