The hole patterns are now in place to lighten it up. It’s down to 8lbs for the metal (Solidworks is reporting 29lbs for the whole thing).
The hole for the output shaft of the ball shifters will be done after the rails are made to keep the two sides identical.
The two square cut outs on the back left are for an ethernet port and a small LED volt meter. The three holes on the other side are for two pressure gauges and a release valve for the pneumatics.
There is also an integrated pneumatic cylinder in the front rail to get out of pins and make the drive more maneuverable.
Ooh, very nice looking! I’m still not totally sold on gears, but that looks like a really nice system…
Can you go into more detail about the “extra features” you’ve integrated into your frame? I have’t seen many frames with a integrated Ethernet jack or pneumatic system, for example.
I sure can, this an accumulation of a lot of random features I’ve seen on other robots when inspecting them or have been posted on CD. The panel mount Voltmeter and ethernet port should make practice a bit easier. The pneumatics stuff is just to give a convenient place to access it. All of this will be below the tops of the bumpers so it should be pretty well protected. Here are the links to all the items.
Not yet. Not sure I expect to, it was just thought their use of miniature to describe something that’s more or less normal size (to FRC) didn’t work for me.
However, we did find lighter ones!
4379K41
and
4379K61
Each C shaped bumper only had 1 clip or 2? Did you test that against other robots, that seems like it doesn’t have a lot of holding force. Was anything else holding them in place? Do you have any pictures?
Each only had 1 clip. The bumpers were supported in the middle by two L brackets mounted to the frame of a WCD style frame. The bumpers sit with one leg of each L against the middle of the C. One of these L brackets had the clip. There were also two L brackets on the bumper that supported the top and bottom of the c against the frame, and flanges on the bumper that locate it side to side by sliding over the L brackets mounted on the frame. When I get a chance, I’ll try to upload a photo.
We’ve already played an offseason with the bumpers, including some elimination matches where we were pretty heavily defended. The bumpers were solid, the only damage to them was that one of the 0s on one of our bumpers peeled a little.
The important thing to remember is that the clips shouldn’t really take all of the force that’s on the bumper. Other features on the bumper can do this. All the clips do is retain the bumper on the frame in a way that can easily be removed.
Interesting, we were planning to do a one piece bumper that drops over the top of the robot. In that configuration I don’t see an easy way to limit to the vertical forces that will act on the latch during impact. We had issues with the double C design because they are weaker where the two C bumpers meet. Our frame bent in when we hit the pyramid once.
Put a small but long L bracket on each side of the bumper that keeps the bumper from getting pushed down. The latch should be more than enough to keep the bumper from going up. (I’d be surprised to see much up forces on a low-to-the-ground bumper in a match.) I believe 971 did their bumpers this way in 2012.
971 also used them in 2013 but they have 8 around the perimeter of their robot.
After doing more research I am looking into using twist latches that are used on road/flight cases. They’re normally rated for a lot of force and you can get them for under $3 each.
I also think it might be possible to build the keeper directly into the frame, instead of having to rivet/bolt it on.
I’m not sure what your thoughts are at this point, but I can help to shed some light into how 971 did bumpers this past year. Below is a picture of our 2013 bumpers.
We actually did not have 8 latches all the way around, as you can see in the picture. Some of the latches intersected with some of the robot components, so we wouldn’t have been able to access them. Also, the bumpers and latches don’t always go together smoothly, and pieces can warp over time, so by the time we actually competed, only around 3-4 of the latches were actually hooked on. The rest were tied away so they wouldn’t jostle around during the match.
We bought the latches from McMaster, but we ended up having the hooks made by a sheetmetal sponsor out of stainless steel, 0.090" thick iirc. We then riveted these onto the frame. We had issues with the hooks bending in 2012. The stainless steel hooks this year did not have the same problem.
This system held up reasonably well throughout the course of the season. Obviously we would have liked to attach the bumpers at more points, but it doesn’t always end up that way. We ran into similar issues in 2012.
I hope this helps. If you have any questions don’t hesitate to ask me or another 971 member.
This cad model is great! I personally really like the Ethernet jack port in the side for easy quick disconnect. What type of design models did you base this off of it? seems very robust and nice. Keep up the good work!
I hope to see the final robot sometime.