pic: Madtown Robotics Drive Proto

[R.C.]

Craig, Thanks a lot. That advice helped a lot. We did run FEA on the frame when I finished the design. I had more pocketed out way too much, including the top. The engineer told me that was way too much and it crumbled under the FEA tests. So that is why we have the bracing setup it like that and you can see that the top of the tubing is not pocketed out.

The gearbox won't be mounted like that, last year we mounted the gearbox with more support. I was hoping to add more support when I included the mast of the forklift or Arm. I had a question about the plates, if i use delrin. How thick should it be and do i leave everything solid except the holes for the bearings? (I will be moving the bolts down)

My purpose was to lose weight, I will redesign them after i get feedback on the thickness of those plates.

The gears will be prefabricated, http://www.chiefdelphi.com/forums/sh...threadid=70259. This sponsor would do it for us. But we are thinking that it would be better to use steel and use an index to make some holes.

Craig thanks for all the suggestions. I am going to be redesigning to your suggestions. If you have any more suggestions, please post it. The reason for shaving so much weight is. Every pound matters to our team, we always add stuff and every year and bearly make the weight limit. But that was because our stuff was way too solid.

Originally Posted by rc_cola1323

Craig, Thanks a lot. That advice helped a lot. We did run FEA on the frame when I finished the design. I had more pocketed out way too much, including the top. The engineer told me that was way too much and it crumbled under the FEA tests. So that is why we have the bracing setup it like that and you can see that the top of the tubing is not pocketed out.

Cool. It's good to see that you've been doing the right calculations. Many teams skip over this and end up with some nicely bent frames that would look quite nice in a modern art museum, but won't function for robotics. My motto has always been that my bot should be able to be dropped wheels down off a roof, and still be able to drive itself into the shop to have the flimsy manipulator fixed from the damage. Driving is everything in FIRST.

Originally Posted by rc_cola1323

The gearbox won't be mounted like that, last year we mounted the gearbox with more support. I was hoping to add more support when I included the mast of the forklift or Arm. I had a question about the plates, if i use delrin. How thick should it be and do i leave everything solid except the holes for the bearings? (I will be moving the bolts down)

My purpose was to lose weight, I will redesign them after i get feedback on the thickness of those plates.

Delrin is awesome. We used the 1/4" thick from McMaster (I don't have the part number on me, let me get back to you on that), and didn't have any problems with strength. The material is so light, cheeseholing the plates isn't even necessary. Just make sure you put washers on EVERY bolt and nut that goes into the stuff. It's also nice to machine, as CNC's cut the stuff like butter. If you think Aluminum is nice to cut, wait till you see delrin get cut. It has a tendency to load the smaller bits, but you can work around that.

Originally Posted by rc_cola1323

The gears will be prefabricated, http://www.chiefdelphi.com/forums/sh...threadid=70259. This sponsor would do it for us. But we are thinking that it would be better to use steel and use an index to make some holes.

Craig thanks for all the suggestions. I am going to be redesigning to your suggestions. If you have any more suggestions, please post it. The reason for shaving so much weight is. Every pound matters to our team, we always add stuff and every year and bearly make the weight limit. But that was because our stuff was way too solid.

Ah, I didn't make the connection between threads.. Well, if the gears are built for you, then go for it.

[roboticWanderor]

Hey there!
Not sure what is gonna go on top of the robot and whether it will provide any extra support, but there does not seem to be much keeping the two halves of the drive train parallel. putting a triangular support on the upper back corners, or bridging the gap about halfway up the chassis would do a lot to keep the two halves stuck together.
If you did that, you could reduce the beefy super structure you have and save more weight than cheese-holes ever could.
Someone else already mentioned my other concerns, good luck!

PS: nice to see you back Craig!

[R.C.]

Originally Posted by roboticWanderor

Hey there!
Not sure what is gonna go on top of the robot and whether it will provide any extra support, but there does not seem to be much keeping the two halves of the drive train parallel. putting a triangular support on the upper back corners, or bridging the gap about halfway up the chassis would do a lot to keep the two halves stuck together.
If you did that, you could reduce the beefy super structure you have and save more weight than cheese-holes ever could.
Someone else already mentioned my other concerns, good luck!

Yeah those were going (bridging the gap) to be added as soon as the rest of the bot was decided upon. We will probably do three to four beams across and one across the top of it.

[AdamHeard]

You may have the resources, but keep in mind there is a lot more to a robot than a base.

If you can make the base that performs the same for 40 units of weight, and 10 units of work as one that is 30 units of weight and 100 units of work, the first is probably a better option. It looks like with this design concept, you can get a competitively light and strong base in short amount of time, don't try to go to far and shoot yourself in the foot. Use that nice start to get a decent base done for sure, which will free up machining resources and allow assembly and test to begin sooner.