good idea or bad?

FIRST General Forum
1

Posted by Rob DeCotiis at 1/17/2001 8:10 PM EST

Student on team #504, RoBUCtics, from Red Bank Regional High School and Jesel.

is it a good or bad idea:
if you’re tight on weight, just drilling holes in all of your stuff so it doesn’t weight as much, suck as drilling holes in the claw that picks up the balls, or something like that?(just in preparation… :))

2

Posted by Jason Rudolph at 1/17/2001 8:45 PM EST

Other on team #459, Rampage, from University of Florida/Eastside High School and .

In Reply to: good idea or bad?
Posted by Rob DeCotiis on 1/17/2001 8:10 PM EST:

You mean Speed Holes??? There is no problem with this, in fact MANY teams end up needing to do this. As long as you leave enough material so as not to significantly reduce the strength of your compnents, you are fine.

Jason

3

Posted by CArobot at 1/17/2001 9:02 PM EST

Other on team #619, CArobot, from Charlottesville Albemarle.

In Reply to: good idea or bad?
Posted by Rob DeCotiis on 1/17/2001 8:10 PM EST:

: is it a good or bad idea:
: if you’re tight on weight, just drilling holes in all of your stuff so it doesn’t weight as much, suck as drilling holes in the claw that picks up the balls, or something like that?(just in preparation… :))

this totally depends on your individual robot. If you built your structure out of 1/16" aluminum and it has some structural funtion I wouldn’t drill it. If it’s not structural or has a lot of built in overkill in regard to strength-drill away.

4

Posted by ChrisH at 1/18/2001 6:41 PM EST

Engineer on team #330, Beach 'Bots, from Hope Chapel Academy and NASA JPL, J & F Machine, Raetheon, et al.

In Reply to: good idea or bad?
Posted by Rob DeCotiis on 1/17/2001 8:10 PM EST:

: is it a good or bad idea:
: if you’re tight on weight, just drilling holes in all of your stuff so it doesn’t weight as much, suck as drilling holes in the claw that picks up the balls, or something like that?(just in preparation… :))

If nothing else it’s very labor intensive, esp. if you’re doing it as a field “repair”. If I was to suddenly find I was over-weight I would take the following steps:

  1. discard any non-functional or marginally functional mechanisms
  2. reduce protective sheet material to the bare minimum.
  3. put large holes in sheet materials that can’t be completely done without.
  4. After 1-3 then think about putting holes in structure. When you do drill structure be sure you drill areas that are primarily in shear. Examples would be the webs of I beams and c-channels. Avoid the flanges as these are generally in tension or even worse in compression.

But first use step 0)

Weigh EVERYTHING. We have a guy we call the Weight Czar, who keeps track of estimated weight and actual weight for all of our parts. If the estimated weight of a system is too high we drop it or work it until it isn’t. We don’t have to drill holes because the extra weight never gets in in the first place. We also track estimated and actual CG.

We learned this in “Ladder Logic” when we showed up to our first competition (the Nationals) and found to our great suprise that our “lightweight” robot was actually 29lbs overweight. We lost those extra lbs in about 4 hours, but the last 2 or 3 were hardest to find.

Remember a good scale can be your best friend.

Chris Husmann, PE
Team 330 the Beach 'Bots

PS. the last two years our offical weight was within 0.5lbs of our estimates

5

Posted by Nick at 1/18/2001 8:43 PM EST

Student on team #240, Mach V, from Jefferson Monroe High School and Visteon.

In Reply to: good idea or bad?
Posted by Rob DeCotiis on 1/17/2001 8:10 PM EST:

It’s definitely okay if you’re careful but remember, 1293456 holes in aluminum = half a pound

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