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 Robot Omnomnomagon

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jtm94
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PostSubject: Robot Omnomnomagon   Sun Apr 15, 2012 2:54 pm

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Amanda

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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 3:14 pm

That's my robot! Very Happy
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jtm94
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 3:28 pm

I drove that robot.

For Christ's sake please make sure we mount the gearboxes in a way that they won't disintegrate.
And please try to find speed controllers that are faster than the Torquemaster BR-XL's. I miss the speed at which this thing used to drive... pale
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jtm94
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 4:55 pm

I would also recommend replacing the aluminum back plate with at least 2000 grade aluminum.

The Wang gearboxes aggravate the entire living hell out of me, but they make the robot less wide.
I think if we can get our final attempt at mounting them down we will be good.

I also think we need to start getting shafts hardened to some degree. Not bonebreaking degree, but our weapons are becoming more and more powerful and we need to make sure the axle can handle the force it can dish out. Especially if the weapon is one-tooth.
If I would have had the banebots in there for against Ringold, I would have mashed that robot so far off of the ceiling that I guarantee we would have had to cut the shaft in pieces to have gotten the weapon off.
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Mr. P

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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 5:16 pm

the aluminum will be looked into.

the gearboxes are fixed. the problem was taking them apart to many times. the original mounting was good for the gearboxes, bad for the frame. the use of a power drill on steel screws into aluminum threads.

the solution to weapon shaft problem is not to heat treat. it is first and foremost the length. we should never need spacers. also the weapon bolts on the weapon block failed in that huge hit causing the weapon to bent the shaft even worse. i believe in changing shaft material before heat treating.

banebot cost us time and money. unless the new batch they bring from china are better their esc will not be used. the torque are slower but there is a rumor a castle link can be used to program them.

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jtm94
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 9:36 pm

If we can only use the same mild steel then it will be hardened over not being hardened.
Spacers shouldn't be needed, but it is easier to build it smaller, the weapons this year fit a lot better than on Mini Nuke.
If S7 is hard to obtain solid chromoly should be used. We can buy it from mcmaster. We used a hollow tube of chromolly on Mini Nuke and it didn't bend that bad being holly. Solid will hold.

I don't trust 1/2 inch shafts.
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Alex P. HASD Bots
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 10:51 pm

half inch grade five ti works great as long as it is well supported, ours isnt even bent and we took/gave some pretty nasty hits
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MikeNCR
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 10:53 pm

You can program the BR-XL's via a Castle link. (I've done it)

I can't think of a reason they'd be slower outside of the calibration being off. One thing I remember from my early talks with Holmes was that you need to calibrate them one at a time (only one esc plugged into the rx/mixer)
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Cody
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 11:27 pm

jtm94 wrote:
If we can only use the same mild steel then it will be hardened over not being hardened.
Spacers shouldn't be needed, but it is easier to build it smaller, the weapons this year fit a lot better than on Mini Nuke.
If S7 is hard to obtain solid chromoly should be used. We can buy it from mcmaster. We used a hollow tube of chromolly on Mini Nuke and it didn't bend that bad being holly. Solid will hold.

I don't trust 1/2 inch shafts.

Te center part of the shaft really doesn't do all the much for the strength of a shaft which is why hollow shafts are nearly as strong as a solid one
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jtm94
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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 11:49 pm

Quote :
You can program the BR-XL's via a Castle link. (I've done it)

I can't think of a reason they'd be slower outside of the calibration being off. One thing I remember from my early talks with Holmes was that you need to calibrate them one at a time (only one esc plugged into the rx/mixer)

What do you program?
They are slower with the dx6i because when you set up the elevon mixing because it lowers the travel of each channel. You can watch it in the setup monitor and I have also searched the problem and that's how people answer to a sluggish BR-XL using a dx6i.

Quote :
Te center part of the shaft really doesn't do all the much for the strength of a shaft which is why hollow shafts are nearly as strong as a solid one

I remember seeing calculation last year proving that false. I respect you and all for, "not knowing anything," Laughing haha, but I don't trust that statement. I think you can take out the center and drop weight without compromising too much strength.

Actually, I will try and find the formula if I still have it at school. It showed that a solid shaft was stronger.
I may have gotten it from the people at pro4mance hobbies that helped us last year.
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Amanda

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PostSubject: Re: Robot Omnomnomagon   Sun Apr 15, 2012 11:59 pm

Didn't Brandon say last year that a hollow shaft was better because it was harder to break, and then made some analogy to an egg shell being hit on its top, how it won't break... I understood with the egg but not so much how it translated to a circle
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Cody
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PostSubject: Re: Robot Omnomnomagon   Mon Apr 16, 2012 12:16 am

Im not saying that solid shafts arent stronger what I'm saying is that when weight is of concern a hollow shaft utilizes it's weight to strength better then a solid shaft
Not only that but your maximum shear stress is at the largest radius of the cross section

A solid half inch shaft will be stronger then a hollow half inch shaft but you could use a larger OD hollow shaft that weighs the same and would be stronger then the solid 1/2" shaft

I really don't wanna go through my notes to find equations

But hey I don't know anything

Ps I was the one that suggested to Brandon about using a hollow shaft last year, I don't remember why though lpl


Last edited by Cody on Tue Apr 17, 2012 2:07 am; edited 1 time in total
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jtm94
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PostSubject: Re: Robot Omnomnomagon   Mon Apr 16, 2012 12:19 am

Brandon said a lot of things.

I know they aren't harder. I get what you mean with the weight:strength. It makes sense.

Run solid, if you need weight take some out of the center of the shaft.
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Koolaid64
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PostSubject: Re: Robot Omnomnomagon   Mon Apr 16, 2012 7:14 pm

The key to a good shaft is how its supported rather then the material. You want to keep your bearing contact point as close as physically possible to the frame. For every Diameter of shaft sized space there is between the weapon and frame your shear forces required to break it are basically cut by four. Think if it like a lever, your pivot point is where it attaches to the frame, the forces are applied at you bearing, and everything in between is your multiplier.

And nice looking bot by the way.

-statics
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jtm94
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PostSubject: Re: Robot Omnomnomagon   Mon Apr 16, 2012 7:52 pm

I'm aware of how the weapons should be on the shaft to avoid bending.
The problem so far with us is that everything has been done out of necessity. We have yet to be able to choose what material we want for our weapon, it has all been given and the beaters can't be made wider to reduce stress. The only weapon that is an exception was Game Over which we chose exactly how it was made and built the robot and had a weapon custom fit to it. It never destructed, bent, broke. A tooth shattered once, but the drum was never in need of replacement.

I don't know why we didn't use S7 or chromolly for the shaft this year as Mr P found it for the price of dirt to make a few shafts.

Quote :
And nice looking bot by the way.

And thank you.


Edit: I do get what Cody and everyone was saying about the hollow shafts. The center material is fairly useless until you start making the tube thin.
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