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 Redoing the Dethinator?

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Jeff L
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PostSubject: Re: Redoing the Dethinator?   Mon Mar 16, 2009 9:05 pm

I know a way to free up some space in that bot Razz :

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=2140

1300 rpm/volt, more than 1/2 horsepower, with a total weight of 3.74 ounces --> $21.00. There are some decent ESCs lower on that same page as well. It may not be possible for a refit of the robot this late in the game, but it may be something you want to look into for later.
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Dan Curhan
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PostSubject: Re: Redoing the Dethinator?   Mon Mar 16, 2009 9:07 pm

I 've never used brushless motors before... it is definitely too late now to change stuff, but we'll keep them in mind for the next one. Razz
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Alan Dreher
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 10:54 pm

Just got back from latest build

When our batteries are charged, we spin up really quick and the shell goes pretty fast. Will be pretty intimidating every time we go above 1/2 throttle because the holes in the shell start sucking air and it makes a horrible whistling sound.

We still have a few bugs to fix, and in general, a fair amount left to do, but we have it working to an extent.

Oh, and weight is sort of well under control(barely). We have to add our weapon assembly still, but we have just about .25 lbs to work with(Currently weigh somewhere around 14.75 lbs..

And Jeff said that if he needed to he could lighten all the gearboxes in the motors the same way he did with Copperhead III. Which would give us a bunch more room in terms of weight.
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:20 pm

i think i may actually look into bigger brushless motors for the weapon...

i'm not sure these little ones are going to be durable enough. I initially designed the bot with 10, not expecting to be forced down to 6...
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Alan Dreher
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:25 pm

Dan Curhan wrote:
i think i may actually look into bigger brushless motors for the weapon...

i'm not sure these little ones are going to be durable enough. I initially designed the bot with 10, not expecting to be forced down to 6...
But at this point, a motor change would mean a major redesign, and we wouldn't be able to make it for Miami.
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That Guy
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:26 pm

Mr. Dubard had found a webpage with an enormous amount of motors and a bunch of specs for each of them. It was just this huge table. If you want I can try to get the site for you and post it here tomorrow?
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:26 pm

If you really decide to change.
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:27 pm

actually it may be worth taking a look at. And alan, never be pessimistic! I can do anything! Razz
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Alan Dreher
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:33 pm

Dan Curhan wrote:
actually it may be worth taking a look at. And alan, never be pessimistic! I can do anything! Razz
What a whole week of all-nighters?
And I don't think Nola would appreciate having 5 delirious teenagers in her house that have been working 72 Hours Straight...
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Cody
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:52 pm

i would look into the brushless, i honestly dont see the point or need for 6 400xl( i believe thats what your using)
i mean besides looking cool as hell! lol


Last edited by HarrisC on Tue Mar 17, 2009 11:57 pm; edited 1 time in total
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Will Bales
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PostSubject: Re: Redoing the Dethinator?   Tue Mar 17, 2009 11:54 pm

If you need any help whatsoever, just let us know and we'll do whatever we can!
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Cody
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 2:20 pm

so i was just looking at a thread on another forum about mini-blender and he said his shell weighs 7.7 pounds!!!
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Alan Dreher
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 3:22 pm

Since we know nothing about Brushless motors, what are you guys using?

Would this be a good motor?
http://www.robotmarketplace.com/products/0-EFLM2005.html
Because it would pretty much be the ideal replacement because we could basically use our same motor assemblies.
Alternatives include:
http://www.robotmarketplace.com/products/0-EFLM2000.html

I am unsure how much power they would get compared with the Speed 400's we currently have(I am sure it is quite a bit more with these Brushless Motors).

They also weigh about 0.02 lb more.(2.9 oz compare to the 2.55 oz of the Speed 400s). But we more than make up for it with the increased power allowing us to remove two motor assemblies(which weigh .55 lb each) Tradeoff for 2 less motors is that we weight one whole pound less. Which gives us room to do some stuff with our weapon.


No matter what we do, it would be expensive, because we would need all new Speed Controllers.

Even with 4 motors, we are talking a $500 redesign(Brushless Speed Controllers are $100. Plus $70ish per motor 2 motors per speed controller[if that is possible with these Speed Controllers]... Still $480 minimum).

Would have greater torque and potentially would hold up better within our bot. I am completely uncertain about the power that Brushless motors have, so two motors may actually be enough... But I am not sure.
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Cody
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 3:31 pm

are you using the colson 1-5/8" wheels, whats the diameter of the shell that they are mounted at and how many volts are you running?
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 3:37 pm

HarrisC wrote:
are you using the colson 1-5/8" wheels, whats the diameter of the shell that they are mounted at and how many volts are you running?
According to our blog:
Colson 2" x 7/8" Wheels to spin the Shell

I believe we are running them at 12V(maybe less... more of a question for Dan)
Not sure about the diameter of the shell where they are mounted, but I do know that our wheels spin along the top-inside of our shell with the shell resting on the wheels when it is assembled.

But dimensionally, the motors I put above are basically within 2 mm of the size of our current motors in both diameter and length...
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Cody
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 3:52 pm

im not the best with electronics, but what worries me is current draw/ amperage, i think youd be alot better off with 2 brushless motors then the 6 400xl, my guess is you could have those given motors spinning at 24000 rpm before drive reductions to the shell
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:03 pm

HarrisC wrote:
im not the best with electronics, but what worries me is current draw/ amperage, i think youd be alot better off with 2 brushless motors then the 6 400xl, my guess is you could have those given motors spinning at 24000 rpm before drive reductions to the shell
Basically... We seized a motor yesterday in our testing...
The thing was absolutely singing until a motor died... And it still was after the motor died... But that sort of thing isn't acceptable. We will definitely need to see if that was just a bad motor and the others won't have that issue, or if it is something bigger than that. We have 5 spare motors due to the cutbacks in our design over the past couple of months.
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Cody
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:09 pm

If you do end up switching to the brushless i would take out the rest of the supports and fab up a bearing block so you could keep two undriven wheels for shell balance and put weight into the shell
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:14 pm

HarrisC wrote:
If you do end up switching to the brushless i would take out the rest of the supports and fab up a bearing block so you could keep two undriven wheels for shell balance and put weight into the shell
So you think two of the above motors would be enough to spin the shell?
I don't know enough about Brushless Motors, but at they really that powerful? Because that would save $150... Which is critical for us.


Last edited by Alan Dreher on Wed Mar 18, 2009 4:15 pm; edited 1 time in total
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Cody
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:14 pm

just rough estimates but that first brushless motor you posted would run nearly 5500 rpm faster, i wouldnt recomend the second cause it runs less rpm/Kv
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:17 pm

HarrisC wrote:
just rough estimates but that first brushless motor you posted would run nearly 5500 rpm faster, i wouldnt recomend the second cause it runs less rpm/Kv
Not about the RPMs, but the torque of the motors. Would they actually be able to spin our 4 lb shell quickly?
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Cody
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:21 pm

Ive never seen those brand motors used before, but i would have to guess yes(gearing aside), i know Bloomsburg only used 2 Feiago brushless inrunners to spin there 5.5 lb shell on xyrus
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 4:28 pm

HarrisC wrote:
Ive never seen those brand motors used before, but i would have to guess yes(gearing aside), i know Bloomsburg only used 2 Feiago brushless inrunners to spin there 5.5 lb shell on xyrus
Whenever Dan gets on we can see what he thinks.
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Dan Curhan
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 8:14 pm

okay i'm on... sorry. I was at work. Razz

Those first motors Alan mentioned look like a good replacement - I just wish I knew how many I need to spin the shell. I've never used brushless motors before...
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PostSubject: Re: Redoing the Dethinator?   Wed Mar 18, 2009 8:55 pm

Dan Curhan wrote:
okay i'm on... sorry. I was at work. Razz

Those first motors Alan mentioned look like a good replacement - I just wish I knew how many I need to spin the shell. I've never used brushless motors before...
I don't know either...
If you think we could do a test with 2 motors without blowing the motors, we ought to try something like that first.

If it doesn't work, bump up to 4.

They are certainly a much higher torque than the current Speed 400s so 4 should be more than enough. But the question is, how much better are they. Because if it could run with 2 motors, that would be absolutely fantastic. We could up the weapon by SOOO much. Put the ring on there, do some big steel teeth... Would be great.

If we can get more replies from people with experience with Brushless Motors, that would be great.

Would 2 of the motors mentioned earlier be able to spin up a 4-5 lb shell?
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