Author Topic: Team Slaughterhouse  (Read 4187 times)

IanMcMahon

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Team Slaughterhouse
« on: March 01, 2015, 10:58:11 pm »
Current Bots:

Ants:
Physique Red
Physique Black

Beetles:
Speed Wedge 3
Project Darkness
Project Excelsior

IanMcMahon

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Re: Team Slaughterhouse
« Reply #1 on: March 01, 2015, 10:59:48 pm »
Lessons learned from Moto for the Projects:

-Don't do a victory gyro dance until after the match is officially over.
-0.08" Ti is thicker than needed for the wedge.
-Most horizontal spinners hit the blade before the pulley.
-Replace the shaft in the weapon motor with one without a slot for a ring. (I broke one motor shaft.)
-Loctite the hubs to the shafts. (One wheel fell off when turning. I think the setscrew came loose.)
-Use smaller tires than 2-1/4". (I think I was overloading the motors at 14.8V + 2-1/4" wheels. The pinions in the gearboxes stripped in Speed Wedge 3 (3) and Project Excelsior (1).)
-Fully heatshrink each drive ESC away from the other. I fried two vextrollers in Project Darkness when the outputs touched each other.
-Glue down the wires going to the weapon motor controller. (The weapon died in one match by sucking in the positive wire.)
-I plan to extend the sides to cover the drive wheels in the rebuild.
-My highest battery consumption in a match was 335 mah.
-The weapon free spins at 5.4 A with crunchy bearings, and full throttle with a locked blade does 22.5 A. The belt smokes and shoots out black crap when you lock the blade and spin the motor.
-This battery would fit better and is slightly cheaper. http://www.hobbyking.com/hobbyking/store/__18201__Turnigy_nano_tech_1000mah_4S_25_50C_Lipo_Pack.html
-Having 6 batteries per bot was wonderful in the antweight class. Having one per bot for the Project beetles, sucked.
-I had two batteries for Speed Wedge 3. I would have preferred 3.
-Bring a proper soldering station which gets up to temp quickly.
-Put new drive motors in whenever possible.
-Bring more bearings & find cheaper bearings. Replace when possible. The bearings do still run when crunchy.
-3/8" UHMW was cut about 1/4" deep by the horizontal spinners.

Lucas Grell

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Re: Team Slaughterhouse
« Reply #2 on: March 02, 2015, 10:30:06 am »
Ouch, that sucks about those speed controllers. If you can, I'd actually slide a small piece of plastic in between them. I use cut up plastic binder/folder material, it's quite light but I'm sure you could get thinner, and still help. I'd also try hot gluing everything electrical, it helps a lot.

Koolaid64

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Re: Team Slaughterhouse
« Reply #3 on: March 02, 2015, 03:25:20 pm »
if you can switch to roller/needle bearing. more surface area means less crunch
-Kyle

zacodonnell

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Re: Team Slaughterhouse
« Reply #4 on: March 03, 2015, 02:29:35 pm »
The needle roller bearings do offer more resistance than ball bearings, but they also avoid the crunchiness better. They are smaller in OD and larger in width than ball bearings generally.  I use them in all my bots and have been happy so far, but I don't spin anything over about 9K. In the tiny bots at higher speeds you might need to go with ball bearings. I think the weta kits were using needle rollers at one point - maybe somebody can chime in to confirm.

Good to learn things from each competition. I try to record how much battery I use in which fight so I can gauge my choice of battery size against the real world. It's tough to simulate actual current usage for a weaponed bot.

-Zac

BranYoung

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Re: Team Slaughterhouse
« Reply #5 on: March 03, 2015, 07:13:17 pm »
In all the Weta kits and Weta-esque beater bars needle-roller bearings are used. In fact, Zac actually used needle-roller bearings in the construction of a 6lb shell spinner, Catapult's, hub and it works beautifully.

Lucas Grell

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Re: Team Slaughterhouse
« Reply #6 on: March 03, 2015, 08:23:15 pm »
We used to use needle rollers in GTO and G6. They worked well, towards the last competition we used them, we ran out of non-crunchy bearings and had to use a bearing that was missing a roller, but they still worked well. They're quite durable but most importantly they are narrow enough to easily fit in a weapon.

IanMcMahon

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Re: Team Slaughterhouse
« Reply #7 on: March 18, 2015, 12:35:24 am »
I am leaning towards these: http://www.mcmaster.com/#5905k131/=wcvafl for the new weapon hubs for the Projects.

Lucas Grell

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Re: Team Slaughterhouse
« Reply #8 on: March 18, 2015, 12:44:42 am »
Is that all the thicker the weapon would be? Ideally you'd have it all the way through the end caps of a drum or the bars of s beater.

IanMcMahon

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Re: Team Slaughterhouse
« Reply #9 on: August 13, 2016, 08:59:46 pm »
Lucas,

I basically never check SPARC, so I didn't see your post. I used three 8mm wide bearings in the hub. Good idea to be concerned if I was only using one.

IanMcMahon

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Re: Team Slaughterhouse
« Reply #10 on: August 13, 2016, 09:03:42 pm »
The real reason for today's post.

I recently bought ten of these $3 used gearmotors from eBay. They are constructed similarly to the larger 25mm Chinese gearboxes. I thought that they might be of value to the new builders who are being very penny conscious. http://www.ebay.com/itm/191913426991?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I have run them through my motor testing methods and have the following data.

Theoretical Operating Specs         
Voltage         7.4   11.1   V
Stall Current  0.9   1.3   A
Stall Torque  16    24   oz-in
Speed          555   833   rpm

For a more direct comparison with Kurtis' products, the following table has the coefficient of kV*kT shifted from 1352 to 1111 to match the specifications of the Mabuchi FK-050SH. This changes the kT to 15 oz-in/A.

Derived Operating Specs with Mabuchi Efficiency      
Voltage           7.4   11.1   V
Stall Current   0.9   1.3   A
Stall Torque    13   20   oz-in
Speed           555   833   rpm

10 of them had an average mass of 29.4 grams with a standard deviation of 0.1 grams.

My tachometer is only accurate to 60 rpm, so that causes the majority of the error in the calculations.The kV therefore could be anywhere from 70 to 80 rpm/V. This would change the kT value from 17 to 19 oz-in/A.
« Last Edit: August 13, 2016, 09:26:41 pm by IanMcMahon »

Koolaid64

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Re: Team Slaughterhouse
« Reply #11 on: August 15, 2016, 09:14:43 pm »
yolo swag, bought 30, they better be good.

-Kyle

TeamAstroBot

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Re: Team Slaughterhouse
« Reply #12 on: August 30, 2016, 12:37:07 pm »
Ian,

Thanks for the heads up on these. I went ahead and pulled the trigger on 10 of them and they have been delivered.

Upon visual inspection they appear to be of decent quality; used as noted on the ebay listing, but they don't appear to have been used for very long. I've not yet done any electrical tests on them.

But I did go ahead and make a detailed solid model, which is attached below. Anyone who would like to use it, please feel free. Everything is to scale.

https://dl.dropboxusercontent.com/u/1598274/China%20Ant%20Motor.igs


« Last Edit: August 30, 2016, 12:43:39 pm by TeamAstroBot »