Author Topic: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks  (Read 20918 times)

BullCrusher

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BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #16 on: September 28, 2017, 12:31:22 am »
or should I go w/ http://www.robotmarketplace.com/products/0-magnum775.html


And something like:

http://www.robotmarketplace.com/products/0-co1-4-441.html



Can you tell if that wheel includes the attachment I'd need to connect the wheel to the motor?  Thanks!

MikeNCR

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #17 on: September 28, 2017, 09:28:48 am »
or should I go w/ http://www.robotmarketplace.com/products/0-magnum775.html


And something like:

http://www.robotmarketplace.com/products/0-co1-4-441.html



Can you tell if that wheel includes the attachment I'd need to connect the wheel to the motor?  Thanks!

The Magnum would be a good option, but seeing as they're discontinued and RMP has 2 left it's a bit of a risk, as the stock count may not be accurate and getting spares will be difficult. To use the 1/2" keyed shaft you'll need a hub similar to the ones here: http://nearchaos.net/chaos-hubs/

You could also pair the 1/2" keyed versahub from here https://www.vexrobotics.com/vexpro/motion/versahubs.html with the wheels here https://www.vexrobotics.com/vexpro/motion/versawheels.html

BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #18 on: September 28, 2017, 09:48:00 am »
Thanks Mike!!

Part of the issue I'm having is that the competition is on 10/21.  I figure I may need to order at least 3 times in order to make sure I have everything I need.  I was thinking of just ordering 1 ESC, 1 battery, 1 motor, 1 wheel, 1 hub, 1 receiver (I have the transmitter), and seeing if I could get it to work.  If it would, I'd order the other parts that I'd need for the bot.

Anyway, that being said, I'd like to order from a company that will ship quick.  RobotShop is good.. I haven't ordered from VexRobotics, but I feel like they'd be good.  I'm not sure about RobotMarketplace.  Amazon Prime is always good..

So, the wheels and hubs look great.  They make sense to me:

https://www.vexrobotics.com/vexpro/motion/versawheels.html
https://www.vexrobotics.com/vexpro/motion/versahubs.html


For the motor, I hate to ask you to search for me, but I spent a good amount of time looking and I feel like I'm not sure what I'm looking at.. ha.  Not sure what gear to get, etc.  I'd like to keep the motor around $80-$100 each, but not sure if that's possible..  Do you see anything on:

https://www.vexrobotics.com


Any help on this one would be awesome.. Thanks for your time!

MikeNCR

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #19 on: September 28, 2017, 09:54:42 am »
I've not used them myself, but these in the right ratio may work well-

https://www.vexrobotics.com/vexpro/motion/versaplanetary.html

The hex shaft option they've got for those will also work with these-

https://www.vexrobotics.com/vexpro/motion/colsonperforma.html

This motor will pair well with the gearbox-

https://www.vexrobotics.com/217-4347.html

You'll probably want a total gear ratio somewhere in the 16:1 to 26:1 range for a 3-4" wheel (this would mean a 2 stage gearbox)

BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #20 on: September 28, 2017, 10:42:14 am »
Awesome!  Thanks!!


So they have a few options here:

https://www.vexrobotics.com/vexpro/motion/versaplanetary.html



I guess I'm going with: VersaPlanetary v2 Base Kit, 1:1, 1/2" Hex Output, correct?


I don't know which gear reduction to choose, can you help me out on this one?


Should I add the VersaPlanetary CIM Adapter or Dual Motor Output


I guess I can just choose the 775pro from the options on the bottom, right?


And then what about the VersaPlanetary Integrated Encoder?



Oh and I know the hex will fit in the Colson wheels, but how do I get them to stay on the how do I get the wheels to stay on the driving shaft?


Thanks for your help here!  Chris

MikeNCR

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #21 on: September 28, 2017, 01:58:34 pm »
In addition to the base kit you'll need gear kits and ring gear kits that will reach your desired ratio (for example, two 4:1 kits will create a 16:1 gearbox and you'll need two ring gear kits - 4*4=16)

If you're not using CIM motors or dual motors you won't need those.

You'll also want one 775pro per gearbox assuming that's the motor you'd like to use.

You don't need the encoder.

The 1/2" hex shaft has a 1/4-20 tapped hole at the end of it. You can use that with a bolt and washer to prevent the wheel coming off of the end of the shaft. (The 1.575" shaft length should work nicely with the 1.5" wide Colsons so you'll just need a washer that's sized for a 1/4" bolt that's got a large enough outer diameter to prevent the wheel from sliding over it - probably 3/4" OD at a minimum)

BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #22 on: September 28, 2017, 02:54:04 pm »
ok, awesome!  So I'll go w/ the screenshot attached (the options are highlighted in red). 

Along w/ the Colson Wheels and hubs (attached pic of this one too)

Cool?  Thanks!

MikeNCR

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #23 on: September 28, 2017, 03:20:38 pm »
You'll need to select quantities(2 for each for a single gearbox) for step 2 on the gearbox, the wheel looks correct. You may be best off either ordering two gearboxes worth of parts now to give a bit more build time or deciding to not worry about getting the 30 built in time for Franklin and focusing on getting that done for Motorama. Even if you do the latter, I'd suggest attending FI with whatever else you've got for the experience.

BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #24 on: September 28, 2017, 03:40:35 pm »
Awesome.. Thanks for the info.. I'll def go to FI either way.  There's a slim chance I can still get this together though.. ha.  And I'm entered, so may as well give it a shot.. right?  Ha.. 

Would this need a brushed ESC or a brushless ESC?  Thanks!

MikeNCR

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #25 on: September 28, 2017, 10:10:37 pm »
Awesome.. Thanks for the info.. I'll def go to FI either way.  There's a slim chance I can still get this together though.. ha.  And I'm entered, so may as well give it a shot.. right?  Ha.. 

Would this need a brushed ESC or a brushless ESC?  Thanks!

Brushed ESC. I'd suggest the RageBridge in this application with the current limit set to around 50A. Using the banebots 775 motor with a 16:1 gearbox (this should be moderately comparable) with this calculator I get 25A for wheelspin per motor - http://sparc.tools/TorqueCalc.php

The reason I suggest double that for the limit is that you may have another 30lbs sitting on top of your bot and having enough power to spin the wheels is handy.

Nutball

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #26 on: September 29, 2017, 01:26:50 am »
It could be too early to ask, but do you have any design drawings or ideas on the general layout? I figure a hammer is good for scoring a lot of hit points, but it's hard to deal damage that way from what I've seen. I think vertical spinners are the best overall, large diameter single sharp tooth with little wedges to lift a bot into the blade would be most effective. You would want the most blade tip speed for the allowed energy.

I found a bit of a confusing point on the rules page. It say spinners are limited to 200j of energy OR 21ft/s tip speed. Does that mean unlimited energy with a 21ft/s speed limit, or unlimited tip speed with a 200J energy limit? That would make sense.

Anyway, just for fun I threw together some rough ideas for a bot with a non high energy storing spinner. I figure the usual top and bottom arms for grabbing. For simplicity, the top arms can rotate up 120 degrees, the bottom arms can rotate down 120 degrees to lift or flip itself over. The top arms, if allowed, could have permanent magnets on the tips, strong enough (maybe with a sand paper coating) to help grip an opponent, but weak enough to be able to let go. A thin blade high power retractable angle grinder could be hidden in the front, so you can grab and cut deep. The arms and grinder could easily be moved by normal high torque standard size servos like what RC cars use. I guess it all comes down to fitting that durably into 30lbs. Of course you could have various attachments for the arms too.

A rough sketch attached

BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #27 on: October 05, 2017, 03:31:58 pm »
Mike, hope all's well!  I got a bunch of parts now and I'm trying to figure it out!  Ha..

If I want to buy plugs so that I can solder the 2 red and black ends to the motor and have a plug to plug in to the battery, which ones would I use?  This is the battery I have:

https://www.amazon.com/gp/product/B00JNL5EKS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1


Something like this?

https://www.amazon.com/Style-Servo-Extension-Variety-Pack/dp/B01JKCKB8O/ref=pd_sim_21_5?_encoding=UTF8&psc=1&refRID=4TN9V9SRB8EC690A2207

or this?

https://www.amazon.com/Finware-Female-Bullet-Connectors-Battery/dp/B01ETROGP4/ref=pd_sim_21_5?_encoding=UTF8&psc=1&refRID=99TVRZFPQCHM9Q9SAJX7


They're mentioned here at 5:03:

https://www.youtube.com/watch?v=LlOHMgo3Sfs&t=302s




Thanks for any help!  Chris

MikeNCR

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #28 on: October 05, 2017, 03:40:14 pm »
Mike, hope all's well!  I got a bunch of parts now and I'm trying to figure it out!  Ha..

If I want to buy plugs so that I can solder the 2 red and black ends to the motor and have a plug to plug in to the battery, which ones would I use?  This is the battery I have:

https://www.amazon.com/gp/product/B00JNL5EKS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1


Something like this?

https://www.amazon.com/Style-Servo-Extension-Variety-Pack/dp/B01JKCKB8O/ref=pd_sim_21_5?_encoding=UTF8&psc=1&refRID=4TN9V9SRB8EC690A2207

or this?

https://www.amazon.com/Finware-Female-Bullet-Connectors-Battery/dp/B01ETROGP4/ref=pd_sim_21_5?_encoding=UTF8&psc=1&refRID=99TVRZFPQCHM9Q9SAJX7


They're mentioned here at 5:03:

https://www.youtube.com/watch?v=LlOHMgo3Sfs&t=302s




Thanks for any help!  Chris

The second one is more along the lines of what you'd want for running power around the bot. I'd suggest having connectors like that between the battery and power switch as well as between each esc and motor to make it easy to work on or replace motors/gearboxes. You'll want to replace the existing main plug on the battery with whatever type of connector you use for the bot. (On that note, you may want to use a different size connector for the Battery-to-switch portion and the esc-to-motor portion so you can't hook them up incorrectly) I also put the female connector on the battery side of the circuit in all of my bots so with connectors that have the contacts exposed on their male connectors there's less risk of a short when something's unplugged.

I'd also suggest a read through this post on my team site: http://nearchaos.net/battle-hardening-the-inside-of-your-bot/

This image from my instructable may be a handy reference as well-

https://cdn.instructables.com/FSB/86VU/I1JW9VZP/FSB86VUI1JW9VZP.LARGE.jpg

BullCrusher

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Re: Newbie! Advice On 30 Pound Sportsman's Class... in 4 Weeks
« Reply #29 on: October 05, 2017, 03:53:39 pm »
Awesome!  That hardening article will be really useful.  I'll def keep it in mind.


With the connection, now that I'm looking closer, it doesn't seem like these:

https://www.amazon.com/Finware-Female-Bullet-Connectors-Battery/dp/B01ETROGP4/ref=pd_sim_21_5?_encoding=UTF8&psc=1&refRID=99TVRZFPQCHM9Q9SAJX7


Would fit in the connections attached to my battery (attached).  Any advice here?  Thanks!  Chris