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Messages - Jeff Gier

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1
Questions / Re: uxcell 1000 rpm antweight motor
« on: November 08, 2016, 03:02:20 pm »
I've worked with them.  Protect your wheels, and run foam wheels or else.  The power, weight and size are all very similar to the silver sparks.  I can't say for sure if the internals are the same, but I find them of similar (medium) durability.

2
Questions / Re: burning up brushless outrunners
« on: October 21, 2016, 03:00:34 pm »
Yes that will happen.  On a brushless motor, there are miliohms or less of resistance per coil.  So if they are stalled the amperage will go as high as the battery can source.

Some controllers have thermal protection and I am not too knowledgeable about what this entails but it might help.  You need to go with a more powerful motor or lower gear ratio.

2) Yes possibly.  Or they both burn up.

3
Questions / Re: Comparing brushless motors
« on: October 17, 2016, 06:47:24 pm »
Theoretically, yes more torque.
However, advertised motor ratings are often not very realistic.  Typically, weight and motor size can be used for comparison.  Motor quality matters to some extent as well.  I am not sure what motors you are looking to compare, but I wouldn't expect two motors of the same size and weight to have different power outputs.  That being said, you probably need to go to a larger motor or lower KV to increase your torque. 

You can calculate the length of the bite your bot will get by knowing the closing speed between the two bots and the RPM of the weapon. As closing speed goes up, bite goes up.  As rpm goes up, bite goes down.  I'd shoot for ~10k rpm for an ant. 
More aggressive (positive rake) and harder teeth will also bite better than flat or negative rake and softer materials. 

4
Questions / Re: Sharpening Weapon Screws
« on: October 17, 2016, 06:38:30 pm »
I think your next best option would be the angle grinder and steady hands.  You only need to take off about .02" from the top. 

5
Questions / Re: V Belt Questions
« on: October 03, 2016, 05:18:32 pm »
I've seen V-belts and pulleys at ace hardware before.  They are steel, so you should be able to weld them to it.

6
Questions / Re: Prevent Weapon shaft from spinning when running drum?
« on: September 23, 2016, 06:04:29 pm »
Don't own a weta, but have built something similar:

Those washers are probably supposed to go between the stator (motor coils) and the drum.  this keeps the drum from rubbing directly on the motor coils.  You may have to take off a side plate to get this to fit together properly.

You could probably just use a bit of tape on the ends of the shaft.  The shaft moving a bit isn't really a problem. 

PS:  The type of motor used in the drum is called a "brushless outrunner".  The setup that the new weta has is often called a direct drive or a motor-in-drum setup by robot people. 

PPS:  The "metal wiring" that holds the shafts on are called cotter pins.

7
Questions / Re: motor maintenance
« on: September 23, 2016, 11:51:33 am »
It's gonna be pretty hard to tell you what is broken based on a couple sentences.  What I would suggest is that you slowly disassemble the gearbox (while taking lots of pictures) to find the problem. 
Then, you would need to find out how to fix the problem.  At this point, we may be able to help you or it may not be something that can be fixed.  Then you would need to source a replacement part and install it.  After all that, it will likely break again.

I wouldn't suggest using copals in a competition bot, but if you want to learn then try and fix them.


8
General Robotics Discussion / Re: New To Combatic Robots
« on: September 14, 2016, 12:59:44 pm »
Welcome.
A good starting guide can be found here:  http://sparc.tools/?p=131

As a new builder, I recommend finding an event that you would compete at and then build for a class they have.  I am not aware of anywhere that runs 1kg robots currently.  Also, this will connect you with a local community of builders.  Where do you plan to compete at?

9
Questions / Re: Transmitter/Receiver issues
« on: July 22, 2016, 05:05:22 pm »
If it is the BEC, then you could be ok.  If not, can't say how long but wouldn't go into combat with it.

10
Questions / Re: Transmitter/Receiver issues
« on: July 22, 2016, 02:23:11 pm »
I've seen this exact problem when using the same sabertooth esc.  Soon enough, your esc will probably die completely. 

11
Progress Reports / Re: Team AstroBot
« on: July 18, 2016, 11:55:00 am »
are you using the capacitor with these motors?  should take care of the noise hopefully, definitely says to use a capacitor on the kitbots site and the fingertech esc site.  I am close to building a bot soon with a spectrum controller and i want to use them..

Yes, I have been using at least one capacitor across the terminals with all of these motors.  With the KitBots motors I even tried several configurations with up to three capacitors, but none of them damped the electrical noise enough to make it drivable.

Same here. Didn't seem to help.

This is too bad.  I know these motors have worked well for me and many others.  Is it possible that something else is causing the problem?  My first guess would be that there is more than one BEC plugged into the reciever. .

12
Questions / Re: Microcontroller Help
« on: June 23, 2016, 11:40:22 am »
Hello and welcome!

Short answer:
Unless you are doing some sort of autonomous control, a supervisory controller isn't needed.

Long answer:
In an R/C system, the Transmitter (TX) and receiver (RX) communicate. The RX takes the signals received from the TX and converts them into a pulse with length 1-2 milliseconds.  1 millisecond is reverse, 1.5 is neutral and 2 is forward. This pulse is sent to an Electronic speed control (ESC).  The ESC has a microcontroller which converts this signal into a motor output.  The ESC also has an amplifier that amplifies the signal to a level that will cause actual movement of the motors. 

You could use a single microcontroller to communicate with the RX.  Then, you would need an amplifier (like an h bridge) per motor. 

For nearly everyone in the sport, off-the-shelf ESC are often more cost effective, time-effective and size-efficient over creating your own system.

Addtionally, most TX are programmabe.  You could program mixes, switches, de-rates, cutoffs and much more with them.  This allows you to keep a dedicated controller in a safe place outside of the robot.

13
Progress Reports / Re: Pizza Slicer - Team Food Fight
« on: October 20, 2015, 10:25:07 am »
That's a lot of weapon power! 

It's probably good to note that the stainless steel shaft you linked is not likely stronger than the stock shaft on the motor.  My turnigy's (but never tried this specific one) have had hardened shafts stock.  If you want to beef it up, you can get S7 or O1 tool steel from mcmaster for cheap and hardened them yourself.  You should be searching for steels with a hardness in the Rockwell C range. 

14
Well you're missing a way to cut the stock into the shape you want.  I suggest a jigsaw for the plastics and a rotary tool, like a dremel with a re-enforced cutoff disk attachment for the metals. 

You will also probably want a scribe and a square with a solid ruler.

15
Progress Reports / Re: Revelation Robotics
« on: September 15, 2015, 12:24:25 am »
@Jeff

When you say "servo city hub" do you mean these: https://www.servocity.com/html/timing_pinion_pulleys.html, or these: https://www.servocity.com/html/smooth_hub_pulleys.html#.VfcgLOmLMcA, and could I use the belts that they sell to go with them? Or can they stand up to the stress?


I don't see anything on servocity like what I had.  I may have gotten it from lynxmotion.  THey looked like these: http://www.lynxmotion.com/p-115-universal-hub-4mm-pair.aspx

I clamped them on the motor and then spun it and put a groove in it with a round file.  Worked well.

I like dead shafts way more than live shafts.  They add rigidity in most cases and I think it is a lot easier to attach a pulley to a blade than to attach a blade to a shaft.

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