blog; Motor Controller Options for 2015

[Wingus&Dingus]

Originally Posted by Nemo

Note to IFI / CTRE: if you make a DC motor controller for FTC to compete with the overpriced / unreliable HiTechnic controllers, I promise to order a bunch of them. Seriously.

Way down under in New Zealand, where it costs even more to buy FTC stuff, we're working on this right now.

[RandomStyuff]

To all those talking about thermal paste, I'm not sure how exactly you intend on applying it. Contrary to the popular belief, thermal paste is a much less successful conductor of heat than Aluminium. The purpose of thermal paste in computers is because nothing is ever perfectly flat, and when you put an aluminium or copper heatsink on a processor, you get small airgaps between the heatsink and the processor. These airgaps are not very good at conducting heat (because air isn't very good at conducting heat), and therefore thermal paste is used to replace those gaps with a more conductive than air material.

Now, unless you plan on using a heatsink on your robot for your speed controllers, or plan on making your entire mounting surface a huge heatsink(which I don't think is a good idea if there is a heating issue, with wires and other things on it) I wouldn't recommend the use of thermal paste. Covering the speed controllers with thermal paste would actually reduce their heat dissipation abilities.

I seriously doubt that any usage within FIRST would require thermal paste. I might mount a large fan in a way that causes airflow in the areas where speed controllers are mounted, that would probably increase heat dissipation capabilities.


NOTE: I'm not an engineer with experience in heat management or anything like that, but one of the sponsors my team had when I was in high school made air conditioning units for aerospace purposes (cooling engines and things like that) - many of the mentors worked there and they liked to give us a little bit of a view into their work

[magnets]

Originally Posted by RandomStyuff

To all those talking about thermal paste, I'm not sure how exactly you intend on applying it. Contrary to the popular belief, thermal paste is a much less successful conductor of heat than Aluminium. The purpose of thermal paste in computers is because nothing is ever perfectly flat, and when you put an aluminium or copper heatsink on a processor, you get small airgaps between the heatsink and the processor. These airgaps are not very good at conducting heat (because air isn't very good at conducting heat), and therefore thermal paste is used to replace those gaps with a more conductive than air material.

Now, unless you plan on using a heatsink on your robot for your speed controllers, or plan on making your entire mounting surface a huge heatsink(which I don't think is a good idea if there is a heating issue, with wires and other things on it) I wouldn't recommend the use of thermal paste. Covering the speed controllers with thermal paste would actually reduce their heat dissipation abilities.

I seriously doubt that any usage within FIRST would require thermal paste. I might mount a large fan in a way that causes airflow in the areas where speed controllers are mounted, that would probably increase heat dissipation capabilities.

I too am not too worried about heat, but if the Victors do end up with a lot of heat, thermal paste could be really useful. Your robot's big aluminum frame has a ton more heat capacity than the little aluminum casing. If the Victors heat up enough to get uncomfortably hot, you could dissipate all of that heat into the robot's frame without raising the frame's temperature by more than a few degrees.
For the purpose of a single speed controller, the robot's frame will be able to absorb most of heat the controller can generate about as fast as it can be generated. The air around the controller is much worse than the frame, and can't possibly keep up with the controller.

[FrankJ]

A bit of scarification. You don't cover your your speed controllers with thermal paste. You put a thin layer between the heat sink & the metal frame you are trying to transfer heat to.. If the internal design of the controller does not use the part of the controller that would attach to the frame as a heat sink then there is not much point in it. The current crop of controllers are a good example of that.

Sonic tater tots don't compare to the supply model of the new controller. If Sonic is out of tater tots, you can order french fries or onion rings. Sonic makes really good onion rings. You can also go to the grocery store & get your own. Or go down to Zestos.

[IndySam]

Originally Posted by FrankJ

A bit of scarification. You don't cover your your speed controllers with thermal paste. You put a thin layer between the heat sink & the metal frame you are trying to transfer heat to.. If the internal design of the controller does not use the part of the controller that would attach to the frame as a heat sink then there is not much point in it. The current crop of controllers are a good example of that.

Sonic tater tots don't compare to the supply model of the new controller. If Sonic is out of tater tots, you can order french fries or onion rings. Sonic makes really good onion rings. You can also go to the grocery store & get your own. Or go down to Zestos.

What's a Zestos?

To interject into this heat discussion, we have run tallons for our drive speed controllers for two years without fans and have never had a problem. I think the whole paste thing is pretty moot.

[FrankJ]

What is Zestos? A local burger/soft serve ice cream joint. Great tater tots. Some things you can sole source. Tater tots isn't one of them.

[AdamHeard]

Originally Posted by Monochron

I feel like I have to ask, how much benefit are you going to see in a 3-4 month period by ordering 40 of these? Would it be any additional burden on your team to order maybe 15 or so for the season, and then order an additional 25 next summer?

While I think we are probably not going to see dire shortages, I don't really get the rationale of purchasing so many at a time. If this is something that a lot of financially able teams do, it may actually have a small effect on supply.

We are a small team and we don't work the crazy hours some of the top teams do. To keep programmers and practice/iteration going without conflict, we build two practice bots.

Also, we don't have a huge amount of funds compared to some top teams, this is a HUGE expense for us to upgrade speed controllers but we've weighed the benefits versus costs and are happy with the decision.

On average our robots have 9-13 speed controllers, so 40 is a good number.

I'm not at ALL concerned for a shortage. People are overreacting hugely over this. I've yet to see a well reasoned argument based on historical data as to why Vex will be unable to meet demand.

The talon launch argument is not relevant as that was (at the time) a BRAND NEW supplier. They had no way of predicting how many people would want as FRC is both a very risk avoidant community, and one that LOVES new toys.

Comparisons to mechanical product shortage are also not relevant.

When you then combine the company that released the talon with the company that has been the primary supplier for 10+ seasons (who has NEVER ran out during season) you have a recipe for success, and happy customers.

Separate from all this, I'm sure Vex is concerned with maintaining their reputation. They essentially just removed the entire backup plan (Jaguar, Talon, Victor), so all the eggs are in the new basket. I'm sure they're very well aware of the consequences of failing to deliver here. Any resources put towards more production of a guaranteed obsolete product (Jaguar, Talon, Victor) would be silly as well, as that just takes away from production of the new.

[Qbot2640]

So...is Thermal Paste a suitable condiment for Tater Tots, or would it just serve to scald the roof of my mouth more quickly on contact?

[FrankJ]

I would recommend ketchup for tater tots. As previously stated thermal paste would stick to the roof of your mouth.

[Lil' Lavery]

Originally Posted by FrankJ

I would recommend ketchup for tater tots. As previously stated thermal paste would stick to the roof of your mouth.

How well does peanut butter transmit heat?

[cgmv123]

Originally Posted by Lil' Lavery

How well does peanut butter transmit heat?

~0.168 W/(m·K) (Page 15)

[FrankJ]

Originally Posted by cgmv123

~0.168 W/(m·K) (Page 15)

So you have 20 metric tons of peanut butter on a train leaving Chicago heading east at 50 mph...

[Lil' Lavery]

Originally Posted by cgmv123

~0.168 W/(m·K) (Page 15)

That's actually peanut oil. While several other peanut products are listed, I couldn't find peanut butter. I guess I'll have to select another substance to transmit heat from my speed controllers on my edible robot.

[Alan Anderson]

Originally Posted by FrankJ

So you have 20 metric tons of peanut butter on a train leaving Chicago heading east at 50 mph...

...and it quickly runs out of track as it reaches the shore of Lake Michigan. Pick a different direction.

[Jared Russell]

Originally Posted by Alan Anderson

...and it quickly runs out of track as it reaches the shore of Lake Michigan. Pick a different direction.

> go north

It is pitch dark. You are likely to be eaten by a grue.

Crap.