Practice Robot Cost

[z_beeblebrox]

For those of you that have built identical practice robots, how much did it cost?

[Mk.32]

Originally Posted by z_beeblebrox

For those of you that have built identical practice robots, how much did it cost?

If they are identical shouldn't they cost the same?

[z_beeblebrox]

Originally Posted by Mk.32

If they are identical shouldn't they cost the same?

The control system and other components for the competition robot are provided in the Kit of Parts.

[Mark Sheridan]

I think we paid another $1000 for a second control system. We bought it in 2012 and we reused it last year and will again this year for the practice bot.

The BOM costs are practically the same for both of the robots. As for parts we make ourselves, we found the doubling the number made was not a big deal it terms of the time cost. Keep in mind we build most of our parts with a laser cutter and water jet, so for us to double our parts is not a big deal. Machined parts is a big ordeal for us and making those parts takes time. We really need to make a jig for some of those parts.

We actually save money by buying in volume in the pre-season, this cuts down on shipping costs. Right now I am looking to buy a bunch of bearings to make sure we are restocked, I making sure we have a ample quantity. Same for gears, shaft material and even wheels. a practice bot is also spare parts, so I guess we are just making sure we have enough spares.

[sanddrag]

Originally Posted by z_beeblebrox

For those of you that have built identical practice robots, how much did it cost?

Double. Plus additional motors. Plus another power distro board. Plus all the time. The additional time it takes to build an identical robot is the biggest cost of all. But the additional development time you get is the reward.

[AdamHeard]

It's hard to answer as the cost changes year to year due to the amount of reuse (both in control system and mechanical components.

I would say averaged out over the years, we spend an extra $2k per year.

[BBray_T1296]

Our sponsor usually manufactures 1 or 2 extra of everything for us whenever we send them CAD, just in case they make a mistake (they never do). We basically have everything structural from there. Combined with our teams obsession with buying way too many of everything and a pile of terrible robots to cannibalize, it costs us very little.

Also, the extra control system should be a 1 time cost. By the time you took that spare shooter off and borrowed the wheel assemblies to fix your worn ones, what use is 1/2 a robot? we just reuse our electronics year to year.

[FrankJ]

We reuse old parts for the practice bot. The Comp bot gets new motors. So much of the cost is already sunk. If not a new control system is about $1500-2000 if you go out & buy it. The chassis is about $500-$1000 assuming nothing exotic. Then you have the mechanisms.

But you also have spares for competition. Keeping in mind the weight restriction for spare at competition.

[DonRotolo]

Somewhat less than double, since the practice bot tends to have more 'recycled' components than the production bot. Our practice bot is built first, and then we bild the production bot using what we learned. The second one always comes out better, and we can build it faster since we know what parts to make and where they fit.

[s_forbes]

If you already have spares for most of the control system components, the material cost of a second robot is all you need to worry about. This can fluctuate a lot year to year depending on your design. If you have a lot of off the shelf transmissions, performance wheels, or specialty parts, the cost can go up pretty quickly (billet aluminum performance wheels seem great until you have to buy 12+ of them). I think the material costs of our practice robots have ranged from around $1500-$2500.

One nice thing about the second robot is that you don't have to sink any additional money/time into R&D, which can be a significant amount of the robot build budget.

[BBray_T1296]

Originally Posted by FrankJ

But you also have spares for competition. Keeping in mind the weight restriction for spare at competition.

Originally Posted by FRC Manual 2013

R21

Teams may bring a maximum of 30 lbs of FABRICATED ITEMS to each event to be used to repair and/or upgrade their ROBOT.

As the rule states, FABRICATED items are limited to 30lbs. This does NOT include unmodified COTS items. Spare motors, sprockets, bolts, nuts, wheels (depends), pistons, brass fittings, air tanks, motor controllers, bearings, pulleys, belts (probably not chain), etc. are NOT included in that 30lbs. Also, for the record,

Originally Posted by FRC Manual 2013

The OPERATOR CONSOLE, BUMPERS, and any ROBOT battery assemblies are exempt from this limit.

So, theoretically, while a spare entire drive-train may weigh 40lbs, since it is possible to separate the system into 2 piles, COTS and FABRICATED, and it may be obvious that one could remove enough unmodified COTS items from the assemblies to reduce the assembly to <30lbs, you should be allowed to take it in.

[protoserge]

Our fabricated materials are typically sponsored and our competition robot sans KoP items runs around $2500. A loaded 4-slot cRIO is $525.

In the past, we used first iteration parts on the practice bot. This last season we had an almost identical build, sans air storage and shooter. We designed the shooter to connect with a few machine screws and a wiring harness since we intended to iterate the entire subassembly.

We have been making 2 robots for the past three years and the added cost is a no-brainer and gives the competition team a huge training advantage.

[magnets]

Our team has a pretty unique build process for our robots that helps keep the cost pretty low. We're pretty heavy into cad, so we know what our final robot will weigh before we even start building it. We begin with a bunch of simple prototype through weeks 1-2. Then we build a wooden robot frame starting in week 3, and slowly add more finalized actuators on to the practice robot during weeks 3/4/5. When our wood bot is done, we build the metal one that kids have been CADing for the past few weeks during the last few days of week 5, and the beginning of week six. Then we improve the metal one until ship day. After, we modify the wooden bot (which at this point is in bad shape) to be a driver practice robot. The wooden robot costs almost nothing more because it's all cheap materials/old motors.

[wireties]

A second robot is usually a little less money for parts depending on how much you buy versus how much you fabricate. The big difference is time. That second bot takes a lot less time to build. And the second bot can make a huge difference allowing you more practice and an opportunity to make the most of the 30lbs of parts on Thursday of your first regional.