New to the hobby- Where to get parts on the cheap?

[npolanosky]

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Weighing in at a whopping 44.2 pounds, here is my initial design for my battle bot! Still needs a spinning drum on the other side for an active weapon, but the chassis, powertrain, and wedge are all done and ready to be built.
The chassis plate is 1/2" HDPE, the frame is 3/4in steel tubing, the wedge is 1/4in steel plate, the top armor is 1/4in polycarbonate, and the side armor is 1/8in steel plate.
Powered by two harbor freight drill motors on 10,000mAh of 22.2v lithium batteries, it should be powerful enough to hold it's own. Plans are to attach a spinning drum with nuts welded onto the outside onto the front with an angle grinder motor. This will (hopefully) fling the enemy robot across the arena, flip them, or tear into their armor.

The 30lb class is not very popular in the US, so I'm building for a 60lb class bot. If I need to add another two wheels and motors I will, but we'll see how this does.

Do you think the botbitz 85a ESCs will be enough?

[maddox10]

The BotBitz TZ85's will hold. The drills is another matter. I suspect a lot of magic smoke in your future;

But the material choise is what I dare to call, old school.
We learned that polycarb isn't as good as HDPE as armor. Polycarb cracks , even shatters.
But HDPE isn't really the best for rigid structures.
Normal steel doesn't have a lot of use anymore in the arena. 1/8" normal steel is a dustcover, not armor. The equivalent in weight in HDPE is 1", and that is an entire other kettle of fish.
And I'm talking 30lbs, not 60.

A drum with nuts welded on. I forsee a lot of mangled nuts, and scratched paint on titanium armor panels.

[npolanosky]

Hahaha, I figured I'd get something like that. So how to I either shave weight to get to the 30lb class, or beef it all up without throwing thousands of dollars at it?
This only took me an evening, I can cook up another design revision fairly quickly.

I know what my ideal robot is like, but I am a little limited in funding, materials and tools available. I can draw anything I want, but keeping it affordable and buildable is another matter entirely. It feels like cost skyrockets if you aren't careful, but I don't want to build something that's going to fall apart if I drop it. Would it be better to make it smaller?

Unfortunately I have to force myself to push this to the side a little, as much as I want to get started ASAP, finals week begins in 3 days- I have to hit the books for a while.

[maddox10]

Time*creativity*resources=robot.

If one of those is 0, you get the normal outcome. 0 robot.

Limited in funds, materials and tools. No easy solution to that, but a team can solve it at least for a part.

What class to participate?
The one you feel best with. I myself tried all except superheavyweights or the new beetles. over here, 220lbs heavies stay the cream of the crop, but feathers are very popular, and on the mainland Europe the 14 lbs Raptors are not unpopular. Ants ain't my thing. Neither does the team go on with those.

Drives. The TZ85's can do a lightweight. Driving a lightweight will need at least 4 normal batterydrills, or you'll have a turtle if you want to keep going. The TZ's can drive up to 3 normal drills each.(parallel)

Armor. What is the purpose of armor? Staying in 1 piece, or make sure the machine stays functional.

[npolanosky]

TIme is about a 6.5/10, creativity...I am great at making do with what I can get a hold of, and resources..I can dig and make stuff happen. I just got off the phone with a friend who has access to a machine shop with a CNC milling machine, 3d printers, welders, lathes, and I may be able to use another friend's CNC plasma table if I ask nicely.

Are there any go-to designs out there for lightweights or featherweights that I can build for my first one and then modify/upgrade as I go til I'm ready for something completely different?

Also, thanks everyone for your help so far!

[npolanosky]

So I just realized how cheap I can build a beetleweight, especially if I buy hobbyking ESCs and flash them myself with an ISP programmer. I think I may attempt that first, it's going to be much cheaper and there are a lot more competitions I can compete in. I can basically build a beetle for $40 of electronics..orange rx, 20a ESCs for $8 each, and some $10 motors. Where is the cheapest source of these "1000rpm" gearmotors everyone talks about?

Also, I ordered two botbitz 85A controllers for a larger bot- I'll play with those as well. I think if I get my ASP programmer I will be able to convert my own turnigy ESCs to robot use for $40 instead of $80...so power will become a non-issue.

[harry hills]

Ebay is best for the motors. Although I think Kitbots sells them and mounts too.

[john_frizell]

You said 'Where is the cheapest source of these "1000rpm" gearmotors everyone talks about?'. Others can advise you better than I but you can get free motors, or very cheap ones, by picking up a couple of old electric screwdrivers at a swap meet or garage sale. As with electric drills, these go for little or nothing once the batteries go bad. They are slower than ones made for robots but they are rugged. First robots are often a learning curve; if I were you I'd build something in time for the next event near you, fight it, and then build a new one based on what you learned and using the electronics from the first one.

[john_frizell]

'Kitbots sells them and mounts too. ' Gearmotors from Kitbots are $12 each, plus $20 for a set of two mounting plates, total of $44.

[npolanosky]

John-The motors aren't horrible, but those mounting plates are pricey. I can make my own mounts no problem. I have a drill press, tap/die set, and countersink bits.

Harry- good point, I thought about that too- I'm just trying to see what the relative cost vs performance is for various parts and sources. I'll probably track down a few electric screwdriver motors also. It's funny, all of a sudden anything with a motor has potential to be a robot part. I have some brushless motors left over from airplanes that may turn into weapon motors eventually as well.

Only two exams stand between myself and going home to build something awesome!