(FW)Nibbler- Horizontal Spinner

[Cameron_S]

So with parts starting to arrive and things starting to happen, I thought I would start a thread for the build of hopefully what will be a horizontal bar spinner. The reason for documenting the build on here is so I can ask for advise from you guys and for you to hopefully catch any beginner mistakes I’m about to make before they happen. Especially considering I’m kind of running before I can walk jumping to a spinner instead going for normal wedge/rambot first. To make sure I don't end up with a half finished robot I plan to first build it as a wedge then add a weapon, so if things do go belly up I should at least have a working wedge robot. Any way here the parts i’m planning on using.

Mechanical
Armour- 20mm HDPE for sides with 10mm top and bottom
Wheels- 125mm Nylon wheels with bike tread and hub inserted with Ellis’ melting in a nut method.
Motor pulley- HTD5 15mm 12 tooth
Weapon pulley- HTD5 15mm 40 toothed (Giving a ratio of 3.3:1)
Shaft- 20mm silver steel
Spinning bar- 500mm*50*15 s7 or hardox. Should weigh about 3kg.
rectangular metal(attaching bar to body)- 1.5mm 20mmx10mm rectangle aluminum as shown in the cad.
Bearings- 20mm standard deep groove ball bearings

Electronic
Drive motors- 18volt drill motors (already brought and had the clutch bypassed with grub screws).
Weapon Motor-NTM Prop Drive 50-60 Series 380KV / 2665W planning to run it on 7s (Should spin the bar at a theoretical 3000RPM after reduction)
Drive ESCs- 2 x 30 amp ones from Rangle Box
Weapon ESC- ESC- 125 amp red brick
Weapon Batteries- http://www.hobbyking.com/hobbyking/s..._5S1P_40C.html plus http://www.hobbyking.co.uk/hobbyking..._2S1P_40C.html in series to give about 26volts and 3000mAh
Drive battery- http://www.hobbyking.com/hobbyking/s..._5S1P_20C.html
18.5volts + 3000mAh
Connectors-XT60s

Maths
These are done with the assumption the bar will be at 2500RPM (15% loss from motor)
Energy-2.2 kj
Bite(5 mph impact)- 5.5cm (quite good right?)
Tip speed- 145mph (scary!)
Questions (sorry there’s a lot)
Am I completely mad to try and build a spinner with no previous robotics experience?
Is hardox a good choice for the bar and does the grade matter?
Could i get away from only having spares of the cheap things e.g bearings/drive motors? What parts are prone to breaking?
Do brushless motors have mounting holes at the bottom? Is it a good idea to mount only to the bottom, or is supporting both sides a better idea?
Is the stall current of a drill motor over 30amp? Is the ESC i’ve mentioned be able to handle the stall current or is the Tz85a a better choice?
Where do people normally buy hardox from? Struggling to find any online sellers that sell something other than digger wear plates.


Cad (minus wheels)