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Thread: Electric Axe featherweight - first build of FW

  1. #1
    Attachment 6967

    I thought I would start an actual build diary for several reasons, 1, keep log of progress. 2, keep me on track and 3, to get suggestions on what I'm doing wrong!

    Intro, Nathaniel, a series 6 RW veteran with Short Circuit, a bot built for series 2 and improved till getting on the show. Built several ants too, but as I have now moved into an actual house where I can set up an actual workshop, I have gotten the bug again, and want to compete with bigger bots than ants.

    My Fiancée has wanted an Antweight bot wit an axe, so I'm making one better and making a feather to compete around the area.

    From my times in RW I had a lot of stuff about including some Electronize esc that had the external relay mod. Sadly I couldn't find them so bought a pair to start me off from this forum.
    Initially I was wanting to go and do pneumatics, so bought the final parts I didn't have, that were paintball tanks and reg before realising I should start of s,all then get the Pneumatic stuff done, so an electric axe was first.
    Attachment 6962 Pneumatic bits
    Attachment 6964 Initial CAD design for electric version

    I started to draw out some designs based on my Pneumatic build, which game me a rough shape, similar to how my heavy would have looked after a redesign for series 7, and from there I have been working in plywood prototyping before I buy anything, so this is where I'm at now.

    Had slight issue where my motor cad model was too short, not taken into account how much the hub of the wheel would space out the motors.
    Attachment 6965. Attachment 6963

    Slight remake of the base fixed that

    Attachment 6968.
    Attachment 6966
    I'm just playing with the ideas of different chassis thicknesses and bulkhead impact zones. It started off as 12mm HdPE now it's 18mm and 12mm hdpe with 6mm aluminium base and hardox wedge and top... although that's ever changing.
    Attachment 6969. 18mm central sections with layered top panels

    What do you guys think of the design? Have I missed anything with the ticknesses of the shell or bulkhead?
    Last edited by Roboteernat; 23rd July 2017 at 16:06. Reason: Sorting pics and awful grammar!

  2. #2
    I like the slotted 'puzzle-piece' design alot - it's amazed me how much more solid it can make a chassis. Are you thinking of making the main cross sections interlocking as well?

  3. #3
    once I have finalised my motor mounts I will make this part intersect with the central supports. I'm thinking these will be made from either 10mm aluminium or 18mm HDPE as it is the main bulkhead, but tneed to work out if I'm having a separate gearbox for the axe mech there or if it's built within the support. Having it separate makes more sense as then if the chassis is bent it doesn't affect the axe.

    Interlocking segments was a must due to the added strength. Will also have angle to bolt it all down with so the panels could be easily replaced.
    Assuming weight is ok, will also have internally some steel perforated sections to protect, but this is not guaranteed weight wise
    Last edited by Roboteernat; 23rd July 2017 at 16:07.

  4. #4

  5. #5
    10mm alu, the weight equivalent of 28mm of HDPE. Or 3mm of Hardox.

  6. #6
    Quote Originally Posted by daveimi View Post
    The axe motor looks like a serious bit of kit
    The motor started out being a Bosch drill motor, thinking I could adjust the clutch to allow a nice sack without damaging the motor, plus I had it spare.
    Then in a box of bits I found several old electric scooter motors, one big and this one that's smaller. Thing is it's a 24v motor, so will be underpowered slightly.

    Quote Originally Posted by maddox10 View Post
    10mm alu, the weight equivalent of 28mm of HDPE. Or 3mm of Hardox.
    Thanks maddox, I may be adding some holes in that plate to bring weight down But keep rigidity, although since making that 2nd frame, I have amended he motor spacing again and need to recut the wooden mockup lol

  7. #7
    Good news,
    Today i recieved my parcels after biting the bullet and going with 12mm HDPE.
    Have had a change of ideas regarding the sides and will be doing some welding of aluminium panels to put onto the hdpe
    and to stop it from resting on the sides.

    What i do need to do however is buy my motor ESC... Payday Friday!
    Also been machining a PCB bed for my mill, looking to make a custom PCB for limiting the axe movement to a single fire when i press a button on the Tx. Hopefully this will be enough to stop 'long' burst of max current on the ESc.
    I could also use it to automatically trigger the return of the axe
    Attached Images Attached Images

  8. #8
    Been wanting to find a suitable battery for my botafter realising I only have 3S batteries... oops, bit of a stupid error there... but s I have an electric weapon I need to go for a 3300 or 4000mah battery.

    Am tempted to go for he Turnigy heavy duty 4000 4S 60c lips pack from hobbyking sadly out of stock for U.K. Sales, prob due to their price reduction to £21.11
    Otherwise it's the 3300 4S for £19.40 sadly out of stock too.

    I'm going to assume these are suitable and hopefully get them soon

    Turns out the 4000 battery doesn't fit into my design...
    Last edited by Roboteernat; 29th July 2017 at 18:59.

  9. #9
    Hey Nat. That Bosch motor you are using where is it from ? As it looks like a Unite Electric 150w Chain scooter motor or are you using it as a stand in.

  10. #10
    Which image are you looking at to see the motor? Can you say it's number?
    The Bosch motor is a Bosch drill motor in my first design shown in 6563, now I am using an electric scooter motor, but a slim version not the larger round ones most use shown in 6568.
    Will find the specs and repost on this message when it's early and not so rainy outside ������
    Think you may be right it being a 150watt motor, not sure what modelits from...

    MY6812 I guess would be a simularscooter motor, a 120 watt 24v dc motor but will check

    It's a XYD-15B 24v 10amp motor with output of 135watts.
    3000rpm, but will be going through a 5:1 gearbox of gears and belt so that should give a speed suitable for tweeting with the ESC
    Last edited by Roboteernat; 30th July 2017 at 20:57.

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