[FW] Tracked 4WD Lifter: Aegis

[daveimi]

Carlo Bertocinni has a good guide to modifying linacs on the biohazard website. He shows you how he modified his to get more power if its any help.

[overkill]

That's a great resource - I totally forgot about Biohazard! Carlo pretty much rebuilt the actuators from scratch, hopefully that won't be required in a featherweight.

[daveimi]

The OP needs a final design and plan from there lol.

[epicentre]

To clarify, is it usually the power of the motor that is the limiting factor on a Linear Actuator's maximum force, then? I had assumed it was the strength of the ball screws (and associated hardware) that limited the force. But reading that Biohazard got over triple the rated force out of his with modifications is very interesting.

[overkill]

The motors are generally under rated compared to the other parts - just remember that you won't be getting ball screws in a cheapo Chinese actuator - they will have ACME nuts.

[R9000]

Alright, things are shaping up, finally received my TZ85 ESCs today, and some of my track components. I've got a linear actuator on the way, and I'm about to order a Turnigy HeliDrive SK3 for modding it, but I still need to figure out what batteries I'll need. Currently I have four 18V drill motors and that motor, and three TZ85s to power the whole lot (I'm assuming one unhacked TZ85 will be fine to drive the SK3, having a max current load of 85A). That's about all I'll need to power, so I think I'll need around 18V total? I'm not sure how much you can push those drills past 18, so I'm thinking a 5S combination would do it. Unsure about how many mAh I'll need though. Of course the ESCs run to 85A max, but I'm assuming it'll be nowhere near that most of the time. Anyone have a rough idea of what I'll need?

[daveimi]

The feathers I've built usually have a 2500 - 3000mah battery and I can get two fights out of that on drill motors. With a lifter you'd prob be fine with that capacity but will need to charge them each fight. The knack is getting away with the smallest capacity you can to save weight.

[adz600]

my electric axe runs 3300 and 4000mah packs 4 x 750 motors so similar setup in terms of power draw

[adz600]

both packs are the same weight but the 3300 pack has a much higher c rating and was an upgrade so I have a choice, newest feather uses 2450mah pack on speed 900 drives

[R9000]

Ah, thanks. Think something like this would be appropriate? http://www.hobbyking.co.uk/hobbyking...dProduct=26733

[adz600]

pack size is probably fine but with 5 motors in your setup you will probably need more then 30c rating

[adz600]

http://www.hobbyking.co.uk/hobbyking...arehouse_.html

http://www.hobbyking.co.uk/hobbyking...arehouse_.html

these would deliver much more punch but the cost goes up

[R9000]

Ah, sorry, I completely forgot about C rating - not used to LiPos. Well, looking at HobbyKing, it seems the best solution is this: http://www.hobbyking.co.uk/hobbyking...dproduct=34854
with a 65C constant output.

-Edit- You sniped me. :P I'll get one of those.

[R9000]

Ok, almost everything's in place now. I'm aiming to get a final CAD diagram down by sometime this weekend. I do have a conundrum however: how do I mount the wheels? So I'm using 18v drill motors (should be simple enough). They have a 12mm outer (right handed) thread, which appears to be M9, and an inner left-handed M5 thread, and the screw protrudes by about 9mm when fully inserted. The screw head is 9mm in diameter. So basically my motor shaft has a 21mm (25mm at a push) length.

My wheels, however, which I suppose I could've been a little more selective with, are around 34mm width including the hub, with a 13mm diameter hole in the middle. The full wheel diameter is 100mm.

I thought about putting a coupling nut in the middle (I've seen a video where they heat them up and drive them into the centre of the wheel, melting the plastic around) but I can't for the life of me find an M9 coupler. I still have the chucks from all the drills, but they don't seem to look hackable enough after taking one apart today. I also thought about getting a new, longer screw and just clamping the wheel on with some washers, but M5 reverse-threaded bar or screws seem very rare, and even more so for locking nuts if I'm using bar. Is it worth getting new, thinner wheels (it would be a bit of a waste of these)?

TL;DR: My wheel holes are too wide and my motor shaft won't reach through, what do?

[daveimi]

Thought you'd ordered a track setup...