[FW] Tracked 4WD Lifter: Aegis

[R9000]

Dewalt or similar beefy drill in low gear add another stage on. Its what most other people with gearmotor powered lifters do. Hardox and careful design and execution will mean its survivable in full combat.

Any examples of these kinds of bots? I need an idea of what kind of protection it'd need.

You do see the odd banebot gearbox on ebay

Yeah I had a look, there's nothing I can really use right now. I'll keep an eye out, though.

[harry hills]

Have a look at Tormenta 2&3 . You'd need a little more reduction again as a longer arm but same principle. I run a gearmotor system too in flatpack but that's pretty useless for you as its 4bar.

Protection wise i'd go one of two ways. Either make it intentionally soft, i.e. thick plastics so it can be broken without massively hindering performance and fixed easily or make it super rock solid, say 8mm hardox arms on a 30mm or so shaft.

[R9000]

Hmm, ok. Well I'd probably go for the second option, but that sounds crazy heavy. Even more torque needed to lift. But I see what Tormenta's like. Kinda a Sewer Snake-ish design. Hmm.

[R9000]

Ok, so I'm thinking, how about ditching the 'orbital' shovel design in favour of a linear actuator lifter, one that just runs through the middle of the robot. Pretty much the same design, but the arms won't be on the outside, so won't be easy to tear off, and I should have plenty of power in a linac. Any thoughts? Too slow? I guess it'd kinda be like Ricky's lifter, hinged somewhere near the back, but the linac would be attached at the middle, I guess.

[R9000]

Sorry if I'm annoying anyone, it's just I could really use some advice here. Can anyone help with the question above?

[overkill]

I always find that the linear actuators are too slow, or they are geared to move a bit faster and have no torque. The motors are usually quite low powered, so if you hacked one with a larger brushless motor and reduced the gearing (not easy), then you might have a good solution.

[R9000]

Hmm. It seems everything I try needs some kind of custom solution. I'd try it, I just have no access to CNC or proper metalworking equipment to make custom gearing. How about something like this or this (both ebay links)? 500N 20mm/s seems decent, when you factor in the fact that the end of the arm will be moving faster tangentially. This, obviously, is assuming everything in the description is true. :P

[overkill]

That's a good price for what looks like a well made Linac. You are getting plenty of torque but only 20mm movement per second and I will bet that the speed is without a load - they usually slow down a fair bit once they get loaded down. Compare that to your original lifter speed and the linac is going at a snail pace. If you you use a highly geared lever to speed up the movement at the end of the lifter arm, you are losing a heap of torque and the geometry of the lever in the closed position is going to be very inefficient. Its all do-able but I sense you want something with better performance .

That linac design with the motor facing backwards is probably the most hackable design compared to linacs with the motor at 90 degrees to the main shaft. It uses gears or a toothed belt to gear the motor down a bit and it should be relatively easy to change the gearing and replace the motor with a faster, larger one.

[R9000]

Alright then. Sorry to keep rattling on, but any motors you'd suggest?

[maddox10]

Depends on budget and machining capacity.

But a guideline. The bigger the diameter, the higher the torque.

[R9000]

Could I just use (another) drill motor?

[overkill]

Probably not; the average 550 size drill motor has around 100 watts of input power making it less powerful than many linac motors. the gearbox output is much lower than the un-geared linac motor so you would get a REALLY slow linear movement.

Like Mario said, bigger diameter is better for torque and to get the speed you want, a motor with a fairly high KV rating will be needed. Something like the NTM5050-580 or SK3 4956-600kv motors from Hobbyking will have way more power and speed than the average linak motor. They are also wider, so you will need to make a motor mounting plate to move the motor away from the linak body. You could draw up a design and get someone to make it, or a flat mounting plate should not be too hard to make with hand tools and a small drill press. you will also need to cut off some of the back cover of the linak and probably get a new pulley and longer belt.

[R9000]

Alright, that's a lot of info. Thanks a bunch! I'll get to work.

[overkill]

UPDATE: I need to build a sportsman lifter and I got interested in the linak discussion so I just ordered one to upgrade / generally mess about with - I will let you know how it performs with an out-runner.

[overkill]

The other small but annoying thing about most linaks is the orientation of the mounting points:



To make your bot lower, its a good idea to drill a new pivot hole at 90 degrees to that, so the body of the linak is horizontal.