Magnexxica

Attachment 7144

I'm currently constructing a heavyweight robot.
The main design aims are:
Invertible.
Compact.
Very heavy armour.
Crushing weaponary.
Highly reliable.

The robot is split into 2 sections, the mobility part and the weapon part. This makes the weapon modular.

There are 9 (A4 sized) 10mm thick hardox500 armour plates which can be moved to different parts of the robot, depending on opponent (e.g. increased top armour for axe/hammer opponents).

The thickest armour at parts of the robot is 42.5mm thick, made of 4 layers of various materials.

The main weapon can exert approximately 75,000N - 100,000N of force. Equivalent to approximately 7500kg - 10,000kg. This is concentrated to two spike like structures.

I'm hoping for this to be completed in 8 to 10 weeks time.

Paul.

Looks good so far, hope this one goes smoothly for you. What sort of drive system are you using on this one?

im no expert on this but to bend and pen hardox (heavyweight thicknesses at least) would you need more then 10 tonne ?

In the past my biggest construction weaknesses have been with custom gearboxes and managing speed reduction in an efficient way. They always became the weakest link. So to simplify things, at least initially, I'm using three motors to power two 10 inch wheels (left and right).

The main drive motor is a full transaxle from a Kymco XL mobility scooter. I've used similar golf buggy transaxles before and they are impressively 'torquey' and reliable. Rated power is 850w, although it'll be running at around 2kw. Energy losses in the gearing are minimal, although I don't yet have a figure for this.

This big drive motor is aided by two geared Pride Go motors, one on each side. These will be running at around 800w each. These use the diffetential (in the transaxle) to be the turning/steering motors too.

A more complex set up than a single motor each side and a set up I've never tried before. Sort of like a hybrid system. It also brings in 2 levels or redundancy. If big drive motor control fails, the 2 smaller motors can keep control. If one of these fails, forward power is reduced but steering is maintained by second small motor.

Needless to say this is a brushed motor set up. I just need to work out the transmitter mixing.

The Kymco XL motor is rated to pull 330kg with a full load.

I think so. I'm hoping to be able to bite the opponent and control the fight from there. But wheels and lighter armour should be vulnerable to the weapon.

Very very ambitious.

My experiences with multiple motors for 1 purpose ain't to favorable.

Also, with that kind of armor you'll have to build very very tiny.

The robot will be compact. A sort of T shape. About 65cm wide x 75cm long. 25cm high.

I know what you mean about the motors. If i do get trouble I plan on operating them totally independently. So the 2 smaller ones won't assist the larger drive motor. They will only steer.

The main weapon doesn't use hydraulics, which saves a lot of potential weight.

Quote:

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Originally Posted by steelefist

The main weapon doesn't use hydraulics, which saves a lot of potential weight.

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How are going too achieve 9-10 tonnes of forces mechanically ?

Be interesting to see how you would achieve it

"About 65cm wide x 75cm long. 25cm high."

Not far off the dimensions of PP3D. I struggled to get 6mm hardox into the weight limit. Second time out most of it was 3mm.

It uses a 3000lb winch motor. About 1400kg of pull on a flexible 5mm dyneema cord. This then has a pulley system multiplying the force by 4 times. The jaw is part of a lever which further multiplies the force by about 30%. The motor is running on a slightly higher voltage than normal too.

My first attempt used 2 ultra strong carbon steel crow bars to deliver the force to the 'teeth'. But the system was bending these bars at the same time. So I've had to beef up the thickness of the steel used. So the crow bars are no longer in use.
Attachment 7145

Pp3d had quite a heavy fly wheel on though I think. About 30kg.

Cool build. Looking forward to more!

Triforce is 680x680x150mm with a 34kg weapon and still manages 6mm armour just fine. So I think that is doable as long as the weapon is light.

I did a weapon test against 1mm thick stainless steel and against 4mm thick aluminium. I'll test different armour against different tooth designs to see what works best.

Here are the videos...

https://m.youtube.com/watch?v=1NmGJIi7QWw

https://m.youtube.com/watch?v=b5cw0dtsrAI

Try it against some 4mm hardoz and see if it makes a dent.

I'm going to test it against 6mm hardox, once I've made a 10mm thick hardox tooth.

Once i hit the limits of what can be penetrated I'll look at making a clamping attachment to squeeze and hold rather than pierce.

In terms of tooth material, it's worth looking at tool steel. We're using H13 that's been tempered to 55HRC.

It looks like a cool build - very interesting if you can with inside the weight limit. Don't forget those removable links!

Quote:

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Originally Posted by emisnug

In terms of tooth material, it's worth looking at tool steel. We're using H13 that's been tempered to 55HRC.

It looks like a cool build - very interesting if you can with inside the weight limit. Don't forget those removable links!

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That's about the same as hardox 600

Quote:

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Originally Posted by TechAUmNu

That's about the same as hardox 600

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A bit cheaper in my experience though. And, iirc, a yield strength of somewhere in the region of 1850MPa. But can't remember

Yeah I'm looking at a few options at the moment. 01 tool steel, other tool steels, hardox 500, and various alloy steels. The shape is crucial too.

I'll be testing an SDS point chisel, a chrome-vanadium steel centre punch and a diamond pen dresser tool (for truing grinding wheels). If I have a tooth point area of even 4mm squared, followed by a cylindrical shaft, it'll be in the region of 1.2 Giga Pascals of pressure (at 2000kg) and 4.9 Giga Pascals (at 8000kg). Something will deform, I need to make sure it's whatever is in the jaw.

These are all pretty inexpensive (less than 5 quid each). These are to test the current (amp) load and the minimum speed (winch slow down) against 5mm aluminium and 3mm stainless steel. I should see what is working efficiently and what tooth materials are beginning to deform at their contact point.

The whole weapon is powered by a small 14.4V 1800mAh Turnigy Nanotech battery. It gives around 35 to 40 seconds of constant maximum weapon power (130 amps).

Apologies, I'm new to this site and should have made this thread in build diaries. I'll move it across.