180mm from the floor to the top edge - you are going to need bigger jaws!
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

if I use the extra hole for more travel it can do over 180mm
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The Engine Whisperer - fixer of things

What crushing force are your jaws cable of creating at the tip?

http://www.parker.com/Literature/Oildyne/Oildyne%20-%20PDF%20Files/Compact-EHA-Catalog-HY22-3101E-7-13.pdf

This hybrid actuator seems to have potential, it weighs around 4.5kg(heavy) but is capable of supplying more than 10000lb's of force with a fast extend/retract.

What tip PSI do you think is necessary to pierce typical robot armour?

Last edited by pilleya on Tue Jun 07, 2016 11:17 am; edited 1 time in total

we reckon something close to a tonne, based on the pressure measured in the hydraulic system.
They are very slow when you want a lot of force, but still give a much better speed / force ratio than a screw actuator.
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The Engine Whisperer - fixer of things

Those Parker actuators look surprisingly similar to what Crushinator has, except they probably don't break

If there is some weight left over, I can always add some extra hight the the armour - it might help protect attacks by axes as well
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

I blame Glen.


the Parker actuators are basically the exact same thing, mine's just an OEM version for a boat engine - that I found at a scrap metal shop.
The standard motors are very heavy, and my one was super rusty which is why it got upgraded.


I'll add super extra height jaws to the list
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The Engine Whisperer - fixer of things

That's probably his way of telling you that his last pay rise wasn't enough. 2Kg for a 560 watt motor is ridiculous! Finding a replacement outrunner with similar dimensions can't be too hard; I guess the important thing is to match the output speed and the shaft diameter?
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

yeah it's not hard to replace the motor - but the Parker actuators are $750 - 1000, so it gets expensive very quickly.

Even though you get a lot of force, even a relatively thin metal cover takes a huge amount of force to puncture if it's well supported, and a very slow weapon is hard to make good use of in a fight.
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The Engine Whisperer - fixer of things

The other problem with a slow acting weapon is that you need a heap of armour (in full combat events) to withstand the beating the bot will probably take before it gets a good crush on it's opponent. OTOH, Little Nipper did the most damage to Mr Mangle in the UK last year and can within millimeters of crushing an ESC.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Smallest hydraulic pump with decent pressure and flow I ever handled is a .17cc gearpump.

Max RPM 9000 = 1.53L/min with a peak pressure of 260 bar.
Pump is about 1 kg and needs 800W input.
Meaning you'll need a 1100W rated Brushless outrunner.
An NTM5060 370KV on 6S sounds perfect.

A ram to handle that kind of power is also about a kg, and will deliver 7000 kg over 75mm stroke.

In short, a Hydraulic Feather razer is possible.
It will be a very expensive machine to build. The frame will have to be CNC milled 7075T7 ali combined with grade 5 titanium armor and the lightest possible drive.

The issue with this design, is as you said it would require a lightweight drive system, but the drive system is the thing that makes the design effective. The drive needs to be able to push itself underneath the other robot, and hopefully have the other robot end up on some sort of raised platform with its wheels completely off the ground. The drive system needs to be powerful enough to drive around while supporting the weight of the other robot, quickly in order to get it against a wall or into a corner where it can prevent the other robot from being able to escape while piercing or crushing it.

I think for a sportsman event this type of robot could be quite effective, if the pincer could also function as a self-righting mechanism or if hoops were used. Because of the varying style of Sportsman robots, several different pincers/blades could be created and the other robot could be measured up (visually) to work out the most effective shaped pincer in order to defeat it.

Scissorhands rides again

After week of drying, out Scissorhands has powered up successfully! The motors probably need to be disassembled and checked for corrosion but everything works for now. Moving along to the next sportsman event, I designed a custom saw blade, mainly because I can't buy anything suitable:



Its made of 3mm Hardox and the teeth should be able to be resharpened many times, unlike a carbide tipped blade that is useless once all the carbide has chipped off. The saw weighs almost 1Kg less than the bar so it may be possible to convert to brushless drive motors like Decimator uses for more reliability.

Mister T:

Not much to report here; I started welding the frame and it was going very poorly at first. I switched to using pulse TIG and the arc is now more focused and stable. The other benefit is that the sound of the arc changes as it gets longer, reminding me to keep the arc nice 'n short.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Great to hear scissorhands lives after the flood.

Re the custom blade.
IAW the sportsmen rules wouldn't the blade need to spin at 400 RPM or less given it is a custom blade and not unmodified saw blade? There would likely be better designs for your 400rpm buck than a copy saw.

It would be less likely to dull, will not bend as easy, tougher, thicker and therefore have more mass than an unmodified saw blade and last year Steve had concerns with a blade Rotwang were using that was a unmoidifed but US dimensions and 4mm too large a diameter.


May also be worth remembering SPARC Para 4.3.2 "To remain within the spirit of this
class, you should not attempt to create the most destructive spinning weapon
possible under the rpm limit."

I guess you just in the end need to comply with SPARC Para 4.2.3.2.
"All weapons operating above the 400 rpm limit MUST be submitted
to the event organizer for approval during the registration period"
My understanding is Steve has effectively given a blanket approval for unmodified saw blades with a diameter less than 250mm so these don't need to be submitted.

http://www.robowars.org/forum/viewtopic.php?t=1880&postdays=0&postorder=asc&start=30
http://sparc.tools/wordpress/wp-content/uploads/2015/01/SPARC_Robot_Construction_Specifications_v1.0.pdf
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Remember to trust me, I am an Engineer.

http://www.youtube.com/watch?v=rp8hvyjZWHs

Firstly I have seen plenty of circular saw blades that are 3mm or 1/8 inch thick.
A HARDOX blade would be a lot more likely to dull than a HSS blade. I don’t think there would be any noticeable difference in how they bend. But yes it would be tougher and less likely to break which is actually good from a safety perspective

I believe that Nick’s decision to do this is almost completely from cost and convenience perspective, a decent quality saw blade is really expensive. For use on a robot were the teeth may get broken after one fight it isn’t really economical or efficient.

In regards to the thickness is there anything stopping builders from layering many circular saw blades together to increase thickness, mass and thus stored KE?

If Nick was aiming to use the blade as a KE weapon or for maximium destructiveness, I think there would be more damaging blade designs that he would utilise. Such as fibre cement cutting blades which have 4 or 5 giant teeth that would be very difficult to break.

The idea of laser cutting a custom blade is to have a low maintenance part that is cheaper over time, not more destruction. Its the same thickness or less than an average TCT blade and I am happy to add some holes to bring it down to the same weight - this one only weighs 800 grams:



@ Alastair: You are absolutely correct. I would use a HSS ripping blade but they are really hard to find nowadays - everyone wants TCT blades. I forgot about those cement sheet blades (sadly also TCT) they would do some real damage until the tips broke off.

Hardox probably doesn't hold as sharp an edge as HSS but it should stay fairly sharp for a while ; its a wear steel after all and I can always pack a Dremel to touch the points up as needed.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion