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Crushinator


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Glen
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Joined: 16 Jun 2004
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Crushinator

Dug up all the photos taken of this lil crusho bot so here's a short build guide.

Andrew (dumhed here) built this in 2 or 3 nights after work before the 2016 vivid comp and I modified it from there for the nationals event as he got banished from the country for reasons we can't discuss here!

In short, he is a hydraulic crusher driven by an electro-hydraulic actuator (EHA from here) used as the tilt and trim for an outboard engine. The drive is a pair of 100w scooters run on 5s lipo.

It all started in 2014 building up to the nationals, i had the ram and thought perhaps i could make an open class crusher with it. Unfortunately and predictably it turned out heavy, so it all went on the shelf till now when Andrew built crushinator as a sportsman class robot.



The day before we started the build we commisioned a big old CNC plasma cutter that we had both built over the previous months and decided to build the robots with it as a test along with Angus' threser, repent. As you can see its worked well from the get go!



First up We cut new scooter drives that are a replica of the originals with a wedge cut out of the front to slot over the frame.




Next were the jaws and forks out of a supremely hard 6mm steel.




Drilling the holes out was not fun due to the steel being over 500 brinell + the extra hardness from the plasma cutting process. The carbide bosch drills got the job done without much fuss though. Andrew found pouring water over the bit as coolant worked good.



The frame goes together as such. 50x25 shs on the front and a 50x50 on the rear spine that all the electronics slide on to. The drive pods weld to the front bar.



Starting to look like a robot! Working on placing the ram rear mount. Also you can see the pressure gauge we tapped into the ram to experiment with. I believe max pressure we achieved was about 2200psi.



The end of the first build night! Andrew was working on crushinator as i fabricated repent was a really hectic time indeed. Crushinators rear actuator mount is 6mm flat bar welded on the sides of the spine tube. The electronics access holes still had to be cut in the top and the electronics tray made here.



Test drive time Smile



And about there is where we got too tired / busy and stopped taking photos lol, but He did quite well at the event. The robot is really well balanced and drives great with the scooter drives, however it had some teething issues as is to be expected of any robot.

Mainly the pump would lock up sometimes and the drive pods were too weak, getting bent by citizen flips. The drive pods were an easy fix as he was nearly a kg underweight, and the locking up hydraulics was due to there being no retention method on the brushless motor. as pressure built up in the pump it would push the motor shaft out of it making the lot loose drive i suspect.

So on that it's time for the rebuild i did. Andrew was supposed to do it but had to go overseas during the time allotted so I got ditched with his ugly baby!

First lets have a look at the hydraulics as this part gets lots of questions.

Here is the complete, original unit. the pump is the protrusion off the right side of the motor. This has all the valving and the pump gears themselves in the bottom. The shiny part above that is the reservoir to store the addition fluid and above that the drive motor itself. The original was a bit like a 100w scooter but was totally gutless, easily stalling. The biggest motor hobbyking sold at the time, aka the 63mm sk3, does not have this problem! Smile

The way the pump works is via a series of one way ball check valves and by reversing the pumps rotation via the motor. This way all functions of the system are automatic needing no complicated solenoid valves and the like. The inner workings are shown later in the post.



Note there is a small threaded hole on the side of the reservoir. This is for the secondary piston reservoir to be plumbed in. The 2nd reservoir is needed as the whole system must be devoid of air in order to operate inverted and not suck air into the cylinder while the robots being tossed about. Inside the piston reservoir is a ... piston Razz with compressed air on one side that is applied with a schrader valve and the hydraulic fluid on the other side.

This is all needed to account for the difference in volume the cylinder rod occupies. There is no real pressure on this part so it's quite light. You may see it mounted on top of the actuator in the earlier pictures. We will revisit some mods to the hydraulics later. For now the rest of the mods!



Not many items had to be fixed but work was flat out and this was all done in two work nights and a weekend, so still quite crazy.

First mod was to change the drive setup. Instead of running the scooters like stock with the motor pointing outward, the motor was flipped around and the brake drum removed from the wheel, allowing the entire setup to be condensed a substantial amount. This allowed about 30mm from each side of the frame to be cut off while still keeping the same wheelbase. Saved a lot of weight too as well as protecting the motors better. The tensioning of the belt was done by moving the motor in slotted holes instead of adjusting the axle position as per the old one, the inner plate made 0.5mm thicker and the outer one was eventually changed to 6mm hard steel.

The inner drive mounts are cut in this photo but the outsides are MDF templates. Initial plan was to make them both 3mm but i ended up going for webbed out 6mm super hard steel ones Smile



Additionally to stop any flexing, 25x25 steel angle was welded onto the rears for cross bracing. This made a major difference for sure. Additionally the work on the jaws had started here. Having two jaws on the original effectively halved the power and caused the jaws to splay apart, so they were formed inward to make one tip.

The plan was to notch the insides with a grinder and bend it, but even ground 90% of the way through the stuff was unbendable and ended up snapping. So the broken section was cut off and the lot welded and blended together.



To make the jaw strong enough to stop the tip twisting out - a brace was welded in the top and bottom. Plasma cut of course! Happy i got it this close by basically eyeballing the measurements in cad.



Welded and blended. Saved a nice chunk of weight doing this as well.



Now back to the drive pod sides. I mulled on the pattern all night but recalled I'd long ago downloaded a topological optimisation program and gave it a go. The results looked really visually appealing so i squared it up a bit and went with it. The look was definitely that grungy earthmover style I'd wanted.




Test cut the first piece from 1.2mm ali to make sure the plasma was all calibrated and good to go before running the two main pieces as i only had enough metal for exactly two D: Fortunately they came out perfect.




Frame more or less done minus some tabs for parts. Getting the pods lined up was a real prick after a couple of work drinks that friday, lol. Took at least 3 goes to get one side done Embarassed



Being the license-less pleb i am, the robot came home with me on the train for the weekend.



In order to start finishing off the new hydraulics! The original pump motor was frankly, a gigantic waste of weight. the motor didn't even change speed at max pressure and the whole setup was shockingly heavy, thus we changed it up to a much smaller SK3 motor with a lighter, smaller reservoir body to be made on my new CNC mill.

The original design was supposed to integrate the piston reservoir into the main one so there was no external parts, but this was complicated to get working on the short time frame that was available and not really any lighter..

Here is the main pump body milled from a block of 80x80x80 6061. The end mill isn't long enough to do the entire thing in one pass so it must be flipped and held in a fixture.



Next the extra stock is bandsawed off. Before starting i went crazy on the bandsaw after having it work like crap for years and modded it to the extreme. Fortunately it now cuts super straight and quick. Epic.



The Remaining stock that was bandsawed off gets milled into the fixture. 4x m6 tapped holes plus a central stub to hold it snugly in position.



Bolted down and ready to hit the go button. Always a time worthy of some clenching. Hngg.




Yay! As expected the lines didn't quite join up top and bottom as it was just aligned with the mounting bolts and not pins, but was damn close. Good enough.



Haven't got pics of the top but that was milled and the motor holes put in. The pump typically would have dowty seals under the mounting bolts but i lost them - so we just pooped this grotty old gasket sealer under them which worked amazingly?

There's an oil seal on the shaft under the large locking collar that stops the shaft pulling out of the pump like at vivid. The shaft is also custom grade 5 titanium! Confusingly it was half the price of standard drill rod. Alrighty then.. The shaft goes into one of the pump gears, driving it with a pair of flats.



As the motor is actually wound for 5 cells vs 12 of the large one - the power is probably about the same despite the weight being so much lower. Sure it will get hotter but it's only intermittent.





All the hydraulic system parts, cleaned and ready to assemble.



This is the valve block bolted up. The raised island on the left is for the pressure relief ball valve. The rightmost one is the manual release valve (if the motor dies and you need to raise your out board motor for instance). The two holes partially occluded by the base of these raised islands are the inlet and outlet for the actual pump itself.



And the inside. The dark coloured seat on the left with the ball on it is the pressure relief. If enough system pressure builds in the pump, it unseats and allows excess pressure to bleed off into the reservoir. The two balls in the slots above it are for the extend and retract feed into the pump itself, whose wear marks you can see in between. These balls roll in their respective directions to block or uncover a hole into and out of the cylinder / reservoir.



Now despite cadding this whole lot to mm accuracy, i dun goofed and drilled the motor holes 45 degrees off basically due to fatigue lol (sure). Meaning the bolt heads touched the raised islands and the pump wouldn't bolt down all the way. Being the lazy entitled shit i am, instead of changing the bolts to countersunks i just milled the top of the valve block off in the cnc to clear.



It worked Smile Here she is all in place. Very nice.



The last day was very blurred so i didn't get photos. But all that was done was to weld a tab on to mount the piston reservoir lower in the body and a mount for the power LED / removable link.

Also threw on some additional 3mm steel bracing on the drive pods and 5mm hdpe top covers to protect the wiring more than anything figuring this is all it would have weight for. Turned out the little sucker was still 600g underweight? HOW??

Very happy with the look. Half bulldozer half snapping turtle Smile




Having discovered that on the last night it was quite underweight, decided to have a go at making a self righting system, which didn't quite get finished due to just being buggered haha.

Its a 3 stage drill gearbox from my old robot demon, retaining the stock clutch system of the drill but with a much stronger spring to account for the increased gearing. I'd decided to put a tiny NTM motor on there with an AFRO 30A esc flashed with simonk reversing firmware.

The mods required lathing the shaft to accept the drill pinion and making a new rear motor plate for the NTM. Total weight is 450 grams. Will try install it for the next event anyways Smile





Thanks for reading and hope that made a bit of sense! First time using imgur too so apologies if any formatting is messed up.
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Post Sat Aug 27, 2016 12:46 am 
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shakesc



Joined: 14 May 2012
Posts: 61
Location: UK


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Loving the build, keep it coming

Post Sat Aug 27, 2016 7:17 am 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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Fantastic build thread - having Crushinator latched on to the back of Sawnado was a scary sight! Did you have any trouble turning down the out-runner motor shaft? I'm worried the shaft will bend when I try it.
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Post Sat Aug 27, 2016 11:35 am 
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Ondray



Joined: 06 Jul 2015
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Nice - I was curious about how you made the beak.

Post Sun Aug 28, 2016 7:08 pm 
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Glen
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Joined: 16 Jun 2004
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Location: Where you least expect


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Cheers! ^^^

quote:
Originally posted by Nick:
Did you have any trouble turning down the out-runner motor shaft? I'm worried the shaft will bend when I try it.


Yeh it was a bit of a worry, but with minimal stick out and hand feeding the tool gently the task wasn't so bad. I used a carbide tool as its what i had on hand but a sharp HSS is probably better.
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Post Sun Aug 28, 2016 7:18 pm 
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Cpnwolfe



Joined: 29 May 2012
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which afros and which version of the simon k did you use? for the selfrighter?
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Post Tue Jan 17, 2017 2:51 pm 
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miles&Jules
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Just read this-unfortunatly we missed the event -but the build discription is brilliant as usual 😎
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Post Sat Mar 04, 2017 5:24 pm 
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