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Warbros - Andre NSW
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evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


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Looking good, it's great to see it moving. Are you going to put some skids front and back to stop it rocking?

Post Tue Apr 26, 2016 6:57 pm 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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As much as I like being a hardcore rocker, yeah I'll put some chopping board down to act as skids. HDPE has a nice low friction co-efficient and it should allow me to drive inside without scratching the floor Smile

Post Tue Apr 26, 2016 10:11 pm 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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This weekend saw the arm mounts go on! I wound up making and trying two different mounting options, one high and center on the frame with a 1:1 ratio and the other lower and towards the front with the 2:1 reduction.

The arms are made out of some scrap steel from the good old council cleanup Smile I got to do some angle grinding and heating up steel to red hot with a blowtorch so I can bend it - lots of heat and sparks - I actually felt like I was doing some metal work!

Attempt one looked like this:


The shaft the arm sits on is some M8 rod, which goes through some flange bearings in the small steel section which houses the sprocket. The sprocket is held by a grubscrew, which will need a good recess to be made to reduce slipping. For the moment the arms are pinned between two nuts, this will be upgraded to being welded to the shaft when I get a chance to visit dear old Dad.

The discovery from this test is that the 'low speed - high torque' window motors are much faster than I expected. I couldn't get a feel for the torque without the arms being welded because the nuts just unscrewed, but based off how quick they were swinging I don't think it'd be enough torque for lift. But this wasn't a problem I hadn't anticipated - which is why I ordered some bigger sprockets as well. I can put the shafts lower and closer to the front to run shorter arms with a 2:1 reduction which will hopefully give me the lift-grab I want. Failing that however I can go to an axe style bot, which part of me deep down would prefer as it is more destructive in intent Smile So at some point this week there will be a trip to the hardware store to get some cold chisels to use as the axe head...

The low front brackets look like this:


And the chain setup looks pretty (will be prettier once I put the washers in to align the sprocket better and cut a bigger hole in the Al) :


The two arms options side by side:


The arms are not their final length yet - I kept them as the full length of steel so I can cut them to the desired length once I've settled on a design. I think I'll take both options to fully made, then choose moments before each fight. I've got the parts and they're real easy to swap out. I'm currently planning on making the top mounts into a dedicated axe weapon and making the bottom ones the lift/grab. I will stick with the lifters as the primary at the moment as that mount is more sturdy. Though I do like that this design allows the axe to reach in front of and behind the bot, and work while inverted!

I also made a stand for the bot, and starting putting the skids on, it's getting close to the polycarb covers going on and being ready:

Post Mon May 16, 2016 10:13 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


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Wow, that's really coming together well. I like the modular weapon idea!

Post Tue May 17, 2016 10:13 pm 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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The modular weapons is more because I don't know what will work until I'm able to weld it - which will be next weekend. So I'm doing what I can for all the options so I'm ready for welding and testing.

This weekend I got the polycarb on and worked on the weapons some more. With the skids on I was able to do a good test drive, and after fidding with the settings to get it turning the right way it drove really well! The nice scratch free polycarb is hard to see, but it protects the electronics nicely:


And the weapons, I've got a chain to attach a flail head (dont know what to use yet - I do have the towball from the old volvo, but it may be too heavy). Then there's the cold chisels which bolt in between the two arms where the chain goes in, then I've got two lifting arms and a grabbing arm...Maximum modular!



The to do list is getting short, but it's still significant, the most important (and proving to be more difficult than I thought) is the master switch/power light. I'm up to my 3rd iteration, the plan is to use an M5 screw tapped into some chopping board to join two pieces of copper. The latest one seems to work, but it's not as sturdy as I would like so I might remake again if I get time. Otherwise I've got a switch from jaycar that *should* handle the current. Also have to shorten the cords to make it neater and put the weapon locking bar on - hopefully I've still got time to polish it!

Here's the dodgy switches:

Post Sun May 22, 2016 10:35 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


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After looking at different options for the power switch I decided to go with a removable XT60 link. Nick was nice enough to print a base on his 3D printer and post it to me, but you could also use this one from Hobbyking. The rocker switch I'd be really worried about being knocked and switched off, if you're going to go with a Jaycar bought switch I'd go with a chunky toggle switch or, probably even better (and what I was considering at one point), a battery isolator switch.

Post Sun May 22, 2016 10:52 pm 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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The rocker switch is a last resortish backup, I am worried about it turning off in a big hit. That jaycar one you've linked looks good, but I bet it's not in stock at the newy jaycar...maybe supercheap will have them.

But I think with a rebuild my homebrew switch will be ok, I just need to make it bigger so I can put some bolts in to hold it together instead of just epoxy.

Post Sun May 22, 2016 11:23 pm 
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Knightrous
Site Admin


Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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The 12V 75A Push/Pull switch from Supercheap Auto is a suitable switch.

http://www.supercheapauto.com.au/online-store/products/SCA-Switch-Push-Pull-Off-On-Heavy-Duty.aspx?pid=120383&menuFrom=1021621#Recommendations

If you mount it in the robot so the push knob of the switch is on the outside, you can set it so the knob keeps it locked in the on position. When you want to power the robot off, you unwind the knob a bit and then press the switch in.

Andrew A used this on Sproing and it worked really well and survived some bit hits against Jolt without any issues with the switch.
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Post Mon May 23, 2016 9:24 am 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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It's getting so close!

The master switch is sorted, I went to supercheap and bought a key operated battery idolator switch - but it was too big with the key in! (they didn't have that push-pull switch in stock) I was hoping the key would come out after it was turned on, but no such luck and the thought of a big flappy key sticking out to get knocked off was unbearable. I pondered on cutting the key down and putting a screw in it but decided to try my homebrew key again first and it worked quite well:



The screw goes through to a piece of copper between the two pieces of chopping board and completes the circuit.

On the weekend I went out to Dads place to make use of his self proclaimed welding prowess on the weapons...I think he may have been retired for too long now, I might pay someone to do it next time:



It doesn't need to be pretty - it just needs to be shiny!

But it was nice to get the family involved. The welds should hold for vivid and if they don't I've got 3 weapon configurations to make use of lol. Just needed to paint them red and it's like it never happened...



I also 'shaved' the wheels, it really annoyed me that only the center ridge of the tire was in contact with the ground so I got a planer out, turned the bot on, locked the wheels on and flattened the profile:



Tonight I got some pool noodle from kmart and made some protective covers for the weapons. I also discovered my 'elegant solution' for the shortage of mixing channels on my transmitter. I bought a v-tail mixer to get it working but when I was looking through the transmitter to change settings back after the 'shaving' I noticed this:



V-tail mixing in the transmitter! Just under mixing options, who would have thought! I had to change a few settings because the v-tail mixing only done channels 2 and 4 but 10 mins later and I didn't need the hardware v-tail mixer anymore! I'm going to count this as a win because it made the hardware in the bot simpler and made the bot lighter Smile I'd chuck in a progress photo of the bot but it's in half a dozen pieces for the painting and polishing. Only other thing I need to do is put in the weapon locking bar and it's sorted!

Post Mon May 30, 2016 10:55 pm 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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Fin.



Actually not quite - still had to add the most important thing:


I done a little testing and smashed some holes in a milo tin, tested the self righting and inverted driving (I took a vid but it's too late for me to want to wait for the upload). Still need to test the other weapon config, but that's for Saturday.

And the safety gear:

Post Thu Jun 02, 2016 11:15 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


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Damn, with those googly eyes you'll be unstoppable! Very Happy

It's looking great, can't wait to see it up close.

Post Fri Jun 03, 2016 8:35 am 
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Ash



Joined: 27 May 2016
Posts: 9
Location: Tasmania


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I love the size, it should be a very difficult bot to dominate unless an opponent can out power it and then there's that lifting fork!

Good job.

Post Sun Jun 05, 2016 9:11 pm 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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Thanks Ash, but turns out they didn't need to dominate me but just wait for my wheels to fall off Smile

Seriously though despite 1:3 win:loss I was super happy with the performance of this bot.

Won my first fight against a fellow newbie - charged straight at his flailing chains thinking they would only do superficial damage but they took both of Hellamax's eyes out! Fighting blind, still managed to get some good hits into the wooden armor. At the start I said I was aiming for the battery, but in the heat of battle I was just going for center body mass. After a good bit of biff the other guys drive motors failed - I think those big tires were too much for the little motors. As he was getting counted out I went to do a victory spin and watched both of Hellamax's wheels fall off lol. So it went to judges decision and I done more damage. I did lose an eye permanently though so it was replaced with an eyepatch...YARR!

So frantic upgrade to the mounting system for the wheels during the break for the next fight against Angus's Repent - the OTHER flailing chain bot of the night Smile So with the confidence in Hellamax's armor cemented I just went straight at him and was going ok, despite the eyes and endcaps being completely ripped off. At first the problem was the height of his bot meant at point blank the arm of my axe was hitting instead of the head. Next problem was a drive wheel slipping. Next the power failed - turned out the solder came off the master switch - doh! At least that was the only time Hellamax was counted out that evening.

So the bigger break meant a busy overhaul of the drive system and fixing some soldering. I was using a lazy method of locking the drill motor clutch and just holding the locking pins on the ozito drills by screwing the clutch spring holder on without the spring. One of these came loose so I ripped it out and put some grub screws in. I also had to pin the wheels onto the axle properly - I was just using the shaft threading into the plastic of the wheel to transfer power - it stripped. So I had to drill and hacksaw some space for a pair of washers to pin them in place - only got it done a few mins before the fight with Brutus.

And what a great fight I was! With the drive sorted it meant I had a full round of glorious axe vs axe biff Smile Hellamax took quite a beating (see the damage pic - mostly from that big black axe). This fight was where I learned an unforeseen benefit of this design - when in a bad position I could use the weapon to 'roll' away and re-position myself. Handy when I was stuck copping a pounding and the wheels weren't contacting the ground. But still wasn't enough to gain the judges favor - Brutus clearly done more damage, though the 6mm polycarb held up impressively. There was one point we all thought it was penetrated, but it was still intact Smile so Razz to all the polycarb naysayers.

Quick tightening of the drive system, charge of batteries and googly eye glued back on Hellamax was ready for the last fight against Voli...so fast, so much under bot. I knew exactly how this fight was going to pan out before I went into the arena. Hellamax was not built to be close to the ground, maybe if I had time to put my lifting arms on I could have put up a bit more of a fight, but only a bit. The disadvantage of a big bot is being an easy target for a small fast bot like Voli. But still I got some hits in and left a couple of marks so there's that. Also the ability to roll off using the axe proved useful. Lasted the 3mins, one wheel was a bit slippy toward the end but I could still move. Biggest problem in this fight that was only a smaller problem in the previous slower paced fights was that when the axe was 'cocked' if it was cocked too far it dragged on the ground or even pushed the wheels off the ground making driving hard to impossible - and while I was fiddling with the axe Hellamax was getting smashed from every angle. The axe also seemed to be jamming a bit, I think with thing bending over the course of the night the chain was becoming loose enough to bunch up an jam in the chassis. Either that or the locking mechanism on the window motors was playing up - will need some testing.

Then the rumble Smile With once drive wheel on only half working I couldn't do much controlled movement - but I didn't need to! Hellamax just bashed everything that came withing reach Smile Got into a good little scrap with First Pick early on, got flipped by citizen flips - incidentally my biggest 'worst case scenario' for Hellamax getting massive damage was getting thrown into the air by a CO2 flipper and landing in its weapon ripping the dogey mount system of the chassis and taking half the electronics with it. Well Hellamax was thrown into the air and landed on the weapon, but held up perfectly Smile Only to get tangled on Twitch and spend a couple of mins spinning around in the middle of the arena lol. Got off, got some more hits in only for it to end all too soon Sad

So - the damage:


The two left pics are the brutalizing from Brutus and the top right shows the cracked weld on the chisel, Dad's welds survived the night!

So, positives:
- The weapon done a nice amount of damage.
- The invertibility was a boon.
- The weapon attacking front/back and upside down was great
- Being able to get out of bad situations using the weapon was super handy.
- It looked great (if I do say so myself).
- The chains stayed on almost all night, and even with one down the axe still worked (though noticeably weaker).

Negatives (or to be improved):
- Wheels. Not. Wheeling.
- The weapon dragging and pushing the wheels off the ground.
- The slack in the weapon chain made fine control impossible.
- Center of gravity being too far back when the axe was cocked to get good traction. (I figured out toward the end of the rumble it actually drove better backwards - when the center of gravity was where I intended with the lifting arms)

So first thing I'm going to improve is making the axe head not drag in the 'cocked' position. It's still about 2kg underweight so I'm thinking of adding another pair of wheels to the back to go 4WD and to have some support for when the axe is cocked. But before I go smacking more wheels on I'm going to make the current ones reliable. I've already got plans in my head for better wheel locking system and a feather for nationals - which really isn't far away...

Post Wed Jun 08, 2016 11:35 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 304
Location: Adelaide, SA


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Awesome write-up, I'm sorry to say I didn't really get to see much of your fights (hopefully they end up on Youtube soon).

Regarding the wheels, speaking to Angus reinforced the importance of squeezing them between two washers on the drill shaft. I'm messing around with that now with the white wheels as I don't think I'll have time to massively redesign the drive system before August.

Post Thu Jun 09, 2016 8:21 am 
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Ondray



Joined: 06 Jul 2015
Posts: 142
Location: Newcastle


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Yeah the pinning the wheels between washers - that's why I was frantically hacksawing and drilling in the bigger break - to make space for the inner washer on my frame. It's what I had for my last two fights - it held up against Brutus but still wasn't enough to last the rest of the night. I also need to pull Hellamax apart to see why the wheel failed this time. Maybe if it's done up tighter that setup will last but I still want to see if I can do something better. I've got a couple (ok a dozen) spare drill motors and a couple of spare white wheels so I'm going to try and get something better made up - especially when I think I want to use the same wheels on my feather design. I will post the progress.

And yeah - the write up - call it (mad) scientific habit Smile I only got to see a bit of your first fight, in fact I think I only saw the first two fights all night - I was so busy doing repairs lol so I'm also looking forward to the vids.

Post Fri Jun 10, 2016 12:22 am 
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