Printable View
That looks beautiful! Ellis is right if you can get that within the 13.6 Kg limit then you can come and play in both competitions.
Going for rear wheel drive only will save weight so that could get you inside as well as making sure you make your pneumatic ram as light as possible.
Keep going, it looks amazing!
you keep mentioning the weight limit as 13.5kg when it is 13.6kg so.......extra 100g to use :)
Ahaa :oops: well 100g could make it or break it, so that to my advantage :D thanks for pointing it out!
been looking ways to attach hdpe together and from what I can understand, the best method apart from fasteners is welding. I've got no plastic welding equipment so I'll try to fiddle with what I have - my idea is to pass a small gauge wire in the ends to be welded, then press the ends together and connect the wires to a battery, the wire should get hot enough to melt/weld the ends in theory. Anyone tried something similar with some success? I'll give it a go tomorrow and see what happens :roll:
http://i8.photobucket.com/albums/a49...Untitled-1.jpg
Maybe give it a go. I think you'll find a blow torch more effective. Although DIY plastic welding is better for repairs than structural joints.
Possibly using tongue and grove joints would be stronger; or just mitre and bolt the corners.
Actualy, the wire idea is being used in industrial piping welding processes. But that requires some expensive machines. It's ment to weld tubes and connections together.Quote:
Originally Posted by Liftoff
The tool I used was a combination machine. A mirror welder but with attachments for wire-welding.
For mirror welding (the mirror is a polished stainless steel plate). Put the tubes in the hydraulic clamps. Scan the barcode of the parts. The parts get pressed at a certain pressure against the mirror. The mirror gets heated to a certain temperature. When the parts have the temperature desired, the mirror is withdrawn, and the clamps press the parts together. Never seen neater butt-joints.
Wire welding requires elbows and straight connection pieces with the wire in them. But the idea is about the same. Push the cleaned parts together, align. Push the wire-connectors from the machine on the studs on the parts, scan the bar code, and press start. When the buzzer sounds, it's ready.
On HDPE welding equipment. After a few failed attempts with cheaper hot air guns and self build nozzles I got myself a second handLeister Triac S. Still not cheap.... But worth the investment. As the Hannibalito's demonstrate.
I have tried welding with this method before, the joint is always very weak. A routed joint and bolts is the best way. If you want to try the welding, for best results place your wire (very fine gauge) with 3mm spacing across the whole joint. This then will be the same as spacing on the pipe joins (hdpe gas pipe)
just finished the experiments, and after lots of flying sparks, burning wire and melting plastic I managed to get some results :wink:
took some of the tips posted here and the end result looks good - to be honest, I'm really surprised by the strength of the weld, but having said that I did not try to break the weld yet.
started off with thin piece of wire
http://i8.photobucket.com/albums/a49...d/P1060582.jpg
and locked it in place with a soldering iron along the joint
http://i8.photobucket.com/albums/a49...d/P1060583.jpg
clamped it an connected it to a 6v battery (had to replace those thin leads as they stared smoking and melting in no time! A pair of jump leads did the job - they got a bit warm anyway!)
http://i8.photobucket.com/albums/a49...d/P1060585.jpg
Close up of the seam
http://i8.photobucket.com/albums/a49...d/P1060586.jpg
and finally a test - that's a solid block of steel weighing about 15kg, left it for 15min and didn't break... tried to shear it off with my hands - no good. But I think if I had to clamp it and hit it with a hammer it will give in...
http://i8.photobucket.com/albums/a49...d/P1060588.jpg
drop the block of steel on it, or hit it hard with a large hammer.
Impressive!
''drop the block of steel on it, or hit it hard with a large hammer.''
I had a go at it, hammer blows no good -it springs back (almost injuring myself in the process :angry:)
The ultimate test: myself standing on it ( now I'm no feather weight at 100kg!) no matter how much I bounced on it, didn't give way. It did get a bit bent though!
I'm really impressed - will surely use it on this build!
http://i8.photobucket.com/albums/a49...d/P1060589.jpg
Fantastic result! Looked relatively simple to setup, too. May have to try this!
Hmm, what resistance does that wire have?
I fear the 6V battery won't like welding HDPE this way a lot.
But congrats on those tests. I'm impressed.
I don't know the resistance, just used a strand from a cable, its 0.4mm dia copper wire maybe 25cm long. Totally ignored whether the battery likes this or not! I'm not much into electrics and wires, just basic knowledge, so I'll ask my brother if he can rig something, maybe a power supply? Seen him using one to operate the robot motors etc, adjusting voltage and current and so on - so I'll ask him before I fry his battery! :lol:
i would make sure the blade is wound in on that plane in the background a couple of pictures back.
it will wear out the blade if left like that.
you can sharpen them on a water stone(if I've not just made that up) or sand paper but i take it you already know that
nice attempt at welding :)
don't tell me you've noticed the position of the blade from the photo!
had to sharpen it a couple of times while trimming the edges of the robot this week - missed one screw and shaved its head, the blade didn't like it at all! It's really good on hdpe though when sharp.
Btw we use oil stones for sharpening over here, water stone could be something similar but I've never used one.
re. welding I'm happy with the result, makes it easier to attach parts where its difficult to use fasteners, wish I had tried this a bit earlier, it would have spared me a lot of sweat and swearing!
Looks perfect
A small update - Now the machine is almost complete, ready for the event this Sunday.
Testing and last minute modifications still ongoing but the results look promising :D
Pics and clips will follow after the event - thanks to all those who contributed by giving tips and advice, it was all appreciated!
Liftoff is now almost ready, finishing touches only remaining :P
It had its fair share of last minute problems, specially with the track drive, which insisted it wanted to go off to one side (cutting a nice groove in the HDPE sides), but that's now solved. The flipper arm was also a bit of an issue as we had no stopper installed and when firing the actuator it kept flipping and locking the arm open, That is solved as well.
Got to put the cover in place and get it dressed up for the occasion now :wink:
http://i8.photobucket.com/albums/a49...d/P1060878.jpg
http://i8.photobucket.com/albums/a49...d/P1060880.jpg
http://i8.photobucket.com/albums/a49...d/P1060883.jpg
http://i8.photobucket.com/albums/a49...d/P1060884.jpg
It is looking really good! I look forward to seeing it tomorrow as I am currently in Malta and bringing my spinner Inertia XL to demonstrate :)
Now that's a coincidence!! :o
Yeah, we'll meet up but, but not our machines.
Final adjustments ready, and its working fine now...more photos and vid clips after the event...
Back from this year's event of robot wars - with a very good result. All the hard work and late nights spent this week paid off as Liftoff made it to the finals and won the event :D
Now I need a break, tomorrow I'll be on the plane for a well deserved holiday!
The machines are getting better every year and is nice to see the competition evolving from simple rambots and wedges to more elaborate machines with movable weapons, having said that our level is still far away from you guys over here - we had the opportunity to see first hand a proper machine brought over from the Uk by Will Thomas - Inertia - it was really impressive to see it shredding a wooden beam, with no effort at all.
Some pics of the finalised build, and some from the event this afternoon:
Mostly finished here, added titanium armour to the sides
http://i8.photobucket.com/albums/a49...d/P1060888.jpg
and some more no the flipper arm, just an extra precaution as I know one of the competitors has a bar spinner which might get stuck in the HDPE
http://i8.photobucket.com/albums/a49...d/P1060890.jpg
Top cover installed - now it looks almost complete.
A planer blade at the flipper tip gives us a high probability of getting under everything. It was a nightmare drilling through it as its 3mm HSS, but a couple of spade drills and a lot of sweat later I managed to put three holes through it :D
http://i8.photobucket.com/albums/a49...d/P1060893.jpg
Liftoff and Inertia side by side, Flipper tip covered after someone cut his hand against it :angry:
http://i8.photobucket.com/albums/a49...d/P1060898.jpg
http://i8.photobucket.com/albums/a49...d/P1060901.jpg
http://i8.photobucket.com/albums/a49...d/P1060907.jpg
Final match, bar spinner Pacman could not reach us with the blade, it got flipped and that was the end of it
http://i8.photobucket.com/albums/a49...d/P1060909.jpg
http://i8.photobucket.com/albums/a49...d/P1060911.jpg
General view of the pits
http://i8.photobucket.com/albums/a49...z/P1060913.jpg
http://i8.photobucket.com/albums/a49...z/P1060915.jpg
First time I seen it snowing in Malta!! :o
http://i8.photobucket.com/albums/a49...04574679_o.jpg
Will and his machine Inertia
http://i8.photobucket.com/albums/a49...z/P1060917.jpg
http://i8.photobucket.com/albums/a49...z/P1060920.jpg
http://i8.photobucket.com/albums/a49...z/P1060922.jpg
And the winner after the battles were over - still like new hardly scratched :lol:
Will try to put it on a diet now as it weighs approx 17kg, and if I could get it down to 13.5Kg I could one day bring it over...who knows!
http://i8.photobucket.com/albums/a49...z/P1060925.jpg
Getting that to 13.6kg shouldn't be hard.
Question: Is that bent bar where the ram hits really necessary ? Would have thought it easier/lighter to have a flat plate across the top of the robot and you ram angled slightly (or are you unable to do that ? I can't tell what the ram looks like at the bottom really).
The robot looks great, congratulations on your event win!
Out of interest, did you run with tracks in the end or just rear drive wheels? If you went for tracks, I'd be keen to see a couple of pictures of them and their assembly if you wouldn't mind during a spare moment. It's something I'm looking into doing myself, and the more research the better :wink:
Original plan was to do without that bar on the actuator, but as we had no time to spare in re designing the thing we opted for what we knew worked for sure...but that is in my mind dave - to remove as much moving parts as possible...
As for the drive, its track driven...its a real pain though to set up, specially if you dont have precision methods of machining things...will give you a detailed description and photos of how it works later on...
(in about 10 days time... I'm off to the airport now :wink: )
More updates to come soonish...
A small recap of the event in Malta two weeks ago:
http://www.youtube.com/watch?v=3TPP2ZgZ8-8
Let me know when the next event is, i would be willing to fly over and have some fights with cobalt
you could use Cobalt against that piece of wood just like Inertia did, or for you maybe a steel tube will be more fitting :wink:
want to fight robots not peices of material :)
I know, I know... :lol:
I doubt any one would fancy a fight with cobalt tho! But maybe one day we might create something which can take a good fight, next event is in a year's time...in the meantime will try to get Liftoff in-line with FRA rules just in case we could come over :roll:
A couple of short clips - final stages of flipper testing
http://i8.photobucket.com/albums/a49...d/th_00008.jpg
http://i8.photobucket.com/albums/a49...d/th_00012.jpg
We were testing that at around midnight as we were quite tight on time, at one point we wanted to throw something in the air just to have an idea if the throw was strong enough. So I set the regulator at 6bar, took the machine out in the front garden and put a 2L water bottle on the flipper edge... and gave it a go... that threw the bottle one storey in the air and almost over to our neighbour's balcony! :o
Monday will try to find time to open up one side where the drive system stays, take a couple of pics and post a description of how we got it set up. It was a real pain to get it working, and we ended up with an emergency set up - it worked but I'm not happy with it, so it will be modified for sure - or totally eliminated and replaced by wheels...
Found some time this morn to open one side of the track drive and took some photos of the internals as promised - Any questions or suggestions for improvement are welcome :wink:
I took quite a lot of photos as they speak much more than words and makes it much simpler to explain.
A quick description of what we used and how it works:
General view of the bottom sides with all parts assembled
http://i8.photobucket.com/albums/a49...d/P1070419.jpg
First to go is the titanium armour plate, this plate also acts as and end plate for the forward roller pin..
http://i8.photobucket.com/albums/a49...d/P1070420.jpg
Next to go is the HDPE side - the hole at the forward side holds the shaft of the forward roller. The hole in the middle was the hole for the tensioner, but that was later discarded.
http://i8.photobucket.com/albums/a49...d/P1070422.jpg
This is a view of how it looks from inside - pretty much simple, the large wheel connected directly to the drive motor, turning the tracks around the forward roller, the track slides along the bottom face of the machine which ensures even and full contact between the floor and the tracks. This eliminates the need of complicated rollers and other stuff you normally see in a tank drive.
http://i8.photobucket.com/albums/a49...d/P1070423.jpg
It was not all plain sailing though, we started off by machining a pair of drive wheels out of Alu. The outer surface was knurled for better grip, but we found out it was not enough in testing phase. It slipped of the thread - most probably bec the knurling used was not coarse enough, so we coated them with a material similar to the threads themselves and that was one problem solved.
http://i8.photobucket.com/albums/a49...d/P1070425.jpg
View of the coated drive roller. It was a pain in itself to machine it in 2 parts to save from machining time and material costs. Its hollow from the other side so that part of the motor can fit inside the wheel, that saved about 10cm from the overall with of the machine
http://i8.photobucket.com/albums/a49...d/P1070428.jpg
This is the HDPE side plate which holds the forward roller in place and pretty much also holds everything in place :roll:
It took quite a beating, infact from the photo you can see that the threads ate away into the sides and sliced a groove. The problem here was that we did not allow for adjustment of the rollers, and without any precision method of drilling perfectly aligned holes for the rollers, the thread is bound to move to one side or the other :cry:
http://i8.photobucket.com/albums/a49...d/P1070424.jpg
The solution had to be a quick fix one as time was running out (we did that 2 days before the event!)
I milled about 1.5mm of the hdpe sides with a router and inserted those two pieces of stainless plates, hoping the threads will slide against them. It worked, but from the photo its visibly polished where the belt was rubbing.
http://i8.photobucket.com/albums/a49...d/P1070435.jpg
This is the thread, its quite durable, having been used for these last four events and survived is a remarkable feat!
We had it made at a local shop which sells conveyor belts, it is sort of got two layers, one canvas at the bottom which looks like bonded in some way, and then a rubber coating is moulded externally.
We always debate between us which is best to have for better grip - a thread with a grooved rugged surface (like we have) or a flat smooth surface? We never came to a conclusion as we tend to accept only physical evidence not theory! :lol:
http://i8.photobucket.com/albums/a49...d/P1070432.jpg
The forward roller...
http://i8.photobucket.com/albums/a49...d/P1070426.jpg
Another issue is the amount of tension to put on the thread. The more you tension the more current the motors will draw. On no load with nothing attached the motor was drawing about 5A. When we put the belt on and tensioned the thing first time, it was drawing about 20A :shock: - that is free wheeling back side up without touching the floor! After reducing the tension and fixing the sides for better slipping of the tracks the current dropped to about 11A.
http://i8.photobucket.com/albums/a49...d/P1070433.jpg
So thats it, if you had to ask me is it worth using tracks I'd say - not really, they're good for looks and for the sake of having a tank like machine but otherwise I think its a hassle, I don't really see an advantage.
Having said that I still do like the track drive, and before giving up on it I want to give it another try - this time I'll make the fwd roller tensionable, and adjustable so that I can adjust the tension and align the belt with the same mechanism...already got a plan for that, but its still in my brains...need to put it on paper and then on to metal! :wink:
Sorry for the long post - hope you find it interesting
That is brilliant! I have wanted to run tracks on a machine for ages and all I could come up with was using double sided timing belts which are horrendously expensive.
That has given me some great ideas for machines!
An idea that might help to tension the belts is this...
http://www.popsci.com/files/imagecache/ ... iagram.jpg
http://www.popsci.com/invention
The machine uses a moving front pulley to keep the tracks in tension so even when the suspension compresses it stays on. Its basically sprung and runs in a grove. That could easily be implemented on your machine with the space you have.
I would't say we spent a lot on the tracks, can't remember off hand.
Re spring tensioning its a really good idea - we had thought about it but couldn't figure out how to do it in at the time...it has to be something compact as even tho space looks abundant, its still tight.
I had thought of using a gas dampers as a tensioner like this... they are 150N each, think they'll work?
http://i8.photobucket.com/albums/a49...d/P1070440.jpg
Next step in this build is to go lighter and get it in-line (as much as possible to FRA rules)
This means that from 17kg Liftoff must shed at least 3.6kg (quite a lot!)
The single heaviest part of the machine is the flipper arm, then the motors, and then the pneumatics...
The motors weigh 1kg each - if I get to replace them by two Gimson GR02 I'd save more than 1 kg.
The flipper arm is a problem, at the moment its 1 square section 1.2mm thick, its quite heavy...don't really have much options, never seen titanium square section, so next option is aluminium.
Think I'll use alu square section 1 by 3.2mm thick 6082T6 but not sure if its strong enough as I need to put some welds to it as well :? And besides I have to calculate the weight lost bec if it's not too much it might not be worth while...
Any advice re aluminium flipper arm?
Right, its shopping time again! :D
Plans for the re-design in the final stages - mainly to do with weight reduction, believe me its not so simple eh!
I wouldn't like to order the wrong parts so my question : I'm downsizing the 5/2 valve from 1/2 to something smaller, will any size do? I'm looking at a 1/8 port size valve - like this
http://www.ebay.co.uk/itm/DC-12V-2-P...item53f148c741
Will it be suitable, I mean what else apart from taking longer to fill up the buffer tank should I expect?
As long it doesn't get liquid CO2 , it should work fine for a while.
And I'm sorry, for that amound of £ that seller asks, I can't even ship you one of the dozen Festo's I have here.
Yeah I know...its dirt cheap! :D in fact I just bought it yesterday
The 1/2 one I have was of a similar make and similar pricing and it worked fine...up till now.
It's not worth spending too much money on something you might end up changing just after a season!
I also got my self a replacement QEV. The one I have installed is a 1/2 but quite bulky and heavy (I think its brass or steel) Found this on ebay, its smaller and lighter and still 1/2 - might need to modify the outlet though as it looks like its 3/8
http://www.ebay.co.uk/itm/160930294213
I have got the latest version of liftoff drawings in the final stages before the mods start taking place - parts started arriving as well, got the GR02's from Ewan, really compact compared the the Makitas I had before!
The basic design remains very similar, and I'm using the same platform - what's changing apart from the motors and pneumatic parts is the orientation or the ram. It will now be in a horizontal position rather than vertical. I've added a self-righting mechanism as I have moved the flipper hinge forward and I'm afraid it lost this ability it had before. I'm still a bit sceptic if the mechanism will work - if anyone could look into it from these pics and see something wrong or any place for improvement, I'm all ears!
General views : Front side.
http://i8.photobucket.com/albums/a49...ps65b32c1f.jpg
Back side. Back cover I'm thinking about a polycarbonate panel, it would look really nice I think!
http://i8.photobucket.com/albums/a49...ps8fa5a42b.jpg
Top panels off - self righter linkage will be a nightmare I think :cry:
http://i8.photobucket.com/albums/a49...ps2a295733.jpg
Flipper and self-righting mechanism in action...
http://i8.photobucket.com/albums/a49...ps905e07b3.jpg
Internal components layout
http://i8.photobucket.com/albums/a49...psf101c5ee.jpg
I'm not an expert but I reckon that will work.
A few things I would change if it was me...
-Use a solid triangle for the ram to push against rather than the L shaped piece
-Give yourself 4WD by running a belt to the front, otherwise the weight out front will act like a massive pendulum making it difficult to steer
-Don't use the Sabertooth 50A [Unless you already have it] and go for TZ85A from Botbitz... Sabertooth's have a bad history in combat (But some people have never had an issue) Its hit and miss...
Besides that it looks superb! Its got this kind of cool angular look to it and has the guts to match!