Full Pressure Cutlet

Hi

I just felt i had to start a topic about this. I have downloaded both videos from the website and all I can say is F**KING HELL

Its brilliant. That hawker flew and the selfrighting is comic.

But that leads me to a question. Why use Full Pressure? Surely a 16bar ram with a larger bore would have the same force and use less co2. Admittedly this may not be as fast but look at m2 it uses 100mm bore ram in a heavy. If you put a 100mm bore ram in a feather at 16bar it would knock people all over the place. I am going with 63mm bore 10bar which is think is loads for a thrower.

What do you guys think?
Is full pressure the way to go?
Will i be out of date with a 10bar ram and high flow rate?

Regards
Ian Mc DOnald

If it fills your needs then it is ok you dont have to go the full press way if you do not want to. I still use 16bar in my heavy and i am happy with it long live low press flippers :)

rips low pressure, 10 bar with a big ram ... and ........ need i say more... it speaks for it self :)

Good design is everything. M2 is really really well designed and thought out, and its performance speaks for iteself. Full pressure or low pressure, if youve thought the design out then both should be equally effective (me thinks anyway:-)

However, I rekon if someone were to put the same kind of thought and planning into a FP setup that Paul Cooper put into M2, then wed have something pretty terrifying on our hands. Oh wait- thats gravity :-)

Seriously tho, buffer tanks and big valves for massive flowrate are the way to go. and the more efficient this (reletively) new technology becomes, the better! The future looks good for flippers, and not so great for arenas:-)

I think one reason for using FP is that it may be easier to fit in the the space in a small robot. I think Paul Cooper had this problem with TKM2 and switched from LP to FP.

delta, my new flipper, uses a 63mm bore ram at probably 10bar. its not just a case of power and speed, the shape of the flipper is very important. M2 works well due to its shape also Chaos2. I believe that cutlet has a good shape, this will maximise the power and make sure the other robot doesnt just keep sliping off the end of the flipper.

Mr McDonald Sir...... The answer to your question Why use Full Pressure? is BECAUSE YOU CAN!!!! hahahahahahahahahahah!!!!!

It just had to be done!

Thanks for the compliment, I have had a lot of fun testing and building it. Cant wait to get it in an arena.

Another reason for going that route was that I had tried a compressor powered Cutlet, and a low pressure C02 version. This was the obvious next step.

If you want my honest opinion of how to build the ultimate feather flipper, and keep within the 12Kg weight limit...... I think the way to go is low pressure with a well positioned in-line buffer tank, and very large piping/flow after the buffer all the way to the ram. Actually the preference would be to have no piping after the buffer at all. Just fittings with big holes in, and a large valve.

Cutlet 540 is restricted at the moment as I have not fitted the buffer tank due to the 12Kg weight limit. I may put it in at an event one day just for a laugh to see how many somersaults it can do!

Ian

A wise roboteer once said to me

Ed, just because you can do something - doesnt mean you should.

.... he was clearly talking bollocks

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

Guys as a question which would be cheeper:
1. A full Pressure flipper consisting of: Co2 Tank, Buffertank, Valve, Ram
2. A Low pressure flipper consisting of: C02 Regulator, Buffertank, Valve, Ram

I know the cheepest is good old fasioned air but interms of co2 which is cheeper based on the same things (i.e. same bore ram and valve etc)

Thanks
Regards
Ian Mc Donald

Depends on quality and wanted force.

Advantage of the LP system. Commercialy availabe parts.Easy to aquire cheap.
Disadvantage. Big and not neccesarely lightweight.More parts involved.

Advantage of a FP system. Simple and can be very small.
Disadvantage, all custom build parts,or expensive parts still to adapt.

If the parameter of thesame bore ram in hold, the FP system will be very expensive and overly powerfull.

Well, my full pressure flipper makes sense as far as i can see, in terms or price and weight. Effectivelly you have components of the same weight in each set up, but youve also got a regulator in LP, its cost, weight, and assosciated freezing probs. Weight is especially important as there arnt that many lightweight 10bar regs around that dont cost a bomb. You can modify some, but my respect (read: fear) of pneumatics is such that I dont trust myself playing around with springs in the reg.

For my full pressure set up, Im half way through building the rams now- surprisingly not as difficult as i expected, and the O-rings were the most expensive part, but Ive been able to build my 40mm bore, 100mm stroke FP ram for about £15.

Working back, weve got the pipes and tubes and so on. Really just a question of using hydraulic instead of pneumatic, and from the bufferto the valve to the ram Im using copper pipe due to increased bore and therefore to make the most use of the G1/2 orrifice on my valve. The valve is a burket- £95 from technobots. You can pick up low pressure ones from technobots for a lot cheaper- the low pressure equivalent (ie 2/2, G1/2) is about the £45 mark iirc. Exhast valve- you could use another burket but that would be silly- very heavy, and expensive, and you dont need the operating speed. Im using a stainless 3/8 ball valve from technobots (about 5 quid) and a servo to do that. weights nothing and only cost about £10. Furthur back youve got the buffer tank- I built this agaon, but that WILL have to be certified. I would imagine that costs tho I need to talk to mario on that one. Low pressure buffertanks you either have to blag or buy or build, tho everyone seems to be able to blag them. further back youve just got your hydraulic pipe from the buffer to the tank. thats nice and simple. And of course the releif valves and gas dumps and what not, but thats all detail :o)

In all Id probably say FP is cheaper, potentially lighter (tho bear in mind the extra weight of the rams and buffer and so on due to greater wall thickness). But obviosly theres the draw back of getting through lots of co2 very very quickly! And the usual health warning applis: dont do it if youre not confident you can etc etc. A common sense approach to robotics will keep you safe for the rest of your life. Hmm, thats puts quite a large number of us in danger :-p

One factor that has been missed above is that the forces involved in a FP set up are pretty huge....This means that you have to build the supporting structure very strong...this can often negate the weight saving that you thought you would make by going to FP in the first place!

Yes that too ;-)

Massive speed is an issue, and if you fail to flip something, the ram can get fairly upset when it fires up into its end stop and some scary speed. You can stick rubber and all sorts in there but it still will get fairly upset. Some calcs showed that my ram would fill in something around the 0.01 seconds mark. So you can imagine it slams open with quite a bang. but again sensible, well thought out designs are the key and you shouldnt have a problem if you keep that in mind.

And one more thing, another down side of a FP system is that you must prove your components are upto the job - no more using LP stuff on a FP system, or just assuming its upto the job.

When the FRA rules kick in (I think), pressure test certs will be needed for any untested equipment which could also increase the cost of the system.

i am using low presure on rebel (10bar)
its almost identical stuff to rip cept im using 32mm bore 100mm stroke.
i have a nice co2 bottle from mr jonno sir a nice ram from mr stu the reg im still sorting out and valve... and the buffer is a 600g canister.
hopefully the build will be over the crimbo hols and you should be seeing it in the new year.
thanks to all you who have bene helping me :)

one thing while we on topics of HP LP FP

FlowRate (mr stus new toy).. going away from ians superb fp feather which i have to comment on you loooon! i dont have enough money for a parachute!!! good job ol man! you really did ;)
but FlowRate... after seeing pics etc and seeing some of the stuff liek the rams. for a LP flipper its looking good. we will have to wait and see...
anyway good luck all and hope to see cutlet asap!

I must say its looking pretty fantastic. Piping so big you could crawl through it, G1/2 valves, really nice, low friction rams, and an excellent set up in terms of effeciency and leverage, it should raise the bar in featherweight LP pneumatics:-)

I like this what Ian said -
If you want my honest opinion of how to build the ultimate feather flipper, and keep within the 12Kg weight limit...... I think the way to go is low pressure with a well positioned in-line buffer tank, and very large piping/flow after the buffer all the way to the ram. Actually the preference would be to have no piping after the buffer at all. Just fittings with big holes in, and a large valve.

Hopfuly, if Ians statement is correct, and i have done the right things, and the right people have told me the right things = FlowRate should follow that stement from Ian.
Eds mentioned the stats so far, big piping, big valve, found out its the same valve that Dominator 2 and Kat 3 use for their Heavy Weight Axes. Big buffer tank in line with the valve, supplied by using 19mm Inner Diameter Piping.
Will see how it preforms soon.

Cut_Let 540 will have the power
But will it have the speed to flip a 12kg Feather higher than a High flow rate LP flipper? We know the difference from Dantomkia and M2. We shell find out in combat within the next few weeks.

Mr Stu

Looking forward to the future of featherweights...

with machines like cutlet 540 (is that a ref to the motors?) and my new (should be ready by Enginuity, possibly as early as Aberystwyth) flipper Whiplash (80mm diameter ram, 70mm stroke, full pressure with buffertank) the featherweights shold become event more spectacular that it was this fantastic year.

It can only be good for the sport.

How does this sound:
1.1kg Co2 Bottle Resevor
High Flow Rate Regulator
600g Dry Powder BufferTank
5/2 10bar Valve with 1/2BSP Fittings
80mm Bore 100mm Stroke Ram

All Running at 10 bar with a set up of 2:1 in movement

What do you guys think?

Regards
Ian Mc DOnald

Very Heavy!
1.1kg bottle does not mean its 1.1kg. It means it stores 1.1kg of Co2. The bottle is proberly about 2kg.
High Flow Rate regulator, - in a feather weight - again, VERY HEAVY! About 800g to 1.5kg. Yor 80mm bore ram 100mm stroke will be over 1.5kg. Your valve will also be over 1.5kg also. My 3/2 1/2bsp is 600g - and thats a special one i got hold of, a 5/2 will be very heavy.

Your 600g Dry Buffer tank - i bet thats 600g stored powerder, again it will weigh more.

Both RIP and FlowRate are pushing the weight limit BY ALOT already, with smaller stuff. RIP has a shell made out of 1.2mm Ti for god sake which weighes sod all for its chasiss. Rip does not even use a Buffer tank due to weight. Well also due to the high flow reg.

Also another thing - the idea of a Buffer Tank is that you dont need a high flow rate Regulator. Unless your Terrorhurtz. The idea is to have a buffer tank which fills your rams about 2 times. (FlowRates buffer tank can fill my rams 3.2 times)

Im sorrry Ian but - keep dreaming.
Using a 1.1kg Co2 bottle - u aint got a chance to start with.
Were all struggerling to fit 600g Co2 bottles in.

Message to James B - 540 is the amount of degrease it self rights - not motors.

Mr Stu

there is no way a 1.1kg bottle will fit in a feather. 600g bottles are too big, as the robot has to be big enough to contain it, but we have to make do!

the main problem the designing of delta is making the robot small enough to contain the bottle.

my 1.1kg bottle for my middle weighs 2.1kg EMPTY, also its about 40cm long.

like stu says keep dreaming!

Arr - i knew it was over 2kg empty. Nice to confirm Alan, Thanks.

Not dissing you Ian etc - like everyone else, just warning you now before you go into a hyper. I do it, everyone does it. You go into some sort of hype what everyting will work, then you start to do it and thing - oh dear. If thats either putting it on CAD or making it hands on as a prototype.

Like Alan Said - even the 600g bottles are too big really. They can just fit in after a push and lot of stpid weight used to make the bot big etc.

Mr Stu

I dont mean to dis you guys and i totaly respect your opinion and respect yous (after all yous have built a working feather) but i think if you do use a 1.1kg co2 bottle you would be unstopable. It would give you litterally hundreds of flips before becoming empty.

Am I correct in thinking that at the end of a fight the 600g bottles are usually empty?

Thanks for that tip stu I did not know that that was the idea of the buffertank.

My thoughts are:
You could build a fully driving and controled base plate for about 1.5-2.5Kg(Bosch 35w Motors, Electrolise Controlers, 12v 2000mah Ni-mh).

You then start to add the chassis to support such a strong flipper which is another 2kg ish. Thats give or take 5kg.

That still leaves 7kg for Pneumatics. 2kg for the 1.1kg Bottle leaves 5kg which I am sure is possible (maybe not with much armour but hey hey)

Maybe I am way wrong and if so Please feel free to say not a hope but Like Henry Ford once said:
Whether you believe you can or you cant, you are right!

Regards
Ian Mc Donald

Ian, your rather gueshish weightcalculations arent bad, but you will run in the Roboteers axomia.
Everything is bigger than messured, weights more than weighted,and costs more.

No, a 1.1 kg CO2 bottle is fine in a middleweight or a low powered heavy, but for a feather its way oversized.
And for yours.. even idioticly totaly over the top too bloody BIG.

Calculate with Uncle Mario.

1 Kg of CO2 is 500 L gas on 1 bar(I know its more, but I use 500 kg to have some room and not to make the mistake like in the early days -overentousiastic positive calculations)
550L gas on board then.
A 63mm diameter 100mm stroke ram uses at 10 bar 3.1 L of gas. The mentioned double acting system uses about double(minus rodvolume)so 6l each stroke. 550/6=91 flips.Now I would say, 70 as a good compromise, due losses in all the parts.
5 minutes are 300 seconds. so every 4.3 seconds you can fire your ram, the complete fight.

Now, we go for a armheight of 30 cm
this system has then a 100 kg lifting capability

Now, we go for the hypothetical BIG BOY on the block, a HUGE FP system bore 70mm stroke 80mm Full pressure ram.(single acting)
600 Grams of CO2= 300L gas
Gasuse each stroke 15.4L
19 actions. So 15 actions(this will be more, due the fact the pressure drops as the system cools down, but with 2 tons on 50 bar,you can afford to lose some pressure-30 bar means this monster still has 1.1 tons)are a good budgetted thing.
300/15= 20 seconds. Every 20 seconds a flipping action ,capable to overpower a heavy.

Lifting capability on 30 cm 513 kg. -This means in featherweight norms about thesame power as Gravity has on the ram, not on the flipperedge.

So the size and volume of a 1.1 kg is even for a gasguzler in featherclass way overdone.

As for the I have 5kg to do this etc i did that, and i was in trouble with FlowRate being studpily over weight by about 2kg. But drastic actions have been done - so should be fine now.

I did your sums and i got about 5kg left over for - batteries, motors, chassis, armour, wiring, speedos. I foud out that my 2 x electronize speedos are about 400g for both. along with RX and team delta to swtich valve on/off - thats half a kg just for electronics. I only left about 200g for all my electtonics, how wrong was i.

Bosch 35 are about 550g each.
So 1.1kg for drive
1kg for Battery
and a structure to cope with a 80mm bore ram and 100mm stroke. Hmmm - unless you use thick ali or nromaly thickeness welded steel or thin ti - i cant see that happeneing.

as for the comment You have built bots, i havnt this is where im trying to help you. I have gone down this path with my pneumatics, done the same things as you. Oh i got this much for this, should be fine well it aint for my stuf, and if your sutff is even bigger, your gona find it EVEN harder. My rams are custom made - VERY light, the i use drill motors and Marios VERY LIGHT drive pod/gear boxes - and im still struggerling for weight.

And another thing - not to get personal or anything, just helping out - what about money Ian? Bosch 35 motors are about £55 each, elec speedos are £30/40 each, valves will be OVER £70, battery will be over £40. All the pneumatic parts like push fits etc all add up in price fast. High flow regulator - mega over £80 at least. Ram will be alot also unless you get that free somewherel.
Dont rely on oh i will get it sponcored either.

Do you have the means to fill your co2 bottle up? Is there somewhere in Ireland for you to fill ur co2 bottle up? Dont say ill find somewhere or theres this place i will ask - make sure your are sure.

Maybe I am way wrong and if so Please feel free to say not a hope but Like Henry Ford once said:
Whether you believe you can or you cant, you are right! Whatever - this is roboteering :proud:

Hope some of the above is helpful.

Mr Stu

Id have to say, it has mostly been verry entertaining :)
I have been thinking of a fether flipper among other things. But reading this I know competition is already fierce, maybe a little too fierce.
Its scary realy. Ill keep on dreaming then, shall I...

Dont keep dreaming- design and build!

How good a robot is on paper counts for very little in the heat of battle. Driving and tactics are everything. I would put my money on a simple, basic, low pressure system with a good design and good driver, against a wimba wamba elephant hurling FP feather any day of the week.

That said, stick a good driver with a wimba wamba elephant hurler, and your laughing:-)

2 years ago the thought of pneumatics scared the proverbial out of me, but having been playing with low pressure stuff a lot over the last year or so, and having someone like Mario to talk to, custom building a full pressure system has become do-able. Thats why I love robotwars- you learn new stuff! And so much of it! I cant think of any other engineering disciplin (for want of a better word) that teaches you both how to build a speed controller (or at least feel confident enough to start toying with the idea) and allows you to work with full pressure pneumatics, learn about manufacturing processes, everything from moments of inertia to knowing tricks for cutting polycarb and so on. I love it:-)

Random as the above may sound with relation to pneumatics, its really just saying that the best designs come through playing and faffing, or at least thats how i get most of my ideas.

I agree with stepan- entertaining and enlightening:-) Good conversations like this are top dog on forums, lets keep it up :D

Here Here.

Mr Stu

i have to say im starting to have doubts about my feather
weighing the stuff at malvern and having 7kg for armour and eletroncis i thought would be cool but you forget about all the little things like screws and conectors and things that add up.
i threw myself in the deep end with ants building a pneumatic flipper.i was pushing it with weight to get it in the limit and over the year and a half of fighting it i have got it lighter and lighter.
my feather is a scaled up version of the ant and im trying to keep at simple as possible but ive been finding its just not that easy!

and ian. i know how you can be. you get quite over ambitious about what you want to do. start simple and build on that. you robot is sounding way to heavy.
jus think about what your going into and take the advise from these people. mario stu eddy alan and stefan have all been in this game for a long time and no wat they are talkng about..
anyway good luck.

(heres a pic from a couple of months ago... argh these motors are gunna be heavy)
http://www.featherweights.org/featherweights/rebel_feather.jpghttp://www.featherweights.org/feathe...el_feather.jpg

Ive got about 1kgs worth of Bolts and Nuts and washers in FlowRate.
I didnt allow a full kg for stuff like that.

Mr Stu

Ive been there with the whole 1.1kg bottle in a feather. Really not a good idea. Ignoring the weight, the tank itself is bigger than most feathers.

P.S you feather is looking very good chris- keep up the good work- looks to be coming along nicely. And assuming those motors are as powerful as they look, keep them! High speed, powerful flippers are great fun- theres nothing like driving another robot into the wall then flipping it oota :D Your task as a robot builder is take your weapon to your opponent (not the other way round) so I say keep em- itll be a good challenge. Shout if you need any help.

You see the reason I said 1.1kg is because that looks like the size that the one in Chriss pic above or is this a 600g?

Also today i bought a 600g Dry Poweder Extinguisher. It weighs as is (including Dry powder and key etc) 690g. Not bad in my opinion considering a 2 liter coke bottle is 60g.

Thanks for the help mario and stu. I am starting to aggree that it may not be possible as even with my simple demo bot I was expecting weight so far to be about 4-5kg. Its 6kg allready but i have just to add the armour (6mm ply) and the solenoid valve.

What do you guys think would be better. 2x2L of air or a compresser and a 2L buffertank? (can do both)

What you think?

Regards
Ian Mc Donald

Pressure Switch - 2L tank, compressior. Dont use a compressior on a bottle of coke plastic crappy thing. Plastic bottles on AVERAGE only go up to about 100psi before things go bang.
Use ur 690g buffer thing with the compressior. - Sorted.

Depends what ur doing. Doe Demo - maybe the 2 x 2L bottles as its quieter. But for battle - the compressior.

Mr Stu
- yes that bottle in Chris picture is a 600g Co2 bottle. Same bottle that Rip, DTk, FlowRate, Cut-Let, G2, Prince of Awe, New PLF, MiniMoth etc all use.

thats a 600g bottle in chriss photo. G2 can get about 145 flips from a 600g bottle (thats double acting as well).

a 2L bottle with a compressor would be best.

Weight again is the major problem with pneumatics in feathers. the compressor system is probably lighter (just) but not as effective.

Remember Co2 requires the facility to re-charge.

people say it cant be done / is not advisable ? That does it. Im gonna build a fp feather with a 1.1 kg bottle. So what If I dont have any weight left for armour ? armour sucks anyway, who needs it, only people who fight defensive !

WJ, it can be done. Thats why Flip in original form had only 1 drivemotor.To save weight on drive and batteries, only 1 speedo etc.Now the feathers may use the 600 gram paintballbottle the choise was made fast.

Project One used A huge 3.5kg bottle.A lot of weight taken up by that could be used better to improve valves and the then unknown buffertank.
So it is still a learning curve,and when a better opportunity arrives, why not?

Ian, let me calculate again.
Your 63mm bore 100mm stroke ram uses 2.3L each action. When using 2 2L cokebottle you have about 3 useable actions, with the last one a feeble lifting of the arm.Starting to push up 124 Kg(41 kg on the front edge of the hypotetical 30 cm liftarm)
I would say, Stus advice sounds very useable.

Well the compresser I got has an auto stop once a certin pressure is reached so would this be ok to run without it being tied back to the rx or what would I use to tye it back if it does need to be

Regards
Ian Mc DOnald

we had one from halfords that cut of the pressure, but the system was no good. we just used the pump and bought a pressure switch from RS (same as cutlet had). This meant the pump looked after itself, but we still had a cut-off switch on the TX.

Alan
How did you link it back to the rx. I dont understand how you did this? Servo etc

Regards
Ian Mc DOnald

Putting a solid-state rc switch in series with the pressure switch would work.