FP HW Tips

What is the normal set up for a UK HW FP flipper? A few others and myself are thinking about building a HW for the flipper upcoming BB event and are wondering what you guys use in the big bots€¦


Also, I wanted to see what you guys have to say about the argument on solenoid valves to control the ram Vs. a low pressure operated ball valve to open the thing super quick.


Thoughts, comments, suggestions, pictures..?.. Woody, Mario.?.?.

Mario advocates multiple Burkerts ...you get a quicker instant flow.
I believe that a ball valve setup is just as good ...if not better.

Your flow or Cv / Kv requirements depend on your ram volume , leverage ratio and mass to move.

Woody, the multiple burkert setup has other advantages.
1)No low pressure needed in the machine, what eliminates the need for a regulator -a thing that cant handle liquid CO2-(and in the UK FRA rules, the multiple PRDs)
2) Straigth from the box solution. Buy Burkert 5404 valves and you dont have to build controling parts for the ball valve. The only thing needed for a sure function is 36V to control the solenoids.
3) Space and weight needed. Compare a 1 ball valve with controling piston, control valve, hoses, connectors and regulator to 4 burkerts set aside. (this is overkill for a 4 bore ram)
4) Pricetag if everything is bought new. All the low pressure parts add seriously to the cost.

But Chad, if youre not on a budget, or have acces to CNC machines, A Woody 3/2 or 5/2 valve with Maddox control soleno¯d is the best of all worlds. (TAN and Ka-Put use these)
No size restrictions at all, instant opening, no LP setup needed, and best of all, lightweight compared to KV

Multiple Burkerts will of course require multiple ram inlets and associated pipework.

You can get an idea of your max required Cv from these two calculators.

http://www.wa4dsy.net/robot/flipperhttp://www.wa4dsy.net/robot/flipper
and
http://www.proautocon.com/tools/pac_cylsizer.xlshttp://www.proautocon.com/tools/pac_cylsizer.xls

Quick example using a 6 x 6 ram @ 750 psi

Force generated by ram approx 21,000 lbs

At a 1-1 ratio ...220lbs sitting directly on the ram ... your optimum ram extend time from Dales calculator would be 0.018 second.

Throw that extend time into the cylsizer ... use 6 bore 6 stroke and 6 rod dia plus a pressure of 750 and drop of 10 ... and you get a required Cv of 197!

Increase your ratio to 6-1 and the force at the flipper tip decreases to become 3500 lbs and flipper tip travel increases to 36... the ram extend time then increases by a factor of 6 to 0.11 sec.

Throw this new extend time into the Cylsizer and you get a required Cv of 32 ...or 1/6 th of the original 1-1 calculation.

All the above calculations are just Math and in practice youll get nowhere near the throws shown.

Id be tempted to go with a 3 way T Ported ball valve of around 1 or more with the above 6 cylinder @ 6-1 flipper ratio....it also gives you a built in ram exhaust valve.


You also might want to consider using the 1 60 bar Jaska valve listed here.... http://www.jorc.com/catalog/us1415.htmlhttp://www.jorc.com/catalog/us1415.html
with a flow 5 times that of a single 1/2 Burkert as an inlet valve.

So many choices ...:)

EDIT ..Another alternative could be a self venting ball valve....thus combining inlet and a small exhaust in one unit.



(Message edited by woody on May 07, 2008)

No question in my mind, ball valve for performance - see http://www.technobots.co.uk/M2XT/M2XT-Home/M2XT_Build/Pneumatics/body_pneumatics.htmlhttp://www.technobots.co.uk/M2XT/M2X...ody_pneumatics .html

for the weight of 4 burkets you mayaswell go for a 1 ball valve and a small ram to operate it. In my opinion its been proven to give a way better flip then any burket powered machine. Hence the new M2 and the new Iron Awe.. also i believe the big american bots used ball valves, toro, the matador, t-minus etc.

Chad ...A fully OPEN 1 full bore ball valve will have a flow equivalent to 10 or more Burkert valves.

With those kinds of flow I doubt you will get more than 1/8 of the ball opened before the ram is extended fully.

Of course Woody, the Burkert has 2 90° angles to pass, the Ball valve is straight trough.

But, the ball valve wont be fully open before the ram has reached end stroke.

i asked my dad abit ago and he said what mario just said

the ball valve wont be fully open before the ram has reached end stroke

though what iron awe is going i would do as that robot is one of the best flippers around

the ball valve wont be fully open before the ram has reached end stroke

Are you sure?

OK ...What is the opening time of a 1 bore 3 stroke ram when supplied with 150 psi by a std 1/4 port 5/2 valve with a Cv of around 1.2?



The ram setup I suggested had a LOADED opening time of 0.12 sec... So...

BTW ..What is the opening time for a Burkert ?




(Message edited by woody on May 07, 2008)

Burkert gives a responce time of 0.05 seconds.

Hehehe, this is exactly what I wanted to see two different views on things and reasons to back them€¦

I like the simplicity of the solenoid valves, on and off, easy to set up and wire, however I don€™t really like the amount of tubing, size and fittings that will be required.

I like the ball valve because of the inline easy open/close but that is another whole system to fuss with and a bit more complex than the on off from the above system€¦

Hmmmmm


What are the normal ram sizes in your HW€™s? We were thinking in the ball park of 6€x8€-ish€¦ What is this Woody valve you speak of? We are trying to get a CNC shop to do some work for us so if might not be out of the realm of possibility.

Cheers Mario ...
Working out the opening time for the ball valve will require finding the load or torque to open it.
A value picked off the net suggests 110 lbf-ins for a 1 ball valve.

Throwing some values in the calculators gives me a loaded opening time of around .09 second ( when using the afore mentioned 1 bore 3 stroke ram @ 150 psi )....increasing the bore to 1.25 gives us some extra OOoomph and reduces the calc opening time to 0.066 second with a required Cv of around 0.5.

Standard disclaimer ...
IF Ive got my calculations correct etc ..:)

A F.P. 3 port valve made by me sometime ago...

http://www.robowars.org/forum/album_pic.php?pic_id=1422http://www.robowars.org/forum/album_pic.php?pic_id=1422

http://www.robowars.org/forum/album_pic.php?pic_id=1420http://www.robowars.org/forum/album_pic.php?pic_id=1420

Currently residing in my Feather:):)

Mario,

I have no problem in getting the ball valve open before the ram fully strokes. Also, its not just about valve operating times, its also about restrictions which serve to slug the gas flow from the buffer to the ram. You have far more restrictions in solenoid valve installations than in ball valve solutions. Having tried both methods its a no brainer as far as I am concerned. Design your ball valve system right and I believe it will out perform multiple solenoid valve designs.

its not getting the ram up i have truble with its getting it back down quick
thats why i left a spring in our hydralic ram to pull it back down, but another 2kg of weight and i im giving up with bungy lol

but either system should work good enough

Im not convinced that the added low pressure set up in the robot is an advantage.

The most ideal solution is to use a fully custom build balanced valve. Or get the QEV -Bufferram- working.

Chad, multiple burkerts just require a nicely designed manifold. Or can be connected to each other with off the shelf hydraulic parts.

(Message edited by maddox on May 07, 2008)

Mario, I totally agree that the LP side is a pain but at the time I wanted the ultimate performance that I could achieve using my own tools. Not only that, but it is variable pressure from 10 to 50 bar controlled from the Tx so I had both a LP flipper and a HP flipper and everything in between. Shame it drove like a sack of spuds and the flipper kept breaking open the back of the bot. The only other design I have tried that came close was a design based on the impact ram principle but that was inherently unsafe and let down by a poor build.

Paul, I can achive the variable pressure as well, nothing difficult to it, just requiring a servo to adjust a setting. But I didnt use it before, because it defeats the KISS idea.

Also, something I learned , flow and pressure , as well ramsize arent everything. In Hannibalito1 I tried several flipper arm leverages and lengths, and its a huge difference, even with minimal changes.

But my own guidelines.
Buffertank volume 3* ram volume
1 Burkert is good for a 70mm bore ram
2 Burkerts are good for 100mm bore
and 140mm bore needs 4 burkerts.

Flipperarm at least 5 times stroke. Point of impact depending on force on the ram, but leverage so that at least 5 times the weight of the to be trown opponent is available on the point.

Mario, a servo to adjust a setting - a setting of what? KISS is fine but if we all kept to that we would all still have mobility motors and fire alarm batteries!

1. My guidlines are 2* ram volume, 3* ram volume only gives an extra 12% final pressure and that is when its too late to do much good and does not always justify the extra weight.

2. Its all about gas flow and far less about pressure

3. A bigger ram is of little good if it is not matched by a corresponding increase in gas flow.

4. Use the Hassocks hog flipper calculator for designing the flipper arm.

The ram opening speed reduces as the load / leverage increases and the fill time - flow - Kv or Cv versus the required flipper TIP speed also reduces.

Optimizing all the variables is key in getting an effective flipper.

i think mario might have come up with the same idea as me paul,

Using a burket as a regulator with a pressure switch on the buffer tank its fed by- closing the burket when it reaches a set pressure..

I havnt attempted it yet, but i remember the pressure switch i bought from you YEARS ago had a screw in it to adjust the pressure setting- i planned to exstend this screw, put a gear on the end and have it engage with a servo to ajust the pressure setting while the machine is in the arena- By calibrating it on the bench with a pressure guage and putting markings on the TX it should be possible to have a close measure to pressure via the remote throttle.

Abit of subject but id be quite interested to know how you solved that with the picaxe system you use?

Chad- i would also suggest the hassocks hog flipper calculator for maximising the effectiveness of your machine.

That is exactly what we are thinking about doing in the new axe setup of Obsidian Dave, the pressure switch is already in place. We will use a set pressure though, not variable as Mario suggested with the servo. Setting it before the event/match is good enough.

http://www.valvepros.com/av-files/sharpe/series_76.pdfhttp://www.valvepros.com/av-files/sharpe/series_76.pdf set up 4

@ paul
The Hassocks Hog flipper calculator is pure theory.
What I use as guidelines is what I learned over 7 years of Robot wars pneumatics.

Its all about juggling weight/size/benefits.
I aim for the 3 times ram volume, but wont cry for it if it is 2.2 times.
I try for a 1 to 1.5 bore/stroke ram, but wont hesitate to divert from that aim if other lay outs give me a better total power to weight ratio.

@ Dave, Youre not far from what I have in mind. But there are some details. Please allow me to keep them for me.

after 15min o CAD I have the first view of what the HW may look like.. ish

http://i79.photobucket.com/albums/j147/wazio/hw1.jpghttp://i79.photobucket.com/albums/j147/wazio/hw1.jpg

http://i79.photobucket.com/albums/j147/wazio/hw2.jpghttp://i79.photobucket.com/albums/j147/wazio/hw2.jpg

6 wheel drive, 6-8diax6 cylinder. 2 2.5lb c02 tanks, Li-p Batt, probably mag motor drive of some sort... All that stuff will come later... If the thing even gets built.

http://www.bugs.nl/media/album/view.php?&path=L3J3L3R3ZW50ZTIwMDQvbmwtYm9yZ2UvRFN DRjAwNjQuSlBHhttp://www.bugs.nl/media/album/view....bmwtYm9yZ2UvRF NDRjAwNjQuSlBH

This tiny Dutch machine is waiting to get finished. But what is in there. A 5.5 ram with 5 stroke fed by 3 burkerts. Those are below the buffertank.
2 1.1kg bottles to feed the monster.
Drive is Bosch 750 and a 2 stage gearbox.

Mario, not sure where you are coming from but the Hassocks Hog flipper calculator is a very useful modelling tool, modelling is used throughout everyday life so why not flippers. I like others who have used it have found it to be very good. Your 7 years of experience is personal to you whereas the calculator is freely available to all. Dont use it if you dont want to but equally dont knock something that others find useful. This thread is titled FP HW tips and the calculator is a great tip for builders trying to work out their fliiper geometry.

Dave, M2XT used an analogue output (2-20mA) pressure transmitter, this fed into a comparitor (PICAXE) where the pressure was compared to that of a signal direct from a Rx. The ouput of the comparitor was used to drive a HP solenoid valve which opened to pressurise the buffer tanks at a controlled rate until the desired pressure was reached when it then closes again.

Paul, if it reads that I ment that the Hassocks Hog flipper calulator is bad or so, sorry.
I just ment that there can be a big difference between predicted results and the real world results.
But as you say, modeling can be a great help to avoid wrong designs.

Mario ..Id strongly suggest that you input that machines Dimensions and flow etc thru the Hassocks Hog Flipper Calc IF you want to get the best performance available.

A quick eyeball of this nicely constructed machine suggests to me that the flow is nowhere near enough for such a large ram and short flipper ratio.

I agree woody, but its not my machine, its just based on the ideas as seen in Gravity.
The ram isnt from my hand either.

But the builder just wanted to build as small as possible.

Itll still chuck an opponent a decent height...but well below the rams full potential.
Hardly matters an awful lot if its succesfull as is.

Where do you guys get your CO2 from? BOC?

My gas supplier is Ijsfabriek Strombeek Bever. CO2 and welding gas.
I guess a bit out of the way for you.

Ive never used them but ...http://gascylindersuk.co.uk/store/catalog/index.php?cPath=22&osCsid=56bb045addbc4e28eb6fac0a 6aa5b6b8http://gascylindersuk.co.uk/store/ca...d=56bb045addbc 4e28eb6fac0a6aa5b6b8

I guess another advantage of having the low pressure system for the actuating cylinder for the ball valve is that you already have most of the plumbing set up to have lower pressure co2 to return the cylinder piston to its starting point.

I think i will have to go with BOC for gas. Woody, the company you suggested just deal with the northwest.

Oooh interesting discussion.
We changed from using solenoid valves in IA3 to ball valves in IA5 because we always seemed to have problems venting the ram properly. We have certainly solved that in IA5 but whether that is purely down to the ball valves or whether the additional buffer tanks help, Im not sure.
Our ram is 80 bore * 170 stroke and the buffer tanks are more than 5 times that volume. We can get around 25-30 flips out of a single bottle of gas.

Rob

Suren ..I retract with about 4 bar on my medium pressure setup ... 20 - 30 bar working pressure.
However most F.P. Rams are now single acting and bungee stop / return so the L.P. would only be used for operating the ball valve ram.

Hi,

I€™m planning on making a FP flipper to get back into robotwars. I have been following this discussion, have spoken to Mario and been to the M2 website, all have been very useful. Now this is my understanding of what I need€¦

1€ stainless inlet valve
Low pressure actuator ram for valve
Regulator (2 stage, for low pressure actuator/high pressure ram?)
2 x 1 litre buffer tanks (made from disposable CO2 bottles)
Manifold in between buffer tanks and SS valve.
Electric valve for low pressure ram
2kg Fire extinguisher bottle for CO2 storage
Exhaust valve? Does this have to be electric? How does this work?
Ram with inlet and outlet port
Bungee cord to return piston
Fittings and pipes (can I use copper piping?)
Liquid stopper?

Anything else? Any and all advice will be usefull!

If you can let me know the best sources for these part as well i would really appreciate it.

I would appreciate it if someone near me was willing to show me their set up and show me how to fill a fire extinguisher. I€™m in Wallington surrey.

I€™m getting the buzz like I got when I made my first robot 10 years ago called Oblivion, anybody remember that? I just know very little about pneumatics.

Thanks