THH1, (Get ready for a book…just a taste of what it would/should entail).
The rate I type at, it takes less time to actually build the system than to type it all in.
Do you have any pics, CAD Drawings and/or video up close currently of your bagged bot (not the bot in the bag, leave that alone), that can be worked from? Time to skype this weekend or much sooner w/ you and an Adult Team Mentor present, possibly a few others? Have any of the necessary materials…Compressor w/ the attached check valve, Compressor relief valve, shutoff switch, the necessary Crio module & board, to fire the selenoids, pwm cables to attach the selenoids to it, (a roll or 2 of that wonderful stuff commonly & normally referred to in the hardware & plumbing industries as "Teflon Thread Sealing Tape, but isn’t really…TTFE?)…Need to look at the pneumatics set up paper or diagram, print it out, and gather as many of the basic required items necessary. (Time to order and get delivery before the weekend is very short…I have the time to help long distance though if you and the team want to try the cool bold plan you asked for help on). You are not afraid of work I gather.
We can start w/ the link… http://frc-manual.usfirst.org/upload/images/2014/1/Figure4-15.jpg (Print it out now please!)
Just to start the project. Even before you think about the ball firing mechanism (and how those cylinders to be used will even attach, is it strong enough and mounted strong enough to handle the forces you will apply to it as built? (Do you have a cad drawing of the bot before it was bagged, or lots of detailed pics or vids that we can discuss together as a group)…Do you have the materials necessary to begin the project, or can you obtain them by the weekend? Will the end result added wt. fit within the 30 lbs. necessary and available? If not, can wt. be reduced elsewhere on the bot at the same time on Thursday at the event while, and at the same time as you still mount and test this added system on Thursday at the event, and still put that robot on a diet too to make wt. after it is completed, at the event? We can see easy enough. 8 days…Plenty of time left.
If done right, and safely, you can pre-build the system components, mount it to a board and test the completed system leaving the air tubes quite longer than necessary, test the design simply and make sure the system holds pressure properly, then dismount it, and box it up in components ready to add to that bot as soon as the bag is removed in 8 days. Trim only one end the tubes there down squarely & carefully to fit, add the required pcs. to make that mechanism work, and test it. (that tubing cut will never go to waste in the future…pcs of the tubing as short as 2" are useful and quite necessary often. Read below about the work and expenses involved first.
Not in any way attempting to discourage you in any way…Please understand that, OK? (Prepare, prepare, prepare).
Lets add up the added weight first to create the required system (grab a cardboard box or plastic bin about 3’ X 2’ X 2’ or so, I do hope you have a scale avail…Now get the Tare / empty weight of the empty box and mark the box). Don’t start to actually assemble anything anything yet, just read it all first. We’ll possibly work from it later.
Start to gather up the parts you do have and will need & weigh them all together. Cylinders you will use (start w/3 and if possible we’ll reduce to 2 if necessary and it fits the parameters, and the mounting hardware currently believed will be necessary to attach it to your existing mechanism? Put those in the box, set the tare wt. and put the box on that scale.
Next you will need to provide a spike relay (set that aside next in that box), to power the compressor…Proper Main Board to the spike wiring, and another breaker for that MB, put a 20 Amp Breaker properly into the spike and set the fuse aside, add mounting hardware for the compressor and the spike to the mix (keep filling that box please). Start to figure out where on the bot you will mount that compressor, spike, gauge, regulator and gauge, and possibly up to 4 tanks w/ mounting clips to mount later where they will be very protected. (Pics or good video and a CAD design drawing, are a must here!)
As plastic tanks and 20" ball pickups, and really hard fast hits do not mix very well w/ this high powered fast smacking game. If you cannot hide and protect them, then I would suggest at least metal tanks instead.
We’ll talk about that later once we see the bot.
Then the compressor is going to be wired directly from the spike, will be mounting the compressor w/ that chrome check valve, a brass close nipple, a brass (female X female X female) “T”, and a push in type tubing female X threaded male fitting to the other side of the brass “T” (all threads properly tape wrapped and tightened), and the brass Compressor Relief Valve properly set not to exceed 125 PSI attached directly to that brass “T” (we’ll get to that later during testing). You are going to be very careful in mounting that compressor Relief Valve to that compressor, and backing up w/ multiple wrenches, every connection tightening sequence when installing that on the compressor so as not to damage the head on the compressor (if it is the model in the link), so you get each joint properly tightened, so as to minimize any later air leakages, but do not damage that compressor). I do know secrets to doing that easily, that I can teach you along w/ proper thread sealing processes. (If your team is not that familiar w/ them). Once you get the knack, it all becomes fairly easy.
Once the compressor is together w/ the valve(s) attached and ready (put that in the box too. Add in another Brass (F X F X F) treaded “T”, and the required shutoff switch and the related wiring, and a high pressure gauge, and low pressure regulator and gauge set…(one is a guage only- will be used for high pressure reads 0- 200 PSI), (the other is the setable regulator w/ guage 0-100 PSI)…In the diagram, the lower right one is high pressure, the upper left is the combination regulator and low pressure gauge set…and that 1 clippard black tank (would contain and store air at 110-120 PSI…120 Max.), is situated on the high pressure side in the diagram.
They do not show on the diagram any low pressure tanks (which if used, would store air at 60 PSI Max), in that particular diagram. (for good measure start w/ 3-4 of the black 2014 tanks if you have them…and add the mounts and mounting hardware…later what you actually will need (to fire that ball), can be fine tuned to reduce the number and wt. if possible. (Put all those in the box too along w/ all the other fittings needed to attach each to the legal pnuematic poly tubing…Throw in at least 1 or 2 rolls of said, your color choice tubing…Make sure it is marked properly along the length of the tubing as legal (or keep that packaging it came in), and add a pressure vent valve and it’s related mounting hardware and necessary threaded / push type release attachment to tubing fitting).
Is that box getting full yet? How much does it weigh right now?
Next we are going to figure out what selenoids you will be using to fire off those cylinders with on (that I will later suggest), as it is required by the rules, that they be installed on the low pressure MAX 60 PSI side…and a base block to use to mount them and supply them from that low pressure regulator on (12 volt type are suggested here)…I’ll help you w/ that choice later, but it is getting late to order those if you don’t have them already for a build this weekend, so ordering would be necessary tomorrow or soon, of all that you may not have along w/ probably overnight expensive delivery possibly added)…and you will need 1 for each cylinder at least, you only need to fire the cylinders one way to shoot the ball up, just vent the other end completely of the cylinders (no fitting installed, your mechanism will return by gravity normally), by attaching no fittings to the opposite ends…3 cylinders should do it…never know until I can see the bot pics.
Next gather a whole host of plastic or metal “T”'s & 90’s, and the like (say 20 of each to just start, and some tubing connector smooth type plugs, get 10 at least…i’ll help again w/ that list), and add them in the box gently. Now what does that box weigh?
That link we have been building a materials list and weight off of, is about 1/2of the actual system necessary, and a bit more than 1/2 of the total wt. necessary to do the whole pneumatic system. That is only the high pressure side up to and through the regulator step down to the low pressure side. But, we have been adding in the actual parts necessary already for that high pressure side also into the box or onto the purchase list.
Actually Designing the working system is next.
Let’s just say we are going to design for 3 cylinders (if 2 cylinders will work for the application, I would reduce the tanks and cylinders by 1, shedding wt.)…I would suggest 1 high pressure tank, then after the regulator, we will 'T" off to the block, and run to each of 3 low pressure storage tanks, then out of each, to the selenoids, then from each selenoid to 1 same end of each of the cylinders (pull up, or push up choice, and mounting direction of the cylinders must be carefully chosen here, along w/ the actual cylinder desired angle of attack (that was what you were asking about earlier, that force multiplier…find your best math student and put him/her to work there), and available pivot locations, and consider the strength of the materials available on that existing ramp and its pivot point and mountings, to change it to an actual 25" ball firing mechanism to determine the actual design force of that to be built new catapult)…each cylinder would have it’s own tank volume in actuality to fire from, but must also be programmed to fire together in tandem. My son could help you w/ the programming later if needed.
Please do not take offense here (changing a Toyota into a BMW, or a Chevy into a Cadillac if you’d rather, in 1 weekend or so can be done…It takes time, materials, and/or money to get them faster, and patience…And a lot of hard work and willingness to learn)…STILL INTERESTED?) Is the team including avail. Adult Mentors actually interested?
If so, get back to me w/ an adult mentor by your side here. We’ll PM first, then, set up the skype setup, look at what you have first (pics at least please), and see if it is possible, see what materials you do have, and possibly get to work. At least that way you would have the components necessary to bolt in ready w/ actual help pre-arranged if smart, you can find from other teams at your event, to then help you install everything, and shake out the bugs and test it.
Getting expert help at the event can probably be arranged right here through CD in advance, I would suspect by listing in the Regionals Section and asking for pre-arranged help. But having a complete design, a plan, and drop in tested components ready, not to mention a little further pneumatics education for the team, would help tremendously in 8 days. And in the years ahead too.
I applaud your teams want to improve your bot after the build/bag season is completed, and between events. That is what that holdback allowance is really for.