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I've got so many stupid questions, that I think I need a new thread for all of them. Thanks for helping me with them so far, everyone here is very helpful.
So far my pneumatic advise is based on this:
Tank-regulator----T-------3/2 valve-prv-ram
/////////// dump valve////////////////
Courtesy of Anttazz.
For the PRV, is it 3-way, or do you use a T before it?
Thanks in advance and for answering my previous newbie questions, George
Im 80% sure you need a T for the pvr
And you need the pvr before the valve (100% sure of that!)
you need the PRV and the dump valve before the solenoid valve
Of course I need a PRV before the valve, I should have realised that.
Thanks, I know I need a T.
I found this diagram quite useful when starting to look into dabbling with pneumatics:
[attachment=1:exbhlwzu]PneumaticDiagram2.jpg[/attachment:exbhlwzu]
And this picture from one of Calum's (calumco) build threads helped visualise it:
[attachment=0:exbhlwzu]calum_low_pressure_pneumatics.JPG[/attachment:exbhlwzu]
(I think the PRV and dump valve come off the block on top of the blue buffer tank)
Hope that helps.
The pictures really do help, the diagram more.
But why is there a second tube from the end of the ram going to the valve? Is this to help the return?
yes
Rams are either single-acting or double-acting. Single-acting sees gas fired into the bottom of the ram, pushing it out. It then uses some form of mechanical return, either a spring inside the ram or, in most roboteers' cases, bungee cord to pull down the flipper arm, thus pushing the ram back in.
Double-acting rams use gas to both extend and retract the ram. For retraction, gas is fired into the top of the ram, pushing it down, while the gas already in the ram from firing it is pushed out and exhausted into the atmosphere. This means you don't need a spring or bungee cord to bring the ram back down. But one downside is that you're effectively using almost double the gas for one flip which, if you have a limited supply, can hinder the usefulness of your weapon.
OK, I want to keep it simple so I'm keeping the single-acting cylinder. Thanks for explaining them.
I'm still looking at speedos, its between Scorpion XL's and Victor 883's. I'm on a budget of around £200 currently to finish the electronics, thats speedos, batteries, possible BEC, and battle switch, and hopefully some valves ready for the flipper.
Of course Victors are best, but it would be cheaper to get Scorpions. I'm running GOLD motors, which have a stall current of 25 amps. The Scorpion XL can do a max of 12.5 amps, for a few minutes. Is it feasible to run a pair of GOLDs on the low ampage from the scorpion?
What sort of ampage can you get from 24 v batteries? (Or are 18v's more suitable?) I've seen bike batteries on 12v with 8 amps, but 18 v with 4a, and 24v with 24a. Of course it all effects how long the battery will run for, but what sort of spec battery am I looking for?
Thanks, George
you only need 1 scorpion, they're a dual speed controller. A scorpion xxl would probably be best at around £120 with fan and enclosure delivered to your door.
for batteries i aim for 3000mah+
In other words,
a.Is it feasible to run GOLD 24v's on a Scorpion XL,
b.What amperage do 18-24v batterys have? I've found from 2a to 15a, does this depend on the mAh?
I would recommend victors because you are very unlikely to need a replacement :). As for batteries, the current is the mAh ratings. You can buy 12-24v packs ranging from 800mAh to 4000mAh (0.8 amps - 4 amps for an hour). Satanix was using an 18v 3300 mAh pack of NiMH cells. It lasts me 2 fights if I'm not ragging it around, and I am running speed 900's.
OK, I'll probably have to get Victors. Better get quality now to save later. I know someone who runs a battery manufacturers, and they have a range of batteries. I'd be looking something around 18-24 volts, 5-20 amps, and a mAh of 3-4 thousand?
My concern with the Victor is it always runs 10% power at least, doesent that make robots awkward to drive?
sigh, mah are the same as amps!
mah= milliamps/hour
Ah= Amps/hour
3.3ah pack is the same as a a 3300mah pack
Whoops, well thats one more thing I can't get wrong next time!
Does the 10% lowest output on the victor affect fights much?
Not really.
The number of ampere a battery can deliver is dependant on the Ah / mAh rating times the maximum current draw C.
a 1ah battery with a 5c mark can deliver 5*1=5A at most
Thanks for all the info, I've got a slightly different question now.
I'm moving onto the drive, what do most people to mount the motors and for custom gear boxes? I'm looking at buying a load of HDPE, it's cheap stuff. I've looked at various build diaries, but can't find enough relevant information.
George
Use a hole saw drill bit to mount the motor if you need to and I think the Golds have screw holes to mount from the front. Can't really remember now.
As for the second part of your question, I am confused, do you mean thicknesses of HDPE?
Team RCC feathers use the MSR 12-XX gearboxes (gearratio 4.5 or 6 to 1). Simple 1 stage dead axle setups. Steel gearbox plate with 5 holes in it. Speed 900 or equivalent. 12 or 15mm axle, bronze or whitemetal bushings. HDPE wheels.Quote:
Originally Posted by roketrhino900
http://users.telenet.be/P3/Mario/Alex%20Finished.JPG
Our new feather, Hannibalito 4, uses the Gimsons. I bolted these in a steel 40*40*2 L section as part of the T frame (another constant in the Hannibalito's)
Quote:
I'm looking at buying a load of HDPE, it's cheap stuff. I've looked at various build diaries, but can't find enough relevant information.
George
High Density Poly Ethylene. Lighter than water. I use for calculations 0.97 kg dm³.
Very tough, virtualy unbreakable, but it can stretched untill breached.
But also soft, can be worked with wood-working tools.
The advantage here is that spinners slice a cut in it, and doesn't transfer the force as readely.
There is no glue for it.Paint peels off. Most chemicals don't even damage it. Only heat, intense UV and Benzene/Toluene/Xylene do that.
Due the softness, threading it is not optimal. Coarse woodscrews do the job, but are weak points. Ancient woodwork methodes that don't use nails or screws (dovetails, hole and dowel) are applicable with very good results. Pity there ain't a lot of good carpenters around here.
You can weld it with hot air, but the welds are weak points as these become a tad brittle. I learned to back up welds with angled metal combined with bolts and nuts.
Normal color is black or white, but colored in depth material is not unheared off.
For feathers.
For frame/monocoque 8mm is the thinnest I would use. The softness gives it a lot of flexibility. Polycarbonate is better in that respect.
10mm thickness protects against most spinners, 20mm seems unbreachable.
5mm is a fantastic dust cover. Team RCC uses it for bottom armor.
Thanks for all the info guys, I've made a 3d model on sketchup, I've bought 10mm HDPE for side armour, I'm using 3mm checkerplate ali for top, I've also bagged myself a Festo ram, I think its 60mm stroke 40mmbore is that OK? It weight 2kg, though.
I bumped this thread to ask about wire connectors, since I remember a discussion about them somewhere else. Are bullet connectiors OK, or will they fall apart?
Will my robot require a frame? The body is slightly lower than metalbeaks in proportion.
Thanks, George
I've got some thin steel bars I'm going to use, I've cut a 480X440mm base, it's wider than it is long because the ram is in parallel with the drive. I know rams are better upwards, but mine is in the classic setup because my mega ram would make the robot incredibly tall. I'll make a build diary and put up some photos once I start mounting stuff, I need some parts from southhampton first.