Yeh they're pretty slow, only about 2.2krpm. Most people run them on 24v so 4.4krpm. They're deceptively powerful aswell. As for the screw no fan motors I've ever seen have screws so I can't comment. What fan motor do you have?
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Yeh they're pretty slow, only about 2.2krpm. Most people run them on 24v so 4.4krpm. They're deceptively powerful aswell. As for the screw no fan motors I've ever seen have screws so I can't comment. What fan motor do you have?
It's from a vauxhall vivaro van
BItzaMK2 runs on 24v and we get plenty of rpm.
I do believe they also have advanced magnets, so will spin much faster one way than the other.
Never seen one with a screw on the shaft!
How did the fan motors you've had been attached to the fan assembly then? My motor seems to go equally fast in either direction, maybe I have an odd one!
The fan was held on with 3 bolts, these were tightened into three threads on a triangular arm that was attached the to shaft.
We just took the fan off, and mounted the one way bearing from the bike to the three holes. Simples!
I know some people weld sprockets clean on also.
I've been working on trax (fw tracked robot) today which uses wiper motors . The problem is I am not sure how to attach anything onto the output shaft (small threaded shaft) currently I have a bit of steel rod with a tapped hole to screw onto the shaft and then a horizontal hole for a split pin to go through and a corresponding hole on the wiper shaft. But my split pin keeps snapping and I've tried a small bolt and that just snapped as well. How do most people attach anything to these shafts?
have you seen the way they attached the wheels to the motors in the real robots books in rex's section
Just had a little look at that but I can't see how he stops the wheel unscrewing when the motor is reversed?
i drilled a hole through the shaft and used a bolt to hold the wheel to it.
the hole in the lever arm that's attached to the motor has lots of grooves like on the shaft so it doesnt spin so if u can imitate that or modify the original lever arm and attach it
Jonny what sized bolt did you use?
M4
I've got it working now. Annoyingly the batteries don't last very long. It not going to be used in combat, more as a remote control off road vehicle so I'd like it to last longer so I may try and get some big capacity sla's, anyone got any suggestions?
Wiper motors being a pain to attach wheels to? Batteries not lasting very long? Sounds just like my Rex's Robot Challenge experience all over again :lol:
I'm assuming you're currently using 12V SLAs but what Ah rating are they? I found something around the 7Ah mark gave a decent run-time, and a quick search threw up these:
http://www.screwfix.com/p/sealed-lead-a ... 0x%20151mm
No idea what they're like compared to other brands but I doubt there'll be much of a difference. If you need something that'll last longer still, just type 12V SLA and the desired Ah value into Google; there seems to be a pretty decent selection for all Ah values.
Currently I'm using 2 12v 2200mah nicds in series to give 24v. it means the motors and batteries get very hot! Can you mount sla's on their side?
Annoyingly just a few months ago my dad found a load of 12v sla's powering our new houses alarm, thought they were useless so through them out! Can't believe it :angry:
I used a 7ah lead acid battery in armerdillo (the worlds slowest robot) and that used windscreen wiper motors, so that would be fine, they are fine on there side, that's how I used it in bruiser, an those Nicds may be enough, just see if it runs for 3 or more.
Ive had a fun day messing around with Trax, here are a couple of photos:
[attachment=2:2wnwvzeq]Trax pic 1.jpg[/attachment:2wnwvzeq]
[attachment=1:2wnwvzeq]trax pic 2.jpg[/attachment:2wnwvzeq]
[attachment=0:2wnwvzeq]trax pic 3.jpg[/attachment:2wnwvzeq]
here is a test video:
http://www.youtube.com/watch?v=C1u6ZHG1sE8
I've been playing around with my pneumatic system and I can't get my 5/2 valve working :angry: it makes a clicking sound when I connect it to a battery but it seems to stay in the same state, I don't have it hooked up to the full pressure (10 bar) instead I am just blowing down the pipe would that make a difference? Does anyone know what might be wrong?
It won't work unless it's hooked up to a compressed gas supply at atleast the minimum pressure.
I've got the valve working but my Trevor regulator is still leaking! I connected it to a fire extinguisher bottle and put on the gas slowly but it started leaking out of the thread between the end cap you twist to change the pressure and the rest of the reg. I don't think the gas is even supposed to get to that bit if the reg. the pressure also seemed to rise a lot, my pressure gauge only goes upto 11bar and it went way past that despite the end cap being screwed up most the way.
Hope that makes sense a that someone can help and diagnose the problem!
Screwed up? I thought it you were sopost to tighten it? Unless I'm just reading it wrong...
Ok, I been trying to get it to work and the regulator is acting very strangly,
We've starting off the the end cap almost completely undone then screwing it on slowly until it got to the desired pressure. We then fired the ram and the pressure wouldnt go back up and stayed very low. We tighting up the end cap a very little bit further, dumped the system and pressure up (by gently turning in the valve on our fire extinguisher) then the pressure went off the scale in under a second and the ram fired with extreme force, we then dumped the excess gas and there was a lot more than usual in the pipes. We we not using a buffer tank but had very long pipes.
Can someone please tell me what I did wrong?
Do it in the other direction, screw it up tight, so that it's at the lowest pressure, and slowly unscrew untill you've found the pressure you want. Or your over pressurising the system, and the gas can't flow back though the reg, so it remains at the high pressure.
Screwing it tight will increase the pressure. Sound like your doing it right, im guessing its sucking liquid through, if your bottles laying flat you could do with a dip tube in it, as i had this problem with Ratchet. Next time you test it try it with the bottle standing up see if its any better. As for it not repressurising, the only thing i can think off is the reg is sticking, was the regulator cold?
The bottle was standing upright, it was a fire extinguisher bottle. The regulator did get cold.
I am still trying to figure this out, is it the tighter the end cap is on the greater the pressure or is it the tighter the end cap is on the lower the pressure?
Also how do people usually set their regulator? Do you just connect a pressure gauge straight into the regulator ?
Fire extinguisher will have a dip tube, so your pulling liquid straight through, they it with the bottle upside down. You should be able to put the gauge directly on the reg. Unscrew the reg all the way out, then wind it in until you reach the desired pressure.Quote:
The bottle was standing upright, it was a fire extinguisher bottle. The regulator did get cold.
No avarage gas regulator can cope with liquids.
By using the extinguisher upright, you're feeding liquid CO2 in the Trev.
If you did set it very low, the reg is closed. And won't let the liquid flow trough.
But a tad higher and the liquid will enter your setup. Depending on total volume in the setup, and the function of the low pressure relief valve, you can get ripping hoses or failing low pressure push locks/couplings, damaged valves , or the worst case, exploding buffers. (luckely you didn't have one)
Concerning pressure gauges and Trevor regulators.
The Trevor has 1 1/8 bsp outlet, that's the low pressure side. You'll need a T-piece (or 2) to have a dump/low pressure PRV and gauge on the basic setup.
Can a prv be used more than once or is it like a burst valve on a bottle so you have to replace it?
They can be used more than once. They are kind of like a regulator in how they work.
Hi, max
We had a play with our oneumatic system last week, and it all went well, one thing you may have to concern is that if you try and increase the pressure by turning the endcap when you have got it connected to the bottle and gas flowing throw it, is that it gets very hard and the high pressure seal may leak.
As for your higher pressure problem, when you turn on your bottle the pressure does go about 1 bar higher than the disired pressure as the reg was starting up, your PRV should blow then and your system should return to your desired pressure.
Have a look at my videos I took whilst during the testing:
http://www.youtube.com/watch?v=oKyUKFhF ... ature=plcp
Oh sorry, got it wrong
2 questions today,
Would 2mm steel be ok for base and armour? It would be well supported.
Also how do you full pressure flippers guys attach a pipe to your bottle, more specifically ones with a co2 nut type thread? I don't understand how you attach a pipe to the co2 nut.
I think that 2mm will be way more than enough!
Hi all,
I've spent the 3 hours just discussing with my dt teacher how my flipper design it wrong rather than getting on building it :angry:
But I do see his point, because the ram is mounted nearly horizontally the force going upwards should be almost zero (cosine of angle times force . if angle is 90 then times force by 0!)
He suggested using a elbow shaped linkage which should mean most the force goes up but it has a lot more parts to go wrong and break and it makes the robot bigger and using the ram in reverse so a bit less force and one of the pivots has to move in a slot.
Also he recons you only need 70mm movement at the tip but I think you want at least double that, what do you guys think?
Max
Just found this post, have you sorted the regulator? From what I am reading it sounds like the O-ring is faulty.
You should be able to fit the reg onto a bottle, vertically. Wind the cap until it is loose, turn on the bottle pressure, wind the cap in until it vents throught the outlet. Wind it back out again and the flow will drop and eventually stop, If it doesn't then there is a problem and you should return it to me. If there is a leak in the reg you will be running at full pressure and will damage your system.
As for your ram, your teacher is looking at the system as force vector problem, when the major concern is gas flow. If the ram moves too quickly it will not have the ability to keep the pressure high, that is why when you look around the pits other machines look mechanically inefficient - it is for a reason - slow down the ram and your gas supply can keep the pressure in the ram.
Pm me about the regulator.
Trev
Thanks trev, I'll have a look at that today.
I just splashed out £1 for a old soda stream hoping there was parts usable in a robot. I know people use the co2 bottles but is there anything else I can use?
The bottles are not really suitable for robot use; they are heavy and should not be refilled.
Don't some people use them as high pressure buffer tanks?
That would be a possible use. There are lighter alternatives though.