I am looking through old footage for various reasons. One of which is there was a bot, name of which I can't remember. I am pretty sure it had one of the few successful pneumatic rams and was really low psi but high cfm. Sent bots flying oota sometimes.Originally Posted by Max
was it m2 theirs was powerful
http://m2robot.com/
That definitely rings a bell! But the bot shown there has a lifter/flipper, not a ram. Hmm.
Slightly pointed upwards, helping it occasionally act as a flipper?
Last edited by Bacon Wizard; 22nd April 2013 at 20:40.
the early ripper had a lp flipper
Anyway, the point I was making is that it was one of the few successful spear/ram jobs due to high CFM rather than high PSI.
I've shy'd away from the car fan motors because they are so big and heavy, plus didn't seem to offer a huge power advantage over the drill motors and gearboxes.
We have a couple of spare all metal Dewalt motor/gearboxes, so hoping to put them to good use. I think they have 700 size cans.
They sound good. Ours is an 885-size can. Also, unless I'm missing something, surely the torque figures for a 550 are dwarfed by those of a good fan motor? Are you sure you weren't looking at motor figures for the fan motor and after gearbox figures for drills? Of course if the power to weight of a fan motor+gear reduction vs a drill motor is in favour of the drill then that makes sense. Either way, I look forward to what you build!
Spawn Of Scutter had what I think was a low/full pressure (I can't remember but I know they tried to run a low pressure ram at full pressure in series 7 and blew the end cap off the ram when they fired it unloaded) spike pointing upwards in series 4 - it was very good at flipping opponents over, but not very good at all at putting holes in them even with the extra gravitational assistance...
The only other robots I can think of that had *serious* spike weapons were 101 and Pain - 101 kept running into the problem of pushing its opponents away instead of doing damage even on full pressure CO2, and Pain's weapon was banned due to the fact it involved barely controlled explosions and the robot didn't work!
Apologies for hijacking thread, I'll go back to lurking ^^;;
@Joey no worries! Spear weapons are an interesting area.
@Ellis, Oh yeh the fan motors are way more torque-y. In terms of stall toque though, drill motors after the gearbox should be sufficient.
My main consideration is the weight (1.6kgs each) and size (110mm Dia, about 60mm deep) for fan motors, and that's without any sort of gearing. They'll also stall at 200a each at 24v, drill motors shouldn't get above 100a (which is the rating SSRs I have).
What reduction did you say you were running? 5:1? It seems pretty quick and can obviously lift other robots fine.
We're running 4:1 after the drill, but of course the drill is pretty big. Size isn't everything (shh! Lol), but it's quite punchy. If you have a smaller motor (885 can or less) you may want to gear higher. That said if you're powering the rear "leg" in a four-bar there's a ratio so you may be fine.
I don't actually know what ratio our drill has in low speed, only that it is about 400rpm at nom. voltage. We're overvolting to where that rpm is theoretically around 580rpm. Take 4:1 from there and the weapon would do about 145rpm. We just kind of round that down, allowing for load and losses, to about 120rpm on the weapon. If you aim for something along those lines you should topple other machines over nicely.
One thing I'll say, though, is that make sure the transfer from the drill to the weapon business is up to it. You may remember we had a real struggle to contain the torque when T2 came into being. Keep the torque limiter if those dewalt gearboxes have one, on its near-max it shouldn't slip when lifting but should when the weapon can't move. It's awful to hear and look at when it kicks in but I think it has saved us more than once!
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