Lizzie - Team Electromaniac - WA Goto page Previous1, 2, 3, 4Next
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Totaly_Recycled Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1346
lol sounds like fun i was also mucking around with magnets for relays but havent finished the project as yet .didnt think of replacing the solonoide core with one mmmm i have two huge 25mm dia 80 mm long iron magnets some where that came out of an old microwave oven probaly just fit inside the solonoide i will have to dig them out .
Also to get 40 to 50 kgs of lift from the solonoide the core has to be about 1/3 already inside the armeture so you only get about 15to18mm of usefull lift.once the core is all the way in it easily holds 100 or more kgs static weight .
Sat Jan 27, 2007 7:53 am
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
quote:Originally posted by Totaly_Recycled:
Also to get 40 to 50 kgs of lift from the solonoide the core has to be about 1/3 already inside the armeture so you only get about 15to18mm of usefull lift.
Hmmm.... reality kicked in. In my calcs I counted on 100mm of usefull force (who needs a ruler). In the light of day, I'm only getting about 10mm.
The magnets jumped about a metre in the air, which makes me look back over my calcs.
There's no iron in this test setup, so it turns out that it should only be able to hold 7kg. So a factor of a hundred out. Oops. Some other useful things the calcs tell me:
The acceleration in the solenoid is 312.5 m/s^2.
The magnets are in the solenoid coil for 8ms.
The magnets have 0.625J of energy at the end of their acceleration.
There is about 15J of energy put into the coil.
Which give the setup 4% effeciency. From what I've seen on the net It's pretty good effeciency for something with no design work.
List of things to do:
Wind longer coil
Buy more magnets (testing longer projectiles)
Make 200V boost converter
Try to take over the world
Sat Jan 27, 2007 10:41 am
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
I think I'm trying to do things the hard way. I might try a nice simple setup of two drill motors.
Mon Feb 05, 2007 7:51 pm
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
I've been inspired by Trav to build a juggernaut. About 500mm long and 150mm high, brick shaped axe bot. Now I'm wondering if 4 sets of pulleys will provide too much friction for a fast acting axe? _________________ They say that he crossed the fine line, from insanity to genius.
Thu Jan 31, 2008 4:49 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
friction probably wont be that much of an issue for an axe bot. Its only going to do a few turns anyway. Belt slip is probably a larger concern. _________________ Mechanical engineers build weapons, civil engineers build targets
Thu Jan 31, 2008 8:24 pm
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
I will almost definitely have a tensioning bar on the belts, but I have some really nasty plans in mind so a bit of a slip will really help in avoiding a fried EV.
Did a simple weight table and it looks like it will come in at 12.5kg, which leaves a whole kilo for all the stuff that I forgot to add in
That weight is including 4 2.2Ah SLAs, for insane amounts of current draw, so if I blow my weight budget, I'll just have to move up to A123s. _________________ They say that he crossed the fine line, from insanity to genius.
If you are goin to buy 2.2ah SLAs make sure you get some decent ones. The supercheap ones are absolute crap and wont last more than a few battles. _________________ Steven Martin
Twisted Constructions
http://www.botbitz.com
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
Yeh, I've got 4 of the old DOSSs that I picked up two years ago. I've also got the jaycar ones that I use for thrashing, but I know that they won't last.
Will see if I can't manage to pick up some pulleys tomorrow, and start screwing things up .
I'm also planning on building another couple of sets of pulse 50s. Did anyone want a set for testing? About $30 for the pair off the top of my head... may be closer to $50. _________________ They say that he crossed the fine line, from insanity to genius.
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
The boards are made by me, and at the moment, my hourly rate isn't that high
If you just want the boards I could probably say $5 plus postage, although I'm thinking of changing the design a bit so I might put a slight delay on production. _________________ They say that he crossed the fine line, from insanity to genius.
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
I do the photo resist with transparency at the moment. When my transparent sheets run out, then I might experiment with the toner.
ATM I'm buying bits from jaycar, altronics, rs and possibly some 20A relays from the net, that Angus spotted a while ago. _________________ They say that he crossed the fine line, from insanity to genius.
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