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Two DC motor lifter question
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Nick
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Those hypocycloid drives that Angus mentioned look quite shock resistant - anybody heard of a supplier?

Post Sat Oct 08, 2011 9:37 pm 
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dyrodium
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I've had a look and it seems to be a very expensive special request item. It's definatley a worthy CNC project, if you can cad the curves accurate enough. Smile

Post Sat Oct 08, 2011 9:45 pm 
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Valen
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There are calculators for them as i recall, they just spit out the curve for you direct in rhino.
Worst case if you can find the formula i'll hack something out.
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Post Sun Oct 09, 2011 10:12 pm 
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Glen
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quote:
Originally posted by Valen:
There are calculators for them as i recall, they just spit out the curve for you direct in rhino.
Worst case if you can find the formula i'll hack something out.


There's an add on already written for it that goes with rhino4, i have it Razz Will have to dig it up though.



TBH a slipper clutch on a normal gearbox is probably a lot less machining intense for the same outcome Razz
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Post Sun Oct 09, 2011 10:18 pm 
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marto
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Yes but by far less awesome!
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Post Mon Oct 10, 2011 11:39 am 
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Glen
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Lol yeah, i think the main issue is balance. unless you have 4 lobes placed 90 degrees to each other it would just shake itself to death if it were using a high rpm motor.

Though looking back on it this was pre one tooth spinner disk days, so perhaps you could do some interesting cad work to get the center of mass around the center axis and it would be perfect. hmm!

Very cool systems though, the reduction that can be had from one stage alone i remember to be rather collosal.
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Post Mon Oct 10, 2011 11:44 am 
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mattmaxsr



Joined: 15 Oct 2011
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Hello all down under,
I'd love to make it down there someday,
but Maui is as far Southwest as I've gotten!!!

after quick look at this thread
Here's what i can add

I'll give you my feeling about designing a weapon system! YMMV

I love interesting designs (novel, unused techniques, things that are just different) they can be awesome!!! I think Stephen Felk is one of the most interesting builders in the sport, I could look at and play with his bots all day!
BUT that's not how I build, I build with more of a old Chevy/Ford work truck. . . Tough and simple!

Ok back on topic

""I am trying to make a lifter similar to sewer snake for a 30lb robot. I am not trying to throw someone to the roof, but just to lift them as I push them to hit them against the walls. I am trying to get a reasonably fast reacting lifter. Could I use maybe two magnum 550 motors (I think they are 20:1 ratio gearboxes) directly driving a single pivot lifter. If not could you guys point me in a direction of what motor might help me accomplish this design. Thanks.""

Ok I can't help you with motors, haven't used the little stuff.

I will lean towards torque over speed, But this is a system. So if you keep it simple and save weight you can add speed to the torque w/bigger motors.
Remember lifter speed isn't all in the arm!?!? Lifter speed plus bot speed can add up to control!
What I mean is if you attack and can get into a good lift position but you are far from a wall, or you just want to flip them over to get a little advantage for your next attack. Use your bot drive speed to help keep them where you want them while you're lifting/flipping them....

I hope this is understandable.

"". Could I use maybe two magnum 550 motors (I think they are 20:1 ratio gearboxes) directly driving a single pivot lifter""

I don't have any Idea what your bot design is going too look like but this could be a bad idea
(Remember I'm not used to building sub 60 lb.ers so the physics could be a lot different)
but using the gear box as the pivot is looking for a failure point! if you go this route look at shock absorbing components in the mount or arm pivot point.


""* The lifter arm needs to travel much less than 360 Deg. for a lift; I picked 90 degrees for the total arm motion. ""

Nick we aimed for travel radius on PipeWench that would let the lifter travel 3 to 5 deg. below grade (or floor level) and far enough upward movement to be able to self right if/when we get flipped! It turned out for us just under 180 Deg.

""* The lifter arm doesn't need to move all that fast, I figured .25 sec end to end was fast enough and a convenient number to work with.
* 0.25 sec for 90 degrees of movement works out to 1 rps or 60 rpm (I did say it was a convenient number! ) ""

That's funny, I aimed for the same numbers on SS but on PW I figured we had enough power to go a little faster. My reasons at the time was to ensure it would self right, if we move the arm to slow it would just stand on her tail. We wanted a little flick to pop it over. I like the way PW comes off the ground and lands on the tires ready to go when it self rights!

""* The Magnum gearboxes have an output speed of 900 rpm @18v, so they would give you 15 rps or a lift time of .017 seconds; too fast IMHO.""

Can't help you on specs for these I have only worked with Mags, Leasons, and EV warriors

as to the equations dcrobotics and nick posted and their questions on torque and speed is getting into work being done or Horse Power. I'm no engineer but when you mix force with time, things get interesting!!!
I also forgot about Aarons page (lost all my favorites when our PC died)
I used similar numbers to Aarons "TAF" and they seem to work for me.

""In that 2nd equation, what does this bit mean: "(Arm Length [inches] * 16 oz/lb""
Arm length is the distance from the tip to the pivot point or where the axle would be

""16 oz/lb"
Their is 16 imperial ounces (oz.) to an 1 Imperial pound (lbs.)
1 ounce = 28.3495 gram
1 ounce = 0.0283495 kilogram
1 lb, lbs = 453.592 gram
1 lb, lbs = 0.453 kilogram
No I don't know this stuff
www.onlineconversion.com
http://www.onlineconversion.com/weight_common.htm

Hope this wasn't to scatter brained but to much over time and procrastination on bot repairs before an event means little sleep. . .
Good luck with all your designs and I hope my 2 cents gives you some food for thought.

Matt
TPCBots


quote:

Post Sun Oct 16, 2011 8:36 am 
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dcrobotics



Joined: 06 Oct 2010
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Thanks for the help Matt. It's really appreciated!

Post Wed Oct 19, 2011 3:46 am 
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mrgrey



Joined: 20 Jul 2012
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Location: india


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hey i wana make a robo for robowar
rules for compitition are
1. not to exceed 35 volts dc
i need a high torque dc motor
can u suggest which motor shall i use.
plz kindly give specifications of it....

Post Sat Jul 21, 2012 12:48 am 
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Philip
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What weight are you aiming at building? In a feather weight, 13.6 kg / 30 lb, you could use BaneBots gear motors. Such as the P60 with a 550 motor. Cordless drills are a good cheap alternative drive system.

Do you have a particular design in mind?
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Post Sat Jul 21, 2012 4:30 am 
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mrgrey



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actually i have a design
max weight can be upto 40kgs
in my design theres big cutter in centre
n i need a high torque powerfull dc motor
thanx 4 help plz suggest me 4 these specs

Post Sat Jul 21, 2012 8:09 pm 
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marto
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OK I know english is not your first language but these posts are annoying me.

Seriously if you had googled. car fan motor dude and Oh you have a design? Drawings, information anything would be helpful. Especially what weight class.
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Post Sun Jul 22, 2012 12:48 am 
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Nick
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One bad post short of a troll?

Post Sun Jul 22, 2012 1:26 am 
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Daniel
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Sounds like the Indian RoboWars.

Post Sun Jul 22, 2012 9:21 am 
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mrgrey



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Location: india


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marto sorry for my bad english. i will post my design sketch and detail info about it.thanx for concern.

Post Sun Jul 22, 2012 1:03 pm 
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