lift winch ideas anyone?

[windell747]

Hi,

I've recently just started designing our lifter. Unfortunately, I don't have permission to release our idea, but what I can say is that we are using a winch type mechanism.

I want to design a small winch capable of lifting just our robot (120lbs) using as many COTS products as possible. Have any of you thought about a design for such a winch.

We are thinking about using two counter-rotating drums that are driven off a single motor. The questions we have is what motor/gearbox to use.

Thanks for your input,
windell

[timytamy]

Would your design be similar to any of these: http://www.chiefdelphi.com/forums/showthread.php?t=80152

What motors do you have left in the KoP after they drive base and kicker?

Thanks,
timytamy

[EricH]

Got a better idea for you, depending on your winch setup. 1 drum, 2 sections, running the outbound cord off one side and the inbound off the other one. I've been on a team that did 3 steel cables off one drum, powered by 2 Fisher-Price motors with KOP gearboxes, for lifting a robot.

Setup: the F-P motors are mounted as described in other threads. Each powered one end of the drum through an adapter. The drum itself was lathed into 3 sections--center was the "incoming" cable and the sides were both "outgoing" during a lift. The incoming cable and the outgoing cables were wound in opposite directions.

What I'd do these days, given that that adapter is no longer in the KOP: make an octagon for a FP-keyed shaft interface, and make something similar for a drum of the appropriate size. Or find a source for it.

[windell747]

Thanks Eric and Timy! We have the FP motors, and the small motors left in the KOPs. We might consider ordering a few CIMs.

How does this idea sound? A CIM (or two CIMs) attached to a worm gear/ gear set that turns one drum. To turn the other drum, spur gears are between the two drums causing them to counter-rotate.

Can we use more than 4 CIMs? I forget what the rule is.

Thanks!

[Vikesrock]

Can we use more than 4 CIMs? I forget what the rule is.


At this point in the season if you don't know it you should at least know where to look:

http://www.usfirst.org/uploadedFiles/Community/FRC/Game_and_Season__Info/2010_Assets/08_The%20Robot_RevF.pdf

[jsasaki]

<R52>
D. One, two, or three additional 2½” CIM motors (part #FR801-001 and/or M4-R0062-12) in
addition to those provided in the KOP. This means that up to five, and no more, 2½” CIM
motors can be used on the ROBOT.

[windell747]

Thank you Jun! I think I was thinking about a rule from a previous season which allowed the use of only 4 CIMs. Its nice to know that we are allowed to use 5 instead of 4.

[the man]

You should assume 150lb for the weight of the robot with bumpers and a batt.

[IKE]

You should assume 150lb for the weight of the robot with bumpers and a batt.

Even if you plan on being light (90 lbs + 10 lbs battery + 20 lbs bumper =120 lbs), "the man" is right that you should assum 150 lbs. as your team may want to add future functionality (reset arm, more poerful kicker...) or may have trouble making it to the designed weight. By the rules though, you shouldn't excede 150 lbs and be competition legal, so that is a better assumption.

[Ryan Caldwell]

Some compact COT winches use planetary systems mounted inside the drum.

Could work to keep things small.

[Dick Linn]

You could use a differential windlass principle for a winch. It's easy to get a tremendous mechanical advantage if you don't mind using quite a bit of cord. Search on "differential windlass" or "Chinese windlass". Same principle is used in chain hoists (chain falls). It might eliminate all the heavy, expensive gearboxes.

Oh, perhaps someone can figure out how to use this 33:1 torque multiplier in a winch application:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93645

[DonRotolo]

Also consider that you don't want the lift to take 15 seconds - design for much faster than that. How many times we've seen a nice lifting mechanism, engaged and lifting with 15 seconds to go....and they don't make it, because their design sacrificed speed for power.

[Alex Cormier]

This would do fine, in fact I was playing with the one we bought for our lift system today. Small, light, cute.

http://www.grainger.com/Grainger/items/6Z001?Pid=search

[joek]

we use pneumatics to lift up the hook, and a winch to pull us up, somehow driven by a CIM

[terryo]

This would do fine, in fact I was playing with the one we bought for our lift system today. Small, light, cute.

http://www.grainger.com/Grainger/items/6Z001?Pid=search

We're using a similar winch driven by a CIM and toughbox using sprockets and chain. A bifold arm driven by 2 Denso's extends the hook, a pair of cylinders lifts up the front wheels, we drive up against the bar and lower the cylinders to attach the hook, then retract the arm and start winching. 2 " dia drum on the 3.1:1 winch gives us over 400# lifting force and gets us above the platform in <10 seconds. (in case an alliance member wants to come along for the ride) :cool:

[martinswat1806]

We are considering meshing two fisher price motors and gear boxes. we used a similar design in 2007 and it worked well for us. a positive is that they are lightweight and still provide all of the power and speed you would need in a winch. Hope it helps.

[lespie]

we are using a hand wench and changing the hand part to the motor and i cant say much more so i cant tell you much more but try a hand wench that has gotten us this far........

good luck
:ahh: :yikes:

[joek]

a wench, that's pretty creative (and heavy)::safety:: , we're using a steel-cable boat winch and a scissor lift

[craigboez]

Anybody know if you can get a winch like these locally, like a hardware store or Lowes/Home Depot?

[Ken Leung]

2 CIM motors for our winch... Overkill? Maybe. :D

[Hastypickle]

All I am saying about ours is that we are using a single CIM directly attached to the drum of a hand winch.

[windell747]

Thanks for the replies everyone! Great advice! So in response to the last reply, is a CIM powerful enough to drive a winch drum directly and lift the robot? I was thinking about a worm and worm gear setup to drive the hand crank shaft on a winch supplied by grainger.

[joek]

Thanks for the replies everyone! Great advice! So in response to the last reply, is a CIM powerful enough to drive a winch drum directly and lift the robot? I was thinking about a worm and worm gear setup to drive the hand crank shaft on a winch supplied by grainger.
not unless you use a gear box with it, we're using one from '07, but a worm gear might work

[Dad1279]

......So in response to the last reply, is a CIM powerful enough to drive a winch drum directly and lift the robot?.....

If the diameter of the pulley is about 1/48th of an inch. Then it must be made of some really strong stuff.....

Or it winds in a block and tackle with about 48 pulleys.....

I would suggest downloading and learning to use JVN Spreadsheet. http://www.chiefdelphi.com/media/papers/2059

[Hastypickle]

not unless you use a gear box with it, we're using one from '07, but a worm gear might work

I forgot to put in that we are using a gearbox. Our tests show that our configuration will work quite well.

[baihooli3022]

hey guys, what Team 3022 did for our winch system. We just basically used the KOP's Window motor, and placed a bearing on the other end of a shaft we fit into the motor. Next, just attach a string, and instant winch made by the KOP motors. We tested it earlier with just our bot's frame (about 40 pounds), and it worked fine. We're about to test it with our robot's near final weight (about 100-120).

[joek]

a window motor is not gonna lift a robot without being geared down a lot

[Mike Betts]

a window motor is not gonna lift a robot without being geared down a lot

Joe,

OK. Let's see if the math supports your statement...

The previous poster stated that he connected a shaft directly to the window motor. The most likely would be a 3/8" diameter...

The spec sheet for the Nippon-Denso gives a stall torque of 10.6 N*m. Now, the maximum power for a DC motor will occur at 1/2 speed and this give a torque of 5.3 N*m or 3.9 ft*lb or 46.9 in*lb.

The radius of the shaft is 3/16" which gives us a lifting force of (16*46.9)/3 = 250 pounds...

Cool!

I will leave it as an exercise for the student to calculate the speed of the lift and as an exercise for the testers to determine if the internal PTC resistor will interfere with lifting operations...

Regards,

Mike

[O'Sancheski]

Can we use more than 4 CIMs? I forget what the rule is.

Thanks![/QUOTE]

this year you are allowed to use up to five CIMs... We are using a 32:1 BaneBot Transmission with a CIM powering it, and it is hooked up to a custom winch system that we built... the one thing that you have to worry about is if you are using any type of airplane cord or such(anything besides an arm) than you will have to make some type of guide to stabilize the robot while you are grappling up.

[Grim Tuesday]

Our winch idea (already made now :P) is here (http://cms.team639.org/node/97). Although, it is a bit overkill, since by my calculations, it can lift about 600 lbs... However, it can do it in about 3-4 seconds to get above the platform, and 10 to get to 7 ft. What you see in the model is a 12--->24, then a 1----->60 reduction. All in all, it is a 120---->1 ratio.