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Simple, cheap & reliable flipper mechanism
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marto
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Simple, cheap & reliable flipper mechanism

So as some of you may have guessed the winch conversation was leading to something and this would be a simple lifter design. (Also potentially Double Dragon rebuild but thats another post)

We have seen the winches used in the past but there is a few issues with them.

Aaron pointed out that they are actually quite dangerous as a winch is really powerful and if it jams someones arm it could quite easily break it. It also needs limit switches. So the options as the stand....

Winch - http://www.ebay.com.au/itm/2000LBS-907KG-Electric-ATV-Winch-w-Remote-Control-/350882332587?pt=AU_Boat_Parts_Accessories&hash=item51b2377fab

Actuator - http://www.aliexpress.com/item/Xpower-New-Linear-Actuator-2-Stroke-225-Pound-Max-Lift-12-Volt-DC-Heavy-Duty-12v/2025224614.html

Scooter Motor + gear (inspired by jameus) - http://www.ebay.com.au/itm/Briggs-Flywheel-Ring-Gear-Kit-B-S-696537-399676-/291209260523?pt=AU_Tool_Parts_Accessories&hash=item43cd6cadeb

Not sure which I prefer would like opinions.

Context - This may be going on a 12mm Ply robot which would be a cut and slot together design with an optional lifter. This may be basis for a green ant nest style feather set and also potentially a kit. I have lots of ideas for making it and plan would be to release design as PDF so you could glue it on to your own ply and cut it out with a jigsaw.

Steve
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Post Sat Oct 11, 2014 9:34 pm 
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Glen
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That actuator looks like a good deal. 12mm per second is slow, but at 100kg odd force you could run it through a 5:1 linkage for 60mm a second at 20kg force. Worth grabbing one i reckon.

Every other option is probably a bit of a pain in the butt for a kit robot. Gear would need a solid frame to stop the lot unmeshing and cable on winch indeed sounds dangerous.
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Post Sat Oct 11, 2014 9:40 pm 
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marto
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My issue with actuator is how the hell do I do self righting with only 100mm of travel.

Edit: wait 250mm of travel.... Might be doable but that is at tip.

Steve
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Post Sat Oct 11, 2014 9:43 pm 
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Nick
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The ring gear set-up looks promising to me. If this is going to be a non-spinner rent-a-bot, then forget about weight limits and traditional armour - just make them about the same size as a feather and nobody is really going to care about the weight.
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Post Sat Oct 11, 2014 10:49 pm 
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Ellis



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Also cheap Chinese linacs aren't exactly known for the longevity. Depends on the level of combat but they might be a pain in the long run.

Post Sun Oct 12, 2014 12:00 am 
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Philip
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quote:
Originally posted by marto:
My issue with actuator is how the hell do I do self righting with only 100mm of travel.

Edit: wait 250mm of travel.... Might be doable but that is at tip.

Steve
Are you still talking about the linked one above? It has 2" or 50 mm of travel. As Glen says, 12 mm per second is slow. Four seconds to open and the same to close. Eight seconds is forever in a fight. It would be faster at double voltage, but kids would potentially be constantly opening and closing the arm risking over heating.

Aussie Battler has 50 mm stroke and can self right. I can measure the ratios and send them to you if you are interested.

There would be a risk of kids getting their fingers caught. 225 pounds at the actuator could make you say ouch. Maybe the arm could close via spring tension rather than being attached to the actuator.

Have you thought about using a cam on a gear motor to open the lifting arm?
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Post Sun Oct 12, 2014 4:26 am 
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marto
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Yeh I did think about that and its looking like it might be the easiest option.

I am wondering if a drill cam would be possible. And how you could attach that.

250mm of travel would be travel at tip with 5:1 ratio which I guess could be made to work.
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Post Sun Oct 12, 2014 7:18 am 
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Nick
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Don't forget that most actuators are only rated intermittent use - one I recently looked at was 1 minute in every 9. If you over-volted it, the rating would go down even further.
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Post Sun Oct 12, 2014 7:45 am 
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seanet1310



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Phil, any chance you can post the photos even if Steve doesn't want to see? Did it end up being like in your build thread http://www.robowars.org/forum/viewtopic.php?t=336&start=1395

As for the actuator, the one in Steve's link motor casing looks a lot like the one I used in my old lifter. Died super quick but was over volted. As Nick said, they often have low duty cycles so if anything I would slightly under volt in a high use version of the green ants nest.
http://web.aanet.com.au/drapc/IMG_0094.jpg
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Post Sun Oct 12, 2014 3:01 pm 
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Philip
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That was the one I was hoping to build but I have had no time this year.

This is the one that I have now.


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Post Sun Oct 12, 2014 4:28 pm 
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Philip
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Here is my idea for a crank that is comparable to the above actuator. A 25 mm crank would give the same travel. The actuator is ~100 kg weight of force or ~1000 N. 1000 N at 25 mm is 25 Nm (is that right?). So I would go for a gear motor that can handle 50 Nm of torque. The speed is less important. Say 1 revolution per second or 60 rpm. Maybe a 545 through a P60 at 132:1 With a support bearing between the gearbox and the crank would suffice. It has a recommended maximum torque of ~47 Nm.

Is the output of the BotBitz gear motors similar to the P60 gear motors? I haven't seen either one of them.
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Post Mon Oct 13, 2014 2:29 am 
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miles&Jules
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I reckon on kojak -They way i have the arm bolted to the winch takeup reel is way more simple to build than an actuator- and acts more like a servo on a kit bot- but yes its more dangerous, heavy and needs limit switches
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Post Mon Oct 13, 2014 11:29 am 
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Jaemus
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Have to say I like the ring gear scooter motor thing, but then I'm a bit biased Smile The biggest advantage Das Boot had in terms of operation and simple construction was that it didnt require limit switches or anything like that, you can stall a scooter motor for long periods without it burning out, and as such my setup just let me slam the stick back and forth like a maniac without any issues apart from the pinion coming off a couple of times, and mind you I had welded the pinion directly to the motor shaft, abusing it yet further Smile

But simply put, it's the simplest to build, linac requires linkage (complication, failure point) and winch requires safety and lots of power, (and is expensive)
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Post Mon Oct 13, 2014 4:05 pm 
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marto
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I was leaning towards winch as I thought it would be simple but by the time you add in limit switches its not really.

I think cam which can just rotate and maybe even put a pin in it like the kitbots so it doesnt need bungee.

Wonder if something like this would be up to it. Or maybe windscreen wiper motor.

http://www.ebay.com.au/itm/37mm-12V-DC-30RPM-Replacement-Torque-Gear-Box-Motor-/260780581961?pt=AU_B_I_Electrical_Test_Equipment&hash=item3cb7bbe449

Steve
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Post Mon Oct 13, 2014 6:47 pm 
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marto
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Or

http://www.ebay.com.au/itm/24V-8000RPM-240RPM-Rotary-Speed-Reduce-High-Torque-DC-Worm-Gear-Motor-/351127931464?pt=AU_B_I_Electrical_Test_Equipment&hash=item51c0db0a48

http://www.ebay.com.au/itm/Ultrashort-motor-High-torque-worm-gear-motor-DC-motor-GW31ZY-12V-100rpm-/231262806708?pt=LH_DefaultDomain_15&hash=item35d85662b4
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Post Mon Oct 13, 2014 6:55 pm 
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