Mantis Claw

LuvMyTJ · May 23, 2018

msinger said:
There are lots of pieces to this design (see them here). I suspect it would take a couple of days to print. While that might be a fun adventure for some, it's probably not worthwhile since these kits can be purchased from Amazon and eBay for about $15.

Days? Not sure what type of printer you have used but it must be slow. If you already have a printer the cost of the filament would be nickles. But as you mentioned, they are not real expensive to buy either.

Lapeer20m · May 23, 2018

I spent the $159 on the gannet bait release (dronefishing) but if I didn’t have that, utilizing some piece that has a breaking strength of about 2 pounds would be perfect. Either a piece of fishing line held by some sort of clamp, or fishing line that will break with 2 pounds of force should be a good safety.

I think 2 pounds is about the absolute max payload mavic could lift, and about 1 pound more than mavic can fly with in a controlled manner.

TheFarmer · May 23, 2018

msinger said:
The claw opens when it touches the ground. You'd need to lower it until it hits the ground and drag it away from the object it was holding so it does not attempt to grab it again when you lift the claw.

Got it... thanks. Just make sure you drop it where there is enough room to fly horizontal for a bit.

msinger · May 23, 2018

LuvMyTJ said:
Days? Not sure what type of printer you have used but it must be slow.

I'm currently running Makergear M2s. They are not slow printers by any means. However, I guess you might think they are slow if you're not into using settings that churn out high quality prints (like the parts I make).

Just for fun, I queued up this Mantis Claw project in Simplify3D and it came up with these estimates:

Wish Bone (x5) = 40 mins
Bot Arm (x5) = 95 mins
Elbow Join (x10) = 80 mins
Claw (x10) = 160 mins
Base (x2) = 32 mins
Top Arm (x5) = 105 mins
--------------------------------------------
Total = 512 mins (8.53 hours)

For some reason, the estimates in Simplify3D are always a little shorter than my prints really take. And you'd of course need to include all of the time it takes to clean the build plate, re-coat the surface, let it warm up, let it cool down so the parts can be removed, etc.

So, yep, you should plan on being at the library for a few days. Don't forget your cot

Simmo · May 23, 2018

In regards to the Mavic getting stuck, thats why the 'string' in my little video is so long. Its actually elastic, and long enough for the mavic to fly down to me where I could grab it if the hook got stuck.

JeffCharger · May 23, 2018

RayOZ said:
Public libraries? They still exist? LOL
I haven't been in one for quite a while. I might have to check one this weekend.

I used our public library to print a lens cap. They have high quality printers and charge by the hour. I think the cost was $5 per hour - includes everything. I think it took an hour. You have to bring an appropriate design. It was a good learning experience.

RayOZ · May 23, 2018

TheFarmer said:
How does one release the object after arriving at the delivery point?

Also... if worried about snagging on something too big, perhaps a friction release (like a clothespin or small clamp) can be rigged on the line where a substantial "tug" on the line would pull it loose. I think a mavic could generate a good jolt on the line with a couple feet of vertical headstart.

I initially thought about tension release, I was half-way typing in the prior comment, but I thought once it releases, the drone shoot up once load is released. So that can't be good it then hits a branch above, of the controller kicks in when it sees a jump in altitude, it might then slow the motors and then it'll drop. Might be a risky option.

JeffCharger said:
I used our public library to print a lens cap. They have high quality printers and charge by the hour. I think the cost was $5 per hour - includes everything. I think it took an hour. You have to bring an appropriate design. It was a good learning experience.

That's cool. $5/hr is reasonable. But if it's going to that >8hrs to print, that >$40. I just bought one on eBay for <$11. I check my local public library's website. They dont have 3D printing facility. Just the old fashion paper printing.

Edin508 · May 26, 2018

Here is a fairly cheap option for your release. https://smile.amazon.com/Top-Race-L...=1527337627&sr=8-7&keywords=mantis+drone+claw

Harrier · May 26, 2018

RayOZ said:
Well... I pulled the trigger and bought one from eBay. Definitely need a way to trigger release just in case it grabbed the wrong object and getting itself stuck. Eg. trying to recover a drone in a tree and gets snagged on a thick branch instead. The fishing line dropper seems like an expensive option, unless there’s a cheap one, cos the one I’m thinking of is the cost >$100. Don’t remember what it’s called.

Try searching Amazon for "rcgeek payload release". Seems to work. Got one a couple of weeks ago but haven't actually used it yet other than testing it on the ground. Winds just to brisk all week. It's only $56.

Leo153 · May 26, 2018

gjmphoto said:
The next time a potato gets stuck on my roof, I'm down for one of these.

LOL very funny!!!!

Pauxier · May 26, 2018

I don't have the links to the mechanism.

RayOZ · May 27, 2018

I was looking for something 'dumb'. No servo, no batteries or transmitters. Maybe just a couple of magnets, at the claw end (so they dont interfere with compass), so if it gets stuck, a bit of tug would release. Another idea I had would be a 3D printed attachment, and has a "e" profile and a tension latch, so when yanked, the string pops to the lower "e" portion, then reverse the mavic to release.

Harrier · May 27, 2018

RayOZ said:
I was looking for something 'dumb'. No servo, no batteries or transmitters. Maybe just a couple of magnets, at the claw end (so they dont interfere with compass), so if it gets stuck, a bit of tug would release. Another idea I had would be a 3D printed attachment, and has a "e" profile and a tension latch, so when yanked, the string pops to the lower "e" portion, then reverse the mavic to release.

@Rayoz

This may work for you?