Project: Single Servo Multiple Drop Mechanism - 3D Printing

[ProfessorFate]

R Side Mech done

Well that 1/8 piano wire is good stuff and tough, but it can be bent, this one is done, I did overshoot and when I do the Left side, I could remake the Right side and try to make it the 4 5/8".

Oh, you can't see from the pic but I filed the bottom ends of the hooks so they would not catch on the wood channel floor



If you have never tried this solder and wire joining method for landing gear, it sure feels strong, just clean it real good and scratch up the surface to be soldered and will hold good. I cleaned that oily rod with acetone then ground the parts to be soldered with my dremil


***** Being kind of rusty at bending this piano wire the bends on the Right side of the picture look too sloppy, and messed up the dimension.

As you can see, those middle hooks that got bent and soldered, have tighter bends, I really got my method down with a really tight good pair of channel locks and a vice grip and a 4# hammer and a 4oz hammer to get exactly what I wanted

I should have discarded that first effort and made another better one, instead of investing in this one, the wire is not expensive and I think, we can get this piano wire at Home Depot (gonna check on their piano wire, see if it is piano wire), this I got from a Hobby Store.

Looking back at this now, I should have tried bending one of those smaller hook pieces in the middle, then that would have got discarded and the next efforts would be right, it only took a few bends to get a successful method


I put green marks where 3,6,and 9 would be for the slots the loops go thru and they look like they will work exactly as planned in unison all the way to B3 with 9 or 10/16" of movement, maximum.


So Smith, yall started talking about this, and I have the Right side of one made for flat servo installation, tell me what you think,


Look like something you want to try?

Even tho I did not make my exact layout, the mech moves in unison, so 3/16 out drops B1, 6/16 drops B2, and 9/16 drops B3, still consistent and will work


Those wire reinforced soldered joints seem incredibly strong.

Tweaking an up angle of 2 degrees should not be done, just file the bottom of the hooks instead
to prevent snagging of hook to slot.
Shorter sleeves like maybe 1/4" may be better because of tweaking the hook ends up, not such a good idea, because the bottom of the hooks can be filed to keep from snagging on the slot the loop passes thru.

This may just be a 1st effort to be discarded and I'll try again, and maybe do the shorter 3 1/8" puller mech below

Leonard

 

[ProfessorFate]

One more shorter bomb release mech -- pull-pull

Hi, this should explain everything, of course you have to deal with how to put the servo in flat this way and deal with assymetrical line up of bombs or make the wire hitting the servo about 1.25", I just started out putting 1" there and saw this, so make the servo contact arm longer than the 1" front to back width of the mech

The good thing you might like about this is it pulls in and starts at 3 1/8 inches each side instead of 4 5/8", it is improved.

Well I built half of this as a push system but might go for this, too


S is for "servo"
the smaller numbers are for 16ths, just did not like the clutter of fractions

Total required wing is now just min of 6 1/4 instead of a full 12" and still 1" width for each bomb

When you print this out, it's actual size just as written.
Leonard

 

[ProfessorFate]

flipped views to print on 8.5x11 helps when shaping squaring wire



Smaller 3.125" pcs

Want the bombs inline, just leave the length that the servo contacts a nice random 1.5" and put a straight line 8" long inside wing channel, lay slotted lengths on the line like they go in channel and decide how short you want to trim the random to.

Mount servo to something like a 2" by 1" piece that should land in both blank spaces, remember on the top side, that mech travels away from the servo but the bottom wire may travel toward your servo mounting

I kind of expect the plank that holds the servo to be attached at diagonal points avoiding the moving mechs that pull inward... you'll see when you lay the pcs out and just imagine each pc moving a max of 11/16" inboard, on one side, one of them moves away but the other converges in a certain area

Actual Size ready to take to work bench and build R n L sides

Leonard




Heyyyyyyyyyyyyyyyyyy Smith, I think this is whut you want, optimized, don't know if it can be made any better.... may be.

Holler back n tell me what you think. think I got so into this I'm gonna put it in my plane, drop 6 bombs with 1 servo

that 1st pc 21.7g or .76oz so about 1.5oz for both plus servo and channel
Lite ply is about 1g per square inch

you know, you just think about something till you get attached to it and make it your own goal too


*** funny how things go and get developed, at some point I think I have it and it can't be improved, then a new better or more space saving idea comes along, one more iteration of development and details

 

[ProfessorFate]

Mistakes Corrected for 1 Servo Bomb Drop Pull Config.




Red dotted lines show where mech moves to, glue servo base plate but not in that area, it pulls inboard

This is a convenient picture with 2 copies for the printer

Numbers and function checked over and over, this must be right

Here this shows where the clear areas are to stick the feet for the servo mounting plate that floats above the flat mech wires like 1/8" or so, the squares, nothing moves there. Put a block stop 1/4" wide in the middle below and cut a hole in the plate to fall in the right area to pull the 2 wire mechs, the outboard spring pulls the mech with a little tension against the stop, but when you drop a bomb, the servo pulls the mech away from the block inboard


This should be clear if you look at it and just see the mech moving inboard by the pull of the servo and dropping the outermost B1 first.... in sequence then




I'll bring it up since I almost thought there was not room for the servo, it and the flat plate that holds it, float above the moving mechs supported by the feet you glue down to the square areas where nothing moves.

It's right, finally.

Now, after so much work on this, it's got to go into a plane.


Leonard

 

[ProfessorFate]

Added back in 3rd sleeve



Might need 3 sleeves to hold it without jamming or catching


Done

 

[Danal The Dragon]

If I gave you the dimensions of a nerf dart it could be different to the nerf dart you would use. There are diferant sizes

 

[smithhayward]

Anyone still interested in me continuing this project? 3D printer has been down for a while pending some tweaking, but I do still want to tackle this challenge...

 

[smithhayward]

I've been doing some research on types of gears and mechanisms so I'm going to try a redesign on this one. I might also remove the magnets or use smaller ones with less power.

My main issue was making the unidirection gear so that I can have the servo actuate the shaft in one direction, and also make it so that a single actuation of the servo will rotate the shaft 90-degrees to release one of up to 4 bombs.

More to come in the next few weeks/months.

 

[saiga556]

I liked your first idea of using a cylinder. This would make the mechanism more comparable with multiple air frames and would also make it easily removable.

That being said your methods for accusing the cylinder, while creative, are too complicated. My thought is that you use a tried and true method for rotating a cylinder with precision. Take a look at how the cylinder on a revolver is rotated. There is a star shaped gear in the center that is acted on by a pawl. The result is a rachet mechanism that turns the cylinder a predetermined number of degrees.

This solution would mean that a simple servo arm could act as a pawl and all you would have to do is attach a racket gear to the axle that the cylinder is attached to.

 

[smithhayward]

Thanks Saiga! I'm going to try to run with this soon. I got bit again by the 3D Printing bug when I found MakerBox (a monthly subscription for sample filaments). I'll go back to the drawing board, draft up something in Blender and post the drawings before my next attempt to print for some feedback.

Could you imagine if humans never had the ability to work together and share knowledge? Most of us would still be using rocks and sticks as tools...

 

[smithhayward]

Eureka!!!

OK you need something to rotate the cylinders and something also to control the rotation.

I didn't have any restaurant napkins to draw this on, so I just used a piece of paper.

View attachment 56281

PROFESSOR FATE!!! I haven't seen you in a long time - I hope all is well!

I just happened to be revisiting some of my old postings to see where things left off and reading this one gave me a few NEW ideas on how to approach this. I was previously trying to figure out how to use a ratchet mechanism to rotate a center cylinder with protruding "sticks" which would sequentially push down on magnet or pressure secured "bombs".

I think that the tensioned rotation using a servo to repeatedly allow/restrict the rotation will suit this just fine. Hopefully will get to draft something soon.

And on another note, I also had an idea that uses a mechanism similar to a nerf gun clip (installed on its side inside a plane wing) [albeit a large wing] and using either some small brushed motors or CO2 to launch the nerf projectiles foward. I also hope to investigate this one further as well.