Author Topic: Colibri Hummingbird Dynamic Sculpture - WIP  (Read 42897 times)

Offline Flyboy Jim

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #15 on: November 21, 2017, 04:32:08 AM »
Kirk,

 I'd love to see (as would others I bet) some pictures of these parts being made. Also some details about your CNC mill. These parts look great!  :ThumbsUp:

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #16 on: November 21, 2017, 01:47:58 PM »
The original DXF files for the colibri consist of one large layout for each of the 4 thicknesses of plywood.  I extracted each part individually and used it to generate a Solidworks model.  Now I am regenerating the individual DXFs for fabrication from SW.

My mill is a Novakon NM200 that I purchased in 2010.  It has a 3HP spindle with a maximum speed of 4000 RPM and used R8 collets.  Up until recently the control was Mach3 using the parallel printer port to communicate with the breakout board.  Now I'm running Tormach's PathPilot control program that eliminates the parallel port and moves much of the low level operations from the CPU to a Mesa I/O board.  The motion is a bit smoother now.  Previously the maximum rapids were 75 inches per minute.  Now I could go a lot higher, but I'm just using 100 for now.  The user interface with PathPilot is a bit better as well requiring fewer mouse clicks for zeroing parts.

I've been using CamBam for g-code generation since the beginning.  PathPilot runs the same code as Mach3 without modification.  I typically will simulate parts using Cutviewer Mill software.  Doing so can detect unintended consequences, and also shows how long the machining will take.  On the fan part, I spend a good while tweaking the settings in CamBam to reduce the machine time.  Normally I use conservative feeds and speeds, but I don't want to overdo it and spend hours watching a part being machined.  I use GWizard for feed and speed calculations.

For model engines, there's typically many parts that get made on the manual mill.  The parts for colibri are almost all curved in some manner, so other than round spacers I expect most of the machining here will be done via CNC.
« Last Edit: November 21, 2017, 01:51:10 PM by kvom »

Offline bent

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #17 on: November 21, 2017, 06:26:05 PM »
Watching with interest  :popcorn:.  We have a CO2 laser cutter at work which would work well for the plywood version of the 'bird (even better in acrylic sheet), but I'm not so interested as to want to spend that much...yet  ;).  Some of Mr. Derek Hugger's other design plans are less costly, though, and also intriguing:

http://www.derekhugger.com/colibri.html

(cut and pasted from the Youtube channel posted by the OP)

simplyloco

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #18 on: November 21, 2017, 06:37:45 PM »
We are driving down to Albir, Spain, in the New Year, having rented a nice bíg Spanish Villa for three months. There's plenty of room there for my new Excalibur saw, and I've dropped plenty of hints about Colibri plans for Christmas... :LittleAngel:

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #19 on: November 21, 2017, 06:51:36 PM »
I think with a laser cutter and wood I'd still use a drill for the holes.  But certainly having all the pieces cut in one go each from each thickness would result in a very fast build.  The same goes for using a large CNC router.

Manually cutting all the wood parts with a jigsaw sounds tedious to me.
« Last Edit: November 21, 2017, 10:03:06 PM by kvom »

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #20 on: November 21, 2017, 11:38:49 PM »
Today's part is called the 'tail mount right', or the support part of the tail mechanism on the bird's right hand side.  In this picture of the assembly it's the dark grey.



The process to make this part has a number of steps, of which the first is to open its DXF file in CamBam and specify the machining operations to be applied:



In this case there are 9 operations as shown in the tree image to the left of the screen. The first 5 are for drilling the various holes.  Then there are roughing and finishing ops for the opening in the center, and finally a profile op on the outer boundary.  To check before cutting metal, I emulate with CutViewer.



The drawing tell me the part will fit inside a 4x4" square of aluminum, and it's specified as 3/8" thick.  Essentially all the parts in colibri are designed to be cut completely through sheet stock, so some means of holding it must be conceived for each.  Since there are 3 1/4" holes, my plan is to attach the stock to a base with screws.  First, I use some spray adhesive to attach it along with a small clamp.  The assembly is mounted in the vise at the mill with a stop on the fixed jaw.  This stop will allow me to remove the work after the drilling in order to apply the screws;  then it can be replaced in the vise in the same position.



For each drill bit and endmill I need to establish the top of the stock as the Z0 position.  PathPilot assumes one each tool is in a software table with a predefined length.  For this to work I'd need numerous tool holders.  Instead I measure each one at tool change using a 1" gauge block.  But I have to stop the program to do so, and then manually restart it afterwards.



The screen on the PathPilot control shows the toolpaths graphically.



With the stock screwed to its fixture we're ready to do the milling ops.



And the final result:



For parts that don't have convenient holes other methods of workholding will be used.


Offline b.lindsey

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #21 on: November 21, 2017, 11:50:54 PM »
That turned out well Kirk. Will be interesting how much weight you need to balance the entire mechanism when it's all out together.

Bill

Offline Flyboy Jim

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #22 on: November 22, 2017, 03:08:24 AM »
Good explanation Kirk. Thanks. I even kinda understood it!  :hammerbash: I can see where this CNC stuff would really open up some doors for projects like this. Actually...... I'm just now machining the rocker arm for my P & W build and it would be a great CNC project!

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #23 on: November 24, 2017, 09:42:36 PM »
A few Thanksgiving parts.  The right side of the tail mount was combined so that the two standoffs are integral (i.e., equals 3 wood parts).



Then in order to combine all the parts made thus far I needed the central piece, called "tail feather mount" in the plans.  Material is Mic6 aluminum, 1/2" thick.  Holding tabs were used for the machining/



After separating, a 1/16" hole was needed for the tail feather pivot.



Now assembling the first two parts.  Note that with the wood version, the 5/32 tube and 2" wood screw are used to align the parts, which would be glued together.  Here we'll use loctite on the tube and a 2-56 screw.  I will avoid trying to glue metal faces if at all possible.



Seems my deburring needs some work.


Offline b.lindsey

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #24 on: November 24, 2017, 09:57:24 PM »
 A little 320 grit paper on a surface plate on those flat sides and they will look perfect !!  Nice idea integrating the parts into one piece as well.

Bill

simplyloco

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #25 on: November 24, 2017, 10:49:41 PM »
SNIP

Manually cutting all the wood parts with a jigsaw sounds tedious to me.

Watching a CNC centre take 4 thou cuts all day seems pretty tedious to me: I have the callouses on the palms of my hands to prove that I like moving machine handles! :insane:

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #26 on: November 25, 2017, 12:42:40 AM »
Further assembly requires accurate parting off of spacers from 9/32" brass tube with a 1/4" ID.  Ordered a 9/32 collet today along with a bunch of colored acrylic sheet for the body and flower.  Should arrive on Monday, along with the gear from Shapeways.  In the interim, more parts to machine.

The 316 SS tube used for the axes of the roller bearings is a bitch to tap (8-32).  I might use a larger drill for the next ones.

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #27 on: November 26, 2017, 08:59:38 PM »
I received the hypocycloid gear from Shapeways on Friday, so continuing with the "proof of concept" I cobbled together an eccentric cam from brass (throw is 0.4") to test the motion.  Here's a short video:

<a href="https://www.youtube.com/watch?v=vSZ1F4ApuJU" target="_blank">http://www.youtube.com/watch?v=vSZ1F4ApuJU</a>

Note that the hypocycloid turns in the opposite direction from the eccentric and makes 1 turn for every 4 of the eccentric.  For the sculpture the gear reduction is 1:2 so that the total reduction from the input crank is 8:1. 

Offline crueby

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #28 on: November 26, 2017, 09:12:43 PM »
Another one of those mesmerizing motions!   

 :popcorn:

Offline kvom

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Re: Colibri Hummingbird Dynamic Sculpture - WIP
« Reply #29 on: December 02, 2017, 01:23:53 AM »
The "feathers" of the tail are five separate parts that use the rack and pin in slots to spread out as colibri flies.  They are to be made from 1/8" red acrylic.  I ordered a 12x12" piece from McMaster and cut it into 4 6x6s.  Two feathers fit on a single piece (closely).  Such thin stock is impossible to hold in the vise as it will just bend under the pressure of the jaws.  I came up with this "fixture".



The acrylic has paper covering on both sides that can be easily peeled off after machining.

Afterwards the two are still attached by holding tabs to the rest of the stock.  The tabs are easily clipped apart and the nubs sanded off.



I regret to say that some mishaps caused unintended breakage so that I have no more stock and only 4 good feathers.  The 5th must attend acquisition of another piece.

Colibri uses a number of SS tubes that attach various parts together.  The recommended tube from McMaster is 1/4" diameter 316L.  Depending on the tube in question, either one or both ends must be threaded 8-32 x 1/4".  The first one I tried to tap normally was a problem.  The material is hard, and my HSS taps had heavy going.  Derek suggested that cobalt steel taps would cut it easily, but rather than that I decided to thread mill them.  I have a single point thread mill that up to now was used only to make studs, so this would be the first internal thread.  It took me a lot of trial and error to find a good set of code, and each thread took 5 minutes of machine time.  So rather inefficient to thread 10 holes, but at least I have the program saved for future use.  Here's the setup.



I got a shipment of aluminum today, so I should be ready to make more parts.

 

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