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On 9/11/2019 at 12:25 PM, Janik Hampe said:

 

I´ll get some Lycra and test out, how flexible it is. Of course I´ll avoid any glueing or stitching if possible. I´ll also look up UV curing adhesives and keep them in mind.

 

 

Well, that´s quite an engineering problem when using 3d printing as manufacturing method. Until now I haven´t been able to design such a mechanism that is reliable, rattle free and doesn´t use lots of material (affecting the sound) at the same time.

I know what you mean.  I was thinking instead of some metal clips or something similar that could secure the two halves together.

 

On 9/11/2019 at 12:25 PM, Janik Hampe said:

 

 

 

 

 

Hi Allen,

 

I have two rolls of PETG here but I´ve never been able to produce quality prints with it. Because of it´s hygroscopic nature, it soakes up lots of humidity from the air. When I was trying it out, it produced bubbly, soft and mushy, almoast foam-like prints that were stupid easy to bend. I suppose it´s the humidity. Or could it be something else?

 

Do you experience similar behaviour? And do you de-humidify your PETG before printing? I´m thinking about getting a food dehydrator for this.

 

On 9/11/2019 at 12:25 PM, Janik Hampe said:

 

I´ll get some Lycra and test out, how flexible it is. Of course I´ll avoid any glueing or stitching if possible. I´ll also look up UV curing adhesives and keep them in mind.

 

 

Well, that´s quite an engineering problem when using 3d printing as manufacturing method. Until now I haven´t been able to design such a mechanism that is reliable, rattle free and doesn´t use lots of material (affecting the sound) at the same time.

I was thinking of metal clips or similar that could secure the two halves together.  Not built into the cage itself.

 

On 9/11/2019 at 12:25 PM, Janik Hampe said:

 

 

 

 

 

Hi Allen,

 

I have two rolls of PETG here but I´ve never been able to produce quality prints with it. Because of it´s hygroscopic nature, it soakes up lots of humidity from the air. When I was trying it out, it produced bubbly, soft and mushy, almoast foam-like prints that were stupid easy to bend. I suppose it´s the humidity. Or could it be something else?

 

Do you experience similar behaviour? And do you de-humidify your PETG before printing? I´m thinking about getting a food dehydrator for this.

 

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16 hours ago, berniebeaudry said:

I know what you mean.  I was thinking instead of some metal clips or something similar that could secure the two halves together.

 

Hm, nice thought. I could imagine some cleverly bent spring steel to work for this. And the halves would need to overlap in some way to avoid any side movement. Good Idea, thanks!

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On 8/29/2019 at 5:28 PM, Dalton Patterson said:

@Janik Hampe 

 

Could you print me one? I want it for CMC5. Make that two please. I’ll break one most likely. 

 

I only need the frame. I’ll work on fitting the fabrics and glueing.  I’ll document and send you all results and tricks. I worked on some waterproof Lav Mic cages back in 2012, they were very successful. 

 

Ive been meaning to make a baseball but haven’t seen any frames until now! 

 

Best,

 

D

https://www.amazon.co.uk/Oball-Activity-Toy-4-inch/dp/B00ZRD99C0

 

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On 8/28/2019 at 2:23 PM, Janik Hampe said:

 

 

Hi everybody,

I started a new DIY project. Since I really enjoy this forum and the wisdom shared I´d like to give something back. Here I´ll share the progress of this project with you.

 

The situation

I have a matched pair of Oktava MK-012 with cardioid capsules and use them for AB / ORTF stereo field recordings. I´d like to have good wind protection for them.

 

Because I own a 3D printer and like to design functional parts I chose to give this approach a try before buying Rycote Baby Ball Gags or something similar. If everything works out I plan on buying just the fur from Rycote. For software I used Fusion 360 and Cura which both are free for non-commercial use.

 

 

The 3D model

I began with modeling the Oktava MK-012 to have a reference. This was pretty easy by just taking measurements and entering them into Fusion 360.

 

mk012.jpg

 

Because the capsule´s diameter is bigger than the rest of the microphone´s body I had to come up with some technique to open up the blimp for mounting and unmounting.

 

Rycote´s twist-to-lock mechanism is great but hard to model and close to impossible to 3D print for several reasons. Moreover that I refused to have the blimp split in the middle because of the increased amount of the mechanism´s material beeing right next to the capsule and probably affecting the sound.

 

My solution to this problem was a screw-on mechanism with 3D printed threads in the back of the blimp. I already printed threads as small as M4 so these bigger threads shouldn´t be a problem.

 

screw.jpg

 

So there´s one small part with outer threads which stays on the microphone and there´s the blimp with an opening in the back big enough for the capsule to pass through and inner threads. Here´s the complete design in it´s momentary version:

 

v1.0.jpg

side_split_view.jpg

 

The first print

Getting the 3D model to be printable was a real hassle. As some of you might know, 3D printers can print overhangs up to 45 degrees. Above that I get´s complicated because your are basically printing in mid air. It all depends on the print temperature beeing not to high and cooling down the printed material as quickly as possible. After 3 failed prints and approximately 15 hours of printing time waisted I finally I was able to get my first half of the blimp. One part of the solution was to reduce the ambient temperature around the printer. Another part of the solution was to actually print faster, to reduce the chance of the filament getting too soft before entering the print nozzle resulting in a mess.

 

I´m printing in grey PLA from the german supplier DAS FILAMENT. The print bed is a sheet of PEI glued onto a glass plate. No heated bed. Print settings: 40mm/s, 180°C. I split up the blimp in two printable parts.

 

IMG_20190827_215449.jpg

IMG_20190827_234958.jpg

 

This first successful one took about 5 hours to print. The look and feel is amazingly similar to my full rycote blimp. It is quite strong, can be bent with force without cracking and has very good layer adhesion. And all of this at material costs of ~50ct.

 

 

Coming up next: solvent welding

Now the next step will be to print the other half. Then I´ll be sovlent welding both parts together using either Dichloromethane or Methyl Ethyl Ketone. Both of them are quite toxic and often times used in paint strippers. This connection will be as stong and as flexible as the main material to ensure no weak points appear when using it in more extreme conditions.

 

Questions, opinions and suggestions appreciated!

 

To be continued...

 




Haa that looks really nice !!! this is exactly how Cinela worked :)  i rem member the guy that started it all talking exactly about this shape he made for a soundguy wanting a small blimp for a documentary , his first blimp :) 

I am following this one !! i dont have use for blimps myself anymore but hell who does not like a really nice done propper DIY adventure !

 

On 9/11/2019 at 3:32 PM, Jim Rillie said:

Except Nagra and Aaton always have it reversed Red for left, Green for right. Some sort of esoteric colour code  designed to drive us all nuts! LOL.  

Edit

<Oh, just noticed in another thread about the nautical reference. Makes some kind of sense.>

 

 

Haha yeah its exactly not as you expect :) hehe noticed that to :) thank god there is such a thing like post.... and maybe some phone calls hehe or i would be screwed ;)

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On 9/18/2019 at 1:30 AM, rempen said:

https://youtu.be/nOOGusih2Eg?t=206

 

This video is not in English  ---  could be useful anyway (but it would have been preferable to have it in English or have a translation).

   -  edit: Jeff Wexler, JWSOUNDGROUP

 

Wow, this one contains lots of great concepts, thanks for the hint!  I especially like the idea of having two openings for passing the microphone through the frame. It´s shown at 9min 23s ( https://www.youtube.com/watch?v=nOOGusih2Eg&feature=youtu.be&t=9m23s ). I might try out that approach as it reduces the printed parts to only one. 

 

And you actually can activate automatically translated subtitles in the youtube player. The quality of translation is kind of bad but you´ll understand most of it.

subtitles.jpg

 

 

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v2.jpg

 

Inspired by the russian video posted here about DIY blimps I designed a frame with two openings. One bigger opening through which the whole microphone can be inserted and a smaller one which still holds the two rubber o-rings and clamps onto the mic.

 

v2.0_rendering.jpg

 

 

I do like version 2.0 very much. Having only one 3D printed part is a way more elegant design than having to thread two parts together. On version 1.1 the thread sometimes came loose when I had the windjammers on and it had to be tightened again. In my usecase, which is keeping the microphones almost always inside the blimps, this version 2.0 really does the trick.

 

Here´s a comparison shot of version 2.0 and 1.1 from above.

 

v2v1.jpg

 

 

 

Also there has been a minor improvement. Because the frame is one solid structure now, the inner o-ring is less accessible. I wasn´t able to remove and recycle it from protoypes that were not longer needed. So I added one additional groove connecting the grooves which the o-rings sit in. This way, both o-rings can be accessed and removed from the outside using a paperclip.

 

groove.jpg

 

 

Coming up next: experiments in heat treatment / annealing ...

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firstStepsAnnealing.jpg

 

heat treatment / annealing

 

I already talked about the low temperature resistance of PLA, my current material of choice. When you search for methods to make PLA stronger, you read a lot about annealing.

 

You anneal a piece of 3D printed plastic by uniformly heating it up just above its “glass transition temperature”, let it crystalize (which it does on its own) and then slowly let it cool down. Now your piece of 3D printed plastic should be stronger, less brittle and able to resist higher temperatures. Perfect for leaving the blimp in the car during a hot summer.

 

In the comparison picture above you can see that the annealed test parts shrunk in X and Z (width) but grew in Y direction (height). This is a common and well known property of annealed PLA and originates in the layers beeing added in Y direction.

 

There are filaments like Proto-Pasta´s High-Temperature-PLA (HTPLA) which claim to have minimal shrinkage / growth and which I might try out. While not having HTPLA around my approach is quite simple. I do measurements of the part before annealing. Then I´ll anneal it and measure again. The factor of shrinkage / growth now can be factored in on the next print resulting in - hopefully - a part that shrinks into the correct dimensions. Which is more critical to the grooves which the o-rings sit in than to any other part of the frame. Getting correct dimensions on there after annealing is essential to securely grip the microphone. And we´re talking 0.1mm precision here.

 

 

Test #1

I´m still trying to find the best, uniform annealing workflow. Because I didn´t want to use the oven from our kitchen, the first annealing process was done in a small pizza oven which on the lowest setting has 100°C. Because it also lacks convection heating I simply heated up the oven for 20 minutes, turned it of, let it cool down to 80°C, then placed the part inside and let it cool down. Repeated the whole process three times.

 

Test #2

The second time, I used big pot full of water on an induction cooking plate which is temperature controllable to 60°C and 80°C. I simply left the piece too long in the hot water, resulting in a warped piece.

 

I´ll continue optimizing this process and will post the results. To be continued...

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Hi Janik. Your version 2 looks really good. 

Good to know about my russian video helped you to develop mini blimp.

I know almost nothing about 3D printing materials. So, I wonder: can one print a blimp as flexible as f. ex. polypropylene?

 

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13 hours ago, rempen said:

Hi Janik. Your version 2 looks really good. 

Good to know about my russian video helped you to develop mini blimp.

I know almost nothing about 3D printing materials. So, I wonder: can one print a blimp as flexible as f. ex. polypropylene?

 

 

Glad you like it. 🙂

 

There are lots of flexible filaments for 3D printing. And there´s also polypropylene available though I don´t think it´s very flexible. Many of the flexibles are based on TPU with some additions and vary from quite stiff to super flexible. The more flexible your filament is when not printed yet, the more tricky the printing process gets. Soft filament tends to jam right before going into the hot printing nozzle and needs really good low friction guidance inside the printhead.

 

In consumer 3D printing there are basically two types of extruders: direct drive and bowden drive. Bowden drive uses a (bowden) tube from the extrusion motor pushing the filament to guide it to the heating element. Therefore you have some loss in precision when you push and pull something that is flexible. Direct drive on the other hand (and my printer is a direct drive one) have the extrusion motor right above the heating element, minimizing the lenght of potential filament stretching. Disadvantages of direct drive extruders are for example the added weight on the printhead which limits maximum print speeds.

 

Coming back to your question: can one print a blimp using flexibles? I guess you could. You would have to print ultra slowly (I´m guessing 5mm/s instead of my current 40mm/s). And more importantly the filament mustn´t be too flexible. Its thin structure has to withstand the windjammer´s weight and securely clamp to the microphone. And finally the last problem: flexible filaments next to nylons, PETG and other advanced filaments are highly hygroscopic, soaking up humidity from the air and becoming useless that way. So a sealed drybox full of silica gel which you directly print out of is probably a must. That´s the main reason why I´m using simple PLA so far.

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On 10/16/2019 at 3:00 PM, Janik Hampe said:

 

Glad you like it. 🙂

 

There are lots of flexible filaments for 3D printing.--------------------------- That´s the main reason why I´m using simple PLA so far.

Thank you Janik for very clear explanation.

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I Janik, extremly nice work !

I try to work on the same subject, since a years, and find your post just now.. It's funny, we take the same way for lot of little things and I'm a little bit perfectionist too..

For the moment, I just make a lot (a LOT) of draw and experiment with direct materials and I will buy a 3D printer next week. I'm very impatient to test and produce all this draw ! So I'm very interested by your work!

Are you ready to post your 3D files, it will be nice to be able to work on it and share some experience or test, idea, improvment and more.

Thank's a lot, keep on invent !

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