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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...

 

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10 hours ago, Mike Westgate said:

What material will you cover this frame with ?

 

mike

 

Hi Mike,

I plan on simply using Rycote Windjammers made for the Baby Ball Gag. They have some silky material on the inside to diffuse the wind that passes the fur. If that´s not enough, I´ll try to glue some nylon pantyhose material to the frame - either on the outside by by pulling it over or on the inside by inflating a ballon and evenly pressing it against the frame. This is also a reason why I split the frame by two. Having two halves probably makes this process easier. But that´s just brainstorming at the moment.

 

What´s your guess on this? Will I need some additional material to cover the frame when I´m using Windjammers?

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@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

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Nice Project Janik! 

 

I like your basket because the weave has a looser structure than the Baby Ball Gag from Rycote. Additional material on the Frame definitely makes sense, to be able to use the basket without fur when there is no to light wind. My Baby Ball Gag without fur is much better against Wind than my Rycote Baseballs, or any Foam protection. I've tried that with my wind machine. Pantyhose seems to be a good idea. Also thin air filter material is used, but sometimes harder to get in small quantities, because often they are industy filters. Keep us updated on the progress :)

 

Greetings

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1 hour ago, 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

 

Hi Dalton,

 

thanks for the offer. I´m glad you´re interested. But I won´t print two and send them over to you since it would be kinda expensive from germany and this is early prototyping stage. So there probably will be major changes until the final design. But I plan on publishing the files when this project is done so by then you might be able to have it printed locally at your area.

 

 

1 hour ago, pillepalle said:

Nice Project Janik! 

 

I like your basket because the weave has a looser structure than the Baby Ball Gag from Rycote. Additional material on the Frame definitely makes sense, to be able to use the basket without fur when there is no to light wind. My Baby Ball Gag without fur is much better against Wind than my Rycote Baseballs, or any Foam protection. I've tried that with my wind machine. Pantyhose seems to be a good idea. Also thin air filter material is used, but sometimes harder to get in small quantities, because often they are industy filters. Keep us updated on the progress :)

 

Greetings

 

Thanks! The material inside my original Rycote blimp actually feels like I imagine air filter to feel like, beeing quite stiff and therefore probably harder to process. Of course it would be nice to use the blimps without fur. But my DIY projects often times suffer from me beeing too much of a perfectionist so there is no progress. For this one I decided to get things done. If the windjammers works, I´ll be using blimp + windjammer outside and foam inside. Simple as that.

 

I´ll keep documenting my progress, stay tuned. Since I work on this between my jobs it only might take a while.

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Nice work Janik!

Instead of panty hose may I suggest Lycra.  It's available in black and is much sturdier than panty hose.  A fabric store should have it in stock and its the material that is often used to make ice skating costumes.  When its stretched you can see through it just like panty hose.  I used to manufacturer circular Pop screens for studio mics and found it to be really transparent sounding yet hard to damage.

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28 minutes ago, berniebeaudry said:

Nice work Janik!

Instead of panty hose may I suggest Lycra.  It's available in black and is much sturdier than panty hose.  A fabric store should have it in stock and its the material that is often used to make ice skating costumes.  When its stretched you can see through it just like panty hose.  I used to manufacturer circular Pop screens for studio mics and found it to be really transparent sounding yet hard to damage.

 

Wow, thanks Bernie for that very valuable piece of information. I´ll keep it in mind.

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Chemicals and tool prep
After reading a little bit about Dichloromethane, its extreme toxicity for humen and the enviroment I decided not to try it out. Instead I ordered 200ml Methyl Ethyl Ketone (short MEK) from Ebay. It turned out that none of my rubber gloves weren´t save enough for working with MEK as it dissolves quite a lot of plastics. So I ordered some quite expensive, thick and robust butyl gloves as well as a glass pipette.

 

 

 

Version 1.1
Meanwhile I had developed the 3D model to version 1.1. The major changes are:

  • Added two rubber o-rings as a rattle-free and slip-free interface layer between the 3D printed part and the microphone.

anker_gif.gif

  • Replaced the thread with a custom profiled thread which has been optimised to be 3D printed (no overhangs above 45 degree).
  • Moved the internal thread from the inside of the frame to the outside. This uses up a little more space on the microphone but enables me to reduce the needed support structures to a minimum resulting in faster prototyping.

The model now looks like this (support structures not shown):


v1.1.jpg

To be continued...

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O-ring installation
Here you see the new o-ring containing part. The technique used here is called “bridging”, uses thin support structures and enables printing over air and steep overhangs. The support layer beeing only 0.2mm thick is easily removed with a deburring tool or a knife. For print settings I doubled the layer thickness from 0.1mm to 0.2mm for faster prototyping. It actually improved the quality as stringing became less of a problem.

 

deburring.jpg

 

... and the finished part with o-rings installed:

 

IMG_20190908_173736.jpg


 

 

Adventures of solvent welding
Finally, the welding of the frame. At first I tried to use pure MEK, brushed on the two surfaces and held them together. The result was disappointing. At some points the parts welded but the connection was weak and I was able to break them apart easily.

 

MEK has a low viscosity like water and the surfaces of the print aren´t flat because of the 3D printed lines have lots of air space between them. I tried to dissolve some PLA in the MEK to get a higher viscosity slurry with a chance of getting more contact area. After hours of the PLA sitting in the MEK, it looked like this. No dissolving of the PLA, only the grey color pigments gets extracted. So back to the drawing board.

 

mek.jpg

 


I did more research. Some people seem to have success welding PLA with Tetrahydrofuran. Some were successful with Acetone (which I also tested and which didn´t work). The differences of ingredients of available printing filaments seem to be quite large so there´s no guarantee for success.

 

Another option would be to print in ABS. ABS is a less brittle, more UV resistant material and can be welded simply with acetone. It requires higher printing temperatures, a heated or at least enclosed print chamber and a really (!) well bonded first layer. Otherwise it will warp from the build platform and the print will fail most of the time. Maybe i´ll concider it for future experiments, but not for now.

 

 

The all-in-one approach
Stepping away from all these chemicals I simply printed the whole frame all in one. I guess I never considered it before because I thought it was impossible due to the very steep overhangs. But I seem to have dialed in my settings for PLA quite well and it turned out very nice. The only disadvantage of this approach is that you can´t glue anything to the inside of the frame anymore.

 

full_frame.jpg

 

 

 

The whole thing now looks like this. I´m quite happy how it turned out so far.

 

IMG_8202.jpg

IMG_8199.jpgIMG_8198.jpg

 

To be continued....

 

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13 hours ago, berniebeaudry said:

Nice!  Have you tried UV cured adhesives?  I don't know if they work on plastics but they look promising.

 

I haven´t. Instead I gave the acetone another shot. But this time I sanded the surfaces of the two frame parts with 100 grit sandpaper and after that with 180 grit. I purposely left the sanding dust on the parts to act as a filler for the still existing gaps. Clamped the two parts together and applied acetone with the pipette.

 

And voilà - we have a really robust connection that set in like 30 seconds! I threw it on the ground with force several times and it didn´t break apart. So I finally have a solution for this problem! 

 

acetone.jpg

 

To be continued...

 

 

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On 8/29/2019 at 10:57 PM, berniebeaudry said:

Nice work Janik!

Instead of panty hose may I suggest Lycra.  It's available in black and is much sturdier than panty hose.  A fabric store should have it in stock and its the material that is often used to make ice skating costumes.  When its stretched you can see through it just like panty hose.  I used to manufacturer circular Pop screens for studio mics and found it to be really transparent sounding yet hard to damage.

 

As glueing Lycra to the inside of the frame becomes possible again, can you recommend any kind of glue for this job? The requirement is that the curing time has to be long enough to apply it to the whole inside of the frame part, get the Lycra into position and pressing it in evenly.

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On 8 September 2019 at 5:58 PM, Janik Hampe said:

 

 

IMG_8202.jpg

IMG_8198.jpg

 

To be continued....

 

 

Janik, have these photos been flipped somewhere down the line or are you being deliberately perverse with your channel markings?

 

Jez

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1 hour ago, The Immoral Mr Teas said:

 

Janik, have these photos been flipped somewhere down the line or are you being deliberately perverse with your channel markings?

 

Jez

 

Hi Jez, could you explain what you mean by that? I really don´t get it. If you´re talking about the cables´ color coding, that´s red for "right channel" and green for "left channel".

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4 hours ago, Janik Hampe said:

 

As glueing Lycra to the inside of the frame becomes possible again, can you recommend any kind of glue for this job? The requirement is that the curing time has to be long enough to apply it to the whole inside of the frame part, get the Lycra into position and pressing it in evenly.

I would suggest gluing/attaching it to the outside instead of the inside.  That way you can stretch it taut.  You may also need to think about sewing or gluing the fabric into quadrants.  A single piece of fabric would need to be folded over in some spots to conform to the hemisphere of the cage.  I would use a thicker/slow drying super glue type adhesive for attaching the fabric, or instead of glue, thin strips of velcro.  If you do still want to go to the inside the adhesive I'm suggesting could work for that.  Or again a UV cured adhesive might work as well.  Here's another thought.  How about just clipping the two halves together somehow instead of gluing?  That way you could easily open up the cage to change capsules or add a foam windscreen.

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11 hours ago, Janik Hampe said:

 

Hi Jez, could you explain what you mean by that? I really don´t get it. If you´re talking about the cables´ color coding, that´s red for "right channel" and green for "left channel".

 

Left, portside, red. Right, starboard, green.

 

As per the Nagra IV-S as the easiest to find example. Or stereo PPM meters.

 

Yep, that was it!

 

BTW, my friend Daniel Rosen gave me two blimp like toys for Christmas, with grommets which happen to fit both my MKH 40 and 8040s, which were dirt cheap. He wrote about it (either in DIY or Equipment) sometime since then. I've used them with success both with nylon girls socks and windjammer and will try to find the link for Dan's original source. Like my Babyball, I had to cover the rest of the 8040 body with some cycle handlebar foam to cut wind across the mic body.

 

What I would really like to see some 3D-er have a go at would be a large blimp for a multichannel rig, accommodating at the least an IRT quad and preferably slightly bigger to handle variable 5.0 etc rigs ... obviously the second step would be to construct the inside suspension (though that for me could still use existing K&M and Rycote parts ... albeit not commercially). Actually wouldn't mind Rycote or others coming up with such themselves, if they could keep it to a non-specialist price ...

 

Still interested what you come up with, pro's and cons, and especially if you look to develop it along multichannel lines.

 

Best, Jez

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On 9/10/2019 at 9:49 AM, Janik Hampe said:

 

Hi Jez, could you explain what you mean by that? I really don´t get it. If you´re talking about the cables´ color coding, that´s red for "right channel" and green for "left channel".

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.>

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13 hours ago, The Immoral Mr Teas said:

 

Left, portside, red. Right, starboard, green.

 

As per the Nagra IV-S as the easiest to find example. Or stereo PPM meters.

 

 

38 minutes ago, 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

 

Hm, interesting. Not beeing a sailor and never having used a Nagra before I simply learned it the other way round. I have a background as a musician, used a lot of cables with red beeing the right channel and assumed this was an universal rule in color coding language. Well, the more you know... 😉

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13 hours ago, The Immoral Mr Teas said:

What I would really like to see some 3D-er have a go at would be a large blimp for a multichannel rig, accommodating at the least an IRT quad and preferably slightly bigger to handle variable 5.0 etc rigs ... obviously the second step would be to construct the inside suspension (though that for me could still use existing K&M and Rycote parts ... albeit not commercially). Actually wouldn't mind Rycote or others coming up with such themselves, if they could keep it to a non-specialist price ...

 

Still interested what you come up with, pro's and cons, and especially if you look to develop it along multichannel lines.

 

Best, Jez

 

Oh, I´d absolutely love beeing able to produce a large surround rig with four or five channels. Or at least a stereo blimp. Although I´d probably need a larger 3D printer as my printing volume already gets maxed out with this project. For those of you who are into 3d printing: I plan on buying a Prusa i3 MK3s or above in the distant future. I also do experiment with 3d printed suspensions, but there´s nothing worth showing yet.

 

For a multi channel blimp, I´ll probably prefer having custom suspensions inside for a more economical and efficent use of space. The blimp really shouldn´t be larger than it has to be to deliver good wind protection. And a key engineering aspect would also be a 3d printable, rattle free and robust locking mechanism to open up the blimp. This is a very difficult one.

 

But let´s put all this into perspective. I´m going to finish this project here. Then I´ll test it intensively throughout winter and next year´s summer with huge differences in temperature, having it inside my car and using it on some of my shoots. PLA isn´t quite a UV resistant material and has a low glass transition temperature. At this temperature it gets soft and can deform when applying force. I´ll probably also try to produce some versions using ABS and test them too. Or nylon which is extremely difficult to print but also extremely tough. And I expect to learn lots of things through these tests. After all this, maybe, I´ll consider some bigger projects using what I learned from all this. We´ll see.

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On 9/10/2019 at 5:26 PM, berniebeaudry said:

I would suggest gluing/attaching it to the outside instead of the inside.  That way you can stretch it taut.  You may also need to think about sewing or gluing the fabric into quadrants.  A single piece of fabric would need to be folded over in some spots to conform to the hemisphere of the cage.  I would use a thicker/slow drying super glue type adhesive for attaching the fabric, or instead of glue, thin strips of velcro.  If you do still want to go to the inside the adhesive I'm suggesting could work for that.  Or again a UV cured adhesive might work as well.

 

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.

 

On 9/10/2019 at 5:26 PM, berniebeaudry said:

Here's another thought.  How about just clipping the two halves together somehow instead of gluing?  That way you could easily open up the cage to change capsules or add a foam windscreen.

 

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.

 

 

 

 

19 minutes ago, Allen Rowand said:

PETG works pretty well, but you'd need to do a lot of tweaking to reduce stringing in a design like this. I use it for anything I expect to be in the sun for any amount of time.

 

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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Just now, 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.

 

Hi Janik,

I store my filament in a plastic container with a reusable silica dessicant like this:

silica.jpg

 

I throw my filament in the oven at 70-80C for about four hours to dry it. I only bake the filament if I have problems printing. I don't use PETG that often, PLA normally does what I need. I recently printed roof panels form my friend's little library in PETG, since it will be outdoors:

 

IMG_20190819_083734.jpg

 

It was somewhere around 36 hours of print time!

 

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