1/2 - 20 Moderator long and short versions

[bduares]

I am not sure. I sliced the files in both Orcaslicer and Cura. Both slicer programs have their own factory presets for the printers I used.

There are differences between the 2 types of printer. The Anycubic is a standard bowden tube/external extruder type with dual Z motors. The Neptune is a direct extruder also with dual Z motors, but it prints many times faster than the Anycubic, so it is possible speed could be a factor. Another possible factor is the Anycubic runs on Marlin while the Neptune runs Klipper. The different operating systems may utilize information in the sliced file differently.

I tried default settings. I tried out several pre-configured settings files that Neptune tuners put online. None worked on your suppressors with the external writing. Where the lettering is located on the cylinders it seems to form a band all the way around the cylinder and also tosses in a few diagonal welts. It's very strange.

When I load up a different type of suppressor, like Kent's fluted or Pete's Tesla, they print fine.

If I recall correctly, some of the other people making the suppressor files are using Tinkercad. Perhaps it does something different than Openscad, but I do not think that is the problem since I have some  designs of other things that include .scad files that have entries inside that must be customized, such as name plates for an office. Those I have exported to STL inside Openscad, then sliced, and printed on both printers fine.

[naptemp]

Here's a really good moderator in 1/2-20 and a shorty version of it as well

I print it with 100% infill. No supports needed.

That moderator is my favorite for pistols/carbines and lower powered rifles.
I have printed 10+ of them in 1/2-20 and 1/2-28.
For the size I could not find a more quiet 1/2-20 moderator.

If you are the designer, I really appreciate your work!

[subscriber]

That moderator is my favorite for pistols/carbines and lower powered rifles.
I have printed 10+ of them

If you are the designer, I really appreciate your work!

Kent is the designer:  https://www.gatewaytoairguns.org/GTA/index.php?topic=218043.msg156590781#msg156590781

[naptemp]

That moderator is my favorite for pistols/carbines and lower powered rifles.
I have printed 10+ of them

If you are the designer, I really appreciate your work!

Kent is the designer:  https://www.gatewaytoairguns.org/GTA/index.php?topic=218043.msg156590781#msg156590781

Thank you Kent for this moderator design.

[naptemp]

I designed a three stage Tesla Valve moderator for the Sumatra.  It is beefed up everywhere, with thicker side walls having material added on the outside, to preserve more internal volume.  The overall length is the same as the shorter mod already printed.

Zipped STL attached.   Images in next post due to file size limits.  Also the reason why the texture and front cap designation were deleted.

Peter, I just printed your Tesla valve moderator (top one in photo).
It is much more quiet than the previous moderator (bottom one) used on my air rifles.

[Blackmagic12]

That moderator is my favorite for pistols/carbines and lower powered rifles.
I have printed 10+ of them

If you are the designer, I really appreciate your work!

Kent is the designer:  https://www.gatewaytoairguns.org/GTA/index.php?topic=218043.msg156590781#msg156590781

Thank you Kent for this moderator design.

Your welcome!

-Kent.

[subscriber]

Peter, I just printed your Tesla valve moderator (top one in photo).
It is much more quiet than the previous moderator (bottom one) used on my air rifles.

Thanks for the feedback, John

Do you find that your more potent air rifles perform better with the TV mod, and that the lower power ones, are not as quiet as expected for such a large mod? 

What power are you shooting at?  What is the bottom mod?

Have you compared grouping ability between mods.  Not a shift on POI, but more scattering, or less.

[naptemp]

Peter, I just printed your Tesla valve moderator (top one in photo).
It is much more quiet than the previous moderator (bottom one) used on my air rifles.

Thanks for the feedback, John

Do you find that your more potent air rifles perform better with the TV mod, and that the lower power ones, are not as quiet as expected for such a large mod? 

What power are you shooting at?  What is the bottom mod?

Have you compared grouping ability between mods.  Not a shift on POI, but more scattering, or less.

I target shoot with lower powered air rifles only.
Probably about 30-35 FPE is the maximum.

I tried the Tesla valve moderator on two 20-22 FPE rifles (.22 caliber) today and they both were very quiet.
More quiet than with any other moderator (of similar size) I tried.

The exit hole seems to be quite generous for .22 caliber.
I did not experience any issues: POI change are minor, no baffle strikes, etc

The Tesla valve moderator seems to be overbuilt for higher FPE rifles.
It weighs about 120 grams and takes 15 hours to print, more than other moderators of similar size.
I think that's because they were meant for that monster FPE Sumatra rifle

Can you make the Tesla Valve moderator lighter, enough for 30-40FPE?
I assume that the main change would be a thiner outer wall.

I plan to 3D print them and replace all my current moderators.

[subscriber]

John,

The baffle bores should print at 7 mm at the first baffle; then taper 0.1 mm radially per 25 mm going forwards.  So, you correct that the front cap bore is large for caliber.  I did that to tolerate 0.25 degree droop or angular misalignment from any source.

The mod was designed for Jared's Sumatra.  I can thin it out for 30 to 40 FPE.  I need to work on my tax return as I have been putting it off.  After making a good dent in that I can get to a lighter mod.

I am surprised and happy that the Tesla Valve mod I designed also performs well at 20 FPE.  The design is my interpretation of Mikes approach.  One large departure is that I increase the peripheral vent area towards the front of the mod; while Mike reduces it.  I have my reasons for doing it, based on my understanding to improve sound reduction.  Mike has his reasons for reducing reverse flow inlet vent count towards the front, almost certainly based on a lot of experience.  Perhaps relating to grouping ability.  That is why I asked about grouping ability with my design.  If it groups well and sounds good, then arguiging that my design violates principles would be a hard sell.  If it shot poorly, there would be a case.  I would rather have a design that works better when tested by multiple users, than be adamant that my approach is better, without any evidence.

So, later on the lighter variant...

[subscriber]

John,

I have shaved off 29.5 percent of the Tesla Valve mod mass, by thinning the outer walls and front cap by 1 mm.  I also thinned the baffles slightly as they were heavier than required for 40 FPE.

The STL is attached

[naptemp]

John,

I have shaved off 29.5 percent of the Tesla Valve mod mass, by thinning the outer walls and front cap by 1 mm.  I also thinned the baffles slightly as they were heavier than required for 40 FPE.

The STL is attached

Thank you.
I will print it and update.

I assume it should work on .177 but it would be a little less efficient because of the large baffle holes.

[OldCrow]

 Here is a Phantom scaled up to your dimensions in the slicer (laid flat on the bed and stretched in x,y to 44 x 195).

I maintain a constant bore clearance from front to back which makes precision printing pretty much mandatory in lengths longer than about 150mm.  You solve that problem by increasing bore clearance towards the muzzle IIRC?  I did that for a while.  There are good arguments for that as there are good arguments for making them longer to increase volume rather than making them fatter to increase volume.  There are always trade offs.

I reduce vent to bore ration towards the muzzle.  My theory is that we create high backward flow by increasing vent to bore ratio and increase pressure by reducing vent to bore ratio.  That might be wrong, but it seems to hold.  I emphasize accuracy over silencing.  Once I have that pellet in calm air.  I want to lock up the moderator in the hope that turbulance remains behind the pellet.  That's my theory anyway.  I am open to arguments to the contrary.

This statement defines my design philosophy.
A moderator which is safe, as accurate as possible, as quiet as the shooter wishes, as durable as the shooter demands and which can be sold at a price the shooter finds acceptable is a “good” implementation.

The best designs improve accuracy any design which trades accuracy for silencing is a "specialty" design.

I think your designs are much nicer to look at than mine.  They favor laminar flow over turbulance.  I subscribe to the idea that inducing as much turbulance behind the pellet as you can is a good thing.  Honestly I'm beginning to think that the only baffle that should be a Tessla Valve is that first baffle.  It may be that the best design we've seen in this thread is the one which started it.

I would be interested to see accuracy tests of all the designs but that is another big undertaking and unlikely to happen.

Other news:  I've just purchased an Avenger limited edition because of the ease of adjusting the regulator and the hammer.  It will greatly simplify my testing.  Now I am looking for a custom barrel for the gun that is longer than the air tube which I can thread 1/2 x 20 UNF.  Then I will have the ultimate testing platform or as ultimate as my resources permit.  Looking forward to this summer.

Peace brother. 

[OldCrow]

I dont generally do designs longer than about 150mm for the reasons I mentioned above.  I've just done a design which honors Peter's 44 x 194 moderator.  This one with the differences he highlighted because I'd like to know what those differences do WRT accuracy and I think he would as well.  So I will attach the design here with the caveat that I don't know if my very thin walls will stand up to a 40 fpe .22.  I am printing one to test with my 25+ fpe .22.  I'll probably put a couple of rounds through it this evening late.  If it blows up I'll make a note in a reply to this post. Use PETG only (or something even stronger and less brittle) for this one.

On the Bamboo it takes 4.5 hours to print.  I added Hilbert pattern to the top and bottom and a wrinkle texture to the sides.  That wrinkle obscures the lettering (which is nice on an FDM print).  I went with gray PETG.  Hopefully it will be presentable.

Meanwhile anyone who wants that STL here it is.

[subscriber]

I assume it should work on .177 but it would be a little less efficient because of the large baffle holes.

You won't notice unless you are comparing a 30 FPE .177 to a 30 FPE .22:

The stock Marauder baffle bore is 5/16".  This applies to .177; .22 and .25.  The .177 Marauder is not louder than the larger calibers, because they typically operate at power proportional to the pellet weight; as in proportional to the bore area.

If you want a .177 specific version of this TV mod, just ask.  Just make sure not to shoot .22 pellets through it 

[subscriber]

Mike,

To sum up your design philosophy:  Any design that during testing, improves accuracy and reduces sound well enough, or better that expected, is a good design.  Grouping ability is not to be sacrificed for improved sound reduction.

I think that the first baffle (or baffle set) the pellet encounters needs to shield the pellet from downstream turbulence.  If the fist baffle is effective in causing most of the air to lag the pellet, then more turbulence towards the front should occur after the pellet is safely ahead of that air, and those baffles.  In other words, more tesla valves towards the front of the mod cannot do more harm that the first one near the barrel muzzle.

I used to always start TV mods with a regular conical air stripper, especially if using a reflex mod or shroud.  For the Sumatra I figured that starting with a TV baffle and using only those would be more effective for sound reduction.  My experimental attitude was, "lets see if the grouping is compromised, rather than assuming it would be".  If starting with a TV baffle does not compromise accuracy, then why not do it?  Certainly, the more energetic the air, the better the TV should work; and the air is most energetic near the barrel muzzle.

There is no substitute for test results.  They trump any theory I can dream up.

Yes, I open the baffle bores towards the front of the mod to reduce clipping risk.  But then I have many mod designs that are well over 6" long.  If someone asks for specific baffle bores, I am willing to custom design that for them.  If that clips, they asked for it.  If I am releasing a more generic design to the public, I am OK sacrificing a dB or two, for reduced risk of a mod clipping when attached to an unknown platform.

The above is motivation for me to provide John with a .177 version of the .22 TV mod he likes.  The deal being that he compares the two mods on his .177 airgun and reports the difference in performance.  So, rather than my declaration that it won't matter, John's test results and opinion are used to calibrate our assumptions.  Of course, anyone else would be welcome to print the mods, test and add their say.

[OldCrow]

That is my philosophy pretty much.   Quiet is important but the hunter needs to hit his target. I have learned a lot from your designs and we think alike about design for the most part.

He will be pleased with that .177.  At that volume and length a simple washer arrangement (as per Huggett) would probably be sufficient.  Learned a lot from studying his designs as well as yours.

Welp I haven't printed one over 150mm in a while so this should be interesting.   The print job is 50% complete.  I'll post pics before I hit the fart sack if I have it in my hand then.

Later

[subscriber]

Mike,

It is great that we can learn from each other.  I used to mimic STO's gas diode designs, with their much more complex curved shapes.  Your simple double cone designs, where the front cone is vented around the periphery, is easier to design, more space efficient, and work better than the STO curvy counterparts.  So, I switched to your design strategy, with my spin on it.  Specifically, I like to reinforce the support "spokes" of the vented front cones.   

I also think it is important to have some solid parallel length between the cones, where the vents end and the small end of the cones begin - for more organized reverse air flow.  I have no proof of that, but that my version of you concept works.

With all things, I try to understand the operating principles of a good design, before I consider improvements.

[OldCrow]

I really like the way the first design in this thread does his first tesla valve and the interesting treatment of the cones that follow it.

I think there is a lot of dead air hanging around the corners of my designs during operation.  Smoother shapes would improve airflow.  Either way I think we are working at the edges of what can be achieved in the space we have.

One thing which I tried and which proved to be very successful is porous baffles and TPA but the difficulty implementing that made me decide that trouble could be handled another day.  I think if our structures were rough on their surfaces and more porous we'd get better damping and not loose any accuracy but ... time to design... time to test...

Later

[subscriber]

John,

It would be interesting to compare performance (sound and grouping) for your .177 PCPs when using the light weight .22 cal TV mod, and the .177 cal version of the same TV mod.  To facilitate that, please print the attached .177 TV mod STL. 

The only change to the .177 version over the .22 version is that each baffle bores on the .177 version are 1 mm smaller in diameter than the equivalent baffle bores on the .22 version:   5.5 mm - 4.5 mm = 1 mm

There are no changes to the TV baffle vents between versions.  Will this change the ratio of forward and reverse flow?  It might.  Is that good or bad?  Sound levels and grouping ability might answer that question.  Hopefully better on both counts, but no harm done if performance is identical.

You can identify the .177 mod by virtue of the obviously smaller hole in the front cap...

[subscriber]

On the attachment size limit, so posting image of above .177 TV mod here: