To Subscriber - Gamo Urban moderator insert similar to the Notos insert

[naptemp]

Why not reduce just the rear end of the insert diameter (near the barrel muzzle); and keep the front part that you have already established to fit well?

How deep does the new insert go in before it jams?  Or more importantly, how much is hanging out from being fully seated?

The stock insert has a deliberate air space around the OD, with those "gills" on the sides.  The stock insert is not the model for what we are doing, as the whole gill aspect is discarded.

The insert goes about half way in before it jams.

We could keep the front part identical and reduce the part that comes after the grooves.

Let's make the outer diameter 29.5 mm (not 30mm as I originally said) after the part with the grooves.

And please make the o'rings groove slightly larger (about 0.5mm).

[subscriber]

Stepped body diameter down on most of the section that goes into casing.  Should print 29.5 mm at reduced diameter.

Made o-ring grooves 0.5 mm wider.

STLs for short and extended LDC versions are attached in one zip file.

[naptemp]

I am printing the short version now.
Will update in a few hours.

[naptemp]

I printed and tried the latest insert version, with the 29.5mm OD.

Now it fits very well in the casing.

In the front I have an o'ring (about 1.5-2mm section) which fits tightly, but the front o'ring has just a small distance to be inserted into the casing, so it's not an issue.

I could fit a 2-2.5mm o'ring in the back, so I can assume that the 29.5mm could be increased to 30mm.

Unless you had some reason for adding it at the end, the rear o' ring groove could be moved to about 55-58mm from the front of the casing/insert.
That way we would add some extra space for the air to expand.

Please send the next short insert version with a 30mm OD instead of 29.5mm.

Also, move the rear o'ring groove to about 55-58mm from the front of the casing end.
Unless, you had reason to have the o'ring at the end.

[subscriber]

Version 3 makes the changes you asked for, above.

STLs for long and short versions attached in same zip file.

[naptemp]

Latest short insert version 3 works well.
I added 2 o'rings and replaced the original baffled with the short insert.
It is much more quiet.

One small change, the OD of the insert cap in front of the external casing is 36.5 while the external casing OD is 37mm.
Can you change that insert cap OD to 37mm?

Other than that I have nothing else to change.

Can you make 3 versions of the insert:
-the short insert which replaces the original baffle
-an extended insert 10cm long, with the same 37mm OD as the external casing
-an extended insert 10cm long, with a 5cm OD and the small taper

I really thank you for doing this.
Many Gamo Urban/Chacal/GX40 (and other variants) will be happy.

[subscriber]

The short muffler version that print 36.5 mm actually has a CAD diameter of 37 mm.  See image below.

I will increase that diameter to 37.5 mm so that it prints closer to 37 mm.  I will create a new extended version with a 37.5  mm (CAD) outside diameter (to print at 37 mm).

The 5 cm OD extended version already exists.  It was in the zip file you already downloaded.  It seems odd that you are not aware of that. 

[subscriber]

The attached ZIP file contains all three STLs, as requested.

You have used up all your free design credits.

[naptemp]

The attached ZIP file contains all three STLs, as requested.

You have used up all your free design credits.

Thank you again.
I do not not need any other changes.

I will print the inserts and post photos.

[avator]

The attached ZIP file contains all three STLs, as requested.

You have used up all your free design credits.

LOL... you have to admit he's kept you busy. What will you do with all that idle time when he stops?

On the bright side, all those rejects he printed will make great reactive targets.

[naptemp]

The attached ZIP file contains all three STLs, as requested.

You have used up all your free design credits.

LOL... you have to admit he's kept you busy. What will you do with all that idle time when he stops?

On the bright side, all those rejects he printed will make great reactive targets.

If something is worth doing then it is worth doing right.
I have printed 9 different versions of various parts until everything was fitting properly.

Thank you again Subscriber.

[subscriber]

If something is worth doing then it is worth doing right.

You are quite right there.

[subscriber]

I will print the inserts and post photos.

Photos would be good, but performance evaluation would be more interesting.

[subscriber]

It has been a week.  I don't see any photos.  I don't see any evaluation. 

I will print the inserts and post photos.

Photos would be good, but performance evaluation would be more interesting.

[naptemp]

It has been a week.  I don't see any photos.  I don't see any evaluation. 

I will print the inserts and post photos.

Photos would be good, but performance evaluation would be more interesting.

Subscriber, many apologies for not posting this earlier.

I have been busy shooting my Gamo Urban almost every day.
I have used the biggest LDC, and shooting from inside a room, since my neighbor's house is 20 feet away.

The Gamo Urban, with your largest moderator insert (the extended 50mm OD one), has become one of the quietest air guns I have at this power level (22-25 FPE).
I am no longer afraid to shoot it because it might disturb my neighbors.

The second largest moderator, extended and flush with the Gamo Urban external casing shoots a little louder, but not much.

Even the smallest insert (replacing the original Gamo Urban baffle) is substantially more quiet than the original Gamo Urban baffle.

For the 2 o'rings, any o'rings which block the air and fit inside the Gamo Urban casing can be used.
I just mixed and matched the o'rings.

These are some photos:

[naptemp]

I only have a cheap $10 decibel meter.
When I have some time I can measure the sound volume for the original Gamo Urban baffles and all the inserts.
I will do this outdoors and in the same setting (distance/angle from muzzle, etc).

Thank you again.

You should post the STL files on thingiverse, and some other places.
There is nothing comparable by a wide margin.

[subscriber]

Thanks for the feedback, John

Those are some smooth looking prints.

[ntrnflxlbs]

The attached ZIP file contains all three STLs, as requested.

You have used up all your free design credits.

subscriber! Hello, Excellent work, I just printed your notos insert in PLA-CF last night and am awaiting delivery of a notos.
this got me thinking About my Gamo silent cat.
I've done quite a bit of CAD and have been 3d printing for over 9 years since a folgertech 2020 i3 kit.
I'd love to take on and remix your excellent work for this Gamo Silent cat as the baffle system is far from silent and more like a stepped-on cat.
once done I'd start a new thread and share the changes while crediting you and giving other members the option to just download an STL and print.
Would you mind sharing the .STEP or .OBJ files for this work as it's really very close to the baffle structure I just pulled out.
EDIT: Looks like I might can convert it in Ansys Spaceclaim so I'll try that.

[subscriber]

Ntrn,

I have attached the STEP files for all three versions in one zip file, below.

[ntrnflxlbs]

I ended up taking a gander at your work and it's wild good. I just updated Moi3d and really need to get better practice in on the tools I have, your skills with solidworks are impressive.
Sadly today isn't the day for practice and I went another route. I may revisit and remix with your permission in the future.
Great news is if this print works, I will be releasing a LARGE moderator in a different forum thread for the Gamo Silent cat where if you gently break the cast plastic seal for the stock moderator(via saw, dremel or otherwise) you end up with 32mm of steel barrel you can epoxy this print on and you keep your cocking leverage, ditch your stock fiberoptic from your scope's line and hush! (printing in PLA-CF, didn't suspect this needed nylon)
we can take this elsewhere if it's best and I'm new here but I'm curious, do the conical cones at these FPS and cool pressure waves (not hot deflagration gases) have a better noise reduction or tone vs a "K style" baffle with clips?
Many thanks Subscriber!