GTA
Support Equipment For PCP/HPA/CO2 and springers ,rams => 3D printing and files => Topic started by: naptemp on October 14, 2023, 04:32:44 PM
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Subscriber, you have made a fantastic moderator insert for the Umarex Notos.
I have 2 Notos and both have your insert.
I really thank you for that.
The Gamo Urban has a similar moderator (permanently glued to barrel) with an insert attached with 2 pins just like the Notos.
The same (permanently attached) moderator is used on several other Gamo and BSA airguns.
The Gamo Urban has been sold for many years and yet no satisfactory moderator appeared.
Unhappy people will just remove the original moderator by any means they have.
Subscriber, I am asking you really nicely if you could make a moderator insert for the Gamo Urban.
Let me know if I can help.
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John,
Considering that I check this gate sporadically, your post makes an interesting alternative to a PM :)
I would need the interface dimension to do an Urban specific design. Removing the stock baffles and measuring their features would help. The cavity in the casing should also be measured as it will be larger than the insert. Diameter and depth, with some idea of the internal shape (pictures). Pictures of the stock baffles too.
Diameters should be measured at a number of places around the part (because they are not actually round). Also, the retaining pin size and locations relative the the front face of the casing; and relative to the front and rear "shoulder" features of the stock baffles. The spacing of the retaining pins around the center is obviously also rather important. The more accurate the measurements the better.
You can't have too many features measured, but you can have too few.
I no longer get GTA forum update notifications, for unknown reasons. So, I will check back here next week. PMs still seem to work, with notifications.
I assume you want an extended moderator, like the one you have on your Notos?
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Subscriber,
Thank you for your reply.
I have just bought a Gamo Urban and will be a while until I receive it.
I used to have one but sold it.
At the time I have printed this insert which fitted perfectly: https://grabcad.com/library/gamo-urban-baffle-core-upgrade-1
That insert reduces the noise somewhat, but I think it is too short.
I think you could the measurements from the stl file above.
An extended moderator for sure.
The quieter the better.
Once I get the Urban I can send the measurements.
This is how the baffles look.
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Thanks John,
The length of the "body" (without the stem) measures 115+ mm from the STL. That is rather short.
I may be able to core out the STL after converting it to a Solidworks part. Then extend it a similar length I used for the Notos muffler; and populate it with my own baffle design.
But, where does the barrel go, relative to that "stem"? What is the stem's function? The Urban front end image does not help answer those questions.
Are the rectangular slots at the front where the retention pins fit? See image with red lines below. If so, then those features have to stay. It would be helpful to see the cavity this insert fits into to extend it intelligently.
My opinion of that STL design is that it has too many baffles, too close together. That the baffle walls are too thick; and that these factors combined reduces the expansion volume excessively.
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Thanks John,
The length of the "body" (without the stem) measures 115+ mm from the STL. That is rather short.
I may be able to core out the STL after converting it to a Solidworks part. Then extend it a similar length I used for the Notos muffler; and populate it with my own baffle design.
But, where does the barrel go, relative to that "stem"? What is the stem's function? The Urban front end image does not help answer those questions.
Are the rectangular slots at the front where the retention pins fit? See image with red lines below. If so, then those features have to stay. It would be helpful to see the cavity this insert fits into to extend it intelligently.
My opinion of that STL design is that it has too many baffles, too close together. That the baffle walls are too thick; and that these factors combined reduces the expansion volume excessively.
Unfortunately I do not remember how the moderator looked internally.
I think we should wait until I receive my new Gamo Urban (around beginning to mid November).
Then I can provide you with detailed dimensions and photos.
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Sure.
The other detail I need is the outside diameter of the stock moderator body. My intent is to match its OD, so the added length does not look odd.
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I got curious so I compared the Urban STL design you linked above, with my Notos extended insert - images below. (the Notos insert version with O-ring grooves was at the top of my file list, so I grabbed that one).
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I printed your Notos insert with orings and it works very well.
Your Notos insert and the Urban insert do look similar, but the Urban seems to have too many baffles.
I will send you detailed dimensions once I receive the Urban.
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In the meantime, the video below shows how to get the stock baffles out.
I see that the pin holes in the front cap are round. It would be very good to know the diameter and placement of those pins. Presumably, the pins sit in the rectangular cut-outs near the front of the STL you pointed at. Probably right in front of the stock rear insert shells.
I have copied the STL's cut-outs but they will not be able to print unmodified with my extended nose insert design, due to the overhangs. I would much prefer to close that space in, leaving round or oval holes for the pins. But, I need more information about the pin placement:
If you tap the pins so they stick out perhaps 1/4" you should be able to measure over the outside of the pins. Then by subtracting one pin diameter you will have the pin spacing distance. Along with the pin diameter will design printable holes, with smaller internal bosses than I have now, around the rectangular cut outs.
As you can see from the attached images, my design does not have the stem, nor the shoulder the stem grows from. My design will use the front shoulder to limit how deep the insert goes into the stock cavity.
I copied the OD of the STL at 28.43 mm (away from the wings). I would like to know the diameter of the cavity, perpendicular to the "wings"; and near those grooves, but no in them.
The baffle design is essentially the same as for my Notos extended insert.
Jump to 3 minutes 45 seconds for pin removal:
https://youtu.be/UOq8lbPBMMk?feature=shared&t=221
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I also only get alarms for personal messages not thread posts.
I will have my new Gamo Urban in about 2-3 weeks.
When I get it I will send you all the dimensions you ask for.
I am sure that there are hundreds of Gamo and BSA PCP owners stuck with Gamo's ridiculous moderator.
That was my main complaint about the Gamo Urban, which was also my first PCP, and really accurate with cheap pellets.
I agree that it would be much better having holes instead of cutouts for pins.
By the way, the outer moderator shell has holes in it (front left and right of the moderator) and you can see the red baffles from the outside.
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The designs you posted look very similar to the Umarex Notos insert.
By the way, the Gamo Urban is capable of significantly more power than the Notos and all the noise that comes with the power.
Can you have a design which is a little more quiet?
I assume that means more silencer volume.
Maybe, a wider or longer extension.
I personally do not mind having a wider moderator.
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John,
I can make the insert longer and wider. The insert section is already a little wider than the Notos' insert. But the length and baffle structure are the same. If you tell me how much extra length and width you can tolerate, or want, I will do the design over to utilize that. Best to start with the internal and external dimensions of the stock casing.
The vents in the stock Urban casing may be why the Urban is louder than you expect. There is a reason why the perforated tubes in an engine muffler are inside a closed casing. I have ranted and railed against moderator and shroud vents a number of times. No need to do it again, here. Except to say that any number and size of side vents that have enough combined flow area to make the report as measured from the font quieter, will make the report louder as measured from the side and rear. I assume the idea is to make it quieter than stock from all sides :)
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In the unfortunate event I ever destroy the "pickle" on my Urban I will opt for the full shroud mod.
I'm lucky enough to be in a situation that the sound of shooting is an issue. Matter of fact, gunfire is a form of music around here. I just think the Urban looks great with a full shroud.
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Shrouds look better; yes.
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That was not meant to downplay your inserts or baffles. I think you are doing a great service for members looking for those options. Like I said.. loudness is a non issue for me and I prefer the clean look of a shrouded gun.... not enough to replace the factory "pickle" though. I don't find it as offensive to the eyes as some others seem to. It looks much better than some of the "soup cans" that some are paying top dollar for.
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Bill,
I happen to agree with you about not liking the snake that swallowed the rat look. Or drawing attention where a shroud would not. I own nothing with pickles, but that does not stop me from designing inserts for people that want to improve theirs.
If my previous reply seemed short, it was because I am not officially awake yet.
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I have received my new Gamo Urban and took many photos (see attached) and measured dimensions.
These are the dimensions in millimeters.
External tube
Length from end of tube to the internal barrel structure (seen in first photo): 122mm
Outer diameter: 37mm
Inner diameter: 32mm
Internal Baffle
Small outer diameter: 29mm
Large outer diameter: 32mm
Total Length: 147mm
Outer diameter of the small end: 12mm
Length of the small end: 30mm
Pins
Outer diameter: 2.2mm
Length: 22mm
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John,
I can make the insert longer and wider. The insert section is already a little wider than the Notos' insert. But the length and baffle structure are the same. If you tell me how much extra length and width you can tolerate, or want, I will do the design over to utilize that. Best to start with the internal and external dimensions of the stock casing.
The vents in the stock Urban casing may be why the Urban is louder than you expect. There is a reason why the perforated tubes in an engine muffler are inside a closed casing. I have ranted and railed against moderator and shroud vents a number of times. No need to do it again, here. Except to say that any number and size of side vents that have enough combined flow area to make the report as measured from the font quieter, will make the report louder as measured from the side and rear. I assume the idea is to make it quieter than stock from all sides :)
I have added photos and dimensions.
The insert may need orings, like the Notos insert.
The insert can be both longer and wider.
For wider, I assume that there will be a small taper to the larger width.
These can be a starting point, and you can pick dimensions if you want:
10cm length in front of barrel
5cm width
2-3cm length of taper
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Thanks, John
There seem to be 11 image files, but they do not all display. Photoshop does not want to open them either.
I will see what I can make of the info that is clear, this evening.
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I just tried renaming the extension from jpg to jpeg and it worked on the file where I tried it!
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The insert's thin end is actually inserted into the barrel structure hole so I think it needs to be there.
The thin end does not fit completely into the barrel structure hole, there is still some space left.
So the between the barrel structure and insert there is space which acts as a first baffle.
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John,
Could you measure the location of the pin holes in the outer casing;
1) from the front end;
2) and the distance between pins?
This can be done by placing the pins in the holes (spanning the tube OD) with enough pin sticking out on one side to measure across the OD of the pins, the subtracting the pin diameter (or radius) to get the center of the hole. If the pins are loose in the holes, find an undamaged drillbit shank that is as a good a fit in the hole (or gauge pin, if you have them). If this measurement is not obvious I will create a sketch, but I think this s fairly standard method, so I start with a simple request.
I need to know the pin hole to should location as I plan to use that as the datum for everything else.
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What is the length of the outer casing, from front face to start of taper?
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What is the length of the outer casing, from front face to start of taper?
The outer casing length without the end cap is 133mm.
The outer casing length with the end cap is 137mm.
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John,
Could you measure the location of the pin holes in the outer casing;
1) from the front end;
2) and the distance between pins?
This can be done by placing the pins in the holes (spanning the tube OD) with enough pin sticking out on one side to measure across the OD of the pins, the subtracting the pin diameter (or radius) to get the center of the hole. If the pins are loose in the holes, find an undamaged drillbit shank that is as a good a fit in the hole (or gauge pin, if you have them). If this measurement is not obvious I will create a sketch, but I think this s fairly standard method, so I start with a simple request.
I need to know the pin hole to should location as I plan to use that as the datum for everything else.
I measured the location of the pin holes in the outer casing;
1) center of the pin to the front end - 6.1 mm
2) distance between center of pins - 28.6 mm
The pins are hollow inside and not completely circular.
They are about 2.2mm on the wider diameter and 2 mm on the narrower diameter.
I think that the holes are slightly narrower than the pins.
By the way, all measurements (previous ones too) have a tolerance of about 0.1-0.2 mm.
I am willing to print several versions until everything fits.
So that I do not print the entire insert every time, could you provide STL files only for the critical parts, like the area around the pins, etc
Then when all the critical parts fit I can print the entire insert.
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Thanks, John
Printing just the critical interface section to check and refine it is smart. Will provide STL with that section.
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John,
I have mostly followed your spec wish list for the Gamo Urban LDC. The STL for the full LDC and a test piece with critical dimension are attached.
I understood what you said about the "snout" on the stock insert. From my perspective, that aspect is to flexible to align the rest of the insert to the barrel in a useful manner. Instead, I have dispensed with the annular flow aspect of the stock design, making the insert body OD 32 mm in CAD. Thus expecting it to print just under that. The 1 mm section by 30 mm ID O-rings should protrude above the insert OD enough to take up any remaining slack and center the insert in the casing in a positive manner. This O-ring is the intended part; or any one similar to it: https://www.mcmaster.com/1295N435/
The space between the insert's first cone (external) and the casing near the barrel muzzle still form the first expansion chamber, so nothing is lost there.
The wall thickness around the retention pin holes at the insert OD was very thin; so I cut the part open into rounded, rather than square slots. I used you pin location dimension to place the slots. They should have clearance with the pins, except on the load bearing size, when the end of the stock casing meets the shoulder of the new insert. Due to sag expected in printing the pins may have 0.2 mm interference when the insert is fully seated against its shoulder. If so, this should be visible by looking through the pin holes, with the insert rotated to make the slots parallel to the intended pin location. I few swipes with a needle file or drill should relieve that to make pin insertion possible.
I suggest you test fit the test piece to see if the 32 mm insert OD can go into the 32 mm casing ID. If pushing the insert in while rotating the part back and forth does not make it fit; and you need to remove more material than you are willing, then I can adjust the OD in CAD by whatever measure is indicated by actually measuring the print OD. You could also scale the part by a fraction of a percent to get a snug fit. The O-rings should take up any slack, if there is any.
If there is interference elsewhere due to a misunderstanding on my part I will correct that. If you prefer the extended section be small in than 50 mm in OD, I can adjust that. It might look good matching the casing OD at 37 mm.
Note print direction, with external cone facing up. Print 100 % infill and with supports off. Use a brim for good platen adhesion.
If you are wondering about the proximity of the O-ring groove to the pin slots, note the load bearing surfaces, and the load path through the printed plastic part - last image below.
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The attached STL is for test piece version 2. It has the pin slots 0.5 mm shallower, radially speaking. Or without added clearance for measurement error; as the measured pin spacing is likely tighter than reality; if you measured outside to outside to get the pin spacing.
If you measured inside to inside for the pin spacing, the V1 is better.
In any event, V2 makes the part slightly stronger; and might help guide the pins better on assembly. You will find out, if you print the parts...
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The attached STL is for test piece version 2. It has the pin slots 0.5 mm shallower, radially speaking. Or without added clearance for measurement error; as the measured pin spacing is likely tighter than reality; if you measured outside to outside to get the pin spacing.
If you measured inside to inside for the pin spacing, the V1 is better.
In any event, V2 makes the part slightly stronger; and might help guide the pins better on assembly. You will find out, if you print the parts...
I have printed both test pieces, V1 and V2.
The pin holes align but need some improvements.
I could force the pins through but the holes are not overlapping well enough.
I attached a photo.
The part in yellow is where the plastic can be seen through the hole.
So a small part there will have to be removed.
I think you can achieve that by moving that groove a small amount (about 0.5mm) towards the rifle barrel.
Need to move the groove on both sides of the insert.
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John,
I moved the pin grooves 0.5 mm as you requested. Test piece and muffler Version 3 STLs are attached.
It is obvious from the non-sectioned image that the pin grooves are not annular rings; while the section image could depict a continuous groove all the way round. A continuous groove might make assembly easier because there is nothing to align, but it weakens the part, compared to two discreet grooves. This is a general comment for anyone wondering about it.
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John,
I moved the pin grooves 0.5 mm as you requested. Test piece and muffler Version 3 STLs are attached.
It is obvious from the non-sectioned image that the pin grooves are not annular rings; while the section image could depict a continuous groove all the way round. A continuous groove might make assembly easier because there is nothing to align, but it weakens the part, compared to two discreet grooves. This is a general comment for anyone wondering about it.
I am fine with having the pin grooves on 2 sides (not continuous, all around), the original cap has the grooves on 2 sides too.
I printed test part V3.
It is better than V1 and V2 in terms of clearance of the pin holes, but there is still a small obstruction of the pin hole.
I think you should make the pin groove wider by another 0.5 mm, towards the barrel.
Just moving the groove 0.5mm (towards the barrel) may not be enough since there may be a variance between various rifles.
You could make the wall thicker, just in the area with the pin and o'ring grooves, if necessary to make it stronger.
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I am starting wonder if the shoulder is meeting the front face of the stock casing - as in the printed part not going in as far as intended. Else, the continuing interference seems odd.
Anyway, try test piece V4. STL attached.
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I am starting wonder if the shoulder is meeting the front face of the stock casing - as in the printed part not going in as far as intended. Else, the continuing interference seems odd.
Anyway, try test piece V4. STL attached.
I printed test piece V4.
The pins go through with little resistance.
But, now the test part has a small play.
It can turn left and right a few degrees even with pins inserted in the holes.
The shoulder contacts the stock casing front as it should, so that is not an issue.
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Subscriber, I just realized that in a previous post I said to move the groove towards the barrel.
I meant to say to move the grooves down towards the barrel, not make the grooves deeper.
If you made the pin grooves deeper that would explain why there is that play in test part V4.
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John,
I just made the pin grooves shallower, without changing anything else. There is a V5 and a V6. V5 has its groove depth reduced by 0.3 mm per side over V4. V6 reduces the groove depth an additional 0.2 mm per side over V5.
I think the reason for this struggle is that the upper edge of the groove has a pure overhang, and is distorting in printing. If I was to make that a 45 degree shoulder it would print closer to the CAD dimensions, even though on the face of it, a flat wall seems to make a better shoulder. For one thing, pin to pin spacing would matter a lot more if the shoulders were at an angle. Hopefully V5 or V6 nails it.
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John,
I just made the pin grooves shallower, without changing anything else. There is a V5 and a V6. V5 has its groove depth reduced by 0.3 mm per side over V4. V6 reduces the groove depth an additional 0.2 mm per side over V5.
I think the reason for this struggle is that the upper edge of the groove has a pure overhang, and is distorting in printing. If I was to make that a 45 degree shoulder it would print closer to the CAD dimensions, even though on the face of it, a flat wall seems to make a better shoulder. For one thing, pin to pin spacing would matter a lot more if the shoulders were at an angle. Hopefully V5 or V6 nails it.
Peter,
I printed and tried both test parts V5 and V6.
V6 is perfect, pin holes are well aligned and pins go in smoothly with just a little resistance.
Also, there is no more play in the part.
Also, the shoulder aligns well with the front of the casing.
Let's continue with V6.
I was thinking that you could provide several versions of the insert.
One of the versions should just replace the original baffle and end cap, and have nothing beyond the barrel.
I can try that version first (since it's less to print) and flush out any problems.
I have many o'rings and I am sure I can find some to fit.
All my prints are done in PETG, although that should not matter much.
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John,
I will send the STLs for a "flush" version and extended version, based on the pin groove geometry of test piece V6. Should be done around 11 PM your time because I need to eat something first.
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Short and Extended LDCs in same zip file - attached
Short version shown below:
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I printed the short insert.
The insert will not go all the way in, because its diameter is a little too wide for the casing, in the area closer to the muzzle.
It goes into the casing OK, but as you keep pushing there is more and more resistance.
I measured again the original baffle.
Its outer diameter is about 29mm along its entire length.
There are some ridges towards the front and back, which make the OD slightly larger in places.
The original baffle goes easily in the casing, so I assume we can make the insert slightly larger.
The 3D printed short insert OD is about 31.5-31.8 mm.
Can you make the insert outer diameter about 29.5mm?
You could keep the insert front with the grooves the same and decrease the insert OD past the grooves, using a small all taper.
Also, can you make the the o'ring grooves about 0.5mm wider.
Please send just the short insert, since it is less printing.
I will print it overnight since the short insert takes about 4 hours to print.
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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.
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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).
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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.
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I am printing the short version now.
Will update in a few hours.
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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.
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Version 3 makes the changes you asked for, above.
STLs for long and short versions attached in same zip file.
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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.
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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.
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The attached ZIP file contains all three STLs, as requested.
You have used up all your free design credits.
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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.
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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.
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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.
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If something is worth doing then it is worth doing right.
You are quite right there.
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I will print the inserts and post photos.
Photos would be good, but performance evaluation would be more interesting.
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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.
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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:
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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.
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Thanks for the feedback, John
Those are some smooth looking prints.
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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.
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Ntrn,
I have attached the STEP files for all three versions in one zip file, below.
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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!
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Ntrn,
You may take any info or designs that are published and use them as you see fit; providing what you are doing is legal.
K-baffles with clips generate a lot of useful cross turbulence to slow down gas exit from the front end. However, unless you have at least one conventional air stripper near the barrel muzzle of an airgun to shield the pellet, such cross turbulence may tend to open groups. There is nothing to prevent you from combining different baffle styles in one moderator.
Airgun moderators do not just manage air flow; they act as sound filters, and/or absorbers. Cone baffles are good as air strippers, and manage air expansion and flow, and block sound, rather than absorb it. Impulse Air moderators use densely nested baffles with an acute cone angle. That works, but if you print that from plastic, the baffle walls use up too much expansion volume (you can't realistically print robust 0.5 mm thick baffle walls, while you could machine them from aluminum). So, to get the benefit of "pointy" cones in a printed moderator, I start with more obtuse cones, where each successive cone angle becomes more acute, and spaced further apart. I could go into more detail why this works, but suffice to say this style of baffle arrangement is quite effective - based on many designs I have published.
There are many baffle styles that work, so there is not one best way. A lot depends on how you make the parts, and the cost goals. Weihrauch moderators use a few flat baffle and wrapped "hair curlers" to good effect. They work by absorbing sound energy by means of the fiber wrap, and by making the chambers resonate at different frequencies; thus acting as filters to each other. However, these moderators do not have effective air strippers in them, so they do not help grouping when attached to potent PCP; unless the PCP has an active shroud with its own air stripper.
Spring piston airguns don't have that much air to manage; but the mechanism can make a lot of noise. So, you may find that a moderator on a springer is not as effective as it could be on a PCP. I would encourage you to try out your ideas and see what happens. Just not to assume that a given moderator is useless, if shooting the Silent Cat is still loud. At least the ones with gas springs do not have steel spring buzz.
PLA is not a very stable plastic; especially at slightly elevated temperatures, such as inside a vehicle, parked in the sun. So, I would not go too tight on baffle bores with PLA. I generally do not go very tight anyway because what you gain in noise reduction is moot, if pellets make contact with the baffle bores. I use 1 mm radial clearance, and then add additional clearance towards the front of the moderator, to the extent of 0.1 mm radial per 25 mm distance. If I have high confidence in the alignment of the rest of the system, including barrel OD to ID I may go tighter. If I have less confidence, I may add additional clearance.
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Credit where credit is due..
Gavin printed and sent me one of Ron's designs for the NOTOS. This one replaces the factory insert and extends the shroud by a few inches. It does work exceptionally well. I really have no need for quite guns where we live but it's pretty cool that the impact of pellet on target is way greater than the report of the gun.
And the fit looks like it came with the gun from the factory. I'm really not a fan of soup can looking objects hanging on the ends of my guns. I much prefer a clean shrouded gun. I think if I was even going to change the Urban it would be a full shroud and the purpose would be purely cosmetic.
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Who is Ron, Bill?
I agree with you that a large pickle on the end of a skinny barrel is not the best look. A bull barrel look is much nicer. That does not stop me from designing pickles for those that want them, or their performance.
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Who is Ron, Bill?
I agree with you that a large pickle on the end of a skinny barrel is not the best look. A bull barrel look is much nicer. That does not stop me from designing pickles for those that want them, or their performance.
LOL... my bad, for some reason I thought your real name was Ron.
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for some reason I thought your real name was Ron.
It seems like my camo is working :)
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Many thanks to naptemp and Subscriber for doing it right and making a great moderator replacement for the Gamo Urban .22. I printed the short version and it works perfectly. Exactly what I needed to fix my gun.
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Thanks for the feedback, Mark
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I printed the short version using PETG on my new Qidi Q1 Pro and it printed perfectly. I didn't need the o-rings since the fit was perfect with no movement whatsoever. I did have to use a round needle file to get the roll pins to line up. The grooves just needed to be a little bit deeper. The sound reduction is way better than that of the OEM baffles and pretty much all I hear now is the sound of the action and the pellet hitting the target. Many thanks to Subscriber and naptemp for developing this. I've also printed a couple of Subsciber's other moderators and they work equally as well.
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We aim to please.