Umarex Notos CRK Review

[TorqueMaster]

Thanks for testing these out!

If I understand it right, the lilac 5-baffle is 3.7" long, same length as the stock red one, and knocked off 6dB over the stock one?  You said "2 dB", but the sample numbers are 6dB different.

The 5" required the housing modification, but after that, it is all internal, and got it down to 9dB lower than stock.

And the 8", requires the same modifications, 3" of it is external, and knocked ~20dB off stock???  Yowza.

Now I'm curious what a 3.7" +2" or +3" (or more) external could do -- to avoid hogging out the housing.

[subscriber]

Now I'm curious what a 3.7" +2" or +3" (or more) external could do -- to avoid hogging out the housing.

I expect that reducing the insert OD to fit in the stock 24 mm ID "can", while copying the rest of the 8" insert detail, would increase the sound to no more than (25.4 x 25.4) / (24 x 24) * 5/8  . 

I think it is worth a try...

[subscriber]

For those of you that want to experience (nearly) Dave's results (above), without boring out your casing ID above the stock 24 mm, I have designed 24 mm shank versions of the 7 and 8 chamber inserts.  The STL print files are attached below.

You will need to drill pin holes to retain the insert, but I am sure Dave will talk you though it.

I am not sure if Dave's results were with the 7 or 8 chamber version, so I include both.  I would go with what he tested; or both.

[Firewalker]

Thanks for testing these out!

If I understand it right, the lilac 5-baffle is 3.7" long, same length as the stock red one, and knocked off 6dB over the stock one?  You said "2 dB", but the sample numbers are 6dB different.

The 5" required the housing modification, but after that, it is all internal, and got it down to 9dB lower than stock.

And the 8", requires the same modifications, 3" of it is external, and knocked ~20dB off stock???  Yowza.

Now I'm curious what a 3.7" +2" or +3" (or more) external could do -- to avoid hogging out the housing.

Yes, 3.7" long on the stock replacement insert.

I was FLYNG through my post, I am sure other mistakes were made to my data collection, I lust scribbled numbers on the back of an adhesive label as I went.

I think what you propose is likely the best drop-fit idea out there as the extra baffles would be external and take advantage of the plume style shape. One think I would definitely change would be to locate and print the pin holes, even if they were mostly filled with print hairs, I had no time to to face my hole starts and I wandered on one hole, the other ran straight but in the end, both pins are good to go and holding the insert sealed to the housing.

If precise hole locations could be located for Subscriber, I am willing to be that he could add them to the print. 

[miksatx]

Lol glad to see the inserts made it.

[Rat Sniper (AKA: PaulT58)]

I think what you propose is likely the best drop-fit idea out there as the extra baffles would be external and take advantage of the plume style shape. One think I would definitely change would be to locate and print the pin holes, even if they were mostly filled with print hairs, I had no time to to face my hole starts and I wandered on one hole, the other ran straight but in the end, both pins are good to go and holding the insert sealed to the housing.

If precise hole locations could be located for Subscriber, I am willing to be that he could add them to the print.

If I didn't have to drill the holes for the pins, I'd definately be interested in trying one!  I just don't have enough confidence in my own abilities, let alone a precision tool (I have a hand drill) to ensure they go straight through and don't damage the factory housing! 

[Firewalker]

Lol glad to see the inserts made it.

Looks so good that I didn't sand or paint the part sticking out. Really nice job, Mike!

[miksatx]

Lol glad to see the inserts made it.

Looks so good that I didn't sand or paint the part sticking out. Really nice job, Mike!

Thanks David! Not too shabby for a $200 refurbished printer.

[subscriber]

If precise hole locations could be located for Subscriber, I am willing to be that he could add them to the print.

Yes please, Dave.  That would make the replacement inserts a lot more valuable.

It just occurred to me that I need to reduce the length of the conical end, as you bored out your casing deeper, when you made it wider.   So, I need to shorten the insert design length to fit into the stock casing.

To make things simple, I could add a slightly tight ring to the OD near breech and shoulder ends of my insert design, so that is what centers the insert in the casing, rather than the cone.  This way, there is no risk of the insert being too long and fighting the pin holes.  All that would need to be managed is the distance from the front shoulder to the pin location. 

Someone needs to provide an accurate measurement of the stock casing ID, as I am betting you measured the stock insert OD at 24 mm.  I am guessing that the casing ID is a bit larger than that.

[subscriber]

Not too shabby for a $200 refurbished printer.

And Mike, if I remember correctly you have only been 3D printing for a few months?  So, your prints are all the more impressive, considering you had to start your journey with a blown mother board.  Something that would put off a lot of people.

[subscriber]

Dave,

Which version of the extended insert did you test?  7 or 8 chamber?

[Firewalker]

If precise hole locations could be located for Subscriber, I am willing to be that he could add them to the print.

Yes please, Dave.  That would make the replacement inserts a lot more valuable.

It just occurred to me that I need to reduce the length of the conical end, as you bored out your casing deeper, when you made it wider.   So, I need to shorten the insert design length to fit into the stock casing.

To make things simple, I could add a slightly tight ring to the OD near breech and shoulder ends of my insert design, so that is what centers the insert in the casing, rather than the cone.  This way, there is no risk of the insert being too long and fighting the pin holes.  All that would need to be managed is the distance from the front shoulder to the pin location. 

Someone needs to provide an accurate measurement of the stock casing ID, as I am betting you measured the stock insert OD at 24 mm.  I am guessing that the casing ID is a bit larger than that.

Knowing that the housing is oblong, an actual measurement was impossible but the tightest portion was what I posted.

Someone else will have to do the precision measurements for the hole locations though as I have bored out to 1".

I do think there will be a market for these as a drop in.

[Firewalker]

Dave,

Which version of the extended insert did you test?  7 or 8 chamber?

LoL!

I could not see inside so this is a Mike question.

[subscriber]

Mike,

Was this the 7 or 8 chamber design that you printed for Dave?

Thanks

58% 9hrs! lol

[miksatx]

Mike,

Was this the 7 or 8 chamber design that you printed for Dave?

Thanks

58% 9hrs! lol

Was the 8 chamber.

[miksatx]

Not too shabby for a $200 refurbished printer.

And Mike, if I remember correctly you have only been 3D printing for a few months?  So, your prints are all the more impressive, considering you had to start your journey with a blown mother board.  Something that would put off a lot of people.

Blown motherboard and hotbed had to be replaced.

[subscriber]

Blown motherboard and hotbed had to be replaced.

Yikes!  Almost as if someone really did not want you to get into 3D printing

[subscriber]

The images below show my best effort at extended inserts (similar to what Dave tested) designed to fit the unmodified Notos "can". 

I scaled the retention pin positions from the images in this thread, and applied a human trait:  When there is no clear reason to choose fractional dimensions, most designers default to full units.  So, the pin to pin spacing seems to land 8 mm away from the centerline, and thus 16 mm center to center, placed in the 32 mm OD casing.  I did something similar for the pin placement from the casing shoulder.

You may need to sand down the rings I added to the insert OD to ensure it is not loose in the casing.  The rings are 0.002" taller than the surrounding OD, so not very aggressive.

The pin holes should print close to 2 mm in diameter.  You may need to chase them, but decide that after fitting the insert OD to the casing ID.

The STL print files are attached, below.  One for the long snout version; the other for the short snout. 

Both inserts will have a cavity ahead of them that Umarex designed as primary expansion chamber, ahead of the muzzle.  The difference between the inserts is how far the pellet has to travel in that primary chamber before it is shielded from turbulence by the first air stripper.  Will there be any meaningful grouping ability difference between the two versions?  I hope someone prints either or both to find out.

This may be my last contribution on this topic for 5 weeks.  I am going walkabout in the Southern hemisphere, imminently.  I need to do my taxes and a few other things before I am ready.


 

[Firewalker]

Wonderful! Thanks again Subscriber!

[Rat Sniper (AKA: PaulT58)]

Those look pretty amazing, I may have to invest in some PETG and see if I can print one!  Thank you for sharing these files!