Umarex Notos Porting

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caliusoptimus

caliusoptimus

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Feb 10, 2024
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I couldn't let y'all have all the fun so I picked one of these up over labor day weekend. Great little plinker! Of course I couldn't leave it alone... had to open it up and start messing with stuff.

Looked like it needed some porting... so I opened up the barrel, body, and valve body to 4.2mm. Also opened up that tiny hole between the plenum and valve... I don't know the size exactly but maybe 6mm. Deburring the sharp edges was basically brain surgery... but It worked out with no damage.

Some eNgInEeR decided to put an oddball extra tiny oring on the barrel... along with sharp edges to cut them. That was nice. I just machined the grooves in the barrel to accept a 1x10 oring, rather than find a source, pay too much, and wait days for replacements.

Results. I did not touch the reg, and the hammer spring is exactly back where it was. 20% more FPE! Nice! That was worth the effort.


Stock:
20240909_193004.jpg



After porting:
20240909_194018.jpg



Hmm... what to do next...

Edit: chrono numbers are Jsb 15.9gr
 
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caliusoptimus said:
Huben dream reg will be here soon which has a 25cc plenum. Probably overkill tbh.
Click to expand...

Anything below 1.5 fpe/cc is not overkill fwiw, and advised minimum is around .8-1 fpe/cc. 25cc will be perfect unless you try to pump even more out of it like Dave has with his :p

Example of a 60~ fpe gun (25 cal shooting 34 gr), you can see the curve graduate just fine even upwards towards 2 fpe/cc, but after that a huge taper which completely flattens out where no more gains are really had.

1725934800217.png

-Matt
 
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caliusoptimus said:
Huben dream reg will be here soon which has a 25cc plenum. Probably overkill tbh.
Click to expand...
If you want to get all crazy on power, it can handle larger ports. A longer barrel and a higher set pressure can get the power up quite a bit. I don’t run at this high of power but it’s an example of what can be obtained from the platform. The whole platform for me is just for experimenting. I’m still running the stock tank and a homemade plenum so as to not run the cost up.

Dave
IMG_6249.jpeg
 
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sb327 said:
If you want to get all crazy on power, it can handle larger ports. A longer barrel and a higher set pressure can get the power up quite a bit. I don’t run at this high of power but it’s an example of what can be obtained from the platform. The whole platform for me is just for experimenting. I’m still running the stock tank and a homemade plenum so as to not run the cost up.

DaveView attachment 495133
Click to expand...
Big powa for a little bbgun!
 
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Lots of mods so far.

Made and mounted some aluminum pic rails. Carbon barrel shroud and threaded stock barrel. Huben dream reg.

Next up is some trigger work. The hammer seems to be fairly soft steel... I might make a new one and harden it to Rc60+. I'll do what I can with the stock one first. Gonna try some stronger springs too. The stock one maxes out around 150bar which gets about 27fpe.

Also gonna slap a 15" barrel on there at some point.

20240916_085901.jpg
 
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caliusoptimus said:
Lots of mods so far.

Made and mounted some aluminum pic rails. Carbon barrel shroud and threaded stock barrel. Huben dream reg.

Next up is some trigger work. The hammer seems to be fairly soft steel... I might make a new one and harden it to Rc60+. I'll do what I can with the stock one first. Gonna try some stronger springs too. The stock one maxes out around 150bar which gets about 27fpe.

Also gonna slap a 15" barrel on there at some point.

View attachment 496520
Click to expand...

You may find that the hammer hardness varies from hammer to hammer and even on one side to the other.

I replaced one that was so soft it rounded completely over in under 1 tin of pellets.

180° and it was hard enough to cycle without marking. QA on hardening is not done in my opinion.
 
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Firewalker said:
You may find that the hammer hardness varies from hammer to hammer and even on one side to the other.

I replaced one that was so soft it rounded completely over in under 1 tin of pellets.

180° and it was hard enough to cycle without marking. QA on hardening is not done in my opinion.
Click to expand...
That's crazy, and is probably a safety issue. I noticed on mine that if the hammer rotates the trigger needs to be readjusted. It can go from being a heavy setting to featherweight just by rotating the hammer.
 
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If you take some measurements, you can tinker around with the attached spreadsheet to play with different hammer weights, hammer travel, and spring ratings which would allow you to understand what the current guns hammer energy is like and what changes you could make to increase/alter them based on a few adjustments.

-Matt

View attachment Hammer_Data_Calculations.xlsx
 
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Stubbers said:
If you take some measurements, you can tinker around with the attached spreadsheet to play with different hammer weights, hammer travel, and spring ratings which would allow you to understand what the current guns hammer energy is like and what changes you could make to increase/alter them based on a few adjustments.

-Matt

View attachment 496553
Click to expand...
Trying to wrap my head around this spreadsheet. From what I can tell... and I'm absolutely not great at physics...

1. The hammer fpe is not correct.

2. The sheet is based on an elastic collision, but the real world interaction is mostly inelastic if: the hammer is not completely opening the valve.

3. What is hammer gap? I've been assuming it's the gap between the fully extended spring and the hammer, in the circumstance where the spring is completely uncompressed when the hammer is not cocked.
 
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caliusoptimus said:
Trying to wrap my head around this spreadsheet. From what I can tell... and I'm absolutely not great at physics...

1. The hammer fpe is not correct.

2. The sheet is based on an elastic collision, but the real world interaction is mostly inelastic if: the hammer is not completely opening the valve.

3. What is hammer gap? I've been assuming it's the gap between the fully extended spring and the hammer, in the circumstance where the spring is completely uncompressed when the hammer is not cocked.
Click to expand...

1) Clarify please? Are you confusing grams for grains?

If I put in my data extrapolated from the sheet into any FPE calculator, it shows as correct. For example 4.8 gram hammer traveling 25 fps = .1 fpe, both on any external FPE calculator and through my spreadsheet. 4.8 grams = 74 grains.

2) The sheet is based on inelastic collision, plus the collision is both, initially inelastic then elastic, and calculating your lock time, hammer momentum and fpe/ke wouldn't change based on such collisions, so moot for the primary purpose of this sheet.

3) Hammer gap is the free flight, or distance the hammer travels without spring tension.


-Matt
 
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