Stormrider with offset LDC

[subscriber]

I made a small change to the front insert, to increase the expansion volume of the first chamber.  A minor change, but "free space", if you want to try version 2. 

Image below compares version 2 to the above version. 

STL for version 2 is attached, below.

[subscriber]

love the look of eccentric cans...

You folks might ask why I did not push the degree of offset to the max, right off the bat?  The answer is because I am concerned about asymmetrical airflow, applying side forces to the pellet.  Either to cause it to deviate from the bore axis, or to cause it to wobble. 


If the 5 mm offset version of this eccentric design shoots well; then:

1. my concerns were overblown;

2. or the deviation / wobble is repeatable; so grouping ability is not affected;

3. or you can get away with shifted air flow in low power applications, that might be more deleterious at higher FPE.


In any event, I am happy to take a design beyond what I think should work well, because it helps me better understand the LDC operating envelope, for what is as much art as it is science.  Certainly, I broke the earlier design; trying to capture the most reflex expansion volume, at the expense of strength (because I reasoned that the insert should be supported by the metal outer tube).   That weakness should be resolved now, with the 5 mm offset design.

[miksatx]

Just printed the front what happened to the little points that line up left and right inserts? how are they held in place with the front bore? and front still to fat lol maybe reduce diameter 1mm?
tried sticking insert in tube maybe 1/16" in it was stuck result pulled a piece off the front lol

[subscriber]

what happened to the little points that line up left and right inserts? how are they held in place with the front bore?

I understood your statement below as meaning I should get rid of the alignment features:

yep no need for the little divots.

When I removed the pips and dimples there was no push back against the idea of sighting down the bore for alignment.  If I knew you found the pips and dimples useful I would have left them in.

Mike,  I hate to say this, but you seem to miss half of my questions and statements.  Then I am left with waiting for answers or comments; or proceeding with the info I have on hand.  I am not blessed with patience, so I tend to charge ahead to try and get the job done with what I have.

I appreciate that you want to avoid printing parts over, because of how long they take.  Well, the design process is not exactly swift either.  And it requires my full attention.

That said, I have been, and continue to enjoy working with you; because you are so eager to try new designs; and so quick to start printing them.

So, I assume you would like the latest design with the alignment pips restored.  I will do that, rather than wait until you make a clear statement.

[miksatx]

what happened to the little points that line up left and right inserts? how are they held in place with the front bore?

I understood your statement below as meaning I should get rid of the alignment features:

yep no need for the little divots.

When I removed the pips and dimples there was no push back against the idea of sighting down the bore for alignment.  If I knew you found the pips and dimples useful I would have left them in.

Mike,  I hate to say this, but you seem to miss half of my questions and statements.  Then I am left with waiting for answers or comments; or proceeding with the info I have on hand.  I am not blessed with patience, so I tend to charge ahead to try and get the job done with what I have.

I appreciate that you want to avoid printing parts over, because of how long they take.  Well, the design process is not exactly swift either.  And it requires my full attention.

That said, I have been, and continue to enjoy working with you; because you are so eager to try new designs; and so quick to start printing them.

So, I assume you would like the latest design with the alignment pips restored.  I will do that, rather than wait until you make a clear statement.

I aplogize with the pips gone i thought you changed up  the alignment design any way i just sent a email asking for a phone talk.

[miksatx]

I just measuered the tube ID .925 is hat my calipers measured. i can understand if you don't want to work with me or this. just might be to much for me to understand.

[subscriber]

Thanks for clearing things up, Mike. 

I updated the Stormrider 5 mm eccentric LDC insert part designs:

1. The OD of the inserts has been reduced to match your measured tube ID of 0.925".

2. I put the clocking alignment features back into the design.   Section image below shows the pips and dimples lining up, as design verification. 

STLs are attached in zipped folder, below:

[miksatx]

Hi subscriber check reply #17 lol

[subscriber]

Hi subscriber check reply #17 lol

Oops!  Who is Frank?   

I think my mind was on a IZZY 46M thread where Frank in Fairfield had been participating.  Or perhaps my mind was just on walkabout.

It was not meant as an insult.  Just like you, Mike, Frank is a stand-up guy.

[miksatx]

the anycubic printed the front insert 23.22/23mm fits great.

[subscriber]

Glad it fits, Mike. 

I would have thought it might be a little loose.  Which surprises me based on yesterday's measurements.

The CAD OD for this front insert is 0.925" or 23.5 mm:

[Back_Roads]

 Sorry to interrupt this fine thread, but the last pic, hit an abstract art nerve in me

[subscriber]

Glad I am not the only one to see a shocked face in that image, James.  You beat me in associating it with Mr Bill, though 

[miksatx]

Ok great news!

[subscriber]

Good.  It fits with no interference. 

How does it shoot?

[miksatx]

Good.  It fits with no interference. 

How does it shoot?

Shoots dead on! with 3 different ammos. from 108dBA to 84dBA big difference.
Thanks So much Subscriber you the best!

[subscriber]

Thanks Mike, for letting me experiment on you.  I was not sure if the split threaded insert concept would work.  Now we know.

I consider the fact that such an extreme asymmetrical design groups OK a data point for future designs.  The open question is if it would still group OK at higher power. 

Some sort of pin or screwed retention system between the front insert and the outer tube is likely going to be required for shooting at 20+ FPE.  Should not be difficult to add that above the offset bore.  If we are clever enough.

[subscriber]

That sound reduction seems useful.  84 dB is still a bit on the loud side.  That makes me wonder what an additional 2" would do.  Or, so the total tube length is 12".

I can conjure up an experimental front insert that works with your current tube and rear inserts.
 It would just have a thicker wall for the additional 2".  If that seems worth the trouble and extra length, then you can decide if you want to get a longer tube that would have the same endcap appearance as what you have now.

I know that seems like work to print another insert, when you want to play.  If I provide the design, you can decide to try it, or ignore it.  Or defer it to later; or never.

The idea of a greater length ahead of the muzzle would make more sense if you were shooting at higher power.  The current length ahead of the muzzle is  5.32".  Adding two inches would increase that length by 38%.  Enough to be useful.

Anyway; just an idea. Ideas are cheap.  The image below should help a little.

[subscriber]

Mike,

I went ahead and created two front insert variants, based off the current one - see images below:

A:  Current front insert as tested by you today.
B:  Experimental Extended insert to use inside the same aluminum tube now containing "A".
C:  Extended insert that is functionally the same as "B", but is intended to be contained in a tube that is 12" long (2" longer) than the tube for "A" and "B" .

The STL files for "B" and "C" are attached below in a single ZIP file.  Should you be tempted to try "B"; and then maybe "C"....

[miksatx]

I’ll see if I can get it apart. May have to make some parts over lol.