Stormrider with offset LDC

[subscriber]

Did you use glue, Mike?   

[miksatx]

Did you use glue, Mike?   

I did sparingly on the 2 alignment pips only. It’s all apart now.

[miksatx]

B Extended extra on the plate.

[subscriber]

B Extended extra on the plate.

You are a good sport, Mike.

If I was thinking of applying glue, it would be a few small dabs near the front end flange.  That way the rear inserts don't get damaged, if you want to take it apart.

I wonder if just wrapping the front insert with masking tape near the front flange would provide enough retention. 

At least until you got serious, then I would be tempted to use one or two short screws, threaded into the aluminum tube or insert, by drilling the assembly from the top, opposite the offset barrel.  I have chosen a spot where the front insert wall is the thickest, but other place could be devised or chosen.

The screw shown below is a 2-56 thread, 3/16" long screw.  A self tapping screw, as used for wood, or soft materials may be a better choice.  Just try not to drill into the insert air space, or you will need to remove the swarf before shooting.

In the case of the shorter tube you have in the location shown below:

[subscriber]

Having figured all the above, I think a pin that passes all the way through the tube from side to side, above the centerline would be better.  For the simple reason that the pin would be in double shear.  However, without having at least a drill press with a vice, and some way of starting holes at a shallow angle to the surface, (such as a center drill or short endmill) the execution would be difficult.

I can think of other ways to make the holes, but they require skill and a bit of luck.  Such as drilling the tube (without the insert installed) square to its surface in two locations, using an undersized bit for the pin.  Then "reaming" or "wallowing" the hole so that the drill bit can pass through both holes.  The reaming those ovaled holes to the pin size.  More opportunity for messing things up than I like to offer as a path to success.  Hence the short screw idea above...

Possible pin locations below.  The forward pin holes put the 3D printed material in compression.  Better than tension, if there is anything dodgy with layer to layer adhesion.  The forward most pin hole would only work with a longer tube.

I would try wrapping the front insert with tape for increased friction, before the trouble of pinning.  The screw retention idea is not as strong as a double shear pin, but is much easier to implement:

[miksatx]

Having figured all the above, I think a pin that passes all the way through the tube from side to side, above the centerline would be better.  For the simple reason that the pin would be in double shear.  However, without having at least a drill press with a vice, and some way of starting holes at a shallow angle to the surface, (such as a center drill or short endmill) the execution would be difficult.

I can think of other ways to make the holes, but they require skill and a bit of luck.  Such as drilling the tube (without the insert installed) square to its surface in two locations, using an undersized bit for the pin.  Then "reaming" or "wallowing" the hole so that the drill bit can pass through both holes.  The reaming those ovaled holes to the pin size.  More opportunity for messing things up than I like to offer as a path to success.  Hence the short screw idea above...

Possible pin locations below.  The forward pin holes put the 3D printed material in compression.  Better than tension, if there is anything dodgy with layer to layer adhesion.  The forward most pin hole would only work with a longer tube.

I would try wrapping the front insert with tape for increased friction, before the trouble of pinning.  The screw retention idea is not as strong as a double shear pin, but is much easier to implement:

Ok masking tape it is lol! With the equipment on hand I’d more likely find a place to drill and tap for an Allen key grub screw up front. All great ideas subscriber. Oh my print failed found the hot end fused to the print really strange.

[dan_house]

Awesome thread !
Thanx Mike and Subscriber for sharing this effort.

[miksatx]

Dang sorry to report no lower dBA with the addition length.

[subscriber]

That is very interesting, Mike.  Do your ears agree with the meter?

I wonder if it is an artifact of the offset geometry.  Or, if the extra length is causing some droop and producing a little baffle strike.  A little clipping would certainly add sound.  If groups are disturbed from before, that might indicate a degree of clipping.  Did you shoot some targets to see what it does?

I assume that your test set-up is identical to before?  How far away is your target?  The reason for that question is that your trap might be making noise that your meter reads as 84 dB peak.

From my end, I was not entirely happy with adding an arbitrary 2".   The way the baffle shapes fan out is not as nice, as when I could make it, if I start with no baffles in the front insert, then fill out the full length.

If you are up for it, I would like to redo the front insert design.  I want to change the baffle progression to be more "natural"; and I want to open up the baffle bores in case there is a hint of clipping with your current insert.  The idea that adding almost 40% more forward length did nothing for the sound seems a little hard to understand.  Unless there is clipping.

Else, we may end up with the assumption that this approach to attaching a reflex LDC to the Stormrider is near its practical design and implementation limit.  Making the reflex section longer would regain angular stability, but you originally told me that the max reflex length you could accommodate to clear the barrel band, was 5", so that is what I used.  (actually 4.8")

If the rear inserts also have some clearance in the tube ID, then wrapping the rear insert in tape will help with the overall alignment of the system.  Perhaps, if the rear inserts have any looseness with the tube away from the threaded area, could you wrap the rear insert with tape in the areas that are loose in the tube, reassemble and test the longer front insert again?

If you are bored with this Stormrider system and want to try something else; I have another design that I did for a skeptic, that is now very impressed when running at 62 FPE.  He was not impressed with my plume-type inserts (as I have done for the Notos and Avenger); so I designed a cloth wrapped K-baffle stack insert.  The design is not offset, so no good for the Stormrider. 

The images below show what the cloth wrapped K-baffle insert looks like.   The thread is custom, so I would need to make a conventional threaded version for general use.  If you have interest.  I would post that to the thread the other chap started, and provide the link here.

Yes, I feel free to share custom designs I did for other people, without their permission.  My thinking works like this:  Unless someone pays me to do a design for them, I still own the rights to the design.  Very few people are interested in paying hundreds of dollars for my design time, so I do it for free.  Even at 5 bucks an hour, for completely new design concepts, I can run up 50 or 100 dollars (or more) pretty easily.  No one wants to pay that for a design, unless it includes parts...  I don't blame them.  So, what I get out of doing these designs, is test results from enthusiasts on GTA; that help me better understand how to make better systems - should I ever want to commercialize this hobby.

[miksatx]

That is very interesting, Mike.  Do your ears agree with the meter?

I wonder if it is an artifact of the offset geometry.  Or, if the extra length is causing some droop and producing a little baffle strike.  A little clipping would certainly add sound.  If groups are disturbed from before, that might indicate a degree of clipping.  Did you shoot some targets to see what it does?

I assume that your test set-up is identical to before?  How far away is your target?  The reason for that question is that your trap might be making noise that your meter reads as 84 dB peak.

From my end, I was not entirely happy with adding an arbitrary 2".   The way the baffle shapes fan out is not as nice, as when I could make it, if I start with no baffles in the front insert, then fill out the full length.

If you are up for it, I would like to redo the front insert design.  I want to change the baffle progression to be more "natural"; and I want to open up the baffle bores in case there is a hint of clipping with your current insert.  The idea that adding almost 40% more forward length did nothing for the sound seems a little hard to understand.  Unless there is clipping.

Else, we may end up with the assumption that this approach to attaching a reflex LDC to the Stormrider is near its practical design and implementation limit.  Making the reflex section longer would regain angular stability, but you originally told me that the max reflex length you could accommodate to clear the barrel band, was 5", so that is what I used.  (actually 4.8")

If the rear inserts also have some clearance in the tube ID, then wrapping the rear insert in tape will help with the overall alignment of the system.  Perhaps, if the rear inserts have any looseness with the tube away from the threaded area, could you wrap the rear insert with tape in the areas that are loose in the tube, reassemble and test the longer front insert again?

If you are bored with this Stormrider system and want to try something else; I have another design that I did for a skeptic, that is now very impressed when running at 62 FPE.  He was not impressed with my plume-type inserts (as I have done for the Notos and Avenger); so I designed a cloth wrapped K-baffle stack insert.  The design is not offset, so no good for the Stormrider. 

The images below show what the cloth wrapped K-baffle insert looks like.   The thread is custom, so I would need to make a conventional threaded version for general use.  If you have interest.  I would post that to the thread the other chap started, and provide the link here.

Yes, I feel free to share custom designs I did for other people, without their permission.  My thinking works like this:  Unless someone pays me to do a design for them, I still own the rights to the design.  Very few people are interested in paying hundreds of dollars for my design time, so I do it for free.  Even at 5 bucks an hour, for completely new design concepts, I can run up 50 or 100 dollars (or more) pretty easily.  No one wants to pay that for a design, unless it includes parts...  I don't blame them.  So, what I get out of doing these designs, is test results from enthusiasts on GTA; that help me better understand how to make better systems - should I ever want to commercialize this hobby.

No clipping still great accuracy. was set up the same way. this low was 89dBA just 5 points higher. i really couldn't hear a difference I had to go look at the meter. 84dBA the quietest in my colletion. I'm happy with the shorter set up for now. i need some better machining capability. 

[subscriber]

Mike; if you are happy, I am happy.

An overall length of 10" seems enough from a bulk/weight perspective.  So, making the assembly longer would degrade the bulk/weight aspect; which would be silly, if there is no gain in performance.


I had an idea for a simple tool to facilitate drilling of the cross pin holes through the 1" OD outer tube (and installed front insert).   It is intended to guide  a 1/8" twist drill, for a 1/8" cross pin diameter.  The nominal pin length would be 22 mm.

The idea is to drill halfway through to the tube center, from both sides of the guide; rather than all the way through from one side.

 The images below shows what the drilling guide looks like, and the preferred print orientation.  The STL is attached, in case you are tempted to try it out.  A thick wall with 20% infill should be fine for it.


So, I am going to make some mods to that felt wrapped k-baffle insert instead.

[miksatx]

Mike; if you are happy, I am happy.

An overall length of 10" seems enough from a bulk/weight perspective.  So, making the assembly longer would degrade the bulk/weight aspect; which would be silly, if there is no gain in performance.


I had an idea for a simple tool to facilitate drilling of the cross pin holes through the 1" OD outer tube (and installed front insert).   It is intended to guide  a 1/8" twist drill, for a 1/8" cross pin diameter.  The nominal pin length would be 22 mm.

The idea is to drill halfway through to the tube center, from both sides of the guide; rather than all the way through from one side.

 The images below shows what the drilling guide looks like, and the preferred print orientation.  The STL is attached, in case you are tempted to try it out.  A thick wall with 20% infill should be fine for it.


So, I am going to make some mods to that felt wrapped k-baffle insert instead.

Got it on the plate see if the ender3 s1 pro can handle it. if you need something printed let me know.

[miksatx]

cross pin tool printed. had to work over the inside with sanding cartridges. tight fit for sure. had to do it on the anycubic. ender3 needs adjusting with a 3lb shop hammer!

[subscriber]

Hi Mike,

What is the measured diameter of the nominal 1" OD tube?  I should have asked you that before you started printing.  Anyway, I assumed it would be close to 1", so made the tool ID 25.7 mm in CAD.  That is 0.3 mm larger than nominal tube OD, because 0.3 mm is typically how much bore shrink in FDM printing on smaller holes - less on larger ones.

It would have been useful for you to measure the tool ID before sanding also, then I could alter my CAD model to produce a tool that would not require sanding.  You could also change the % dimension in your slicer to something like 100.5 % on the X and Y axis to make it fit looser.

I wanted minimum clearance to provide good alignment, not just have the tool fall over the tube.  At the same time, I do not want anyone to struggle with the parts I design.

Is the tool stuck on that tube section now?

[subscriber]

It can be useful to print calibration "parts" from time to time.  That will enable you to adjust the part size in the slicer, or in CAD, to compensate for a given printer, print mode and material. 

A short section of a long complex print makes an ideal calibration print.  Or, you can print some of these calibration prints and measure them to get an idea of what you printer is doing:  https://www.gatewaytoairguns.org/GTA/index.php?topic=204046.0

I can take any of my part models and cut off everything, except the most important features, to create a test print for a given job that does not take the full print period.  You could interrupt a print once you have the important bits done, to measure just them.  It all depends on what takes longer; sanding the real part, or pre-printing a calibration print first.

If a dimension prints such that a fit is too loose, then sanding off material obviously won't work.  Here pre-calibration would be most useful.

[miksatx]

Hi Mike,

What is the measured diameter of the nominal 1" OD tube?  I should have asked you that before you started printing.  Anyway, I assumed it would be close to 1", so made the tool ID 25.7 mm in CAD.  That is 0.3 mm larger than nominal tube OD, because 0.3 mm is typically how much bore shrink in FDM printing on smaller holes - less on larger ones.

It would have been useful for you to measure the tool ID before sanding also, then I could alter my CAD model to produce a tool that would not require sanding.  You could also change the % dimension in your slicer to something like 100.5 % on the X and Y axis to make it fit looser.

I wanted minimum clearance to provide good alignment, not just have the tool fall over the tube.  At the same time, I do not want anyone to struggle with the parts I design.

Is the tool stuck on that tube section now?

The aluminum tubing OD 25.34mm  cross section pin tool before sanding, bottom measured 25.21 & 25.26 top 25.33 & 25.35mm. Is the tool stuck on that tube section? Yes it is but can be moved up or down the tube. But this piece of tubing was polished up some.

[subscriber]

Modified the fixture bore by making it 0.15 mm larger than V1.  Doubled the fillet radius at the top and bottom of the hole so the edges are less likely to catch.

STL for V2 attached

[miksatx]

Modified the fixture bore by making it 0.15 mm larger than V1.  Doubled the fillet radius at the top and bottom of the hole so the edges are less likely to catch.

STL for V2 attached

On the plate!

[miksatx]

fits the long tube perfectly. now i need to buy a 1/8" drill.

[subscriber]

Great!
You also need to figure out where to place the alignment tool to get the pin located where your want it.  It is up to you where you want the cross pin, but the images below should provide some insight.

Dimensions are measured from the front and rear ends of the aluminum tube.  Not the inserts.

The location of the green circle and dimensions pass through the front insert outside of the air space.  So no dust should enter the pellet path.  If you place the pin through the air space, you need to remove the insert and blow through it from both ends of the bore, to get the swarf out.

I could modify the design of the front insert to add plastic in your preferred pin location, so you can drill the assembly and forget about the swarf.  Or you can use the green pin location, below.