Author Topic: 2240 Power Adjuster / SSG ? (Read 1937 times))

WobblyHand · « **on:** May 31, 2023, 05:03:37 PM »

Not sure I fully grasp everything from the SSG thread, but here's an attempt at a model of one. Can someone look it over to see if I captured the basics? I can clearly see the need for a cap over the end, which I can add, but I first want to make something simpler just to see if I have the basic dimensions ok. I hope to machine everything from steel scraps and odds and ends on hand.

The original spring is about 2" long uncompressed, maybe 1.5" when the cap is on. Should I replace the spring? If so, what am I looking for? Stiffer?

I am looking to get more shots out of this. Thanks for any insights.

nervoustrigger · « **Reply #1 on:** May 31, 2023, 06:35:46 PM »

Looks like a winner. The jamnuts allow you to set the amount of free flight, and the purple part manipulates the hammer spring preload.

Regarding the OEM spring, you’ll probably need to shorten it. The way I approach it is to remove one coil at a time until the velocity drops to about 90% of the original, and then use the preload adjustment to bring it back up to about 95% of the original. When adjusted in this manner, efficiency will be good and it will not be nearly as sensitive to temperature changes.

mackeral5 · « **Reply #2 on:** June 01, 2023, 09:02:42 AM »

Quote from: nervoustrigger on May 31, 2023, 06:35:46 PM

Looks like a winner. The jamnuts allow you to set the amount of free flight, and the purple part manipulates the hammer spring preload.

Regarding the OEM spring, you’ll probably need to shorten it. The way I approach it is to remove one coil at a time until the velocity drops to about 90% of the original, and then use the preload adjustment to bring it back up to about 95% of the original. When adjusted in this manner, efficiency will be good and it will not be nearly as sensitive to temperature changes.

Am I misinterpreting or did you transpose your explanation of setting gap and preload?

nervoustrigger · « **Reply #3 on:** June 01, 2023, 10:15:27 AM »

Whoops, yes I wrote that backwards. Thanks Mike!

Should have said:
The jamnuts allow you to set the amount of hammer spring preload, and the purple part adjusts the amount of free flight.

CraigH · « **Reply #4 on:** June 01, 2023, 11:46:55 AM »

Spring rate depends on the desired effect (and the platform). Generally the SSG uses a lighter spring with 1/2" to 3/4" preload (again platform dependent).

Shot count could be 50% to 100% higher depending on SSG components and tuning.

WhatUPSbox? · « **Reply #5 on:** June 01, 2023, 01:53:13 PM »

The stock spring on mine was L=33.8mm, OD=7.6mm, t=0.84mm (Thickness measurement is a little sketchy). The measured spring rate was about 3 N/mm or 17 lbs/in.
If you are also going after a light trigger pull, the hammer spring compressed force can affect the low end of the trigger pull.

Spacebus · « **Reply #6 on:** June 01, 2023, 02:19:27 PM »

I spent a while looking for an off the shelf/plug and play SSG, but settled for a simple power adjuster. I look forward to seeing your results!

WobblyHand · « **Reply #7 on:** June 01, 2023, 04:04:14 PM »

Quote from: Spacebus on June 01, 2023, 02:19:27 PM

I spent a while looking for an off the shelf/plug and play SSG, but settled for a simple power adjuster. I look forward to seeing your results!

I'm working on a PID controller for casting right now. The SSG will be next.

Depending on how frustrated I get with cutting holes in the steel ammo box, I may jump to the lathe and start the SSG. Looks like a relatively simple lathe project.

CraigH · « **Reply #8 on:** June 01, 2023, 04:30:36 PM »

I neglected to mention above (Reply #4) "at about the same power level".

WobblyHand · « **Reply #9 on:** June 04, 2023, 12:05:52 AM »

Made the green piece today and got part way through the magenta piece. Trying to figure out the work holding for the magenta. Single pointed the 3/8-24 threads on the magenta, to match the tapped 3/8-24 threads on the green piece. Drilled and reamed the magenta piece to a hair over 3/16". Probably will leave the head section long, so I can hold it and form the hex head, and then cut off the extra piece.

Today was a lathe day, also made an LDC barrel adapter for my 2240.

Nvreloader · « **Reply #10 on:** June 04, 2023, 10:34:20 AM »

WH
If you didn't know, here is the all the info on SSG's
https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.340
pg 18/post#355 has all the designs.

I was just looking at them for a design for the Dragon Fly II rifle types.

HtH,
Don

WobblyHand · « **Reply #11 on:** June 04, 2023, 10:54:22 AM »

Quote from: Nvreloader on June 04, 2023, 10:34:20 AM

WH
If you didn't know, here is the all the info on SSG's
https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.340
pg 18/post#355 has all the designs.

I was just looking at them for a design for the Dragon Fly II rifle types.

HtH,
Don

Thanks Don.

Yea, it's a long thread, thanks for pointing out where there's a good synopsis. Have to go looking for a hex head long 10-32 screw. I don't mind turning down the screw a little, but making that long spring guide from scratch might be a stretch. The length to diameter ratio is quite large and it would be tough to have uniform diameter. Or I could just use rod stock and thread both sides. Now that I have typed all this out, it seems obvious what to do. I should have the rod stock...

Bruce

Gippeto · « **Reply #12 on:** June 04, 2023, 02:20:14 PM »

Quote from: WobblyHand on June 04, 2023, 10:54:22 AM

I should have the rod stock...

Bruce

Indeed.

I did (and still do) make the short ones needed by turning down, but have been using 3/16" drill rod on "longer" shafts. Suggest single pointing the threads to ensure everything ends up running straight and to close tolerance.

Regards,
Al

WobblyHand · « **Reply #13 on:** June 04, 2023, 03:22:01 PM »

A little progress, got the cap finished. The adjuster is done. I single pointed the 3/8-24 thread on the adjuster. Guess I will also single point the 10-32 threads on the shaft. Needed to break for lunch.

Discovered, that although I have all sorts of hardware, imperial and metric, I have no 10-32 nuts!

Well, I do have a 10-32 tap and a hex collet block... I'll check to see if I have some smaller hex stock. Hmm, maybe I can skip hex nuts and make knurled jam nuts - that doesn't sound bad.

Spacebus · « **Reply #14 on:** June 04, 2023, 04:37:56 PM »

Quote from: WobblyHand on June 04, 2023, 03:22:01 PM

A little progress, got the cap finished. The adjuster is done. I single pointed the 3/8-24 thread on the adjuster. Guess I will also single point the 10-32 threads on the shaft. Needed to break for lunch.

Discovered, that although I have all sorts of hardware, imperial and metric, I have no 10-32 nuts! Well, I do have a 10-32 tap and a hex collet block... I'll check to see if I have some smaller hex stock. Hmm, maybe I can skip hex nuts and make knurled jam nuts - that doesn't sound bad.

I was going to suggest round knurled nuts if you had access to the right materials or tools.

WobblyHand · « **Reply #15 on:** June 04, 2023, 09:35:26 PM »

After I made the nuts, err, umm, I found the 10-32 nuts. They are relatively large, so I don't feel too bad about making some knurled jam nuts in stainless. I think I need to add some nylon or something to the adjusting nut I made, it is a bit loose when everything is assembled. I also need to make a nut for the end of the rod that fits in the hammer cavity. I could just jam two nuts together and turn off the flats. Probably will take pliers to get the nuts apart, don't know how well that would work.

And I see some errors that I made in the design. Made the plug too deep, I measured 8.68mm, I made mine 13mm, so it would hit the hammer at cock. Will turn the end to make it shorter. Maybe I can do that tonight. If I make another plug, I will have to change how I machine it, changing the order of operations. I used that length to hold the part, if it's not there, I need to make it differently.

It will probably take an iteration or two to get there...

WobblyHand · « **Reply #16 on:** June 04, 2023, 11:04:11 PM »

I jammed two ordinary nuts together on the bottom of the rod and turned them to a hair under 8mm, which fits inside the hammer. As for the cap, I can make an 3/8-24 screw with a tighter fit and use it to hold the cap against a collet and then trim the length to 8.9 mm. The adjuster screw is too sloppy, I went too far cutting the threads, I'm not happy with that piece. Maybe I can wrap the screw with teflon tape to tighten it a little.

WobblyHand · « **Reply #17 on:** June 05, 2023, 07:13:10 PM »

Turning down the cap wasn't that bad. Found a piece of 3/8" rod stock that I had single pointed for practice, and amazingly I had done it at 3/8-24! It was a nice fit to the tapped hole in the cap. Spun it onto the end and stuck the rod in the collet up against the collet face. Turned on the lathe and it was running true. For this it didn't matter, but it was gratifying to see. So I just turned down both the cap and the screw.

Unfortunately the SSG rod is too long, by about 0.3" I will cut off the bottom and re-thread it. If I understand correctly, we want the rod to not be in contact with the hammer when adjusted?

WobblyHand · « **Reply #18 on:** June 05, 2023, 09:15:10 PM »

Well, blindly going along here, not sure if I cut off too much or not enough. Had to turn out the adjuster, just to get it to cock. Is that what you do? Not sure what to do next.

Edit: what to do next is, to put in a cartridge and see what happens. It shoots. And with my printed LDC it is quieter. I will have to spend some time adjusting things. The spring needs to be cut, among other things. The long set screw I have holding the LDC adapter to the barrel is not a very good front sight. Have to think about how to make a front sight, but that is for later.

WhatUPSbox? · « **Reply #19 on:** June 06, 2023, 12:54:07 PM »

I have not done SSG's but what I try to do with the power adjusters is to start them at the equivalent position to the stock cap. For an adjuster it is just a geometry check. For an SSG I guess it would be an equivalent energy imparted on the hammer. For my 2240, the energy in the stock spring is about .122 J. For the SSG, you don't get all the compressed energy back. Some of it stays in the spring and some of it goes into moving the mass of the shaft and nuts.

I ended up putting the front sight on the LDC to take advantage of the extra sight distance. I then made (printed) a new rear sight blade to set the gap width.