116 replies to this topic

[rork]

Yeah, my integrated secondary uses half a +bow spring, and even at my size, I have to flip the gun around, grab the grip in my right hand, the charge rod in my left, and pull it apart, due to the fact that the reversed plunger makes the gun roughly twice as hard to cock. Actually, in my experince, when you cut the spring, it makes the gun significantly harder to prime. A full spring, while requiring a stout pull, is smooth and easy to pull, whereas half a spring requires more of a sharp yank to compress.

[Draconis]

Perhaps we need to look in to a different spring from McMaster? I will look in to it.

[hereticorp]

Draconis, on Jan 28 2009, 06:46 PM, said:

Perhaps we need to look in to a different spring from McMaster? I will look in to it.

I would do that myself except I am completely confused about how to order particular springs.

What I think we need is the same diameter, a larger distance between coils and a thinner wire weight. Resulting in a lower pull weight.

I'll let you know about the AR-15 springs tomorrow, I have some in stock for Longshot mods so I can try em out.

[A side of nerf]

Yeah, I've always been skeptical of buying springs I couldn't test out myself which is why I worked off of the +bow springs which I knew worked for the +bow. My largest concern would be that the springs I ordered would not be what I expected by the dimensions on the site and then I'd have to deal with re-shipping and what not.

[Draconis]

I think, and I should actually check this to be sure, that the main issue is the spring constant. As long as the constant is lower, and the spring is of a compatible size, then it should require less effort to compress. I could be way off, though.

[hereticorp]

Draconis, on Jan 28 2009, 07:21 PM, said:

I think, and I should actually check this to be sure, that the main issue is the spring constant. As long as the constant is lower, and the spring is of a compatible size, then it should require less effort to compress. I could be way off, though.

Checked the AR-15 at 5.5" in the LpL CS and it is WAY too weak, gets 25-30' max.

So what we need is something a little less powerful than the +Bow spring and a little more powerful than the AR-15.

[Draconis]

hereticorp, on Feb 3 2009, 02:31 PM, said:

Draconis, on Jan 28 2009, 07:21 PM, said:

I think, and I should actually check this to be sure, that the main issue is the spring constant. As long as the constant is lower, and the spring is of a compatible size, then it should require less effort to compress. I could be way off, though.

Checked the AR-15 at 5.5" in the LpL CS and it is WAY too weak, gets 25-30' max.

So what we need is something a little less powerful than the +Bow spring and a little more powerful than the AR-15.

How close are the coils when the catch is in place? Is there enough space that you could move the catch forward a bit to harness more energy?

I spoke with the McMaster-Carr folks about how to choose a spring, and frankly, the whole thing is retarded.

Quote

Actually, the constant doesn't have any rating on the spring. The constant is a reverse engineered number to calculate the number of coils to cut. To determine what spring is best for your application, you need to figure the pounds per inch of travel (which is the rate) and then use the spring constant divided by the number of coils per inch. For the proper length, you then divide by the spring rate.

So, I guess we need to determine how much force we want at full draw, and what the length of plunger stroke is. I don't have mine handy, or I would measure it. I'll check tonight.

EDIT: By merely thinking logically, I have located a good candidate: 9637K25. Same wire size, 2.18 coils per inch versus 3.09, and an OD of .968" versus .844". So basically, It can compress to a shorter length, and requires a little less force (constant of 84 vs. 130) due to the slightly larger OD. I will buy a pack with my next order.

Edited by Draconis, 03 February 2009 - 06:40 PM.

[hereticorp]

Draconis, on Feb 3 2009, 06:06 PM, said:

How close are the coils when the catch is in place? Is there enough space that you could move the catch forward a bit to harness more energy?

I spoke with the McMaster-Carr folks about how to choose a spring, and frankly, the whole thing is retarded.

Quote

Actually, the constant doesn't have any rating on the spring. The constant is a reverse engineered number to calculate the number of coils to cut. To determine what spring is best for your application, you need to figure the pounds per inch of travel (which is the rate) and then use the spring constant divided by the number of coils per inch. For the proper length, you then divide by the spring rate.

So, I guess we need to determine how much force we want at full draw, and what the length of plunger stroke is. I don't have mine handy, or I would measure it. I'll check tonight.

EDIT: By merely thinking logically, I have located a good candidate: 9637K25. Same wire size, 2.18 coils per inch versus 3.09, and an OD of .968" versus .844". So basically, It can compress to a shorter length, and requires a little less force (constant of 84 vs. 130) due to the slightly larger OD. I will buy a pack with my next order.

No, there was no space left for extra pull, and the cock was stupidly easy.

The whole thing is indeed retarded.

I've gotta order some more polycarbonate anyway, so I'll pick up a pack with those and do some testing. Thanks for searching that out for us.

I also found a good candidate for the catch spring:

9654K101 - Steel Extension Spring Zinc-Plated, 1" Length, 3/16" OD, .023" Wire $6.83 per pack of 12.

At the moment I'm using an ACE spring who's number I don't remember at the moment, but it's 1" long by 1/4" OD. The McMaster one is 1/16 smaller OD and the same length, should work perfectly.

[Draconis]

hereticorp, on Feb 3 2009, 04:05 PM, said:

No, there was no space left for extra pull, and the cock was stupidly easy.

The whole thing is indeed retarded.

I've gotta order some more polycarbonate anyway, so I'll pick up a pack with those and do some testing. Thanks for searching that out for us.

I also found a good candidate for the catch spring:

9654K101 - Steel Extension Spring Zinc-Plated, 1" Length, 3/16" OD, .023" Wire $6.83 per pack of 12.

At the moment I'm using an ACE spring who's number I don't remember at the moment, but it's 1" long by 1/4" OD. The McMaster one is 1/16 smaller OD and the same length, should work perfectly.

Yay! It may be a while before I am ready for another order... Would you be willing to sell me one of the 9637K25's from the pack you purchase?

[hereticorp]

Draconis, on Feb 3 2009, 07:15 PM, said:

Yay! It may be a while before I am ready for another order... Would you be willing to sell me one of the 9637K25's from the pack you purchase?

Sure, no problem. I'll let you know when I place the order.

Alrighty then, I got the springs in and they are SEXY.

Works really good in the LpL CS, I haven't tested it on the L+L yet, but I'm a little worried that it won't fit in the plunger tube, it's quite a bit larger around than a +Bow spring.

We'll see.

Edited by hereticorp, 10 February 2009 - 10:14 PM.

[Draconis]

Excellent! I am anxiously awaiting further news....

[hereticorp]

Ok, I tried it out and it fits perfectly, it couldn't be any larger though, I'll get ranges soon.

I have to say, I LOVE this spring for the LpLCS, it fits so much better into the plunger tube than the +Bow spring and it makes cocking the gun much easier.

Ranges:

Ten shots per gun, 4" PETG barrel, 2" Single BB Stefan.

LpLCS - +Bow Spring: 62, 63, 65, 65, 66, 67, 70, 70, 71, 72
Average: 67
LpLCS - LpL Spring: 58, 58, 59, 60, 62, 62, 64, 66, 66, 68
Average: 62

L+L - +Bow Spring: 62, 62, 63, 64, 64, 65, 66, 68, 68, 68
Average: 65
L+L - LpL Spring: 55, 55, 56, 56, 58, 59, 59, 61, 61, 62
Average: 58

The guns can definitely use a heavier stefan, I will test with Double BB and Type S sometime in the future.

Edited by hereticorp, 11 February 2009 - 01:19 PM.

[A side of nerf]

I love you...

That spring looks great and even with the minuscule amount of decreased range, it seems worth it for an easier draw.

Edited by A side of nerf, 11 February 2009 - 09:58 PM.

[Draconis]

A side of nerf, on Feb 11 2009, 06:58 PM, said:

I love you...

That spring looks great and even with the minuscule amount of decreased range, it seems worth it for an easier draw.

Well, we love you too. Not in the way VACC jokes about, but it was a stroke of genius to build these.

[hereticorp]

Draconis, on Feb 11 2009, 10:06 PM, said:

A side of nerf, on Feb 11 2009, 06:58 PM, said:

I love you...

That spring looks great and even with the minuscule amount of decreased range, it seems worth it for an easier draw.

Well, we love you too. Not in the way VACC jokes about, but it was a stroke of genius to build these.

The spring works so much better in the pistols that it's well worth the slightly decreased range.

The only problem is that you have to cut a bigger circle of polycarb to hold the spring in place, it has to almost match the ID of the PVC being as the spring is so big. I'm thinking of bending the end piece 90 degrees to compensate a little.

Anyway, here's a pic:



The compression ratio is actually a little higher on the LpL, meaning it gets harder to pull more quickly, but the overall pound pressure is lower. It makes for a very smooth draw.

[d12rule1]

Great idea this is one of my favorite homemade guns

[VACC]

d12rule1, on Feb 20 2010, 09:15 PM, said:

Great idea this is one of my favorite homemade guns

If you insist on necroing every topic containing anything you like, I'll have to insist on banning you. Read the Code of conduct and follow it.