57 replies to this topic

[Ryan201821]

So yesterday I finally got my 4k. I went to work on it right away. Here is my Airtech 4000 Overhaul.

After seeing how much potential the 3k had, I figured I could do the same thing, but have twice as many barrels.
But with twice as many barrels, and a blaster that is twice as big, there is twice as much work.

Modifications

• Replace barrels
• Improve seal
• Increase airflow
• Replace pump
• Increase pump stroke
• Rear-loading

Take it apart. Internal picture.



First thing to do, which is the most time consuming, is modding the turret.
I gutted the entire shell, but the you'll have to unscrew the screw on the end of the turret.
You'll also have to unscrew the two screws that hold the airtank in. Here's a picture.



Getting the turret apart is a bitch. Everything is solvent welded together. Unscrew the screw that holds to barrel spacer in the front of the turret.
Then it's time to pull out a pot and some water. Dip the turret in near boiling water to annihilate the solvent weld.
Then you'll have to pry the top piece of the turret off.





The stock barrels should fall off now, along with the air restrictors. If they don't, you can yank them out with a vise.

Sand down the ridges on the back of the turret.



Drill 9/16" holes through the back of turret to accept your PETG and make it rear-loading.



Clean it up with a hobby knife.



Now get out your PETG and electrical tape. Wrap the tape around the end of the barrel 1 1/2 times.
You can glue them in if you'd like, but I left mine with the option to remove them later if they break. Make a barrel spacer or two if you have the materials.





This step might be unnecessary, but I figure it couldn't hurt. I filled the little dimples between the barrels with hot glue. Load your barrels with darts and glue away.



Let it dry and clean it up with a hobby knife.



You also do it with epoxy putty, but I didn't have any on hand.

Now it's time to modify the airtank. The airtank is huge, slightly bigger than the 3k and almost twice as big as a 2k tank. Cut off the puny nub.
I also cut off the plastic piece that was used for the existing auto-rotation mechanism for a later step in the modification.



Now you'll need a 1 3/8" OD x 1/2" x 1/8" rubber washer, and metal washer of the same size. Essentially, a +bow washer.
You'll have to cut off the bottom portion of the rubber washer in order for it to fit in the shell. It should look like this.



Glue the trigger spring. This will help the air release faster and give you a much better trigger feel.
The 4k's trigger is made of thick, sturdy plastic, so you don't have to worry about it breaking.



Now it's time to put the turret and airtank back together. I added a new spring for the rotation mechanism, along with replacing the white cap that went on end of the rotation mech.
I replaced it with a random metal washer I found in my garage. Anything will work as long as it keeps to spring from moving out of place.



================================================================

End of Part One, Picture Limit - Do not reply

Edited by Ryan201821, 26 November 2009 - 03:40 AM.

[Ryan201821]

Assemble the airtank, turret, and rotation mechanism before putting it all back into the shell. Next thing to do is secure the pin attached to the top half of the rotation mech.
You can do this anyway you'd like. I used the original piece of plastic from the blaster, as shown in the picture above. Hot glue/epoxy putty the shit out of it until it's secure.
Make sure your barrels line up with the rotation mechansim before you glue it all down.

Now it's time to replace the pump. The original stock pump blows. It's too small and has a large diameter making it difficult to acheive high pressures in the airtank.
I chose to replace it with a 1500 pump. It's the only pump I had that was skinny enough to fit in the shell with minor modifications. First you'll have to dremel down these parts on both sides.





Now take a piece of 3/4" PVC the length of the stock pump. Wrap the 1500 pump 4 times with electrical tape in several places and glue the PVC over it.
Wrap electrical tape five times around the outside of the 3/4" PVC to fill the gap for the trigger.
Pictures to help explain.





Instead of using an actual 1500 pump, I used a 2k pump in a 1500 pump tube. You'll have to modify this to fit

Cut the shell so you'll be able to have a longer pump stroke. Do this on both sides.





Dremel the pump handle to increase the pump stroke going the other way.



You will also have to cut off the trigger guard since it will be in the way now.



Almost done. All you have left to do is cut the rear-loading slot, and put everything back together.









=========================================================================

Final thoughts and comments:

The 2k pump wasn't the best idea. I have to pump it at least 10 times to get decent pressures.
Even though I incresed the pump stroke, it's still relatively short and I can only get 3/4 of a full pump. I also hate the original pump handle.
It's too short and small for a normal person's hands. It makes pumping very cumbersome.

With 12 pumps, I'm easily breaking 100'. From my side garage door to the tree across the street it's 112' and darts are smashing into it.
When I replace the pump again, I should only have to pump it eight times or so to get comparable results.

I'm very happy the way it turned out. Should be an awesome primary.


Enjoy!


Also, If you have a Hornet pump, I'm looking to buy one. Please pm me.

Edited by Ryan201821, 06 November 2009 - 06:34 PM.

[white moonlight]

Why am I not surprised.
As always awesome gun, and the spacers look sweet.
How may effective rear loading holes are there 3 or 4 I can't tell from the picture.

12 pumps isn't bad especially when the range and the fact that it's a turreted gun make up for it.

Edited by white moonlight, 05 November 2009 - 06:21 PM.

[JATDO]

I love you...
You are amazing with these air guns. I had no clue the 4k had this much potential.
When you changed the pump you lost the auto rotation right? Just like the 3k when you change the pump you loose the auto rotating.
But still AMAZING work.

[Ryan201821]

Yeah I got rid of the auto-rotation mechanism. It would have been more work than it's worth to get everything to work.

There is three good rear-loading slots. I'm going to make a spacer with dart slots later so it will be easier to load.

[TantumBull]

I like it, but I prefer auto-rotation over rear-loading. As someone stated you do lose the auto-rotation. If you value this over rear-loading, then I recommend this mod, which can be easily adapted to a 4k. I'll be updating that thread soon with a fix to that piece that broke at the end.

Anyway, I do like how you executed your mod to incorporate rear-loading. Like I said, it boils down to preference. I suppose with my way you would also be stuck with the stock pump. So yeah, this definitely has some major upsides.

[oh1134]

That is really cool. The only thing I would have done differently was to replace the pump with a dual action pump to cut on pumping time. By the way, you have 999 posts, so you may want to do an awesome post soon.

[jubjub517]

Damn it Ryan, you beat me. I guess I'll just have to think of something else to do with it, that is if there's anything left for me to do. Did you have to strengthen the trigger spring? I found on mine that it was too weak to close the air tank, it was Stock too.

Btw, this is my all time favorite gun. Glad to see someone make this gun worthy of a war.

[Kid Flash]

I might have to do this since I have a stock 4k with a broken rotation.

[Hi Yah]

Great work as usual. I definitely think the at4k is an underestimated gun. Nice mod.

[Samzilla]

Wow you seem to be juicing all the power you can get out of all your guns and recently your air tech gun! Maybe youll optimize a at1k next week. Instead of replacing it with a hornet pump why not a magstrike pump. I think they have the same diameter but the magstrike pump is longer.

Edited by Samzilla, 05 November 2009 - 07:13 PM.

[dizzyduck]

Instead of replacing it with a hornet pump why not a magstrike pump. I think they have the same diameter but the magstrike pump is longer.

I was actually about to suggest this. In terms of pressurization, the Magstrike pump offers the most bang for your buck.

[Ryan201821]

I could use a Magstrike pump. I might as well just use the RF20 pump I have, but I'll probably end up using a Hornet pump. I guess it just depends on what I can get my hands on.

Did you have to strengthen the trigger spring? I found on mine that it was too weak to close the air tank, it was Stock too.

No, the stock spring is still in there. I'm not having any issues with the trigger.

[Nerf Bros]

Crap, another amazing weapon for you to shoot at me with.... Nice job though, extremely clean!

[L3G10N]

Ryan this is getting ridiculous.

I love this and if you could get your pump count down just a bit it would be absolutely unstoppable.

Your fantastic.

You've created some of the greatest air guns know to this forum. It's like you feed your guns steroids.

[eliman]

wow. Just wow.

[Daniel Beaver]

The AT4k pump handle really is just... terrible. The pump replacement significantly increased the ergonomics of the AT3k, and I think you owe it to yourself to put a hornet pump in there, if only just for the new handle. Besides, 10 pumps to get it up to pressure seems like it would be problematic in a war setting.

Finally the AT4k gets the beastly overhaul it deserves. I look forward to getting shot by it.
...
...on second though, maybe not...

[dubcwill]

As the SM3K is very similar to the AT4K, this could be possibly be done on the 3K, right?

[Ryan201821]

As the SM3K is very similar to the AT4K, this could be possibly be done on the 3K, right?

Already working on it.

[dubcwill]

As the SM3K is very similar to the AT4K, this could be possibly be done on the 3K, right?

Already working on it.

Alright!

[Draconis]

As the SM3K is very similar to the AT4K, this could be possibly be done on the 3K, right?

Already working on it.

OMG. Go get a job, dammit. Yer making the rest of us look lame. Sad to see the autorotate go, though. Seems like it would be easier to ensure that your barrel is lined up correctly before you shoot.

[Zorns Lemma]

Like I said, it boils down to preference.

You must be into some kinky shit because ramrodding that many barrels to gain an extra .5s on the rotation (you still have to pump more than once) is pretty masochistic.

[faddle]

Ryan you did an awesome job, especially with the barrel. Although I think the pump is terrible you did a good job.

[NerfRogue83]

Outstanding as always Mr.Mcnumbers! That blaster will certainly get +3 intimidation points on the field during play. The barrel spacers look perfect too.---Rogue.

[TantumBull]

Like I said, it boils down to preference.

You must be into some kinky shit because ramrodding that many barrels to gain an extra .5s on the rotation (you still have to pump more than once) is pretty masochistic.

I never said anything about ramrodding. I blow my darts down PETG.