another hdd post

bdb12586 · May 07, 2011, 02:39:08 AM

Ok on one of the posts about hdd building and materials somebody said they put a piece of tubing in there hammer spring as an hdd and it was working for them. I never gave it to much thought but since I had my gun apart to install slightly stronger valve spring( I was running a real light one and wanted a few more shots) I decided to put a piece of fishtank air tube 15/16â€ in the hammer spring. The gun cocked as smooth as always couldnâ€™t even tell it was in there. I put it a cartridge and it pierced it no problem but after every shot I got a little psst out of the barrel, a little co2 leaking. I should also say the gun was a lot quieter. So I removed the tube and everything is right back to normal. Anyway what Iâ€™m getting at is I still have a light spring in my valve and am going to try to shorted my poly tube a little at a time and see how I make out. I was hoping some other people here might try it and see what results they get. I know at first glance it wouldnâ€™t seem the tube would work but as the spring recoils it will vibrate causing the spring to bend slightly and grab the tube. I think. Any thoughts

NorthStaR · May 07, 2011, 02:52:00 AM

Sounds good. I've got some of that tube. I presume its the same as what would be on an air pump and stone or skimmer?
Surgical silicon tube. I'll give it a go over the weekend.

bdb12586 · May 07, 2011, 02:54:05 AM

cool let us know how it works for you.

NorthStaR · May 07, 2011, 03:01:20 AM

BTW what length in 'mm' did you cut? Sorry imperial metric - I just don't understand inches!

arkmaker † · May 07, 2011, 03:03:24 AM

The gas leak doesn;t sound promising. It did quiet it down though??
Rich

NorthStaR · May 07, 2011, 03:05:35 AM

Maybe it was a bit too long. Plus the light spring.

bdb12586 · May 07, 2011, 04:00:26 AM

Quote from: NorthStaR on May 07, 2011, 03:01:20 AM
BTW what length in 'mm' did you cut? Sorry imperial metric - I just don't understand inches!

if I did it right it comes to 23.8mm. basically you want it as long as you can and still cock it.

bdb12586 · May 07, 2011, 04:06:29 AM

well I just changed the spring again after trying different lenth tubes. I went back to the original spring and the 15/16" poly tube. the good news is it sounds quieter and it doesn't leak, the bad news is I had shortened the piering valve so it took about 10 shots to pierce the tube. hopefully tomorrow I'll get to do some shot counts with and with out to see how it works, because I changed springs I have no start cpount so I have to work backwards starting with it installed and then taking it out

Toolmaker · May 07, 2011, 04:21:31 AM

Hmmm, I've heard of putting a piece of tubing over the exhaust stem but not in the hammer spring. Let us know how it works out!

quickster47 † · May 07, 2011, 04:30:28 AM

Quote from: bdb12586 on May 07, 2011, 04:06:29 AM
well I just changed the spring again after trying different lenth tubes. I went back to the original spring and the 15/16" poly tube. the good news is it sounds quieter and it doesn't leak, the bad news is I had shortened the piering valve so it took about 10 shots to pierce the tube. hopefully tomorrow I'll get to do some shot counts with and with out to see how it works, because I changed springs I have no start cpount so I have to work backwards starting with it installed and then taking it out.

Do you really mean 15/16"? That is nearly 1". Is that the OD or is that the length?

Carl

bdb12586 · May 07, 2011, 04:35:45 AM

thats the length

quickster47 † · May 07, 2011, 04:38:35 AM

Thank you. Now that makes more sense. Do you think the length is critical to the proper operation?

Carl

bdb12586 · May 07, 2011, 04:41:48 AM

well I can tell you I shortened the first one I did and it still leaked. I figure the more area covered the better it may work. I also thought position would matter but it always seems to work it's way to the middle of the spring

tatsumi · May 07, 2011, 01:20:28 PM

Hi, was me with the tube. You want it around 6mm, any longer and it messes with the spring I found, also fit it in the rear of the spring and I kept my brass guide in the hammer side of the spring.
My xt has power hammer spring and no valve work as yet. On my as2250xt page I posted results from before and after.
Hope that helps,
Ian

arkmaker † · May 07, 2011, 01:36:35 PM

A little more research found that this is basically one of the tricks used on springers to quiet them down. From what I have read, the spring uses a guide and you use shink wrap around the guide, then slather everything with tar grease.

So, on a 2240, if you have a power adjuster with a guide in yhe spring. You make the guide diameter small enough to fit on a piece of the shrink wrap and just short of the compressed spring length. Slap some moly on and you have the same effect and do not need to worry about the polytube binding.

This link explains it better than me;
http://www.eairgun.org.uk/use-of-shrink-on.html

Rich