Jump to content

Recommended Posts

After getting my S12 up and running, which took some time, my confidence level in tinkering had grown significantly - removing gas block, enlarging ports, increase barral hood size, feed ramp mods ect made me feel like I could do just about any mod I wanted. The one that felt too complicated was the left side charging handle, which, after much thought, I just went for. I had some help from my buddy with the right tools, and here is how it went:

 

First, I bought a Tapco piston rod from CSS for like 11 bucks:

 

camera1784.jpg

 

Uploaded with ImageShack.us

 

I cut the threaded side off with the dremel:

 

camera1786.jpg

 

Uploaded with ImageShack.us

 

After setting it against the carrier, it looked like it was too big around, and welding would get in the way of the action:

camera1789.jpg

 

Uploaded with ImageShack.us

 

 

 

 

so I wanted to make it smaller. At this point I was intent on doing the whole thing in my basement (ie minimal tools), other than some quick welding, so I put the cut rod in the cordless drill and took it to the grinder:

 

camera1792.jpg

 

Uploaded with ImageShack.us

 

 

 

 

I tested it on the long side I would clearly not be using, and had the drill turning the opposite direction of the grinder, and turned it down pretty quickly to this:

 

camera1797.jpg

 

Uploaded with ImageShack.us

 

 

 

 

I realized that it would be short from the piston head to the carrier, and the taper would increase the size and deafeat the purpose of turning down in the first place, and the grinder would not get detail enough to remove it, so I busted out the dremel again to remove the transition:

 

camera1798.jpg

 

Uploaded with ImageShack.us

 

 

I ended the night with what I figured would be the finished handle:

 

camera1801.jpg

 

Uploaded with ImageShack.us

 

 

The next day I wanted to take the new handle with the gun to my buddy, just to see how much room he needed to weld, should I chamfer(?) and basically get the piece ready for him to weld. He was pretty stoked on the idea and dove right into helping me bust it out right then and there. His primary concern was having a strong enough weld to hold it on, and it was determined that drilling a hole in the carrier would provide extra strength and relieve some of the recoil forces from the weld, so he measured my work from last night and took a carbide bit on the drill press and drilled a 1/4 inch hole into the carrier:

 

camera1857.jpg

 

Uploaded with ImageShack.us

 

camera1858.jpg

 

Uploaded with ImageShack.us

 

 

A quick cut and the handle fit right in:

 

camera1860.jpg

 

Uploaded with ImageShack.us

 

 

Then it was determined that a silver braze would be better suited than weld, which we did next:

 

camera1862.jpg

 

Uploaded with ImageShack.us

 

Then cooled it off at the water fountain:

 

camera1864.jpg

 

Uploaded with ImageShack.us

 

 

It fit pretty well right away, I have some filing to do, but relatively clean install:

 

camera1865.jpg

 

Uploaded with ImageShack.us

 

 

 

Then it was time for the top cover, which I intended to do with a dremel/file, since it was tough thinking how to support in the mill. My buddy kept it simple, and put a long socket inside and clamped from there - you can see it in this pic:

camera1868.jpg

 

Uploaded with ImageShack.us

 

a couple of passes and it was set! We eyeballed the length and it came out sweet:

 

camera1869.jpg

 

Uploaded with ImageShack.us

 

Overall time was about 2 hours, difficulty level I would say 6 out of 10. Drill/Mill was absolutely priceless in making it easy, cobalt bit to drill the carrier was crucial. Overall cost was $11 and a 12 pack. Can't wait to get this out for a test run!

post-21036-035617200 1281724647_thumb.jpg

post-21036-015256300 1281724750_thumb.jpg

Edited by negev5021
  • Like 7

Share this post


Link to post
Share on other sites

I'd like to hear how the silver is holding up to the recoil as opposed to a weld, though I'm sure the slot drilled into the carrier will help.

  • Like 1

Share this post


Link to post
Share on other sites

Do you mind uploading the pics to the forum instead of using imageshack?

 

 

Not quite sure how to do that, but I will try here. After getting home and playing around with the conversion I noticed that the top cover was not milled out enough. The action would cycle, and I could get to BHO, but when releasing the BHO it moved further back than the cover would allow, and I could see the cover moving. So I had to open it up all little more with the bench grinder. What I would suggest is after you get the handle on, pull the bolt all the way back, till it hits the rear trunion, and mark it:

 

post-21036-045186000 1281724311_thumb.jpg

 

 

Then when you put the top cover back on you can see how far you have to go:

 

post-21036-064513100 1281724355_thumb.jpg

 

I will try to upload photos direct on the first post Nailbomb, I think I got it now.

Edited by negev5021

Share this post


Link to post
Share on other sites

Nice, let us know how the silver solder holds up.

In this application I wouldn't be worried.

 

What is the tensile strength of a brazed joint?

Joint strength depends on several factors: clearance between parts, base metal composition, service temperature and joint quality (low voids, good penetration). Joint design will also affect strength.

 

The bulk tensile strength of silver braze alloys is 40,000-70,000 psi. When brazing copper-based alloys, failure will occur in the copper or brass. For copper this is usually the annealed strength of the copper alloy. When brazing steel or other ferrous metals, joint strength over 70,000 psi can be achieved under the right conditions.

 

Keep in mind that braze joints are primarily lap type joints, so strength is a combination of tensile and shear. Joint strength is directly influenced by the above mentioned factors. The only way to accurately determine tensile or other values is to test the brazed assembly.

 

being that side stress is the major factor in this case, and he counter sunk the welded joint(ie: drilled) I wouldn't be worried in the least. If properly braised it will last longer than his grandkids.

Share this post


Link to post
Share on other sites

Range Report:

 

Silver braze lasted approx. 50 rounds, and flew off and smacked me in the face! Bummer, but better now than match day this weekend. Back to the drawing board... any idea on the best weld/attachment method?

Share this post


Link to post
Share on other sites

TIG would be stronger than silver solder.

 

Just out of curosity, did you use use flux when you braised? Stainless to mild steel is a bi-metal joint and you probably need the flux to help it flow.

Share this post


Link to post
Share on other sites

Range Report:

 

Silver braze lasted approx. 50 rounds, and flew off and smacked me in the face! Bummer, but better now than match day this weekend. Back to the drawing board... any idea on the best weld/attachment method?

 

Tap the hole, thread the new handle, screw it in, then weld it.

Best solution I can think of at the moment.

  • Like 1

Share this post


Link to post
Share on other sites

Not sure about the threading thing, as the hole is drilled, and larger than the part that goes in there. Perhaps a new handle?

 

I took it back to the dude who did the brazing, and he had his dad do it this time. I was sceptical about doing the same thing twice, but being totally unknowledgable of the issue, I bit my tongue and let the guy go. He appeared to do it differently in that he brazed a bit, then took a wrench and turned the handle to apparently work the braze into the hole.

 

Here is a pic of the broken unit:post-21036-052594500 1282146804_thumb.jpg

 

You can kinda see that the braze was just on top of the seam, leaving a ring around it, but not down the hole.

 

I sure hope it works! I was also hoping he would TIG weld the thing really bomber, but in hindsight, there is little room for a seam around the handle without hitting the reciever on the bottom, the top cover on the top (easy enough fix), or the trunion in the front that would prohibit lock up, so if they think this will hold up, we shall see. Tough part is I won't be testing prior to 3 gun this weekend, so flyin blind!

Share this post


Link to post
Share on other sites

Yea if you did thread it you would have to make a new handle, but I would trust it more than brazing or welding alone.

Share this post


Link to post
Share on other sites

All I can say is this is a great idea to do-

 

While threading would help I am not sure its possible on a hardened bolt.

 

Mig or TIG would work but I bet the hole would have to be bigger to fill with metal and stay out of the way of the cover and receiver.

 

 

Share this post


Link to post
Share on other sites

I actually used a piston for my left side handle. I just cut it to length and tig'd it on in the same spot you drilled and torch welded.

 

Mine works fine.

 

I think you turned it too thin, and the heat from the torch weakened it further.

 

 

Edit: Sorry, I reread the whole thread and realized the shaft didn't snap.

 

If you TIG the handle on with a good weld, you can grind off any excess to clear the trunnion and the receiver without compromising anything. You may not even need to bevel/fill the handle at the joint, although that makes for a larger contact if you're worried.

 

Again, mine works fine.

Edited by Heath_h49008

Share this post


Link to post
Share on other sites

Well, shot the match last weekend and everything held up, so I am feeling better about the 2nd braze. Time will tell -

 

I did have a few FTF again which is getting pretty old... but clearing them was much easier with the charging handle on the left. One day this thing is gonna work 100% -

Share this post


Link to post
Share on other sites

If you mill the bolt down about an 1/8" around the hole you drilled and Tig weld it. Its not coming of without a fight

Share this post


Link to post
Share on other sites

There is ONE THING I saw nobody mentioned here. I suspect what cause this failure was the rapid cooling of the braze under water, cause the steel to become brittle. I have done my own charging handle and used tig to weld them. The procedure I used is as follows:

 

Charging handle material: 304ss

 

Tig rod : 1/8 309ss

No preheating required unless ambient tempature is under 60 f

 

(though this is debateble as some say the carrier on the s12 is chrome/molly which should be preheated, and heat treated after welding)

 

I personaly don't prefer to heat treat machined parts unless absoultely nessesary as they tend to warp.

 

I DO recomend slow cooling your welded product by means of wrapping in insulation and letting cool to ambient tempature.

 

I did not do a Left side handle I did a right upswept but reguardless of that you would be better to countersing a slight indentaion and bevel your handle piece to get a better penetrating weld.

post-32655-0-68608800-1306693032_thumb.jpg

post-32655-0-77404100-1306693057_thumb.jpg

post-32655-0-49765000-1306693177_thumb.jpg

post-32655-0-10264700-1306693204_thumb.jpg

post-32655-0-72478200-1306693275_thumb.jpg

  • Like 1

Share this post


Link to post
Share on other sites

Drilling and tapping the carrier, and threading your piston rod shank is probably the best method, but I wouldn't even weld it. You can roll pin it so it's removeable. Similar to the rivet holding an AK piston assy into the carrier. Look at the pic in post #9. You can drill straight down through the carrier, and install a roll pin to prevent the handle from the threads backing out. That way if you ever do want to change it, you can fairly easily. Just my 2 cents.

Share this post


Link to post
Share on other sites

Drilling and tapping the carrier, and threading your piston rod shank is probably the best method, but I wouldn't even weld it. You can roll pin it so it's removeable. Similar to the rivet holding an AK piston assy into the carrier. Look at the pic in post #9. You can drill straight down through the carrier, and install a roll pin to prevent the handle from the threads backing out. That way if you ever do want to change it, you can fairly easily. Just my 2 cents.

I see two problems with drilling and taping like this: 1) Just like the op rod..over time it will wear and begin to wobble, and removing a tapped bolt that's been "set" isn't easy. It tends to eat up threads and gald, especally on stainless type alloys. 2) If you wish to change it or go back, now you have a hole to fill with, with what exactly? If you had a weld on handle you just chop it off with a saw, whip out the grinder, flapper wheel or file and feather it in....it'll look like it was never even there. Most importanly about welding is it's permanet and STRONG with ZERO possiblty for wobble or wear, if done correctly. Not trying to argue, but you might want to ask yourself "why don't the pros ever do this?" If it's so much better. Just my opinon.

Edited by poolingmyignorance

Share this post


Link to post
Share on other sites

Yes on a butt weld (stringer) for a pipe you need to purge, but not for a structural weld, the gas shield from the nozzle is sufficient in most cases.Especially if you cheat like I do and use an oxygen regulator, and really crank up the flow. You can have a fan blowing right on ya while ya weld and you wont' have to worry about porocity. And typically you use the same gas that your welding with, which never in my experience has been Co2.

Share this post


Link to post
Share on other sites

Nicely laid out sir. I love the idea of an ambidextrous charging handle design. Keep up the good work

Share this post


Link to post
Share on other sites

I vote for drilling and threading. So here is my way:

1.1" or 1.25" or 1.5" steel shoulder bolt (screw) 5/16"-18, shoulder 3/8". get any size you like.

2. Drill bit 17/64" Cobalt

3. 5/16"-18 tap set of 3 ( tapper, plug, bottom)

4. Red thread locker or any high strength epoxy.

5. My experience in metalworking.

6. I have the multi process welding machine but I prefer a simple way.

 

DSCN3791.JPG

ttfo1qyh9yw4v93tq8tr.jpg

Edited by MonaDeRio

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Tromix - Lead Delivery Systems
Dinzag Arms
CHAOS, Inc
Mississippi Auto Arms, Inc
Cobra's Custom
Carolina Shooters Supply
R & R Targets
LONE STAR ARMS
SGM Tactical
Mach 1 Arsenal
K-VAR
C&S Metall-Werkes
American Specialty Ammo
Csspecs Magazines
Phoenix Technology
Evlutionz LLC


  • Chatbox

    Load More
    You don't have permission to chat.
×