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Posted: 2/8/2010 10:13:24 AM EDT
[Last Edit: 4/9/2011 10:15:31 PM EDT by unclemoak]
I decided I wanted to build my new sbr upper with a Knight's URX II, I went into it knowing I was either going to have to have it installed by a dealer or make my own wrench for it because Knight's uses a propietary barrel nut, the wrench for which, they don't sell to civilians. Now since I'm a pretty handy person and work in a machine shop, I don't think the task of making my own wrench will be that awfully hard, so this thread sets out to show you how an average guy can successfully (hopefully) install a URX II.

The specs for the upper are as follows:

Barrel - Noveske Crusader 12.5" in 5.56
Receiver - Larue Stealth
Rail - Knights URX II Midlength
Muzzle Device - Knight's Triple Tap
BCG - Denny's Super Duty M16



I'll upload the pictures later on when I get home from work.

The first thing I had to do was get the barrel nut on the barrel. Since Noveske ships their barrels with the gas block already installed, I had to carefully remove it before I could slide on the barrel nut. After I had the barrel nut on, I took some rough dimensions from it to get working on the CAD model of my wrench design. I found that the nut had 11 notches in it, each notch having a radius of about .185".

One thing that needs to be taken into account when designing the wrench is that there's not much space for the wrench to fit into the cavity of the rail.

Here's the basic design that I'm going to rapid prototype first to make sure it fits, then machine/waterjet/whatever it for the final piece.


More updates will come as I have more time to work on it.
Link Posted: 2/8/2010 10:17:15 AM EDT
I hate you.
Link Posted: 2/8/2010 10:20:40 AM EDT
As always, I look forward to your threads. Sounds like an awesome build and challenging undertaking. Thanks for always sharing such interesting/detailed info.
Link Posted: 2/8/2010 10:23:07 AM EDT
I'm definitely in for more info. This could make or break my URX purchase and allow more people to successfully install/adjust their URX.
Link Posted: 2/8/2010 10:26:17 AM EDT
Link Posted: 2/8/2010 10:31:00 AM EDT


but the catch is it's probably always out of stock.
Link Posted: 2/8/2010 10:31:28 AM EDT
[Last Edit: 2/8/2010 10:32:50 AM EDT by unclemoak]



Yes. I know you can get one. I'm just too cheap to shell out $260 for a wrench I'm going to use once, maybe twice. Since I have access to all sorts of machines I might as well learn a thing or two and make my own.


Originally Posted By JV3:


but the catch is it's probably always out of stock.

They had two in stock over the last two weeks or so. But they rarely have them as I'm sure KAC doesn't let too many of those go out their doors.
Link Posted: 2/8/2010 10:57:15 AM EDT
I always love your posts.
Link Posted: 2/8/2010 10:58:15 AM EDT
Originally Posted By unclemoak:



Yes. I know you can get one. I'm just too cheap to shell out $260 for a wrench I'm going to use once, maybe twice. Since I have access to all sorts of machines I might as well learn a thing or two and make my own.


Originally Posted By JV3:


but the catch is it's probably always out of stock.

They had two in stock over the last two weeks or so. But they rarely have them as I'm sure KAC doesn't let too many of those go out their doors.



Exactly, at that price they can keep it. I thought you also had to pay another 250 for the jaws to hold the URX in place also?

I want a URX II very badly, the integrated sight, heat shield, and removable bottom rail are winning features. If you get this to work do you think you could sell a few ont he side?
Link Posted: 2/8/2010 10:59:07 AM EDT
Originally Posted By unclemoak:



Yes. I know you can get one. I'm just too cheap to shell out $260 for a wrench I'm going to use once, maybe twice. Since I have access to all sorts of machines I might as well learn a thing or two and make my own.


I think anybody who WOULD pay that for a wrench is delusional.
Link Posted: 2/8/2010 11:08:29 AM EDT

Originally Posted By Falar:
Originally Posted By unclemoak:



Yes. I know you can get one. I'm just too cheap to shell out $260 for a wrench I'm going to use once, maybe twice. Since I have access to all sorts of machines I might as well learn a thing or two and make my own.


Originally Posted By JV3:


but the catch is it's probably always out of stock.

They had two in stock over the last two weeks or so. But they rarely have them as I'm sure KAC doesn't let too many of those go out their doors.



Exactly, at that price they can keep it. I thought you also had to pay another 250 for the jaws to hold the URX in place also?

I want a URX II very badly, the integrated sight, heat shield, and removable bottom rail are winning features. If you get this to work do you think you could sell a few ont he side?

To be quite honest with you, I don't even know how that URX clamp thinger is supposed to even work.




I'm planning on using one of these to span the receiver and rail while I'm tightening up the nut. It's a action block made by PRI that will either hold the bottom of the receiver, or span the top like I plan to do.



Link Posted: 2/8/2010 11:18:45 AM EDT
Originally Posted By j_king:
Originally Posted By unclemoak:



Yes. I know you can get one. I'm just too cheap to shell out $260 for a wrench I'm going to use once, maybe twice. Since I have access to all sorts of machines I might as well learn a thing or two and make my own.


I think anybody who WOULD pay that for a wrench is delusional.


If I was runnning a shop stocked and sold a lot of URX IIs (or selling URX II equipped custom uppers) I'd pay for it and charge 20 bucks for installs. I'm sure after a year or two it would pay for itself.

Link Posted: 2/8/2010 2:47:50 PM EDT
If it works, I have first dibs on renting it from you :) I have been getting prices for install on the URX's; $40-170 :(
Link Posted: 2/8/2010 2:50:01 PM EDT
When you look at the pic of the KAC rail block thingy, look at the lower left hand corner; the rail fits into that slot. The upper and rail go in that contraption, then put upside down in a vise so you can tighten the barrel nut. I have the instructions laying around here somewhere...

Originally Posted By unclemoak:

Originally Posted By Falar:
Originally Posted By unclemoak:



Yes. I know you can get one. I'm just too cheap to shell out $260 for a wrench I'm going to use once, maybe twice. Since I have access to all sorts of machines I might as well learn a thing or two and make my own.


Originally Posted By JV3:


but the catch is it's probably always out of stock.

They had two in stock over the last two weeks or so. But they rarely have them as I'm sure KAC doesn't let too many of those go out their doors.



Exactly, at that price they can keep it. I thought you also had to pay another 250 for the jaws to hold the URX in place also?

I want a URX II very badly, the integrated sight, heat shield, and removable bottom rail are winning features. If you get this to work do you think you could sell a few ont he side?

To be quite honest with you, I don't even know how that URX clamp thinger is supposed to even work.

http://www.operationparts.com/v/vspfiles/photos/22515-2.jpg


I'm planning on using one of these to span the receiver and rail while I'm tightening up the nut. It's a action block made by PRI that will either hold the bottom of the receiver, or span the top like I plan to do.
http://media.midwayusa.com/ProductImages/Large/878754.jpg




Link Posted: 2/8/2010 2:51:54 PM EDT
You don't think the rapid prototype would be strong enough for use as is? I thought perhaps you wouldn't need to make it out your metal of choice if you're only gonna use it once...
Link Posted: 2/8/2010 3:24:38 PM EDT
Every rapid prototype I've seen is an odd plastic/polymer material.
Link Posted: 2/8/2010 3:32:21 PM EDT
Originally Posted By 98snakebite:
Every rapid prototype I've seen is an odd plastic/polymer material.


Same here.
Link Posted: 2/8/2010 3:52:51 PM EDT

Originally Posted By StreetSpeed:
You don't think the rapid prototype would be strong enough for use as is? I thought perhaps you wouldn't need to make it out your metal of choice if you're only gonna use it once...

Won't nearly be strong enough. I have an FDM (fluid deposition modeling) rapid prototyper that makes the part out of ABS plastic. It can be used for non-structural parts, but nothing load bearing. I've used it before to make a race car intake manifold, but we had to press aluminum bushings on the ends to re-enforce it.
Link Posted: 2/8/2010 3:56:46 PM EDT
Make two...I'll buy the second one off you
Link Posted: 2/8/2010 4:15:47 PM EDT
Pictures as promised.

The proprietary barrel nut KAC uses.





Installed on the Noveske 12.5" barrel



I used gage pins to determine the size of notches in the barrel nut. I found that the .185" one was a pretty good fit.





What I got in the box from KAC. The Upper and lower portions of the rail, three rail covers, two screws to secure the bottom section to the top section of rail. (barrel nut not shown)

No instructions




Cool integrated flip up front sight







You can see two different sets of threads. The rail itself screws onto the receiver threads, then you slide the barrel into the rail, and the barrel nut threads into the rail forcing the barrel against the receiver. I was kind of curious how they did it, but after looking at it, understand how it works.









Rail Covers


Lower portion of the rail








heat shield with sweet KAC logos and whatnot








Where those screws thread into







Misc











Link Posted: 2/8/2010 4:24:04 PM EDT

Originally Posted By matt58:
When you look at the pic of the KAC rail block thingy, look at the lower left hand corner; the rail fits into that slot. The upper and rail go in that contraption, then put upside down in a vise so you can tighten the barrel nut. I have the instructions laying around here somewhere...

<snip>



That seems to be how it would appear to work. What I don't understand, is what all that extra shit (the faux rail portion) is for? The PRI one I have will do the same thing in terms of clamping both the upper and rail and doesn't cost $280.
Link Posted: 2/8/2010 4:25:48 PM EDT
Originally Posted By unclemoak:
...I've used it before to make a race car intake manifold, but we had to press aluminum bushings on the ends to re-enforce it...


Tell me more about this... I may need to IM you about an idea I have.
Link Posted: 2/8/2010 4:28:35 PM EDT

Originally Posted By 98snakebite:
Originally Posted By unclemoak:
...I've used it before to make a race car intake manifold, but we had to press aluminum bushings on the ends to re-enforce it...


Tell me more about this... I may need to IM you about an idea I have.

It was for a small open wheeled race car that uses a Honda CRF450 motor. If I remember, I'll get some pictures of the old intake tomorrow at work.
Link Posted: 2/8/2010 4:33:10 PM EDT
Originally Posted By unclemoak:

Originally Posted By matt58:
When you look at the pic of the KAC rail block thingy, look at the lower left hand corner; the rail fits into that slot. The upper and rail go in that contraption, then put upside down in a vise so you can tighten the barrel nut. I have the instructions laying around here somewhere...

<snip>



That seems to be how it would appear to work. What I don't understand, is what all that extra shit (the faux rail portion) is for? The PRI one I have will do the same thing in terms of clamping both the upper and rail and doesn't cost $280.


If I understand it correctly, the KAC block is also used to REMOVE the rail after install which is difficult as the rail is often attached to the receiver with Red LocTitie. You use the KAC block as a wrench...or maybe you use the receiver block as a wrench and put the KAC block in the vice. One or the other
Link Posted: 2/8/2010 5:29:53 PM EDT
tag
Link Posted: 2/8/2010 5:51:32 PM EDT
very nice

i will be keeping a close eye on this thread.

that's gonna be one sweet upper when your done
Link Posted: 2/8/2010 7:42:44 PM EDT
If I remember correctly, the first URX's had a ring nut of sorts that was threaded into the threads on the rail, then you threaded the assembly onto the receiver, then barrel and the KAC barrel nut. It took a while to get it right because you had to "time" the ring nut in the rail in order to get it as close as you could to the receiver and still have the top rails aligned. Thats when (i think) you had to use a barrel nut wrench that was really long; as long as the barrel. This new rail looks much simpler to install; if you have the right tools that is ;)
Link Posted: 2/8/2010 7:46:48 PM EDT
Link Posted: 2/8/2010 7:50:39 PM EDT
After re-examining the pics of the rail and barrel, I am left confused. How does the barrel fit flush against the receiver if the rail is screwed on to the receiver? How do you time the rail so the top rails align and there is minimal to no gap between rail and receiver? Do you have any pics of the barrel in the rail WITHOUT the barrel nut on? Thanks for the info and by the way, GREAT POST!
Link Posted: 2/8/2010 8:22:30 PM EDT
[Last Edit: 2/8/2010 8:27:13 PM EDT by unclemoak]

Originally Posted By matt58:
After re-examining the pics of the rail and barrel, I am left confused. How does the barrel fit flush against the receiver if the rail is screwed on to the receiver? How do you time the rail so the top rails align and there is minimal to no gap between rail and receiver? Do you have any pics of the barrel in the rail WITHOUT the barrel nut on? Thanks for the info and by the way, GREAT POST!

You time the top rail by using something like the PRI action block that holds both the receiver and the rail via the picatinny portion. To eliminate as much gap between the rail and the receiver, you just tighten it the whole way, then back off until the rails line up. Some places take the rail and machine off just enough so that when it is fully tightened against the receiver it lines up perfectly. I thought about doing this, but I didn't want to have to re-anodize the rail.

Here's what it looks like when you machine the back of the rail to eliminate the gap.



Here's what the gap typically looks like




This is how the rail works. The rail (red) threads on to the reciever threads (black). Then you slide the barrel (gray) in and it is held in place by the barrel nut (yellow), which also threads into the rail

Link Posted: 2/8/2010 8:33:38 PM EDT
[Last Edit: 2/8/2010 8:42:05 PM EDT by ch11x]
Unless something has changed, be aware that the heat shield may have to be trimmed at the barrel nut end for proper detent / lower rail seat. This is due to the newer style barrel nut dims vs. original steel.

Also, here is what I purchased to keep picatinny rail & receiver aligned...still haven't time to try it out:

YHM picatinny vice block.








Link Posted: 2/8/2010 9:23:44 PM EDT
Originally Posted By unclemoak:

Originally Posted By matt58:
After re-examining the pics of the rail and barrel, I am left confused. How does the barrel fit flush against the receiver if the rail is screwed on to the receiver? How do you time the rail so the top rails align and there is minimal to no gap between rail and receiver? Do you have any pics of the barrel in the rail WITHOUT the barrel nut on? Thanks for the info and by the way, GREAT POST!

You time the top rail by using something like the PRI action block that holds both the receiver and the rail via the picatinny portion. To eliminate as much gap between the rail and the receiver, you just tighten it the whole way, then back off until the rails line up. Some places take the rail and machine off just enough so that when it is fully tightened against the receiver it lines up perfectly. I thought about doing this, but I didn't want to have to re-anodize the rail.

Here's what it looks like when you machine the back of the rail to eliminate the gap.
http://photos.imageevent.com/smglee/mstn/huge/IMG_0102.jpg


Here's what the gap typically looks like
http://stickman.rainierarms.com/galleries/Magpul%204/IMGL2831-A-1024-Stick.jpg



This is how the rail works. The rail (red) threads on to the reciever threads (black). Then you slide the barrel (gray) in and it is held in place by the barrel nut (yellow), which also threads into the rail
http://i43.photobucket.com/albums/e398/unclemoak/rail.png


That summed it up perfectly for me. With the labor involved in installing this very tight and flush, I see now why some companies charge so much! Thanks a ton! That really helped me out!
Link Posted: 2/8/2010 9:33:55 PM EDT
[Last Edit: 2/8/2010 9:35:27 PM EDT by RussellAthletic]
Man the URX is so bad ass. I love the integral sight and the way the rail covers a SBR barrel. The price is just brutal. Where did you get yours?
Link Posted: 2/8/2010 9:39:27 PM EDT

Originally Posted By RussellAthletic:
Man the URX is so bad ass. I love the integral sight and the way the rail covers a SBR barrel. The price is just brutal. Where did you get yours?

I got mine straight from Lawmen's.
Link Posted: 2/8/2010 9:41:53 PM EDT
Originally Posted By RussellAthletic:
Man the URX is so bad ass. I love the integral sight and the way the rail covers a SBR barrel. The price is just brutal. Where did you get yours?


I'm right there with ya! For me, it is worth saving for a little while longer if I have too in order to afford. As far as price goes, the cheapest I found was at www.operationparts.com. $483 and some change for rifle length. And they had three in stock!
Link Posted: 2/8/2010 10:13:55 PM EDT
I've been wanting to built a rifle with one of those rails. I'm wanting to see where you go with the wrench you need to make.
Link Posted: 2/9/2010 12:39:57 AM EDT
Mine's at Lawmen's being installed now, but I'd love to buy a wrench from you if you make any extras.
Link Posted: 2/9/2010 6:05:45 PM EDT
So here's the rapid prototyping process. First you take a CAD model that I pictured earlier and save it as an .STL file, which basically triangulates all the features on the part and the file is basically all the vertices of those triangles.

Then you open the .STL file in the software for the FDM (type of rapid prototyper, short of Fluid Deposition Modeling) The software programs all the paths for each layer of material (the part is build layer by layer from top to bottom) The red in the picture represents the actual finished part, the grayish blue is support material that will later be removed.


Here you can see all the individual layers. I think there were something like 70 some in total, each about .001" thick.



Put a tray into the machine for it to build your part on


Press go


It does its thing for about 45 minutes



And when it's done, you have a freshly prototyped part out of ABS plastic





The black portion is the actual part. The brown stuff is a water soluble support material that is chipped off or you can put the part in an ultra-sonic bath to remove it.


I chipped it off because it wasn't that complex of geometry. Sometimes with intricate parts, you need to put them in the ultra-sonic bath.


Cleaned part, ready for fitting.






Fits on the nut like it's supposed to


Fits the torque wrench like it's supposed to




Does quite fit around the barrel and into the bottom of the rail





So I cut off the ends, so it engages 7 notches instead of 9 like I planned on.


And it fits pretty well




I made another one that was a little beefier, in hopes that when I make the steel version it will be plenty strong enough.

New one is on the left



New one is on the top



New one is on the left



New one is on the top



New one is on the bottom



Link Posted: 2/9/2010 6:05:51 PM EDT
[Last Edit: 2/9/2010 6:29:33 PM EDT by unclemoak]

Originally Posted By unclemoak:

Originally Posted By 98snakebite:
Originally Posted By unclemoak:
...I've used it before to make a race car intake manifold, but we had to press aluminum bushings on the ends to re-enforce it...


Tell me more about this... I may need to IM you about an idea I have.

It was for a small open wheeled race car that uses a Honda CRF450 motor. If I remember, I'll get some pictures of the old intake tomorrow at work.


Here is a picture of the intake that we made last year with the rapid prototyper.










Link Posted: 2/9/2010 6:14:40 PM EDT
Smart man with some smart toys to play with. Good job building the wrench!
Link Posted: 2/9/2010 6:19:55 PM EDT
So when can we buy them?
Link Posted: 2/9/2010 6:24:52 PM EDT
FSAE Car?
Link Posted: 2/9/2010 6:34:46 PM EDT
[Last Edit: 2/9/2010 6:36:24 PM EDT by LOMartin]
Very cool stuff.

Nice to see CAD being put to use on a DIY project like this.
Link Posted: 2/9/2010 6:56:19 PM EDT
How does the URX rail compare to the DD Lite rail?

Is it's main selling point the integrated features? Or is it weight? Strength? etc.
Link Posted: 2/9/2010 7:02:19 PM EDT
impressive work ! I whish I had your skills, and your machines ;) !
Link Posted: 2/9/2010 7:04:33 PM EDT
Originally Posted By hokeyplyr48:
How does the URX rail compare to the DD Lite rail?

Is it's main selling point the integrated features? Or is it weight? Strength? etc.


The URX main selling point is the brand name stamped on it.
Link Posted: 2/9/2010 7:10:33 PM EDT

Originally Posted By Jonny_Flashbang:
Originally Posted By hokeyplyr48:
How does the URX rail compare to the DD Lite rail?

Is it's main selling point the integrated features? Or is it weight? Strength? etc.


The URX main selling point is the brand name stamped on it.

I think the brand name, the integral front sight and sling mounts are all a big plus for the rail.

Link Posted: 2/9/2010 7:25:46 PM EDT
Slide the wrench further down the bbl where it is more tapered and then bring it back to the nut. As long as the bbl is small enough at some point behind the gas block you are all set.

One of the main features of this new wrench is being able to install a bbl. with the gas block allready installed.

We are working on a way to reduce the cost of the URX.

Nice job on your project. If you want to come down to Florida after you get done with school drop me a line.
Link Posted: 2/9/2010 7:48:53 PM EDT
[Last Edit: 2/14/2010 10:33:49 AM EDT by unclemoak]

Originally Posted By 030:
Slide the wrench further down the bbl where it is more tapered and then bring it back to the nut. As long as the bbl is small enough at some point behind the gas block you are all set.

One of the main features of this new wrench is being able to install a bbl. with the gas block allready installed.

We are working on a way to reduce the cost of the URX.

Nice job on your project. If you want to come down to Florida after you get done with school drop me a line.

Thanks Mr. Knight

I actually considered doing exactly what you mentioned, but the wrench wouldn't fit past the lugs along the sides of the opening on the bottom of the rail with the first wrench I prototyped today. For that matter, it was to big to even rotate around the inside of the rail to tighten the but. The second wrench I made today, I reduced the overall diameter of it so that it would do exactly what you are describing. So I suppose that I could at the two teeth back onto the wrench so that it would engage more teeth.
Link Posted: 2/9/2010 8:33:51 PM EDT
man, i wish i had the knowledge and access to the machinery you have. that is just amazing work! WOW!
Link Posted: 2/9/2010 8:43:31 PM EDT
Damn, pretty neat toy you got to play with there.
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