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unclemoak
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Posted: 2/8/2010 10:13:24 AM
[Last Edit: 4/9/2011 10:15:31 PM 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.
"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
Gardner
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Posted: 2/8/2010 10:17:15 AM
I hate you.
Jeep297
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Posted: 2/8/2010 10:20:40 AM
As always, I look forward to your threads. Sounds like an awesome build and challenging undertaking. Thanks for always sharing such interesting/detailed info.
RussellAthletic
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Posted: 2/8/2010 10:23:07 AM
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.
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candyflip
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Posted: 2/8/2010 10:26:17 AM
JV3
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Posted: 2/8/2010 10:31:00 AM


but the catch is it's probably always out of stock.
unclemoak
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Posted: 2/8/2010 10:31:28 AM
[Last Edit: 2/8/2010 10:32:50 AM 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.
"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
Remman
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Posted: 2/8/2010 10:57:15 AM
I always love your posts.
“To preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them.” Founding Father Richard Henry Lee
Falar
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Posted: 2/8/2010 10:58:15 AM
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?
j_king
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Posted: 2/8/2010 10:59:07 AM
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.
unclemoak
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Posted: 2/8/2010 11:08:29 AM

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.



"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
Falar
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Posted: 2/8/2010 11:18:45 AM
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.

matt58
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Posted: 2/8/2010 2:47:50 PM
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 :(
matt58
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Posted: 2/8/2010 2:50:01 PM
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




StreetSpeed
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Posted: 2/8/2010 2:51:54 PM
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...
98snakebite
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Posted: 2/8/2010 3:24:38 PM
Every rapid prototype I've seen is an odd plastic/polymer material.
RussellAthletic
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Posted: 2/8/2010 3:32:21 PM
Originally Posted By 98snakebite:
Every rapid prototype I've seen is an odd plastic/polymer material.


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

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.
"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
LockingBlock
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Posted: 2/8/2010 3:56:46 PM
Make two...I'll buy the second one off you
unclemoak
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Posted: 2/8/2010 4:15:47 PM
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











"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
unclemoak
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Posted: 2/8/2010 4:24:04 PM

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.
"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
98snakebite
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Posted: 2/8/2010 4:25:48 PM
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.
unclemoak
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Posted: 2/8/2010 4:28:35 PM

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.
"Now see, I just respond to this sort of stuff by striking the keyboard repeatedly with my genitals and hollering really loud." - Swindle1984
LockingBlock
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Posted: 2/8/2010 4:33:10 PM
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
mdguy90
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Posted: 2/8/2010 5:29:53 PM
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1iviper
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Posted: 2/8/2010 5:51:32 PM
very nice

i will be keeping a close eye on this thread.

that's gonna be one sweet upper when your done
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