Going to use U Drive screws on a build - part numbers in this thread!

Nightman · 04-21-2007, 10:39 PM

Going to put a Romanian AK together with U drive screws that I read about on the AR forums ( Thread HERE ) They say they hold just fine. I figured I would add red Locktite for good measure. Looks like it will be a super easy build with no need for a $50 rivet tool

Here are the part numbers from McMaster-Carr :

Order Date 04/21/2007

Shipping Method
Ground
Shipment Details

Products
Quantity Part Number Description Unit Price Total Price

1 Pack 91654A190 18-8 Stainless Steel Easy-Drive Screw Nail No. 8 (.167" Dia) X 1/4" Length, Packs of 100 $4.43 $4.43

1 Pack 91654A192 18-8 Stainless Steel Easy-Drive Screw Nail No. 8 (.167" Dia) X 3/8" Length, Packs of 100 $4.79 $4.79

1 Pack 91654A240 18-8 Stainless Steel Easy-Drive Screw Nail No. 10 (.182" Dia) X 3/8" Length, Packs of 100 $6.25 $6.25

1 Pack 91654A291 18-8 Stainless Steel Easy-Drive Screw Nail No. 12 (.212" Dia) X 1/2" Length, Packs of 100 $8.80 $8.80

Merchandise $24.27

Applicable shipping charges and tax will be added.

So, what do you all think? I will post pics when I get 'r done, but it will be a couple weeks before that happens. I am not sure if the screws highlited in red are needed or not, but they are cheap enough, so might as well have them here if I need them.

chrry · 04-21-2007, 10:57 PM

You will still need rivits and or screws for the two lower trunion holes and the trigger guard. The No. 10s and 12s might have too large a head to look right. Good luck.

Nightman · 04-21-2007, 11:03 PM

Yep, I also picked up a rivet kit and a screw kit. I have all 3 options for assembly.

Nightman · 04-21-2007, 11:12 PM

I just searched and realized that there were LOTS of threads here about U Drive screws. Sorry about posting it again!

I see that people are worried about strength of U drive screws. I would imagine that the stainless ones would be plenty strong? Stainless metal is a B*tch to work with!

motorhead · 04-22-2007, 02:46 AM

there's been an ongoing debate about these, your poll pretty much reflects the opinions. the main concern is not the strength of the fastener, but pulling out of the trunnion. they do lack the clamping force of either screws or rivets. so far, no reports of loosening have turned up. let us know how yours works. BTW- i use screws, that'll start a whole different debate.

allesennogwat · 04-22-2007, 03:16 AM

Nightman · 04-22-2007, 03:36 AM

^
^^
^^^
^^^^
^^^^^
^
^

I figured the "It has worked for years with the original design" point of view would be expressed. I agree that the design is pretty much flawless, but there is always more than 1 way to skin a cat.

bobotech · 04-22-2007, 03:38 AM

The problem with u-drives is that they are a blind fastener with no retainer behind them. A screw build has the threads being a positive lock onto the trunnions, a rivet has the backside flange being a positive lock (sort of like a nut and bolt) however the u-drive only has a forced fit being a lock.

You could compare a u-drive to being similar to a screw build with MUCH coarser threads. The lazy spiral pattern on a u-drive is much less than the very tight spiral of threads on a screw. You could look at a 10-32 screw and compare it to being simliar to a screw of 10-5 with the only advange being that the 10-5 u-drive will force its way in to the hole.

Thats why I don't like the u-drives, they just don't seem to have the same clamping force as rivets or screws. They might be fine but I just would worry.

AKBuilder7255 · 04-22-2007, 01:40 PM

Hey Nightman, You said that you have three ways to assemble your Kit at your discretion? Trust me on this when I tell you my opinion; Rivet your kit, it is a lot, and I do mean alot easier, than going with the miticulous chore of drilling/reaming and tapping your front and rear trunnions for a screw assembly and then on final assembly making sure you get your #271 red- loctite where it belongs without getting any of it on your finished receiver/other parts, if you finished the receiver first of all. As far as the U-drive method, I wouldn't even consider it. I have done both screw and rivet methods with the more of my builds being on the screw built side and I tell you that Riveting is the only way to go for ease and simplicity. Screw builds (Semi-Auto only) will be as strong and as good by all means and last as long when done correctly, but IMHO, Rivets are the simplest and fastest way of assembly. I am a bonifide and very accomplished screw builder when it comes to assembling these kits in this method and I do believe "STRONGLY" that this method is a very good way to do these, especially your first one with a 100% receiver, leaving just about 0% chance of messing anything up, but ONCE you do (set) 1 rivet you'll say to yourself....Why in the hell didn't I do this from the very beginning. The trouble that most of us have or (had) is the intimidating factor of actually compressing this small medium steel fastener with some success. Simple solution: Just get in there,... and do it......piece of cake.....Good Luck, Nightman, on whatever method you decide to use. T.C. Ken in Pa.

Nightman · 04-22-2007, 01:58 PM

Thanks for that informative post, AKBuilder7255!

How would I compress the rivits without a rivet tool? Is there a way? THat is the main reason that I am looking at the U Drive screws. I don't really have the means to construct a modified bolt cutter, and I don't want to spend the $50 on a pre-made one until I am sure I will be building more than 2 rifles.

I have 2 flats and 1 80 bent receiver coming from akparts, and I ordered a 100% from NoDak. I have a romanian kit coming from akparts, and a romanian kit coming from ak47s.com.

So as you can see, I have 2 rifles to build. The 2 flats will sit at my place until it is my turn with the bending jig that is making its rounds on this forum. I think I am # 13 on the list to receive it.

KernelKrink · 04-22-2007, 11:14 PM

Quote:

Originally Posted by Nightman

I don't really have the means to construct a modified bolt cutter, and I don't want to spend the $50 on a pre-made one until I am sure I will be building more than 2 rifles.

You don't have a bench grinder or angle grinder? Most places that sell the cheap Chinese imported tools have small angle grinders for around $10. Not gonna last a lifetime, but more than adequate for modfying bolt cutters.

Nightman · 04-22-2007, 11:21 PM

Quote:

Originally Posted by KernelKrink

You don't have a bench grinder or angle grinder? Most places that sell the cheap Chinese imported tools have small angle grinders for around $10. Not gonna last a lifetime, but more than adequate for modfying bolt cutters.

So all I have to do is get a cheap pair of bolt cutters (I'm thinking Harbour Freight) and grind them flat? What about the divot for the rivet? How is that put in the cutters?

My next question would be where to get the rivets in bulk like the U drive screws? Anybody have part numbers?

KernelKrink · 04-22-2007, 11:37 PM

Yes, the first step is to pretty much grind the beveled cutter edges down flat. The divot is not normally put in the jaws, the original design uses a small steel plate placed on the outside of the receiver with the divot drilled into it. The boltcutters are then placed over the plate and inside the trunnion. The inner jaw is ground to clear the trunnion, but a small "tooth" is left on the end to compress the rivet down into the recess inside the trunnion. If you wanted to, you could divot the outside jaw itself ( I did) but the steel is so damn hard you will need a carbide ball shaped burr to cut into it. Do a search on boltcutter rivet tools and you should get lots of pics of the various ones people have made. On your divot, either style, just drill into the steel far enough for most of the pre-formed rivet head to seat within the divot. You want a small sliver of head to stay above the surface though, this supports the head but doesn't allow the steel to touch the receiver.

Bulk rivets are usually ordered from Centaur Forge or McMaster Carr. Do a search on rivets and you should get the part numbers you need.

AKBuilder7255 · 04-23-2007, 01:01 AM

+1 on what KernelKrink said....The Kernel summed it up in a nut-shell, per say. I couldn't even try to add to that if I tried. T.C. Ken in Pa.

Nightman · 04-23-2007, 07:10 AM

Wow KernelKrink, thats some great info! Thank you!

Nightman · 04-26-2007, 06:46 PM

Dear lord, did I waste money!

Popped some of these in just to try them out.

DEFINITELY NOT GOING TO WORK!

they had loosened themselves up before I got 4 of them in place. What a waste of $30. Well, lesson learned.

Anybody want to buy these fasteners off of me cheap? The whole lot of them for $15 shipped to your door. Not a joke, I will sell them to anyone who thinks they want to give them a try.

$15, going once.......

ronin · 04-26-2007, 07:09 PM

I'm just glad you found out *before* you shot with those udrive gadgets in place.

fxboom · 04-26-2007, 09:55 PM

Quote:

Originally Posted by Nightman

Dear lord, did I waste money!

Popped some of these in just to try them out.

DEFINITELY NOT GOING TO WORK!

they had loosened themselves up before I got 4 of them in place. What a waste of $30. Well, lesson learned.

Anybody want to buy these fasteners off of me cheap? The whole lot of them for $15 shipped to your door. Not a joke, I will sell them to anyone who thinks they want to give them a try.

$15, going once.......

Did you drill into the center of the old rivit and while the drilled out rivit was still there, using a press? the u-drives need to press the rivit against the trunion wall.
It's like filling the rivit again with steel and buldging.
if you drilled the rivit out completly the u-drive will not grab the trunion sidewall of the hole because of trunion hardness, and work themselves loose..you need the old rivit to act as a expansion piece compressing against the walls of the hole.

DutchV · 04-26-2007, 10:59 PM

There were a few threads recently on AR15.com where guys had built with U-drives and had them loosen up.

Not an easy thing to get right, apparently.

View Poll Results: What do you think of the U Drive screws?
Heck, I've been building with U Drive screws for a while now! Where have you been?	4	21.05%
I am definately going to try it!	2	10.53%
I might try it, we'll see.	2	10.53%
I won't try it EVER!	11	57.89%
Voters: 19. You may not vote on this poll

04-21-2007, 10:39 PM	#1
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	Going to use U Drive screws on a build - part numbers in this thread! Going to put a Romanian AK together with U drive screws that I read about on the AR forums ( Thread HERE ) They say they hold just fine. I figured I would add red Locktite for good measure. Looks like it will be a super easy build with no need for a $50 rivet tool Here are the part numbers from McMaster-Carr : Order Date 04/21/2007 Shipping Method Ground Shipment Details Products Quantity Part Number Description Unit Price Total Price 1 Pack 91654A190 18-8 Stainless Steel Easy-Drive Screw Nail No. 8 (.167" Dia) X 1/4" Length, Packs of 100 $4.43 $4.43 1 Pack 91654A192 18-8 Stainless Steel Easy-Drive Screw Nail No. 8 (.167" Dia) X 3/8" Length, Packs of 100 $4.79 $4.79 1 Pack 91654A240 18-8 Stainless Steel Easy-Drive Screw Nail No. 10 (.182" Dia) X 3/8" Length, Packs of 100 $6.25 $6.25 1 Pack 91654A291 18-8 Stainless Steel Easy-Drive Screw Nail No. 12 (.212" Dia) X 1/2" Length, Packs of 100 $8.80 $8.80 Merchandise $24.27 Applicable shipping charges and tax will be added. So, what do you all think? I will post pics when I get 'r done, but it will be a couple weeks before that happens. I am not sure if the screws highlited in red are needed or not, but they are cheap enough, so might as well have them here if I need them. Last edited by Nightman; 04-21-2007 at 10:45 PM.

04-22-2007, 03:16 AM	#6
allesennogwat Curio & Relic AKaholic #: 3738 Join Date: Apr 2005 Posts: 32,441	__________________ Daraclor: A brand of anti-malaria pills which we had to drink every week while on the border. Legend had it that these would make you turn yellow and that you wouldn't be able to tan.

04-26-2007, 10:59 PM	#19
DutchV Member AKaholic #: 7027 Join Date: Nov 2006 Posts: 113	There were a few threads recently on AR15.com where guys had built with U-drives and had them loosen up. Not an easy thing to get right, apparently. __________________ Making the bad man go away since 1982.

04-21-2007, 10:57 PM	#2
chrry Member AKaholic #: 5903 Join Date: May 2006 Location: NORTH TEXAS Posts: 459	You will still need rivits and or screws for the two lower trunion holes and the trigger guard. The No. 10s and 12s might have too large a head to look right. Good luck. __________________ New World Order Money----- AMMO!!!!!

04-21-2007, 11:03 PM	#3
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	Yep, I also picked up a rivet kit and a screw kit. I have all 3 options for assembly.

04-21-2007, 11:12 PM	#4
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	I just searched and realized that there were LOTS of threads here about U Drive screws. Sorry about posting it again! I see that people are worried about strength of U drive screws. I would imagine that the stainless ones would be plenty strong? Stainless metal is a B*tch to work with!

04-22-2007, 02:46 AM	#5
motorhead EVIL GENIUS AKaholic #: 6093 Join Date: Jun 2006 Location: peoples republik of kalifornia Posts: 14,187	there's been an ongoing debate about these, your poll pretty much reflects the opinions. the main concern is not the strength of the fastener, but pulling out of the trunnion. they do lack the clamping force of either screws or rivets. so far, no reports of loosening have turned up. let us know how yours works. BTW- i use screws, that'll start a whole different debate.

04-22-2007, 03:36 AM	#7
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	^ ^^ ^^^ ^^^^ ^^^^^ ^ ^ I figured the "It has worked for years with the original design" point of view would be expressed. I agree that the design is pretty much flawless, but there is always more than 1 way to skin a cat.

04-22-2007, 03:38 AM	#8
bobotech Member AKaholic #: 7703 Join Date: Feb 2007 Location: Spokane, WA Posts: 174	The problem with u-drives is that they are a blind fastener with no retainer behind them. A screw build has the threads being a positive lock onto the trunnions, a rivet has the backside flange being a positive lock (sort of like a nut and bolt) however the u-drive only has a forced fit being a lock. You could compare a u-drive to being similar to a screw build with MUCH coarser threads. The lazy spiral pattern on a u-drive is much less than the very tight spiral of threads on a screw. You could look at a 10-32 screw and compare it to being simliar to a screw of 10-5 with the only advange being that the 10-5 u-drive will force its way in to the hole. Thats why I don't like the u-drives, they just don't seem to have the same clamping force as rivets or screws. They might be fine but I just would worry.

04-22-2007, 01:40 PM	#9
AKBuilder7255 Veteran Member AKaholic #: 5400 Join Date: Feb 2006 Location: Erie, PA Posts: 1,403	Hey Nightman, You said that you have three ways to assemble your Kit at your discretion? Trust me on this when I tell you my opinion; Rivet your kit, it is a lot, and I do mean alot easier, than going with the miticulous chore of drilling/reaming and tapping your front and rear trunnions for a screw assembly and then on final assembly making sure you get your #271 red- loctite where it belongs without getting any of it on your finished receiver/other parts, if you finished the receiver first of all. As far as the U-drive method, I wouldn't even consider it. I have done both screw and rivet methods with the more of my builds being on the screw built side and I tell you that Riveting is the only way to go for ease and simplicity. Screw builds (Semi-Auto only) will be as strong and as good by all means and last as long when done correctly, but IMHO, Rivets are the simplest and fastest way of assembly. I am a bonifide and very accomplished screw builder when it comes to assembling these kits in this method and I do believe "STRONGLY" that this method is a very good way to do these, especially your first one with a 100% receiver, leaving just about 0% chance of messing anything up, but ONCE you do (set) 1 rivet you'll say to yourself....Why in the hell didn't I do this from the very beginning. The trouble that most of us have or (had) is the intimidating factor of actually compressing this small medium steel fastener with some success. Simple solution: Just get in there,... and do it......piece of cake.....Good Luck, Nightman, on whatever method you decide to use. T.C. Ken in Pa.

04-22-2007, 01:58 PM	#10
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	Thanks for that informative post, AKBuilder7255! How would I compress the rivits without a rivet tool? Is there a way? THat is the main reason that I am looking at the U Drive screws. I don't really have the means to construct a modified bolt cutter, and I don't want to spend the $50 on a pre-made one until I am sure I will be building more than 2 rifles. I have 2 flats and 1 80 bent receiver coming from akparts, and I ordered a 100% from NoDak. I have a romanian kit coming from akparts, and a romanian kit coming from ak47s.com. So as you can see, I have 2 rifles to build. The 2 flats will sit at my place until it is my turn with the bending jig that is making its rounds on this forum. I think I am # 13 on the list to receive it.

04-22-2007, 11:37 PM	#13
KernelKrink Curio & Relic AKaholic #: 2036 Join Date: Apr 2004 Posts: 7,683	Yes, the first step is to pretty much grind the beveled cutter edges down flat. The divot is not normally put in the jaws, the original design uses a small steel plate placed on the outside of the receiver with the divot drilled into it. The boltcutters are then placed over the plate and inside the trunnion. The inner jaw is ground to clear the trunnion, but a small "tooth" is left on the end to compress the rivet down into the recess inside the trunnion. If you wanted to, you could divot the outside jaw itself ( I did) but the steel is so damn hard you will need a carbide ball shaped burr to cut into it. Do a search on boltcutter rivet tools and you should get lots of pics of the various ones people have made. On your divot, either style, just drill into the steel far enough for most of the pre-formed rivet head to seat within the divot. You want a small sliver of head to stay above the surface though, this supports the head but doesn't allow the steel to touch the receiver. Bulk rivets are usually ordered from Centaur Forge or McMaster Carr. Do a search on rivets and you should get the part numbers you need.

04-23-2007, 01:01 AM	#14
AKBuilder7255 Veteran Member AKaholic #: 5400 Join Date: Feb 2006 Location: Erie, PA Posts: 1,403	+1 on what KernelKrink said....The Kernel summed it up in a nut-shell, per say. I couldn't even try to add to that if I tried. T.C. Ken in Pa.

04-23-2007, 07:10 AM	#15
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	Wow KernelKrink, thats some great info! Thank you!

04-26-2007, 06:46 PM	#16
Nightman Member AKaholic #: 8097 Join Date: Apr 2007 Location: Red Lake Falls, MN Posts: 156	Dear lord, did I waste money! Popped some of these in just to try them out. DEFINITELY NOT GOING TO WORK! they had loosened themselves up before I got 4 of them in place. What a waste of $30. Well, lesson learned. Anybody want to buy these fasteners off of me cheap? The whole lot of them for $15 shipped to your door. Not a joke, I will sell them to anyone who thinks they want to give them a try. $15, going once.......

04-26-2007, 07:09 PM	#17
ronin Trying to Get a Grip Gold Contributor AKaholic #: 6354 Join Date: Aug 2006 Location: USA Posts: 9,704	I'm just glad you found out before you shot with those udrive gadgets in place.

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