has members had problems with the recoil lug being symmetrical? nilebartram
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has members had problems with the recoil lug being symmetrical? nilebartram
There is an issue with stamped recoil lugs not being flat if that is what your asking. Most people purchase a precision ground one.
In addition to not being flat stated by Robinhood the thickness may vary side to side and top to bottom. The thickness variance often is the cause of barrel action misalignment in a combination with poor barrel/action thread fit.
This misalignment was often blamed on mis-drilled scope base mounting holes. More often than not replacement of a stamped lug with a ground one will remedy most of the misalignment between scope & bore.
My .02
It always helps to clean any proud metal off the face of the action and the recoil lug when you are installing a new recoil lug to your savage.Quote:
Originally Posted by mnbogboy2
A good while back sharpshooter posted a picture of a process at savage. It showed what I think to be the reason for the proud metal at the barrel action junction where the barrelled action was being straightened with a press at that joint. If you look close to enough actions you will see the flat spots from what I believe to be that process. I wish Fred would repost that.
I like to see that video too. I've always thought that the tooth pattern was knurling of some kind to straighten and work harden the face of the action.Quote:
Originally Posted by Robinhood
I don't know if I have ever seen a tooth pattern. Do you have a picture?Quote:
Originally Posted by Texas10
Now you got me curious. I might have grab one from the safe and tear one down. I usually clean up the face with a big bastard but some don't take much so there may be something left on them to see??Quote:
Originally Posted by Robinhood
A bastard file seems aggressive. :o Maybe a fine hone.....
Robinhood good catch. My mind sees what I am trying to say but my words often stumble.Quote:
Originally Posted by Robinhood
Definitely can be agressive, care must be taken with the quadrant pressure applied. The wide file can encompass the whole end at the same time and material taken off in the areas desired while still keeping it flat. Especially handy if you are squaring it to the threads (have a test fixture with barrel threads and a hardened flat surface using blueing). I normally take light cuts and should have said finish it with 600 grit paper on a sheet of glass. For a work of art you may want to finish finer.
I was recently filing down my OEM barrel nut and recoil lug to do a DIY accurize job on the cheap. You can see where the lug was obviously proud..
Attachment 6159
Key on the lug is that thickness side to side & top to bottom is equal. A couple thousandth difference can cant the barrel towards the "thin" side. The precision ground lugs solve this but a file & careful measurement with a micrometer will get you close. Filing the nut without a fixture of some sort can be a carp shoot. They can get out of "square" real fast. I have cleaned up factory nuts with fine sandpaper on a sheet of glass. The flatness/thickness of the lug is most important.Quote:
Originally Posted by celltech
IMHO
Thanks for the input. I should have said I was using a hone and not a file. I was lightly and carefully just taking off the crappy surface finish. I did the receiver end as well, and honestly it's initial surface was even worse with a lot of marks left from the factory milling.Quote:
Originally Posted by mnbogboy2
Quote:
Originally Posted by Robinhood
Quote:
Originally Posted by Texas10
My recently disassembled 110 tactical (I am rebuilding to 223) had that pattern on the face of the receiver. I never thought twice about it and assumed it was just tool/chatter marks from when it was manufactured. At least that is what it looked like to me. Having been around a lathe and doing some hobby machining, I have seen patterns just like that when the tool chatters.
It is all moot for me now as it is at Fred's getting a time and true as we speak.
I think you can make out the "tooth" pattern from this pic when I was chasing the scope hole threads.
Thanks, Now I easily remember seeing that. I would like to see the process and reasoning behind it. We knurled shafts to tighten them up on occasion.
Interesting.Quote:
Originally Posted by celltech
For bearing fits I'm sure. (head in hands)Quote:
We knurled shafts to tighten them up on occasion.
Wow.....I guess I can't say you guys have a lack of imagination! Let me regain my composure, and wipe the coffee of the screen, then I will tell you a story...
Looking at that again, it is not knurling unless done in a lathe. With no reason to do that my guess is it more likely was a result of a fixture or devise with "gripping" capability. If indeed this came from a straightening operation, they did not want the receiver to twist. An example is a "Nord lock washer" or bicycle style axel nut.Quote:
Originally Posted by celltech
Next guess while we wait for sharpshooter...
Good pic of what I was referring to. I have noticed that the process they use leaves a build up of metal at the outer edge of the worked area, and can heave the recoil lug off to the side a bit, noticeable when held to a light source as light coming from between the action and the recoil lug.Quote:
Originally Posted by celltech
I remove this with a flat plate and 600 grit wet/dry paper, rotating the action every few strokes.
Despite all the speculation, I can tell you that the "tooth pattern, knurling, chatter" or what ever you want to call it, has no intentional purpose. It is simply tool marks left from an endmill. Some are worse than others, and what you see in the pic is worst case scenario. To visualize the whole operation, I start from the very beginning.
Prior to 2008, receivers were made the old school method, utilizing mostly early machines used in WWII production, and a few newer CNC machines purchased back in the late '80s. There were several single machining operations, done by separate machines dedicated to that one particular operation. In this type of production, each receiver was fixtured in no less than 20 separate machines to complete the basic machining process.
The first process was to cut the bar stock to length, followed by gun drilling the bore of the receiver. It was then reamed to size and the O.D. was turned between centers. At this point, the raceways are broached in.......and this is where it goes kinda sideways. The broaching operation uses 2 separate broaches; one for the raceways, one for the guide fin cut, which could be on either side, for a right or left hand action. This operation leaves a very large burr on the receiver face end of the action. To remove the burr, the receiver was simply placed in a vee block and ground off with a 9" disc sander. This was NOT a precision operation by any means, and almost certainly no receiver was ever "square" to start with. Looking at earlier actions would give you the impression that they were trimmed with a chop saw. At this point, that end was where the all of the dimensioning started from.
Then the subsequent operations started, milling the port, the magazine opening, the tang and trigger reliefs, by leap frogging them on Cincinnati horizontal mills with fixtures just for that particular operation.
Fast forward ahead to one of the last operations, threading the receiver. At this point, the business end of the receiver still looks like a keyhole. In order to remove the excess material, the receiver is set up in a vertical fixture on a CNC mill. The fixture is no more than a vee block, with a pneumatic clamp. It has a feature to align the raceways square, and to locate the height off the rear bridge. If the receiver blank was slightly short or long, that discrepancy will end up on the length of the tang, which is not important.
Now, I must comment that using a vee block to locate the receiver is probably not the most precise way to keep it centered with the machines zero. Any differences in O.D., or stray chips in the fixture will cause an off center situation, but that was production standards at the time.
The first operation on this machine was to bore the I.D. to minor thread diameter, that was done with a 3/8" endmill, utilizing a circular interpolation cycle.(basically the mill moves in a circular pattern) Once it was to full depth, it changed over to helical interpolation to cut the ramps,(it moves in a circular pattern and drops at the same time.) Once these 2 cuts were made, the tool was manually changed(remember this machine was from the 1980's) to the thread mill tool, and the threads were milled in (using helical interpolation). At this point, it went to yet another machine to cut the recoil lug notch.
Because the last operation was done in the same fixture, the receiver threads and the lug abutments are now square to each other, but not necessarily to the receiver face, or the bore of the receiver......and that's how they left them.
Enter the 21st century. In 2008, Ron Coburn decided to take the plunge into modern technology. The company purchased 4 new Okuma machining centers. This changed the whole ball game. By 2010, they satisfied their return on investment and purchased 8 more. This new technology changed the entire process of machining operations, and reduced time and labor.
With multiple axis machining capabilities, it combined many operations to the point that a receiver need only be fixtured 3 times.......not 20+.
The first operation only changed slightly with past endeavors. The billets were drilled and reamed, but not turned on the O.D. The burrs from the broach are knocked off with a facing operation. What comes next is where the game really changes. The broached billets are set into the machine between "bow tie" centers. The "bow tie" centers have 2 wings that engage the raceways not only to drive them, but also to orient them to the machines coordinates. The first operation is turning between centers to make the billet concentric with the I.D. After that, every machine operation that can be done between centers is accomplished. Milling the port, the magazine cut, the trigger assembly cuts, and all of the holes that need to be drilled and tapped. In this instance the reference point is the rear action screw hole. This is what the future operations will index off of.
The second fixturing will result in all the operations on the tang end. The receivers are now bolted to a tombstone fixture,and done 4 at a time.
The last operation is the business end, and it is also done 4 at a time. The fixture is not a vee block anymore, the receivers are held by an ER collet. This method insure that all work pieces are held to dead center.
What differs in this last operation is the tools. Instead of a 3/8" endmill like what was used prior, the frist tool is a 3/4" endmill that is plunged to depth, then transitioning to that circular interpolation to get the diameter. It then comes back up to cut the receiver face, using the same circular interpolation. This insures the depth of the lug abutments and makes the receiver face square with the threads and the abutments. The tool now changes to a 3/8" endmill to cut the ramps, then to a 3/16" to cut the lug notch.
What you are perceiving to be teeth or notches are actually tool marks left from an endmill. Even though they look like a straight line, they are circular, left by a larger mill. Earlier versions are not so much pronounced, but I'd bet that the cycle times was increased for production purposes.
Thank you Sharpshooter.
Thanks Fred.