Well I know what you were thinking......."Is that bald guy ever gonna get back in the garage....I'm ready for some more projects".......(admit it, that's what you were thinking huh?) Yep, it seems like months since the last project, and I've been busy as a one legged man in a...nudist colony....well something like that, I always get those sayings messed up.
In order to do this project the right way, I have had to change my standard operating procedure a little bit. I normally do the work at night or on weekends and then head straight to the computer to post the details (normally within hours)....but that just wouldn't work this time. There are a bunch of reasons for this.....here I'll explain......
REASON #1 - This project is the first one that I have undertaken where I KNOW that others will be following along with me......wow that's a lot of responsibility, what if I get started down the wrong path and then find out too late that the way I am doing it will not work? Oooops....that would mean that everyone following along with me would do it wrong also, and we would all be screwed......I just couldn't live with myself if that happened. So this time, I went all the way from start to finish BEFORE opening my big mouth...eerrr keyboard (whatever)....
REASON #2 - I have decided to "try" to produce a made-for-internet mini-series (kinda like a TV show) that will follow along with the entire project......the idea is that each week you can go view the whole thing just like a television show and actually see (and hear) the steps involved. Now don't get me wrong, I'll still be doing the website updates just like I always have, but this time we have full motion video to go with it. Well I did the math and there just aren't enough hours in a week to be able to DO the work, WRITE about the work, PHOTOGRAPH the work, VIDEO the work and EDIT the work, oh yeah and theres that pesky little thing called a job too........just ain't gonna happen. I wouldn't be able to do the shows at one week intervals. So, instead I did all the milling, filing videoing (is that a word?) photoing and other stuff ahead of time. That means that I have 7 days to do the write-ups and edit the video for each update. I think I may be able to actually deliver the RCG-TV series on time that way.....but if I had to fit in time for performing the steps .....well you get the idea.....
REASON #3 - Mrs. Ryan and I are in the process of buying a new house and we will need to pack boxes and stuff like that for the move. I didn't want to have to stop right in the middle of a project and perform a major move.....no telling how long that would take me out of commission. This way, I have enough "project stuff" to feed into the website until after we are snuggled in our new digs.....(well I hope so at least). I know how "nasty" you can get when there's nothing new posted...hahahaha (just kidding)
So now you know why I had to get a head-start on the next project......I don't think it will change the feel of the site.....I made tons of notes along the way so it'll be just like the other projects. I'll write the segments in "real time" format just like always, but you'll know the little secret hahahaha......
There, you see? I haven't been slacking off or being lazy after all.......(admit it you thought I was just being lazy didn't you?)......Ok, so I guess we are starting at the end and going backwards (well sort of)....so in keeping with the tradition (and so those following along will feel confident that I know what I'm doing hahaha) I guess I should post an "until then" picture.......
Hope you'll follow along......it's gonna be a lot of fun baby !! I'll start getting the write-ups and videos posted very soon......but until then..........
Here we are.....the start of a new and exciting project. This project is a lot of fun, and it's a bit more challenging than the ones we have done so far. This time I'm going to have a lot of milling to do. I want to create a nice custom AR-15 carbine by starting with a 0% raw forging.
The raw forging is just a solid hunk of metal with no holes or milling done to it. It's very high quality from the looks of it. The outer surfaces are very smooth with no pitting or dents. If I do this right, I'll have a very nice high quality AR-15 at the end.
I thought it might be a good idea to start off by going over some of the tools I needed to collect in order to do this, and to share some observations that may be helpful to anyone that might be thinking of doing a similar project.
Here is a picture of my "blueprint table" with all the tools laid out on it so you can get an overall view of what is needed for a 0%'er.
Hmmm, where should I start? Well, I guess I have to start with an item that is specific to this project, you know, stuff I never needed before now. Namely that big ole' buffer tube tap. You'll need the tap unless you are good at cutting threads on a lathe AND you make a special jig to hold the frame for threading. Personally, I looked into it and decided it was much easier (and less expensive) to just get the tap and be done with it. The tap is a 1 3/16 x 16 TPI and is available through either the Tannery Shop or via Brownells. It's pretty much a "must have" item (well at least for me it was).
Next lets discuss drill bits (and/or reamers). I learned a lot about this particular subject during the project so instead of saving it for the "what did I learn" section, I figured I'd go over it now so you can be thinking about this as I continue. Here is my "idiot's philosophy" on the subject of drill bits.......
There are basically two different ways that you can go when it comes time to put holes in the forging......you could use the "Chuck/Bit/Reamer" method or you could use the "Collet/Bit" method....either one should work just fine, and I've done it both ways.....personally, I like the collet/bit way of doing it for reasons I will soon explain. First a little background so you can see where I'm going with this.......
I studied the blueprints for the AR-15 lower for about 3 days before I ever started cutting. This allowed me to formulate a plan in my head and see the big picture of where I was going with the project as a whole. This picture shows you what it looked like in the garage for the first 3 days. I made a lot of notes and found that the holes I would be drilling each had a different "tolerance" example: The take-down pin hole had to be .251 +- .001 which means that the ideal size for that hole should be between .250 and .252 (pretty darn tight tolerance). The other holes ranged anywhere from .001 to .004 of acceptable variance.....so to make things easy I decided to hold ALL hole tolerances to the .001 level and then I didn't have to remember the variance for each one.........ok, I know what you are thinking....... What does this have to do with anything? Well it does actually, I'll explain.
The placement and size of the pin holes are one of the most important parts of the whole project. If you put a hole in the wrong place, or make the hole too big or too small, there are TONS of things that could happen. Maybe the sear will not engage the hammer, maybe the safety will fail to engage, maybe the mag release will not hold the magazine high enough to feed a round.....the list goes on. So choose a method and then go with it.
One way is to use a drill chuck to hold the drill bit and then follow up with a reamer. This would give you a good true hole right? But unless you buy a really high quality (spelled expensive) drill chuck, you will probably have more than .001 worth of "wobble" in the chuck itself. A good high quality ball bearing drill chuck is also fairly large and it eats up Z-axis room. You can use a normal ole' chuck like we all have in our tool box, but if you do that you need to "downsize" the drill bit sizes. Example: If you use a .250 drill bit to drill a hole using a normal chuck, it will normally come out at .253 or higher due to wobble.....so you would need to use a Letter drill number "D" and then follow it up with a .250 reamer if you wanted to get a good tight tolerance. Don't get me wrong here......I know that drill chucks are available to do the job, but I can't afford one personally.
Instead, I used a collet to hold a high quality American made drill bit and that did the trick (for me). I was able to get better results (tighter tolerances) with the collet than I was even after using the reamer in a drill chuck. Of course if you wanted to do it up really high tech, you could use an undersized drill bit in a collet and then follow up with a reamer held in a collet.....but that would require a heck of a selection of collets hahahaha......I got true .001 tolerances on all holes (except 1) by simply using the collet/drill bit method. It also means you DO NOT need to buy reamers. Let me say that again.....if you use a collet and a high quality American made drill bit (the imports are normally not as accurate) By going this route it also gives you about 4 inches of Z-axis travel during all the drilling operations (the collet sits flush with the spindle but the drill chuck takes up room) The only hole I could not find a collet for was the 13/64" hole for the mag release. For that one I used a drill chuck and just accepted the slop (that hole has a tolerance of .003 by the way so the chuck is fine)
So.......now I'll get to the point (finally huh?). The tools you need to collect will be directly related to the method of drilling that you decide on.......see I told you I was going somewhere with this whole long drawn out discussion. You can print out the next page if you want a hard copy of the list.
Tools List (Collet/Bit)
Tools List (Chuck/Bit/Reamer)
You'll use all the items in the list (including the 3x5 index cards) if you follow along the way I did it.
Much more to come as we get into the write-ups for the actual milling steps, hope you'll stick around..........but until then........
It's time to get down to the building progress. Today's write-up details the steps I took to drill all the holes in the side of the forging. I decided to start with the holes so that I'll have some points of reference for all the rest of the milling steps. I use the front take-down pin hole as my primary reference point so it's important to get that puppy done first and make sure it's done right.......
I started the whole project by spending 2 days going over the blueprint with a fine toothed comb and doing a bunch of math calcs to devise a plan. I did all the math twice just to double check myself and then I made up a bunch of 3x5 cards to use as my guide. I still kept the blueprint handy to visually check everything, but from here on out, I will be using my notes and the 3x5 cards for all the cuts I make. By doing it this way I saved a ton of time and I made it "idiot proof" so I could keep everything straight in my head. This was particularly important due to the fact that I have no clue how to properly read a blueprint. (never had to do it before).
The very first thing I did was to plane the top and bottom edges of the forging so I would have a nice straight clamping surface. This way I can clamp the forging in my vise on it's side and not have to worry about it being canted or crooked. I used my machinists lever to get the top plane "basically" straight. This picture shows the piece being leveled and this picture shows how it looked just before I started to cut.
I used the biggest endmill from the Grizzly large endmill set to cut the top surface down just enough to where it was level. The point here is not to try to take it down to it's final dimensions.....just to get a nice straight area to clamp onto. This picture shows how it looked after I planed the top edge. (be sure to stop before you reach the "curve" of the rear buffer riser. We'll cut that later.) Then I just flipped the forging over and did the same thing to the bottom edge. This picture shows how the bottom looked after I made a quick pass over it.
Now I have a nice flat surface, so time to mount it sideways in the vise with the left side of the forging facing up. From this position I have access to the area I need to drill all my holes, so off we go...........
I used the boss (the round raised area on the left side) as a starting point to find where the front take down pin should go. A member of the forum submitted an excellent print that shows the measurements for locating the front pin using the boss and so I used his print. Here is the print I used for locating the front pin hole. I used a edge finder to locate the center of the boss and then moved my table to the starting point according to the print. After I reached the location for the front take-down pin hole I locked the table and zeroed the DRO's. This will become my absolute zero for the rest of the hole drilling process. All my measurements are in relation to this zero point. So it now becomes only a matter of moving the table a set distance away from this zero.
Like I said earlier.....I am using a set of 3x5 cards that I keep right next to me while I'm doing all this. the cards show how far every hole is. Here is a copy of the card I used for drilling the holes. All those technical terms make my head hurt, so I just used the words OVER and DOWN instead of some fancy X or Y coordinates.....it just makes it easier for an idiot like me to keep everything straight. (The cards are just a rough sketch and the holes are not to scale or anything but the measurements are correct. ) By reading my card all I had to do was move the table until the display read whatever it says on the card. This made it REALLY easy compared to trying to decipher a blueprint each time. If you don't have DRO's on your mill, it's just as easy (well maybe just "just as easy") all you have to do is count the revolutions and use the scale that is built into your mill (if you trust it) or you could use dial indicators.....the method doesn't really matter as long as you have some way to be able to accurately tell how far you are moving the mill table each time.
Here is a picture of one of the holes being drilled. I used a small center drill to start each hole and then followed it up with the appropriate sized drill bit. ** Note** The first hole I do (after the front takedown pin hole) is always the bolt hold open hole. This is the only BLIND hole (meaning it doesn't go all the way through to the other side. I always do it first so that I don't forget and zone out....all the other holes go through to the other side.
The rest of the holes are done the same way....move the table, lock the X and Y axis, center drill, then drill bit......repeat as necessary.
I learned so much about drilling during this part of the project. I dispelled a few rumors and even got a chance to make some cool index cards hahahaha.....
One of the main lessons that I learned was about the need for reamers. I found that if I used a collet to hold the drill bit instead of using a drill chuck....I was able to bypass the need for a reamer. The collets hold the bit so straight that they cut a near perfect hole every time. If you combine the collets with a good quality American made drill bit I think you'll be surprised at the results. I learned this on the second forging that I did. On the first one, I used a center drill followed by a drill bit followed by a reamer. All held in a drill chuck.....what I discovered was that when it came time to use the reamer, I wasn't actually removing any metal....the reamer wasn't even touching the sides of the hole....that's because the drill chuck had enough "wobble" in it that it made all my holes a tiny bit (just a hair) over sized, even when I used the right sized drill bit. The only way around this would be to use an undersized drill bit and then follow it up with the reamer. This of course would mean 3 tool changes for every hole !!!
So on the second forging, I tried just using a center drill followed up by a good high quality drill bit held in a collet....the results were fantastic. I got just as good results with the collet as I did when I used the under sized bit and the reamer combo......just food for thought. You may find (like I did) that you don't even need the reamers at all.
The only exception to this rule was on the mag release button hole. I couldn't find a 13/64 collet so I had no choice but to use a drill chuck. Since this hole isn't critical (you have +- .015 tolerance) I didn't worry about it. I just used a center drill followed by a 13/64 bit and never looked back. Turned out just fine.
A quick note about the index cards. Mine are just hand drawn, they do not need to be to scale or very fancy........all that is important is that the measurements be correct and that you can visualize which hole you are working on......so my rough drawing is fine for these purposes. It would be way too much trouble (and not worth it) to try to get everything lined up perfectly and drawn to scale. Just as long as you can understand it and keep track of the holes and you have all the measurements at your finger tips, that's all that matters. You could accomplish the same thing by just making a text listing of the holes.......something like this:
over - 0
down - 0
over - 3.082
down - .1940
Blind depth - .5400
over - 3.082
down - .5625
etc..........you get the idea. For me, it was easier to just
draw a silly little picture, I'm a "visual person" so the picture made
it simple for me, but either way would work fine.
Much more to come.....hope you'll come back soon.........
The buffer tube area....hhmmm where should I start? Well first off I guess I should discuss the set-up I used to gain access to the rear area......seems like a good place to start.........then we'll move on to the more interesting stuff.
I am very new to machining and so some times I'm not really sure how to properly "Hold" the workpiece in order to do my cutting....like everything else, I'm learning as I go but it's not always easy to figure this stuff out the first time you try it. The way I held my forging worked well, but it certainly is not the only way......well before I bore the heck out of you, I'll tell you what I did.
I used a medium sized angle plate that I bought from Grizzly and a few pieces from my clamping kit to hold the forging in a "rear facing up" position so I could have access to the buffer area to make my cuts. I like to do the big hole that the buffer goes into BEFORE I cut the fire control or the magwell, this allows me to really crank down hard on the clamps and not have to worry about crushing the fragile fire control or mag well. The rear buffer area needs to be planed down to its final dimension and the holes al need to be cut.....this type of cutting (particularly when using the big endmills) puts a lot of torque on your setup. If the set-up isn't clamped down good and tight, then you are just asking for vibration trouble. Here is a picture of the way I clamped my forging onto the angle plate. If you look carefully at the picture you'll notice a small scrap of metal used to level the forging against the angle plate.....you need this little "shim" if you want to clamp the forging flat against the plate.....this is because of all the little bumps and "sticky-outies" on the side of the forging.
Ok, so the forging is mounted on the plate and leveled up (side to side and front to back).....next I need to make a planing cut to shave the rear end doen to its final dimensions. I used this 3 x 5 card to to get the math right. All I did was stick a 1/4" drill blank into the rear takedown pin hole and then move the cutter down until it just "kissed" the edge of the pin that was sticking out of the side. Then I move the cutter up 1.003 and reset my DRO's (this is now my Z-axis zero point).....it's agood idea to take a look at the depth of the cut and make a judgement call as to whether or not you think you can make it in one pass. I normally do a shallow pass first to see if everything is level and to see if the angle plate set-up is holding tight. If your level is off by even a tiny bit, you will see the "thin silver line" widen and/or thin out as the cutter moves across the face of the metal. After I am satisfied that everything looks good, I just plane it down using my 1 1/2 endmill. Here is a picture of the rear buffer area after it's been planed down.
After it was planed down and smooth I went ahead and found my zero point for the "big hole"....this 3 x 5 card shows how I find my zero. I use an edge finder and go until I touch the edge of the drill blank that is sticking out of the rear takedown pin hole. Then I move over .754 on the Y-Axis and lock the table and zero my DRO's....this is now my Y zero point. To find the X-Axis zero point I simply use the edge finder and touch both sides of the forging then divide by two......then lock table, and zero DRO's.......now we are set-up directly over the center point of the big hole.
I use drill bits and then work up to a 1 1/8" end mill, going up by only about 1/4" size each time until I open the hole up to it's final 1 1/8" size. Here are a few pictures of the process. Picture1 Picture2 Picture3
I looked all around and I can't seem to find the photo I took of the 1/2" buttplate holder hole being cut......sorry. I just used a 1/2" endmill and went .200 deep. This 3 x 5 card shows all the measurements for the holes. They are all in relationship to the CENTER OF THE BIG HOLE because that was our zero point. Or here is another way to look at it in this 3 x 5 card.
After the buttplate hole I moved over and cut the little detent hole. The detent hole goes all the way through until you break through into the rear takedown pin hole. Here is a picture of drilling the detent hole.
The last hole I drill while in this position is the bolt hold open latch "roll-pin hole"...I don't use any measurements for this hole. I just remove the top clamp from the angle plate (leave the bottom one on) and then use a nail or a transfer punch to tap a dimple in the center of the ears. The placement of this hole isn't critical....just put it in the middle and you'll be fine. I tapped the transfer punch lightly with my gunsmithing hammer to make a dent and then used a long drill bit to go into the hole. I just didn't want the skinny little drill bit to wander around, that's why the dent......here is a picture to help you viusalize.
Please don't pay any attention to the fact that the fire control is cut in some pictures and not in others....as I already stated....I did a total of 3 forgings during this project. I screwed up the first two and got the 3rd one right.....some pictures were already taken so I didn't re-take all the photos each time......I just use the ones that turned out the best to help illustrate the part I am writing about. The written text IS the way I did it on the one that turned out right....ok?
Much more to come.......stay tuned.
*** Coming soon please check back later ***