Tools and materials needed. Drill press or power drill. I use an inexpensive Harbor Freight
8-inch portable table top drill press which does just fine for polymer and 6061 lowers. I've used it for "75" lowers as well and
had some trouble with that. I had to set the drill pressed the lowest
620 rpm setting. Even then I had to make sure to give the
press a break after every 3/8" hole to keep from overheating. Vice. This is needed to clamp the jig
down while routing out the lower. 3/8-inch drill bit. This is needed to
drill out the bulk of the material in the fire control
group pocket and to drill out the hol for the safety selector. 3/8" stop collar. This is used to set the drilling depth for the bulk of the fire control group material removal. 5/32" drill bit. This is used to
drill the hammer and trigger pin holes. 19/64" drill bit. This is used to make one hole for the end mill to pass through when milling out the trigger hole. 1/4" end mill. This is the size
needed to work with the Easy Jig. I purchased the recommended one and a
half inch cutting length end mill. This longer cutting length can bite into
the template if you're not careful. 80% Arms, the manufacturer of the Easy Jig now sells an end mill with a short 3/4" cutting length that will not cut into the edge of the jig even on the
first passes. They also sell this end mill as a package
with the required drill bits and stop collar. 1/8" hex key or Allen head bit.
This is used to tighten the template bolts. 3/16" hex key or Allen head bit. This is used to tighten the top jig bolts.
3/32" hex key or Allen head bit. This is used to tighten the 3/8-inch stop
collar. Router with 1/4" collet. The
80% Arms video shows the use of a full-size and a laminate trim router. I used a
Porter Cable 690 fixed base router for all milling. Cutting fluid. This is to lubricate and
cool the cutting. I use cutting fluid I got from Ace
Hardware just because it was convenient but there are better ones out there.
WD-40 is not a cutting fluid but it's better than nothing. Masking tape. This helps to highlight the
inner edge of the template and to tape of the lower to protect it from
chips. This is especially helpful in machining a pre-finished or anodized lower. I use the bright green automotive tape
but the light brown standard tape probably work as well for these purposes. Eye and ear protection. A metal shaving in
your eye will really ruin your day and maybe even more. And because no one wants to go deaf on the installment plan. Small brush. This is useful for brushing metal
shavings out of the jig and lower during and after the lower completion. Shop vac. For me this is a must have to
clear out chips from the work area and the fire control group pocket after each pass with the end mill. Assembling the receiver in the jig. Start by running the top two bolts
through the un-threaded jig wall holes and the
takedown pins of the receiver. Then thread the bolts into the opposite jig wall that contains the threaded screw holes. Tighten the bolts in an alternating
manner until the bolts are flush with the outer jig wall. Do the same for the bottom two jig bolts. Then finish tightening the four bolts in
an alternating pattern as you might tighten the lugs on a vehicle's wheels. The bolts do not need to be torqued down.
Just snug to keep the jig walls parallel. The bolts will stick past the jig wall
about a 1/16 of an inch once snugged up. One thing I learned after finishing my
first anodized lower is that small aluminum chips from the machining process can flow with the cutting fluid in between the jig and receiver. These
chips can then become embedded in the anodizing. I asked 80% Arms how to remove
these chips and they recommended a Scotch Brite pad and soapy water. This worked only to the extent that you
can also remove some of the anodizing to get the embedded chips below the surface. I would not recommend doing this. Instead, to prevent the problem, you want to keep
the chips from getting into the finish in the first place. I do this by taping off all areas of the receiver that will not be machined or are between the jig
and the template. If there's a gap to plugged, plug it. Just don't get the tape between two mating surfaces such as the jig wall and the templates or you will
cause a dimensional problem due to the thickness of the tape. Attach the pocket drilling template to
the top of the jig and insert one template bolt through the template and thread two turns into the jig wall. Do the same for the opposite and diagonal template bolt. This will ensure you have your jig walls
parallel and spaced apart correctly. This will become more important if you have a modified jig being used with a non-80% Arms brand lower. Finally, insert the remaining two template
bolts and tighten in an alternating fashion until snug. Use a piece of tape and cover up the two
rear pocket holes so you do not accidentally drill into them. Using the rear shelf template, set the
drilling depth with the lock collar on the 3/8" bit. I prefer to set my drilling depth just shy
of the bottom of the depth gauge. This prevents the small divots I
sometimes see after completing the machining. Now place the 3/8" drill bit into your press or hand drill. Drill out the
holes in the fire control group pocket using the template as a guide. Use the cutting fluid to keep the drill
bit lubricated vacuum out the chips between passes often. You may need to use a screwdriver to
push out some of the chips that may become wedged between the template and the
receiver. Do not press down hard into the template or you could end up with divots in the final pocket. bottom. Let the end mill do this final
pass for a better finish. Also check the depth and tightness of the lock collar often to prevent over-drilling. I choose to alternate which holes I'm drilling so the heat from drilling does not concentrate in one area. So I may start with the first hole and
then skip two holes, drill that hole, skip to the last hole
and then go back the second hole in the template and
drill that. I don't know if this does anything of worth but it makes me feel
better doesn't have any downside that I can think of. Once the fire control group pocket is milled out you can move on to the rear
pocket. Skip this part if your 80%
lower is already milled in the rear takedown pin area. Remove the top rear jig bolt so you do not drill through it. Remove the tape from the template and set the drilling depth
using the guide on the trigger pocket template. Drill out the two rear pocket holes to
the newly set depth of 0.63 inches. Remove the pocket drilling template and vacuum out the chips from the machined area. Reinstall the top rear jig bolt. An optional but recommended step is to prepare the
trigger pocket template by applying a line of masking tape around the inside
perimeter. This will help the inner edge stand out
so you're less likely to cut into it when using the end mill in the router. The tape must not extend past the
template. I find that a half width of tape from an 18 millimeter roll is just right. This
step isn't required if you're using the 3/4" cutting length end mill now being sold by 80% Arms. Now it's time to move on to the router
work. Wipe down the top of the jig wall and place the template spacer with the longer end
towards the receiver extension hole, also called the buffer tube hole. Then stack the fire control group
template on this spacer so the smaller end is towards the buffer tube hole and the lip is facing up. Finally, place the router support base
over the lip with the recessed bolt holes facing up.
The router base only fits one way so if your holes do not line up rotate the support plate 180 degrees. Now insert the (4) 1.75" template screws through the template stack and secure to the jig
walls in the same alternating fashion. Secure the assembled jig into the vice.
I prefer to install the jig so the buffer tube hole is closest to me. I find it easier to mill without
touching the template when it is in this orientation. Install the 1/4" end mill into the
router. Allow the end mill to bottom out and
then raise it up about an 1/8" and tighten the collet. Set the depth of
cut to the first hash mark on the rear pocket template. If you have a variable speed router you
can adjust the speed now. With my 1 3/4 horsepower
model I set the RPM to 2000 rpm. When using the end mill I prefer not to use
any cutting oil but my passes are shallow enough that I find it
is not needed unlike the 3/8" drill holes which remove a lot of material at
once and cutting fluid is needed. Insert the end mill bit into the furthest hole,
turn on the router, and gradually connect the drill holes to
each other in a zig-zag pattern. Once all the holes are connected you can begin
milling out the area starting from the middle and working outwards. Because of the way a router rotates the end mill will want to move around the area being milled in a clockwise direction. Make one complete pass around the
middle area of the trigger pocket and then a second pass closer to the edge of the template. Use caution not to get too close to the template or your end mill could bite into the template. It is better to err on the side of caution and stay way from the template for that
reason. You'll be able to get right up the template once the cutting surfaces are below the template walls. Once the first
pass is complete move the router to the middle of the pocket and turn it off. Wait for the router to stop spinning and then remove it from the jig. If you try to take the router out while
the motor still spinning you could nick the side of the template or injure
yourself. Wait the extra 5-10 seconds for it to
stop completely. Set the second and subsequent depths of
cut in progressive 1/3 to 1/2 hash mark increments. Using large depths of cut will decrease
the time spent milling but will also increase the work on the router, end mill and possibly cause you to jerk the router into the template. I recommend taking shallower cutting depths at least until you reach the point where you feel comfortable with the process and know what to expect from the
tools you're using and the lower material you have. For stronger materials like 7075 you'll
want a shallow depth of cut while a polymer receiver can get away with
the larger depth of cut. Likewise, if you're using a lower powered router you may want to take shallow passes to
reduce the load on the router/ Continue these cuts until you reach the
second to last hash mark. By this point the cutting surfaces of
your end mill will have cleared the jig template. Now you can allow the shank of the end mill to touch and follow the template as a guide. Keep in mind you are now going to be cutting a lot of material between the template and where you stopped your cutting passes. Go slow and make several clockwise passes as you get progressively closer to the template. The final pass that touches the template will determine how clean your finished edge will be. Don't force the router into the template. Just make more and more light passes until the end mill no longer removes material as you run the shank along the template wall. Continue making more passes as before but this time take the passes all the
way to the template wall. For the final hash mark of cutting depth
I recommend breaking it into four increments. The first pass two passes should be 1/3 hash mark passes and the remaining two should split the
remaining 1/3 hash mark so you are taking 1/6 hash passes. So it'll
go 1/3, 1/3, 1/6, 1/6. This is to ensure your final cuts will
be very clean and also because the 3/8" holes drilled previously will have a coned bottom, because of the
drill bit shape, not a flat bottom like an end mill cut. This means your end mill will actually
be doing some of the vertical cutting so you want this to be a very shallow
cut. In fact I start these final two passes in one of the center holes just
in case the router tries to jerk it won't cut into a receiver wall. You actually need to hover the router
slightly above the jig, turn it on, and then slowly bring the
router down to the jig. During this process you will be
drilling a hole for the flat bottom end mill to sit in and start the finishing passes. Once the last two passes are complete
you can move on to the rear pocket template. If you are using an 80% receiver that already has the rear pocket complete then this will not be necessary. There will be a section of metal between the pre-machined rear pocket and the trigger group pocket if you do not
connect them in the next steps. This is fine for an AR-15 style receiver but
you can still machine it out if you wish. Remove the router support plate and the
trigger pocket template Reassemble the jig with the rear
pocket template under the router support plate. Remove the top rear jig screw so it does not get milled through. Milled out the rear pocket just like
before but this time using the depth gauge for the rear pocket. Do not complete any finishing passes
until the cutting surface of the end mill passes the template walls. Because this area is shallower than the
trigger pocket I wait until all of the roughing passes have been made
before completing the finishing passes. Once the rear pocket is milled out you're
in the home stretch. Now it's time to milled out the trigger hole. We begin by drilling a large hole for the
end mill to pass through. Disassemble the templates and spacers
from the main jig. Install the trigger template to the jig
walls using the 3/4" screws. You will only use two screws installed
into the jig walls. The trigger template needs to be
oriented so the guide hole is closer to the rear of the jig. Using a drill press for this hole will keep it perpendicular to the template but even a hand drill carefully will be fine as this hole just allows the end mill to pass through the receiver. Install a 19/64" bit into your press and drill through the trigger hole. Be careful once you pass through the
bottom of the receiver so you don't end up putting the drill bit into the trigger
guard. Remove the drill bit and then
disassemble the template from the jig. The Easy Jig instructions say you do not
need the template spacer for this next step but for a full-size router you will need
to retain the spacer. Use the 1.75" screws instead of the shorter 3/4" screws. Otherwise the full-size router will run
into the back of the receiver. Install the trigger template onto the
jig using the template spacer and the longer 1.75" screws. This time you want the template spacer with the long side facing away from the buffer tube hole so only two holes in the spacer line up with the holes in the jig. The
trigger hole template will go over the spacer, lip side up, so the trigger hole guide
is towards the buffer tube hole. Then the router support plate goes on top
of that with the recessed holes facing up. As before, the holes only line up one way. Secure the stack to the jig using (2) of the 1.75" screws. Because of the depth of cut needed using
the template spacer I had to reset the end mill further out the router. If I didn't do this the router collet would
bottom out on the template before the hole was cut through. I get my initial depth of cut for the
trigger hole by putting the router on the template base and bottoming out the end mill on the
receiver bottom, not allowing the end mill to pass through the trigger hole. Then I place the end mill over the trigger
hole previously drilled and increase the cutting depth about
1/16". This means you will not be cutting out the trigger hole in one
pass which I find makes a cleaner cut. Make a first clockwise pass around the
hole until the shank of the end mill rides
along the template. After this first pass I stop the router, and increase the cutting depth so the end
mill passes through the hole completely to finish the hole in a second clockwise
pass. Remove all the template pieces from the jig. Place the jig on one side so you can drill
out the safety selector holes. Because the bolts holding the jig
together stick out you'll need to prop the jig up on the two templates labeled MAIN and REAR. If you are using a hand drill in a vice you do not need to use the templates as spacers. Install a 5/32" bit into your drill and drill both the trigger and hammer pin holes on the first side. You do not need any cutting fluid for
these operations. Flip the jig over and do the same for
the pin holes on the other side. Then install the 3/8" bit in your drill and
drill out the safety selector hole on the current side. Flip the jig over and do the same for the safety selector hole on the other side. Keep the 3/8" bit in the drill for now. Disassemble the jig completely. and remove the now completely machined
lower. You will likely have to do some minor reaming to the safety selector and
trigger/hammer pin holes. The Easy Jig instructions
call for a reamer but I just used the same drill bits. Use
caution and slowly work the drill bit in the receiver holes. Make short passes and check the fit of your safety selector and pins often. You don't want to accidentally oversize these holes but you don't want them to be too tight either. Once you have the safety selector hole
sized correctly you can install the 5/32" drill bit and do the same process for the trigger/hammer pin holes. Check that the safety selector
detent slides into and out of the hole and that nothing is stuck in the grip screw hole.
You may need to clear out the safety selector detent hole with a drill bit if it has a chip or flashing from the
drilling operation. If everything checks out you can wash the drilling fluids and
metal chips from lower with soap and water. Be careful not to scrub any metal chips
into the anodized finish. Soapy water and a gentle toothbrush will
lift away the particles. After cleaning you can wipe down the lower and set it out to dry or put it in an oven at a low temperature, around 150 degrees Fahrenheit for 10-15
minutes to evaporate any remaining water. If you use the oven method make sure you
allow the lower to cool completely before handling. Thanks for watching and be sure to visit
the 80percents.com website for more tips, reviews of 80% lower brands
and to join our 80% lower building forum.
