Has anyone tried those end mills specifically made for aluminum?

You know the really high helix kind, I got this one called "Alumpower" or something.

Anyways I got it, put it in the mill and made a really deep cut (.200) and it's cutting through aluminum like it's not there at all. I think it's the ticket for milling lowers.

Have not tried them, I would be interested to trying them out.

Me too...  Link please?

I have one of these from amazon along with a couple similar from enco.  They all work very well to rough out the pocket.

This is what I got

http://www.ebay.com/itm/131673859472?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

They're highly polished and when cutting aluminum it's almost as though you're machining hard wax... it's that good.

Added a couple more docs and fixed some links.  Heard the 80% sub-forum is a go!

If so, can we maybe include promoting discussion of the Defense Distributed Ghost Gunner CnC machine?

There aren't any forums I've found that have anything other than a random question on occasion.



I've got no personal experience using one, but there's serious interest in moving in that direction on my part, and I've got to think that there are other people who have the interest in pursuing that option as well as some people who must have cranked out a lower or two on one.



Thanks for any inclusion that may come of this.



 

I looked hard at the "Ghost Gunner" but went with a mini mill because I can do other things with it, I only have about $1200 in my mill and lathe set up with the tooling and would have more and have to wait longer to get a ghost, the mini mill works great for lowers and I can still do other things with it.

The Ghost is neat and is effective for what it does, but you can do so much more with the mini mill.

Dang, I wish I had heard of these before.  They look like they might save some time and effort...

Ghost gunner is a one trick pony. It does AR15's (and it can't even do ones without the rear lug machined) and that's it. For the price you can buy a X2 type mill, and a DRO to go with that. Though personally I would go with a G0704/BF20 type mill because the taper gib is a lot easier to deal with, plus the mill has all sorts of mods you can do to increase its travel, speed, etc.

My eyes aint what they used to be, (cataract in my dominant eye is acting up over time),  so being able to get into the craft through a certain amount of automation is a factor.



As much as I'd like to be able to do all those other cool things on an all  purpose mill, it just aint gonna happen.
 

Added some more links.  Tons of info out there.  I'm just trying to put as much as reasonably possible in one place.

Bump with some action shots of recent projects.  Without using a jig, you can watch as it comes to life!


Just scratching the surface to lay it out


One last hole and she's done!

I haven't seen much traffic on the 80% threads.  Hopefully everyone is enjoying what's left of summer and has lots of projects to post up when the snow flies.

I've been building a lot of 80%'ers. I love these threads - thanks for posting

How are you making out on your 308 AR paperweight project...?

Thanks for posting it here and best of luck with it...looks like it
will turn out really nice.

Marry Christmas.

The 308 pistol is done.  Still haven't finished the rifle...

Curios also?

Personally I don't.  I make all mine straight.  I'm sure some worry it could be conceived as intent, but as you said, many manufacturers do this too.

Great info thanks

I haven't added much in a while, but I've been getting a little more shop time as of late so hopefully I'll have more to contribute.  

Archive save bump, happy building!

You are the MAN!

I'm looking at mini mills and see Little Machine Shop has them for $599.99 plus shipping now.
What is the difference between the Sieg X2D and what HF offers? I thought they were the same machine.

The HF is $631 to my door.
Little Machine shop is $818 to my door.

Just a note:

You really should drill and ream the hammer, trigger and safety holes first.  It ensures the holes don't egg-out on the near side, and is the standard way it is done.

If you read Ray-vin's notes, that is how he recommends.

Why?

To increase the bearing surface for the safety.  Especially important if you can't ensure a full .001" thick anodizing layer.

If you are looking at the X2, they are basically the same as the Grizzly 8689 and the HF mill, there may be little tiny things that are different but not enough to really make any difference.

I have the Grizzly 8689 and the same parts for the HF fit it.

LMS is charging $218 for shipping?  I believe Grizzly has the 8689 on Ebay right now for $649.00 plus $80 bucks shipping so $218 seems really high.

I know a buddy of mine ordered the HF model back in Dec when it was on sale and then used the 20% coupon and was not charged any shipping because he picked it up at the store.

One thing that is good about the X2D is it is a solid column machine, which to a lot of people feels make a real difference, it does take away the possibility of deflection in the column, the HF machine is a moveable column, like the Grizzly 8689, but I have not found it to be a problem on milling my lowers or anything else for that matter.

Just to add, I just checked and with the 20% coupon that HF has this month, it makes theirs $560

mini mill comparison

Thanks Max, I looked and couldn't find that darn page for some reason!

I drill (actually endmill) first sometimes, sometimes after, but I've never seen a difference.  I do drill from each side though regardless of order of operation.  If you drill from one side straight through, I would expect the close side to open up some when you hit the far side.

just wanted to add a side note here

been doing some 80's and bought the 80 percent arms easy jig to use as soft jaws

1st time i tried to mill a lower i went to get at the back pocket by buffer threads
and pulled the rear screw holding the jig together thinking vise pressure would keep it in place

wrong! lol

this reply is about my solution to that problem

i got a carbine buffer tube and a 1 inch piece of aluminum bar
sanded the bar til it fit tight in the tube  to act as a plug

drilled a ++ 1/inch hole down thru and milled a shelf relief on the underside where the stock  lock block sits
to allow a washer to sit flat on underside of buffer tube

i then have a 1/2 inch stud sticking up off the table or top of a vise
which allows me to adjust up or down and lock in place the buffer tube which i screw into lower
this lets me indicate flat the top of the lower along X axis
was having a heck of a time indicating things flat and this really helped

i dont have pictures but im doing another one soon so ill put pics up then
also a buddy bought a used caswell anodizing kit and couldnt get it to work
so i played with it and am pretty confident with it now so ill share my thoughts about it soon

its really no big deal the most important thing is solid connection to the part
and battery acid
lots of battery acid

Does harbor freight sell a solid column machine? I don't see one listed on their website, but I'm very interested.

Thanks

I don't believe they do, I have never seen one from them.

Going from one side through a solid block with an undersized drill and reaming to correct sized with a good sharp chucking reamer is the best way to get properly sized and aligned holes....

And, I would not suggest drilling with a regular end mill if you want a clean hole. best use one of these:

In the perfect world, or even in most production environments, yes.

My garage is neither. I have learned my (and my equipment's) limitations.  I know if I drill from one side all the way through the lower, the most accurate the hole will be is as accurate as my $900 Chinese mini-mill and $8 end mill is capable.  In reality, it's much worse.  Flex in the bit will open up the top of the hole considerably by the time it comes out the far side.  The bit will walk.  I know my mill is not perfectly trammed, so even though I drilled one hole all the way through to ensure the resulting two holes are aligned, the hole on the far side is going to be in a different location than the top hole. Maybe not by much, but it will be off at least as much as the tram of my mill plus the error of how level I placed the lower in the vise.  Compounding / stacking tolerances.  
My mill gets trammed when: 1. I notice it's off. 2. when I think I did something to wreck it. And 3. when I have time.  Guess how often that is.  
Tramming the mill, I can only get my $900 Chinese mini-mill so good with my limited knowledge, the machine's limitations and the cheap measuring instruments I have available.

Much like the difference between a high end cnc production environment and the local machine shop running as a job shop, my "garage work" is just that.  Sometimes you have to work around what you have and do the best you can with what you have.  My abilities slowly improve, I slowly aquire better tooling and I have made a lot of improvements to my mill, but I'm also well aware of my limitations and always have to find ways around them.  

Again, I'm not a machinist.  I have learned most of what I know through trial and error.   I've learned a lot form this forum, a few others and youtube gun and machinist channels.  A professional machinist on a professional machine will certainly have a different method of skinning cats.

I have the Harbor Freight mini mill, and waited until I got a 25% coupon via email.

With a simple drill-press you should be able to drill a 5/32 hole through a one inch block and keep it straight and without wander. Certainly, better that trying to get two holes co-axial by drilling in two set-up   It's a matter of technique.

1) Use a center-drill to locate the hole.  Regular jobber drill bits, even the best, do not have a well defined point.  However, the corners are very accurate.  Center drills are short and stiff enough to not deflect on contact with the work.  Drilling so the chamfer is just a tad bigger than the drill bit diameter allows the drill bit to center accurately in the hole.  It also obviates the need to chamfer the hole on the near side.



2) Peck drill. One of the main reasons drills wander is chip build-up in the flutes.  It does not build-up evenly, so there is uneven pressure on one side of the drill, this causes the drill bit to flex, and if the machine is too flexible, it will flex as well.  Withdraw the bit and clear the chips often and don't just reverse the down feed, hold the drill at depth for a second to clean up the bottom of the hole.  Snatching the drill out of the work leaves little shear bumps on the bottom of the hole, these will interfere with a clean start when you next start to drill.

3) Calculate the correct down feed speed (yes, even if you are hand feeding) for the size of cut and the type of cutter.  Material only cuts so fast, attempting to force the bit into the work faster than it can cut will bow the bit, even in aluminum, and cause the bit to wander in the work.  If you think your machine is too flexible (and most mini-mills are) over-feeding the tool will cause the machine to flex as well, so go real slow, slower that you think you need to.

4) Work up in bit size.  Don't try and drill a 5/32 hole with a 5/32 drill bit first, especially if your machine is flexible.  Start with about a #30 or 1/8 or so and work up.  The finished hole should be 2% to 3% smaller than the finished hole. Use a reamer to finish the hole.  

Checking the tram on a vertical mill takes a few seconds.  Take a machinist square and put it on the table, with the drill bit you are about to use in the chuck, run the drill down and check for daylight between the bit and the square.

Another thing, if you think you are getting your holes co-axial holes going from both sides, you're fooling yourself, here's why:

Finding your datum - When you break set-up you will have to re-establish the X-Y zero.  No matter what kind of method you use to find it, edge-finder, wiggler, cigarette paper, there will be some error.  If you feel your machine is not the most rigid, your problems are exacerbated.

Finding the hole location - Lead screw error, or DRO error, there will be some error in obtaining the distance from the X-Y zero to the intended location of the hole.  Again, this error is made worse with a sloppy machine

Drilling error, human error and other errors - did the drill bit tip move when you entered the work?  Did you dial in the exactly the same number?  Did the dial move after to set it?  How sloppy is the machine?

If you follow the process described in my earlier post your co-axial error from that process is going to be less than the above errors.  That’s why that is the process used by machinist for the last two centuries.

And, another thing drilling across an opening like the fire control pocket is possibly the last thing you want to do.  You cannot use a center drill to locate the hole, so you are dependent on the drill bit tip to locate the hole, which as stated earlier ain’t the best.  Whenever a drill bit hits a flat surface it will wander in a circle until it starts cutting (which is why we use a center drill), as the tip wanders the back end in the upper portion of the hole is now cutting the upper hole.  And it probably isn’t all that round.  If you use a reamer after, you have a better chance of getting two holes the right size, depending on how wallowed out the upper hole was after drilling, but the concentricity will be lost.

Another thing about hole drilling:  Reaming will not straighten a hole.  Reamers are designed to be flexible enough to cut and even amount of all sides of the pilot hole.  They will follow the pilot hole very closely.

OH, and one more thing, the perpendicularity of the holes to the centerline across the lower is only required to be 0.005” total.  However, there is zero eccentricity allowed in the two holes on opposite sides.  Having your head off a ¼ of the degree and drilling in one pass to get a straight hole is preferable to two holes eccentric by 0.001”.

ALL good info.  

As the mention of tolerances.  I think most over estimate the requirements for this stuff to work.  The first lower I milled is off in nearly every measurable way possible and still functions 100%.

I don't believe so, if you look at the bottom of the column it has the degree wheel so you know what angle you have adjusted the column to, just as my Grizzly does.

Same here. I waited for a sale and a 25% coupon. My mill ended up costing around $450 IIRC.

On and one last thing:

End cutting end mills are not the best thing to use for drilling a hole, they do not self center like drill bits.

If you already have a hole and what to make it bigger, they're great, but making a hole from scratch, you'll end up with a sloppy hole.  The smaller the end mill the worst results.

I just used a .250 end mill to make a .280 recess about .050 deep.  Used an old endmill in a sloppy cross slide vise on an even sloppier drill press.  Bonus points if you know what I might want such a recess.  Project is close to completion.  As embarrassing as it may be, I'll be posting a lot of images.

Sorry, I should have specified "deep holes".

Deep holes being holes greater than three times the cutter diameter.

Back to the original subject:

for those interested in 80% receivers I suggest reading Ray-Vin's notes on  a 0% receiver.  Some of his notes are a little conservative, such as using a drill bit for rough hogging.  Personally, I never bothered to do that, just plunge cut with a 1/2 inch center cutting end mill.  It doesn't leave the prettiest of finishes but your going to clean in up with the 7/16, so what does it matter?

Most importantly, like the AFCarbon15 said earlier, know what your machine is capable of.  If you are using a mini-mill take light cuts.  Mini-mills aren't as rigid as, say, a 58 inch Clausing....