Let's get this out of the way: I don't know much about drill presses, and this is my first time doing this so I will sound dumb to some of you guys.


So I have the Craftsman 9" Drill Press (Model No. 137.248030) and I want to finish this polymer lower I have.

I need a X-Y Vise and I don't know what to get. the table on the press measures about 7" square. Does anybody have any idea which one I should get? I don't know if the mounts are universal or not...

Thanks, guys.

I would recommend a larger drill press first, or a mill. I don't know if you're going to have enough room on that to do what you want.

Watch 20+ YouTube videos, I've watched hundreds.  There are several that discuss the downs of cheap vises and some that discuss remedies.  If you're like me, you'll learn a lot more by watching than reading.

Polymer is a lot easier than aluminum.






























I would use this one as an example of what not to do or at least a realistic idea of how it could go.  

Let me tell you from recent experience you do not want to go with a cheap x-y vise. I bought one from Harbor Freight and it was so sloppy that I ruined the first polymer lower that I attempted to build.
I bought a standard vise and was able to drill the entire thing by swinging the drill press arm and adjusting the lower and jig in the vise. Of course it took considerably longer, but it worked well and I am very pleased with how the lower came out.

For a poly lower you really don't need an x-y, just a good mill vice to hold the fixture. Move the vice as needed to rough out the pocket. Once you get down to the nitty gritty, clamp the vice and slide the lower back and forth.

Thanks for the input, guys.  



How much larger would you suggest?  If this goes well, I want to buy some aluminum receivers.

If 7075 receivers (plural) are in your future, just spring for a mini mill.  You'll be glad you did, and you won't waste money on destroyed lowers or a jig you don't need.  A new, larger drill press and a jig will easily be half the cost of a mini mill.  You'll have to buy a decent vise either way.

Harbor's mini has gone up a little to $599, but there is a 25% coupon for Sunday the 5th.  And FYI, the Shars 5" swivel vise  is actually a pretty decent unit for the money.  I run a 6" Palmgren swivel, but that's a $600 vise, and it's too big for the mini mill.  Shipping on these things is a little brutal, but that's life; they're heavy.

Would that be the cheapest way to get an introductory milling machine?  I'm seeing some for about $200.

I suppose it's a "you get what you pay for" sort of deal, in the long run.

Those reconfigurable ~$200 things barely qualify as toys.

Think of it this way: if a full size Lagun/Clausing/Kondia/Sharp, etc are the professional grade instruments, the Seig/HF/Gizzly/LMS mini is the high school band instrument, and those $200 things are the plastic flute you buy for your toddler.

The mini mills are plenty use able as-is, but they are also upgradeable, including larger tables, power feeds, ball screws and even CNC conversions.  They are very popular, and therefore well supported.

I would abandon any plans to use just a drill press especially if there a aluminum receiver in your future. Drill presses are strictly designed to cut vertically, not laterally  and they don'like to do so. At the very least you will have a lot of chatter which will not allow you to get a smooth finish And you just may end up with the whole Jacobs chuck falling out of the spindle.

Don't overlook a router based jig. They will give you a finish that will rival a mill but at substantially less money ($80 router vs $600 mini mill) Also You will need to spend a couple of hundred for something like this in order to be able to use a mini mill for anything.
http://littlemachineshop.com/products/product_view.php?ProductID=4491&category=

Where is the 25% coupon located?  I've looked on their site but don't seem to see it.

Pops up on the main page when I visit

http://www.harborfreight.com/

http://images.harborfreight.com/hftweb/home-page2015/images040315/easter2015-coupons1.jpg

Thanks, I see it now.  Right there in RED!

I agree with 66, a mini mill is your best bet. A knee mill is even better but you're going to be spending quite a bit more on one of those. I'm just waiting on someone to buy me a Mazak horizontal ...

I've been using a Shop Fox D2730 3-Inch Cross Sliding Vise with good results. It is not a professional item, but it works well for me. It is inexpensive. (How many lowers will you build?) You will need clearance between the table and the chuck. Here is a link to Amazon for the pic.

I got one of the cheaper X-Y vices off eBay. It has a lot of backlash, but I installed some iGaging DROs so I can measure the actual table position, not turns of the positioning screws. With good technique, I can maintain tolerances of a few thousandths. I also put one on the quill of the drill press so I can precisely measure how deep I'm drilling or milling.

Okay, I slept on it and a mini mill isn't really in the cards for me at the moment.  So I just ordered an Anderson Arms lower from Fatboy Tactical for $40 to get this rifle going and I'll probably sell off the polymer lower I have (I've heard they're sketchy, anyway)

Thanks, I guess.  I learned a lot in this thread.

Drill press is more than good enough to finish an 80% poly lower.

So which jig did you decide on?

Would this work?



http://www.harborfreight.com/6-inch-cross-slide-vise-32997.html  

I finished my aluminum lower on a sears 12" table top drill press.
I put the lower in the jig (stealth arms jig kit - note: the safety hole was off ) and put all that in a drill pres vise.
The top jig had small holes to drill out some of the material then removed that and used a bigger bit to remove most of the material.

At this point a mill bit would have been nice but I didn't have one so I used a 3/8" carbide rasp.
(I'm not sure a mill bit would have worked with free-handing)
Then, taking off maybe an eighth of an inch depth at a time, I moved the vise slowly around clearing out each layer leaving a little along the sides for smoothing later.  Noisy as hell but it worked. The drilled holes gave a gap to lower the bit into (raise the table up to) to start. Do one layer and raise the table a little more. Repeat until deep enough.

When depth was reached, I used the rasp lightly against the sides (again, moving the vise/assembly) to smooth and shape them. The inside has fine chatter marks but it's on the inside so I don't care.
Everything fit and worked. (other than the safety check but that was a different problem- see above).

The vise adds mass and friction on the table to help control movement and catching/jumping. Small/slow/smooth movements are key.
It's not the safest or easiest way but it worked with the tools I had on hand and I would have no problem doing another the same way.
If I was going to be doing more than a few I would invest in a small mill.

NOTE: DRILL THE PIN HOLES LAST! Trust me on this, it's a bitch drilling that far into aluminum with thin drill bits. They wander.
The instruction sheet said to drill them first. I don't recommend the Stealth Arms kit although those were the only two problems with it.

I have the drill press OP mentioned, and there's no way I would try to use it to do a lower.  My carpenter neighbor refers to it as "the Barbie Drill Press", which is not entirely inaccurate.