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AR-15 80% Lower Milling

caprio

Plastic
Joined
Jan 24, 2013
Location
Discovery Bay, CA
AR-15 80% Lower Milling - Mill Recomendations

I have an 80% lower and need to complete it. I've seen a few video where guys complete
these with only a drill press. Seems a bit crude.

I'd like to know if one of the smaller milling machines like the ShopFox
or Harbor freight milling machines would be adequate for the job?

ShopFox M1036 Features ~$400

Motor: 0.2 HP, 2A, 110 Volt, single-phase
Drilling capacity: 1/4-Inch
Spindle taper: JT1
Spindle travel: 1-1/2-Inch
Table size: 3-1/2-Inch by 8-Inch

Harbor Freight Mini Mill 2 speed variable ~$500
Horsepower (hp) 4/5
Maximum speed (rpm) 2500
Minimum Speed (RPM) 1100
Number of speeds Variable
Spindle Taper R8
Voltage (volts) 120
Chuck size (in.) 7/64 in. - 1/2 in.
 
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That #1 Jacobs Taper would steer me away from the Shop Fox pretty quickly. You don't really want to be holding end mills in a Jacobs chuck.
 
Mini Mill. Harbor Freight vs. ShopFox

Thanks for the comments so far. Please keep them coming.

I was leaning towards the Harbor freight. It has a 4/5 HP rating while the ShopFox
only has a 0.2 HP. I like the digital depth gauge on the ShopFox. The harbor freight
comes with the feed table. The shopFox it's extra. HF mill has a 1/2 chuck, SF looks like
it only takes 1/4" bits? HF has 20% coupon so I can get this for $399 and have it today :)

Sorry if this is a stupid question. Don't both of these mills have Jacob chucks? AFAIK a Jacobs
chuck is a generic term for the common power drill type chuck.

I have an 80% lower and need to complete it. I've seen a few video where guys complete
these with only a drill press. Seems a bit crude.

I'd like to know if one of the smaller milling machines like the ShopFox
or Harbor freight milling machines would be adequate for the job?

ShopFox M1036 Features ~$400

Motor: 0.2 HP, 2A, 110 Volt, single-phase
Drilling capacity: 1/4-Inch
Spindle taper: JT1
Spindle travel: 1-1/2-Inch
Table size: 3-1/2-Inch by 8-Inch

Harbor Freight Mini Mill 2 speed variable ~$500
Horsepower (hp) 4/5
Maximum speed (rpm) 2500
Minimum Speed (RPM) 1100
Number of speeds Variable
Spindle Taper R8
Voltage (volts) 120
Chuck size (in.) 7/64 in. - 1/2 in.
 
You (and everyone else looking at these table-top ChiCom mills) needs to understand something about Chinese machines:

When you, I or anyone else in the US says "1 horsepower," we're thinking of a horse like a Percheron or a Clydesdale.

When the Chinese Commies say "1 horsepower," they're pointing to a picture of a Shetland pony and saying "Well, it looks like a horse... it has four legs and eats hay, right?"
 
Understood. I really hate to buy Chinese crap and prefer American made. Can you recommended
an alternative? I've been searching around on eBay and Craigs list but just haven't found a reasonable
priced unit.

Thanks.
 
I assume the HF comes with a jacobs-type chuck on a arbor, but its primary tool holding method is the R8 collets. These are much more appropriate for holding tooling that will develop side thrust than a chuck, which I have seen broken of its arbor with a stub left in the back of the chuck.
 
For most people who aren't going to use machines full-time, they could do FAR worse than to seek out a Bridgeport with a J-head. That's the head that needs you to change belt positions on a pulley to change speeds. They're nearly bulletproof and idiot proof.
 
If you have the room for it keep looking for a used Bridgeport. Although I did a lot of work on my first mill (Jet Bench-top), I do kind of regret buying it now. It has been collecting dust since I got my Bridgeport running. I was a PITA to do a lot of things on it. The table was too small... There was too little clearance under the ram for some things... When raising the head on the column the zero would change. too short of a stroke on the column... You can do a lot with a small mill. I'm not saying it CAN'T be useful, but you will spend MANY more hours do things on a small mill.

I paid $70 for my Bridgeport... No I did not miss type that. It cost me JUST over $200 for parts to get it up and running. Less than $300 for a J-head Bridgeport.

Then there is the VFD ($150)... For the most part I can forget that it's a J-head now. It runs from about 500RPM to 3,000RPM without changing the belt position. That covers 90%+ of all my work.

Then there's the ball screw, pulleys, belts, Hardware, motors, drivers, power supplies and software for the CnC conversion I cooked up. I was on the hook for about $4,000, total, at that point. Add the DRO, tool holders, Pump for coolant... I could go on. The point is it is probably best not to buy a mill at all :-) It will never be big enough, or bad enough and there will always be something else to add to it (I'm about $500 away from adding the 4th axis).

It's kind of like a combination new girlfriend/heroine addiction. You will spend all your time and money on it...
 
For most people who aren't going to use machines full-time, they could do FAR worse than to seek out a Bridgeport with a J-head. That's the head that needs you to change belt positions on a pulley to change speeds.

Three letters... VFD. It will run a 1/2" EM down to 65SFM (@500RPM) and tops out at 3,000RPM. It's a little slow for a 1/16" EM so I have to watch my feed rates. I might be able to run the motor faster but I don't want to damage the old beast. I have dilutions of getting a higher RPM 2HP inverter duty motor for it... New precision bearings...

For slower speeds... Back gear! It's great for running the coaxial indicator. With no load on the motor like that I can turn the spindle at about 20RPM without changing the belt. If I drop the belt I can get down to about 14RPM and still have usable torque or about 3RPM with light to no load.

They're nearly bulletproof

You basically have to roll the damn things off a truck to do any damage to them! (that's how I got mine for $70)

and idiot proof.

I know what your saying... However, NEVER underestimate idiots!
 
One of my 1st machines was a used jet bench top mill/drill. 15 or 16 inch??
It would work for your project and plenty of other projects without the foot print of a BP or BP clone and the transportation hassles.

In fact I still have it and use it multiple times a day for drilling and save my BP clone from the bearing abuse of hogging holes up to 1-1/4" diameter in steel.
It is way faster to set up and get drilling than with a BP and has a #3 morse taper for larger bits.
It is also far simpler to work on if it has issues.
 
Three letters... VFD. It will run a 1/2" EM down to 65SFM (@500RPM) and tops out at 3,000RPM. It's a little slow for a 1/16" EM so I have to watch my feed rates. I might be able to run the motor faster but I don't want to damage the old beast. I have dilutions of getting a higher RPM 2HP inverter duty motor for it... New precision bearings...

Exactly my point. For less money than one can spend on a piece of ChiCom scrap, you have a real machine. VFD's are great... but not absolutely necessary to get useable work done with a J-head machine.

Just don't tell the wife about the relative size difference ... and how there will have to be a car parked outside if you get the Bridgie instead of the ChiCom bench mill.
 








 
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