Mills And Lathes

[Carlos]

[edit: I broke these post out of another thread. The mini-mill topic deserves it's own thread, for sure. I'd hope this thread follows the path of "positive feedback", rather than...something else. -- Kyle F.]

Merlin, the topic of the mini mill came up once before with a variety of opinions expressed; I am here to tell you that the Mini Mills from Harbor Freight and Homier are fully capable of precision work if used with patience by a skilled, un-hurried operator. (links below)

Last time, there were some people who weighed in against the mini mill & I think most of them were retired machinists who used other people's money to buy Bridgeport industrial mills and USA Starret brand high precision tools totaling tens of thousands of dollars. I think some people hate anything made in China or Tiawan; I doubt any of them even tried machining on a mini mill & if they did, they tried to compare it to a fifty grand Bridgeport (which is not a fair comparison).

Well, below is a list of links to folk's pages where the precision of the mini mill has been shown time and again. Take a look at all these pages & I believe you will see the many great things that the mini mill can accomplish with the patience & ingenuity of a home workshop machinist.

www.littlemachineshop.com (this site sells all parts for the mills & compares several mills. Also has a good how-to).

http://www.mini-lathe.com/Mini_mill/Main/mini-mill.htm (actually about the mini lathe but with links & honest assessment of these machine's capabilities)

http://www.varmintal.com/alath.htm (another home hobbiest who was a machinist by trade & took the time to work with these machines with great results).

www.harborfreight.com (the source of my mill)

www.roderuscustom.tzo.com (take a look at his 1911 project built on a mini mill. The forum there let me to Blind Hogg at www.blindhogg.com where I was inspired to try parkerizing guns for the 1st time).

I would love to have a full sized mill & a full machine shop at my disposal but that is not likely to happen anytime soon; I get by just fine with my mill. I guess it still sort of bothers me when people look down on such a mill for gunsmithing. I'd love to see more folks learning precision machining & milling at home; how many potentially great ideas go unrealized because some shooter did not have access to machine tools?

Regards,

D.C. Johnson

[Carlos]

Forgot to add that my mill is a model 44991 and is listed on this comparison chart: http://www.littlemachineshop.com/Info/minimill_compare.php

Regards,

D.C. Johnson

[Merlin Orr]

Thanks much for the info and taking time to put this togather. Just looked at the first link and know much more than I did. Looks like a considerable learning curve...but fun if you take your time.

[Carlos]

A couple of tools are necessary/useful for the any gunsmithing mill.

First and foremost is a mill vice. An ordinary vice will not do. You need a machinist vice which fortunately, is not very expensive. I selected the 3" Precision milling vice; it cost $84 and weighs 26 lbs. It is pictured above mounted on the mill and at the link below. I usually use it without the degreed swivel base for greater rigidity and clearance. An exception was the front cocking serrations (similar to STI) that I did on a past project; there I needed a set angle (15 degrees). Here is a more complete explanation about the various types of suitable machine vice for the mini mill.

http://www.littlemachineshop.com/info/gett...MiniMill_08.htm

[Carlos]

An alternative to the vice is the more time consuming clamping kit that allows you to mount a work piece right to the table. Remember playing with an erector set as a kid? Everything was loose until you tightened the bolts; a clamping kit works the same way. It can be very frustrating to use, but sometimes necesary.

Follow this LINK to the full page.

[Carlos]

You will need some precision measuring tools; if you own a reloading caliper then you are already familiar with how to measure down to the thou of an inch. The dials on a mini mill are graduated in these.

A similar tool is the dial indicator. It is graduated in thou and is spring loaded. It can be used for leveling work.

It is critical to level the work relative to the spinning bit or mill, not simply to some other surface, Though I own a fancy Starret machinist level, I rarely use it as every other surface has to be perfectly level too for it to work. Here is a poor photo of a dial indicator with a 1" range being used to level a 1911 frame:

(click here for full sized picture)

[Rising Sight]

Last time, there were some people who weighed in against the mini mill & I think most of them were retired machinists who used other people's money to buy Bridgeport industrial mills and USA Starret brand high precision tools totaling tens of thousands of dollars. I think some people hate anything made in China or Tiawan; I doubt any of them even tried machining on a mini mill & if they did, they tried to compare it to a fifty grand Bridgeport (which is not a fair comparison).

You can pick up a decent used Bridgeport Series 1 for $2000-$3000 if you look around. For fifty grand you could get a nice brand new 3-axis CNC Series 1 with plenty of tooling.

[robomanusa]

The mini mills look nice and I am sure are capable of plenty. I thought about buying one, but after spending 12 years working for Milacron here in Cincinnati, the last thing I wanted to see was a machine when I got home from work, LOL.

[Carlos]

Gear Head - I agree with you that a used Bridgeport, w/ a little TLC & a skilled operator, can do just a nice a job as the small chinese bench top mills. The machining skills that deliver quality results on a home workshop bench top mill will work the same way on larger industrial machines, like a Bridgeport.

Regards,

D.C. Johnson

[Merlin Orr]

What I am now wondering is - what part of building a 1911/2011 type gun CAN NOT be done with a bench top mill...??

[Flexmoney]

For some reason, I had the thought that they didn't have enough travel to cut the bridge area for a ramped barrel? Anyone?

[Harmon]

threading a barrel!

idk about the barrel ramp...

[Harmon]

Flex, the smallest mill harbor frieght sells has the following capabilites:

X axis 9inches

Y axis 4 inches

Z axis 1-3/16

it might not work with a real 1911, but you should be able to take the grip off a 2011 and cut your ramp cut that way...or im confused as to why it cant cut the bridge area

[Carlos]

It can be done. We are talking about the face cut on one type of ramp cut: the Nowlin/Wilson that is the only ramp cut found on factory STIs (the Clark/Para is easy to do on any mill incl the mini mill).

Here is the 1st of 2 methods:

Sorry for the 90 degree rotation & poor focus.

You will need the supplemental gear track for the mini mill ($14). This gives you sufficient travel to move the head high enough for the specialized N/W bridge cutter. The frame (sans grip) is simply held in the vice and trued to the head, then cut as normal. As far as rigidity, there is plenty to long as you keep the feed rates reasonable; though I had my doubts about my set up, the tool is piloted and uses the dust cover as a guide. It is actually more rigid than it looks.

The second method that likely does not need the additional track is to use a precision ground angle plate (a 6" ground iron plate should work). Attach and true plate, then use the clamping kit to attach the frame to the plate (and true that too). Finally, use the x&y to position it in the center and lock down the table. More than enough rigidity with such a set up.

As far as threading a barrel, the mill does not thread barrels as its a job best left to a lathe. I have used a 1 1/8" tap in the mill to tap the hole in an AR-15 lower for the buffer tube; I also used the mill to drill & mill the hole.

Regards,

D.C. Johnson

[Carlos]

As far as the other cuts on the ramp (or all the cuts on a Clark/Para) the frame is simply held in the mill vice, trued, and the cuts made as usual:

Regards,

D.C. Johnson

ps - the above-mentioned precision ground iron angle plate is pictured in the background of the photo above.

[robomanusa]

What I am now wondering is - what part of building a 1911/2011 type gun CAN NOT be done with a bench top mill...?? 

<{POST_SNAPBACK}>

If you had the time and willingness...there is no reason you couldn't make a complete 2011 frame on a mill(mini-mill)...might have to make yourself a few fixtures along the way, but it can be done.

[Merlin Orr]

Nick

Know what you are saying.... Perhaps I should have included "reasonable done with a mini mill" in my question...

[robomanusa]

Nick

Know what you are saying.... Perhaps I should have included "reasonable done with a mini mill" in my question...

<{POST_SNAPBACK}>

LOL... you could get away without making the fixtures, but, you have to think, since your making one complete, will you stop with just making one?...I wouldn't, LOL, so while doing the first one. I would make things easier for the next.

I have never touched a mini-mill, all my work has been on Devlig's...

[BrianH]

You can also just purchase a barrel with a Clark ramp. Nothing wrong with them and much easier to finish.

[Stumpnav]

For those of you bit by this bug, Harbour Freight has there small mill on sale for $459.

[shred]

Also check into the Taig models.. a bit smaller but US-made and much nicer out of the box. I've been playing with a CNC converted one for a few months now which is great for engraving.

[rtr]

Holy shit Shred your really Oprah's boyfriend?

[Carlos]

Holy CRAP that is nice work!

For those interested, CNC = Computer Numerically Controlled machining.

Basically, a computer is hooked up to a mill or lathe. The computer operates the machine using special motors called "stepper motors". If you hve ever flipped up the front of your ink-jet or the old dot matrix printer while it was printing, then you have witnessed a computer operating stepper motors.

You have also seen the effect in 2 dimensions on the printed paper. A CNC mill works in a similar fashion only it has to take into account at least 2 more variables: a third dimension and speed/feed rates (mills do not simply zip through steel like a router through wood; precision machining requires that steel must generally be removed in very small amounts in pass after pass).

The beauty of a CNC however is that the computer does the cutting. Downside is that you still have to do the programming and set up (time consuming the 1st time; there after its easier).

Some set ups are easy; things like lettering are done with a special program where the letters are already programmed in and such programs only require that you tell the CNC machine what letters & the size/location of the work; you get letters of a fixed depth & they are perfect every time. Other things, like an STI/SV frame from a billet, might require up to 8 or more "operations" and thousands upon thousands of passes back and forth by the machine. THese are typically done inside a special cabinate called a CNC machining center where coolant/lubrication is constantly sprayed onto the work, collected, filtered & re-sprayed. The best of these will even sellect different size mills or bits from a special rack and can accurately compensate for tool wear. Such centers are vastly expensive and require skilled operators.

While there have been a few successful conversions of the mini-mill to CNC, in my opinion the precision is not there to begin with & hard to build into the system. For CNC work, it pays to get as much initial precision as you can reasonably afford. My experience was with my friend Joe's CNC conversion of a Rong Fu mill ("CNC Masters" did the conversion I believe) though sadly Joe passed away before we were able to use the machine to its potential.

Regards,

D.C. Johnson