Author Topic: So you're looking to buy a mill...  (Read 12079 times)

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LESchwartz

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So you're looking to buy a mill...
« on: January 29, 2008, 11:58:00 PM »
So you're thinking about purchasing a milling machine for your home workshop.  There is a multitude of machines to choose from (especially once you cross the $1000 threshold).  And by while by no means the definitive work on the subject, here are the results of my research to help get you started.

The following mills seem to be the most popular choices:

  • Sieg X1 Micro Mill:  The name says it all:  A $300 mill with a minuscule table, and at 1/5 hp it's widely considered underpowered.  For an additional $200, you can purchase a larger table and tilting column to convert your X1 into a "Super X1", but by then you've spent as much as you would have for a Sieg X2.  Recommendation:  Pass and buy a mini-mill.

  • Sieg X2 Mini Mill:  This is the "gold standard" of bench top mills.  $500 gets you a basic square column mill, from anyone of several companies (HF, Grizzly, etc, etc).  Since this mill is so popular, there is a wide variety of accessories available.  The X2 also has an interesting "45 degree tilt column" -- and while 45 degrees isn't enough for horizontal boring operations, it is enough to save you from having to purchase a tilt vise.  Now for the downsides:  The table size is wanting (15" x 3.5", which is slightly smaller than the Super X1 table).  In addition, don't believe the specified HP rating:  350 watts is 1/2 hp, not 4/5 hp.  Finally, some users have expressed concern that the column mount allows for flexing.  Recommendation:  Despite the downsides, the low entry price makes this mill a best buy.

  • Sieg X3 Small Mill:  These are capable square column bench top mills with a medium sized table (21" x 6") and decent power (3/4 hp).  They're are sold by a variety of companies (HF, Grizzly, etc) at right around $1000, and are a reasonable step up from the Sieg X2 -- offering twice the power and table area.  Unfortunately like the smaller Sieg mills, the head doesn't tilt.  So boring operations will need to be done vertically -- which may or may not be a problem, depending on if you can fit your work under the X3's 14 inch spindle clearance (don't forget to allow room for the tooling and vise).  Recommendation:  YMMV.

  • Round column mills (similar to the Rong Fu RF-30 series):  These are sold by a many different companies (Enco, Grizzly, etc), and your $1200 buys a lot of machine:  Spacious table (typically 28" x 9"), plenty of work clearance (18" spindle to table), plenty of horsepower (up to 2hp), and maybe even a stand.  No doubt about it, these are commercial machines at a reasonable price!  Now for the downside:  The round column means you'll need to square the head each time you raise or lower it -- and depending on the operation, you might have to raise the head just to change tooling.  Some folks claim success mounting a laser to the head, and using it to square the head to a target across the room.  As with all the mills considered previously, the head doesn't tilt -- so you can't do horizontal boring operations.  Recommendation:  YMMV.

  • Sieg Super X3 Small Mill:  All the features of the Sieg X3, plus a 90 degree tilting head and a more powerful motor (1 hp).  The tilting head lets you bore horizontally when the work is too big to fit under the spindle.  Unfortunately the current pricing of these mills allows you to step up to a Rong Fu RF-45 Clone for about 20% more.  Recommendation:  Nice mill, but seriously consider an RF-45 instead.

  • BF25, G0704, LM25, etc:  The machine itself is about 100 pounds lighter than an X3 -- that's not a good sign for rigidity.  But pound for pound, the design should be slightly more rigid than a x3 based on the boxed column on the bf25.  The base is about the same size on the bottom, but much less beefy.  The table is larger and so is travel, but that saddle looks very skinny. I doubt the table will hold the 150 pounds that the X3 will.  The X3 is also taller. The X3 Throat is almost 2 inches larger and it has a bit more spindle height above table.  Drilling capacity & end mill capacity are only 3/4 that of X3. Dials are calibrated .002 compared to X3 .001 and .0005 on Z.  All in all, I get the impression that this mill is lighter duty than X3. I place it somewhere between the X2 and X3.  However, the larger table size and travel is a big plus, as is the lower price.  Recommendation: Nice mill, if you've been considering a X3 or SX3, this mill should be given serious consideration.

  • Rong FU RF-40 Clone:  These are sold by a many different companies (Enco, Grizzly, etc), and priced somewhere between a round column mill and the RF-45.  These are your basic round column mill with a twist:  a direct gear drive that allows the head to be tilted.  I haven't found one that does more than +-45 degrees -- so you still can't do horizontal boring operations, but it might save you the cost of a tilting vise.  Recommendation:  YMMV.

  • Rong FU RF-45 Clone:  The Taiwanese-built RF-45 square column mill has been very well received -- and while the Chinese-built clones can need tweaking right out of the crate, they're about 1/2 the price of the genuine Rong Fu.  This puts a RF-45 class mill in your hands for as low as $1500 (Enco, Lathemaster, etc).  These mills are more capable in every aspect than the Sieg Super X3, and are a big step up from any of the mills considered previously.  Recommendation:  Best buy.

  • Used Bridgeport, et al:  These are large, accurate, multi-ton industrial mills -- which can often be purchased for as low as $1500.  So for your money you get a real industrial strength machine.  But this also means that you have to find space for your new behemoth, as well as an outlet for 240v 3-phase power -- not to mention that your "new" mill could turn end up needing a tune-up or even a rebuild before you can even use it.  Recommendation:  Wonderful deals can be had, but use extreme caution if you’re not an expert on judging the condition of a used mill.

In addition to the milling machines themselves, there are several options that can significantly add to the cost.  These include:

  • Tooling:  You choices are typically R8 and MT3.  R8 is much more popular, while MT3 Works a little better on smaller mills.  Recommendation:  R8.

  • Power feed:  Power feeds basically provide a motor to turn the mill's table screws.  This can be very handy when making long cuts on large tables, since the motor turns the screws more smoothly than you can -- and without your constant attention.  You should seriously consider purchasing this option if you a buying a mill with a large table, or will be doing a lot of work with your mill.  Note that there is no need to purchase this option if you are buying CNC.  Most mills allow for retrofit of this option.

  • DRO (digital read out):  Nice feature, but not a must have.  Basically, this feature speeds up your measurements.  Most mills allow for retrofit of this option.

  • CNC (computer numeric control):  A really nice feature, but very pricey and not a must have.  CNC allows for the computer to control basic milling operations.  In addition, the computer can precisely control multiple axis at the same time, giving you the ability to create complex shapes.  Most mills allow for retrofit of this option.  Note that on some mills adding CNC will remove your ability to manually control the mill, but you can do that via the computer -- kind of like playing a video game.
« Last Edit: February 15, 2012, 10:08:11 PM by LESchwartz »
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LESchwartz

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Re: So you're looking to buy a mill...
« Reply #1 on: January 30, 2008, 12:40:29 AM »
This picture shows the scale of the X2, X3 and RF45 mills. Notice the mass of the RF45 over the X3.  Note:  I borrowed this photo from fignoggle.com, where they have allot of info on smaller mills.


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7.62x39

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Re: So you're looking to buy a mill...
« Reply #2 on: January 30, 2008, 01:04:11 PM »
Another thing to keep in mind. Getting something with a R8 collet vs the Morse taper will open the doors to a lot more tooling

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Re: So you're looking to buy a mill...
« Reply #3 on: January 30, 2008, 04:21:26 PM »
R8 collets are the way to go on large machines doing big work. A full set sits by our Bridgeport.

Similarly for a lathe the 5C collets are a dream.
(Yes there are times when 3 and 4 or more jaw chucks are needed.)

Repeatability is the name of the game on any type of Vert. mill.

The Bridgeport mentioned above does have power feed however it is something that I typically elect to not use. I guess if you're doing production or super long cuts then it would be a go.
For me feeding by hand gives me a good insight on what is happening to the tooling and material being used.

 Something like those at the top would be neat to have at home or in ones garage. I looked at a 'home' mill just recently. I don't think it was any of the brands listed above Larry.
There was so much slop in the 'handles' that I stopped right there and didn't pursue it further.


« Last Edit: January 30, 2008, 04:26:36 PM by Fragger »
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LESchwartz

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Re: So you're looking to buy a mill...
« Reply #4 on: February 06, 2008, 07:44:58 PM »
I don't know enough about mills to make a judgment about what's good and what's not.  But a machinist buddy of mine was thoroughly impressed with my $500 X2 . . . but then I'm sure his expectations were low.

Larry
« Last Edit: February 06, 2008, 07:53:49 PM by LESchwartz »
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LESchwartz

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Re: So you're looking to buy a mill...
« Reply #5 on: February 06, 2008, 07:52:12 PM »
BTW, I noticed there are now some RF-40 clones available, so here's the blurb I added to the original post:

Rong FU RF-40 Clone:  These are sold by a many different companies (Enco, Grizzly, etc), and priced somewhere between a round column mill and the RF-45.  These are your basic round column mill with a twist:  a direct gear drive that allows the head to be tilted.  I haven't found one that does more than +-45 degrees, so you still can't do horizontal boring operations, but it might save you the cost of a tilting vise.  Recommendation:  YMMV.

Larry
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LESchwartz

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Re: So you're looking to buy a mill...
« Reply #6 on: February 15, 2012, 10:09:40 PM »
BTW, I noticed there is a new Mill from Grizzly, the G0704.  So here's the blurb I added to the original post:

BF25, G0704, LM25, etc:  The machine itself is about 100 pounds lighter than an X3 -- that's not a good sign for rigidity.  But pound for pound, the design should be slightly more rigid than a x3 based on the boxed column on the bf25.  The base is about the same size on the bottom, but much less beefy.  The table is larger and so is travel, but that saddle looks very skinny. I doubt the table will hold the 150 pounds that the X3 will.  The X3 is also taller. The X3 Throat is almost 2 inches larger and it has a bit more spindle height above table.  Drilling capacity & end mill capacity are only 3/4 that of X3. Dials are calibrated .002 compared to X3 .001 and .0005 on Z.  All in all, I get the impression that this mill is lighter duty than X3. I place it somewhere between the X2 and X3.  However, the larger table size and travel is a big plus, as is the lower price.  Recommendation: Nice mill, if you've been considering a X3 or SX3, this mill should be given serious consideration.
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