Homier Mini-Mill Review

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Head Assembly

The head assembly is quite similar in construction to the Grizzly mill, and the major parts look as if they might even be interchangeable with the Grizzly. The head can be quickly moved up and down the column by means of the drill-press-style 3-arm handle. The large silver knob on the right side is a fine-feed adjustment knob that allows the head to be moved up and down with precision to .001".

head1=.JPG (46496 bytes) specs=.JPG (52466 bytes)

Mounted to left side of the head is the motor control box. On the front, a chip shield with adjustable height is provided for safety. The chip shield is the same as the one on the Grizzly mill which I found to be of limited use.  The basic idea is good, though, so I made one that I like much better and use religiously. I'll be adding my design to the modifications page at a later date.

On the back of the head is located the Hi/Lo gear lever. This lever selects the speed range - 0 to 1100 RPM in LO range and 0 to 2500 RPM in HI range - by engaging gears within the head casting. Most milling operations are done in LO range, with HI range being used mainly for drilling with small diameter drills. HI range is also useful for making light finishing cuts of less than .005" depth.

hi_lo_lever=.JPG (41206 bytes) torsion_arm=.JPG (34245 bytes)

A spring-loaded arm helps to offset the weight of the head. The arm slides along a stud mounted to the side of the head. Early models of the Grizzly mill used a pressurized gas piston mounted in the column for this purpose. The torsion arm seems to work fine, but Steve Bedair reports that it prevents the head from getting as close to the table as is sometimes necessary - he modified the mounting to solve this problem. (This used to be a link to Steve's site, but that content is no longer available)

Rapid movement of the head up and down the column, referred to as Z-axis movement, is accomplished by turning the drill-press-style 3-arm handle. This handle can move in and out on its shaft to switch from coarse-feed to fine-feed. In fine feed mode, the silver knob at the front of the head moves the head up and down in increments down to .001".

z-axis=.JPG (35745 bytes) z-axis_dial=.JPG (29293 bytes)

This arrangement is identical to that on the Grizzly and suffers from the same weaknesses: there is considerable backlash (nearly a full turn of the silver dial- but this can be reduced with some work) in the fine-feed drive, and a tendency for the head to slip downward during cutting operations if it is not tightly locked in place by means of the gib locking lever (visible below the hub of the 3-arm handle). On the plus side, this arrangement works very well for drilling operations and, with care and practice, can produce milling cuts to a desired depth with acceptable accuracy.

Spindle and Drawbar

Unlike the Grizzly mill, which has a #3 Morse Taper spindle, the Homier mill sports an R8 taper spindle typical of Bridgeport and similar full size mills. I have not used an R8 taper before, so I have no real basis on which to comment on the pros and cons, but some machinists seem to prefer them. There is a wide variety of tooling available for the R8 taper, so finding end mill adaptors is easier than for the #3MT variety. Below the Homier and Grizzly spindles are shown side by side for comparison.

spindle=.JPG (33793 bytes) Spindle_.jpg (27939 bytes)

Shown below is a comparison of the drill chucks and arbors for the Homier Mill and Grizzly. The right hand photo shows the corresponding drawbars. For both types, the drawbar mates with a female thread in the top of the arbor and, when tightened, draws the arbor tightly into the spindle so that it will not work loose during cutting operations. The R8 taper has a spline along its length that must be aligned with a key in the spindle.

The Morse taper is known as a locking taper and the R8 as a non-locking taper, the difference being that a non-locking taper tends to release from the mating taper more easily once the drawbar is loosened. For either type, you generally need to tap on the top of the drawbar with a brass or plastic hammer to release the arbor.

chucks=.JPG (30060 bytes) drawbars=.JPG (37702 bytes)

To keep the spindle from rotating as the drawbar is being tightenend a spindle locking pin is inserted into a hole in the side of the head assembly. Of course, the locking pin must be removed before starting the mill, or the gears could be damaged. Steve Bedair made a spring-loaded locking pin to avoid this risk.

lock_pin=.JPG (88655 bytes)

Collets and Adaptors

Shown below is pair of R8 collets and a 1/2" R8 end mill adaptor. Either can be used to hold end mills, but the collets are less expensive - I purchased a set of six (1/8-3/4 by 1/8) from Enco (P/N 231-4606) for about $23 from the sale flyer. This set will hold just about any end mill you are likely to use. By comparison, the single end mill adaptor (Enco P/N 210-0106) was $12.99 in the sale flyer.

You will need several to hold end mills with various shank diameters. Be sure to order one or the other when you get your mill, since none are provided. The #3 Morse taper adaptors for the Grizzly mill run about $18 each and are much harder to find, however the Grizzly mill comes with a 3/8" and 1/2" collet to get you started.

collets=.JPG (21248 bytes) collet1=.JPG (24663 bytes)

Motor and Electronics

Mounted on top of the head assembly, the motor is indistinguishable from the one on the Grizzly mill. It is labeled with the standard 4/5HP rating which no one I know really takes seriously. 1/2HP is probably closer to reality, but the motor has plenty of power for this little mill, so it's really not worth debating. As many of us have discovered: you will break the gears before you stall the motor.

motor=.JPG (66223 bytes) motor_label=.JPG (71448 bytes)

Electronic controls are mounted on the box on the left side of the head with the speed control knob, green power-on pilot light and fuse holder on the front and AC power and emergency stop button and yellow overload pilot light on the left side. The silver on/off toggle switch found on my early model Grizzly mill is gone but not really needed, since the speed control knob switches the motor off when rotated fully counterclockwise.

controls=.JPG (44124 bytes) ps_box=.jpg (41574 bytes)

The power supply is mounted in a separate box at the top rear of the column. A small DC fan ventilates the box to keep the electronics cool. The power supply design is basically the same as the Grizzly model, but has been updated to use surface mount technology. Gone is the daughter board with the speed control pots; these components are now mounted on the main board - a much more robust design.

 power_supply.JPG (118292 bytes)

Well, that's all for now.   Thanks for visiting.

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