Rong Fu RF-25 Mill/Drill Specifications & Views
Last updated on Friday, April 19, 2013 05:59:02 AM Eastern US Time Zone

Specifications, Belts Drive, Speeds, Fine Down Feed, Motor,
Integral Light, Milling Vises, Power Feed, Quill Arms, Machine Mounts

Original unmodified RF-25 mill configuration. The 4" vise has been replaced by a 6" Parlec vise,
DROs added, & the standard incandescent light replaced by a halogen lamp. The mill is at the
upper limits of weight & size that I could move safely down a hill & into my lower level walkout.
See RF-25 Mill DRO & X Y Z axes scales. RF-25 Mill Tachometer & SFM

 
RF-25 mill table slot dimensions where: 24mm = 0.945", 14mm = 0.551", & 10mm = 0.394".

Belt Drive

Runs very smoothly & quietly. Multiple pulleys provide ample torque & no gears to break. Drawbar nut is 17mm.

Forward (up), Stop & Reversing (down) switch.

Speeds

12 speeds. Easy to change; note & set two numbered pulley positions.

Fine Down Feed

The fine down feed housing is held to the mill with two hex bolts. To add some backlash adjustment to
the fine down feed, the housing was removed, the two 9mm mounting holes were opened up to about
9.5mm & the screw heads were turned down a few thousandths. There was also paint over spray on the
worm gear that was removed. Be sure to re-grease the worm gear. These relaxed tolerances allowed
additional housing movement to mesh the gears much closer & thus reducing backlash.
All 3 axes scales (1 division = 0.001") were verified as accurate.

Depth stop & quill lock.

Motor

1 hp, 110VAC, 60 Hz, single-phase, fully enclosed, externally cooled, motor.
Note motor locking leaf bolt for belt adjustment & the two, OEM 19mm (¾") column locking nuts.

Possibly due to the OEM bolts not being hardened, they were beginning to strip. The OEM head-
locking cross bolts are a non-standard size of ½-12x7 with 13/16" hex heads which makes it very
hard to find a direct replacement. A standard bolt is ½-13 with a smaller, ¾" hex head which would
not properly fit into the cast recess that prevents turning. The bolt holes were already 9/16" & did
not have to be opened up so I bought hardened, Grade 8, standard 9/16-12x7 bolts from Bolt Depot.
This size has the requisite 13/16" hex head & fit through the holes but the bolt touched the mill's column.
I lathed the center area down to ½" as well as relieving the area under the head. The bolts fit perfectly &
 are now all hardened, bolt/washer/nut assemblies. A ⅞", 12-point deep socket, used with a long-handled
⅜" drive ratchet work nicely. A 12-point socket engages the nut quicker (using less wrench movement).
The best alignment is achieved by tightening the top bolt first & then going back & forth several times.

Integral Light

Installed a vibration-resistant 60W light in the mill head's internal cavity. The large upper plastic housing holes
allow heat dissipation via convection. The upper bracket is shown. A porcelain socket & rotary switch were used.
The AC cord is held by a cable tie down. This is similar in function to my OEM light in the Jet floor drill press.

The bulb sticks out to give a better light dispersion angle & good accessibility for changing.

Cutting with the halogen light on but the built-in lamp off.

Cutting with both the halogen & built-in lamps on.

Milling Vises

Parlec PSW-6900. The upgraded vise is several orders of magnitude improvement over the 4" model.


First selected Kurt-style 4" milling vise (37 lbs.) Used hardened bolts &
washers with standard T-nuts. Parlec 6" vise now being used on the RF-25.

Swivel base for the 4" mill vise. Remove to increase Z distance & overall rigidity. Used only as needed.

Power Feed

Variable speed power table feed has high torque throughout its range, works very well.
Clamps onto table end. An integrated travel-limit switch is mounted on the front edge of the table.

Left/Right direction lever, variable-speed dial & momentary extra high-speed (yellow) button.
Gear attached where original handle was located (black plastic gear cover removed for illustration).
Power table feed operation manual.

CAUTION: Do not change power feed directions suddenly, especially at high speeds.
Move lever to the center, neutral position & wait until motor stops.

The yellow gear cover removed. Use graphite-based grease not silicon type.

Bottom view showing the motor engaging the X-axis gear that replaced the left handle.

Table travel-limit switch.

Quill Arms

Removed all of the quill levers so they do not contact the piece when working close to the vise.
This configuration allows much better access to the two column locks, belt tension lock, & DRO.
I made & installed ½-12 threaded aluminum plugs to give it a finished look & keep the chips out.
 I like the extra control afforded by the fine down feed & have no need for the levers.

Machine Mounts

Vibration-absorbing machine mounts (from Enco) supporting (optional) Rong Fu cabinet.
Teflon furniture moving pads (attached with double-sided foam tape) are under the feet.

Specifications, Belts Drive, Speeds, Fine Down Feed, Motor,
Integral Light, Milling Vises, Power Feed, Quill Arms, Machine Mounts

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