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Rong Fu RF-25 Mill Drill Tap Specs & Views

Original configuration. See RF-25 Mill DRO & X Y Z axes scales. RF-25 Mill Tachometer & SFM
4" import vise has been replaced by a 6" Parlec vise, DROs added, standard incandescent light replaced by a halogen lamp.

 
24 mm = 0.945"
14 mm = 0.551"
10 mm = 0.394"

Runs very smoothly & quietly. Drawbar nut is 17mm.

Depth stop & column lock.

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

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

The fine down feed housing is held to the mill with two hex bolts. To add some backlash adjustment to the fine down feed,
I removed the housing, opened up the two 9mm mounting holes to about 9.5mm & turned the screw heads down a few thousandths.
There was also some paint over spray on the worm gear that needed to be 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 three axes scales (1 division = 0.001") were verified as accurate.

1 hp, 110 VAC, 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-SAE standard size of ½-12x7 with
13/16" hex heads which makes it very hard to find a direct replacement.
A SAE 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, SAE 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).

I have found that highest accuracy (best tram) is achieved
 by tightening the top bolt first & then going back & forth several times.

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

Kurt-style 4" milling vise (37 lbs).
Used hardened bolts & washers with standard T-nuts. Moved this vise to the floor drill press.
Parlec 6" vise now being used on the RF-25. Moved the 4" vise over to the floor drill press.
See Measurement Instruments for tramming techniques.

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

Power feed works very well; clamps onto table end.

Left/Right direction lever, variable-speed dial & momentary high-speed (yellow) button.
Gear attached where original handle would go (black plastic gear cover removed).

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

Table travel-limit switch. This has been modified for the DRO X-axis scale mount.

Vibration-absorbing machine mounts (from Enco) supporting (optional) Rong Fu cabinet.
I use Teflon furniture moving pads (attached with double-sided foam tape) under the feet.
Similar mounts used on the lathe & band saw.