Jet
BD-920N 9x20 Lathe
Specifications &
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Last updated on
Sunday, March 10, 2013 09:42:05 PM
Eastern US Time Zone
Original Design, Jet BD-920N, Specifications, Belts, Gears, Gear Ratios, Lathe Machine Mounts
9x20 Lathe DRO X & Z1 axes Scales. 9x20 Lathe Tachometer & SFM BD-920N manual.
Original Design
Original 8"x17" (195mm x 450mm) Emco-Maier Compact 8
(Austria),
father of the current breed of 9x20 lathes.
Jet BD-920N
DRO-equipped Jet
9x20 belt drive metal lathe Model BD-920N &
S-920N stand manual.
The lathe is at the upper limits of weight & size that I could move safely down a
hill & into my lower level walkout.
| Swing Over Bed | 9" |
| Swing Over Cross Slide | 5-5/16" |
| Distance Between Centers | 20" |
| Hole Through Spindle | 25/32" (0.78125") |
| Spindle Mount | 1½ x 8 TPI |
| Spindle Taper With Sleeve | MT3 |
| Number of Spindle Speeds | 6 |
| Range of Spindle Speeds | 130 - 2,000 RPM |
| Number of Longitudinal Feeds | 27 |
| Range of Longitudinal Feeds | 0.005 - 0.011"/rev |
| Number of Inch Threads | 27 |
| Range of Inch Threads | 8 - 56 TPI |
| Number of Metric Threads | 11 |
| Range of Metric Threads | 0.05 - 3 mm |
| Max Tool Size | ½" x ½" |
| Max Compound Slide Travel | 1⅞" |
| Max Cross Slide Travel | 5" |
| Max Carriage Travel | 16" |
| Tailstock Spindle Travel | 1-9/16" |
| Taper in Tailstock Spindle | MT2 |
| Steady Rest Capacity | ¼" x 1⅞" |
| Follow Rest Capacity | ¼" x 1⅛" |
| Width of Bed | 4½" |
| Overall Dimensions with Stand | 37½" L x 20" W x 45" H |
| Main Motor | ¾ HP, 1 Ph 115V only |
| Weight | 235 lbs. |
| Stock Number | 321373 |
Belts
Jet BD-920N Belt Lathe Pulley Ratios
See the variable-speed DC
motor upgrade.
Reduce high
idler belt tension & belt breakage by
installing an S-link on the spring.
Using the clutch, slip the Gates
5M710 belt (USA) for heavy
and/or high RPM loads. The 85 teeth
170XL050 timing belt on the motor is from Polybelt.
Timing belts are identified by
3 parameters
& are marked as follows - 170 XL 050
Where: The first number is the belt length in inches (170 = 17.0").
The letters denote the pitch; the peak to peak tooth spacing (XL = 1/5").
The last number is the belt width in inches (050 =
½").
The lathe incorporates several OEM safety features: pulley slip-clutch on
lowest speed, thin V-belt drive, plastic lead screw gear,
Aluminum safety shear pin at the gearbox output shaft connection to the lead
screw.
Gear
Ratios
Gear ratios for feed rates. See
Jet feed gears.
Other 9x20 lathes have additional gear
sizes that are interchangeable with the Jet
BD-920N. Gear ratio charts
differ among the machines (Jet vs. Enco).
Bought additional gear sizes (120T, 127T) to have more ratios.
The 97 lb OEM lathe stand
is low in height to accommodate the
installation of machine mounts which can easily
add 1½ to 2 inches to the lathe's overall
height. Each mount has a steel cup with a rubber vibration absorber &
an adjustment
screw. The six holes in the stand are threaded (⅜-16 for a Jet) but I drilled them out
to 9.5 mm for
a tight fit to the Enco machine mount
M10-1.5 adjustment screws. There are four mounts under the spindle & motor
since
that is where most of the weight is located; six mounts total. They allow easy leveling of
the machine.
Check the front-to-back leveling on both the left & right sides of the
bed to insure that it is not twisted.
Addition of the machine mounts increased lathe height,
afforded adjustment, reduced noise, reduced vibration &
eliminated any
possible walking. Teflon furniture moving pads
(double-sided foam tape) are used under the feet.
Similar pads are used on the
mill/drill & the
band saw.
Machine feet manual.
