BD-920N 9x20 Lathe
Last updated on Sunday, March 02, 2014 09:24:54 AM 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 8"x17" (195mm x 450mm) Emco-Maier Compact 8 (Austria), father of the current breed of 9x20 lathes.
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 safely move 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|
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.
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.