Magnum Industrial MI-31550, Operating Manual

10

MAINTENANCE 

MAGNUM INDUSTRIAL 20" HEAVY-DUTY PLANER 

MI-31550 / MI-31552 / MI-31553

19

WARNING!

Before performing any maintenance, ensure the power switch is OFF and the power cord is unplugged

REPLACING GEARBOX OIL

You should change the gearbox oil after every 2,500 hours of 
operation. Use 80W-90 gear oil. To change the gearbox oil, 
follow these steps:

1.  The gearbox is located behind the panel on the right 

side of the planer. To remove the panel, first remove the 
handwheel. Next unthread and remove the feed speed 
adjustment knob. Then remove the panel.

2.  Place a container under the 

DRAIN PLUG (A)

 and 

remove it using a 14 mm wrench. Once the gearbox 
is drained, reinstall the 

DRAIN PLUG (A)

, and then 

remove the 

FILL PLUG (B)

 using a 14 mm open wrench. 

See Figure 19.

3.  Fill the gearbox with a 80W-90 gear oil until it reaches 

the hole. Reinstall the 

FILL PLUG (B)

, and replace the 

panel, handwheel and feed speed adjustment knob.

FIGURE 19: CHANGING THE GEAR OIL

PERIODIC MAINTENANCE

•  Inspect the ON/OFF switches before each use. Do not operate the planer with a damaged switch. If you notice any damage to 

the ON/OFF switch, replace it immediately.

•  Keep the machine and table clean and free of sawdust, wood chips, pitch or glue. Regularly, vacuum or brush off loose debris 

and wipe down the machine and the table.

•  Occasionally apply a light coating of paste wax to help protect the table surface and reduce workpiece friction. Ask your local 

branch for suggestions on aftermarket surface cleaners and dry lubricants based on what is available in your area.

•  Avoid using silicon-based products that could react with wood-finishing products such as varnishes and lacquers or oil-, 

solvent- or water-based stains.

•  Periodically inspect the power cord and plug. To minimize the risk of electrical shock or fire, never operate the planer if you 

notice its power cord or plug is damaged. Replace a damaged power cord or plug at the first visible signs of damage.

•  The drive gears, chain and elevation screws should be cleaned of wood chips, dust, debris and old grease. After cleaning, re-

lubricate according to the lubrication instructions on page 11. Don't over lubricate. 

•  Regularly inspect planed workpieces for signs of damaged or worn inserts. Replace damaged or worn inserts immediately.