Grizzly G0758 owner manual Adjusting Gibs, Adjusting Leadscrew Backlash

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Adjusting Gibs

Gibs are tapered lengths of metal sandwiched between two moving surfaces to control how much friction they have when they slide past one another. Correctly adjusting the gibs is critical to producing accurate milling results.

Tight gibs make table movement more accurate but stiff. Loose gibs make table movement sloppy but easy. The goal of gib adjustment is to remove unnecessary sloppiness without causing the ways to bind.

Tip: Many experienced machinists adjust the gibs until there is just a slight drag in table movement.

Screws on each end allow gib adjustment to increase or decrease the friction between the slid- ing surfaces of the ways.

DISCONNECT MACHINE FROM POWER BEFORE ADJUSTING THE GIBS!

Make sure all table locks are loose. Then, loosen one gib adjustment screw (see Figure 44) and tighten the opposing screw the same amount to move the gib, while at the same time using the handwheels to move the table until you feel a slight drag in that path of movement.

Y-Axis Gib Screw

X-Axis Gib Screw

(1 of 2)

(1 of 2)

 

Figure 44. Location of gib screws.

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Adjusting Leadscrew

Backlash

Leadscrew backlash is the amount of free-play movement in the leadscrew (when changing the direction of rotation) before the attached device begins to move.

Leadscrews must have a certain amount of back- lash, but over time, this will increase with normal wear. Generally, 0.003"–0.006" leadscrew back- lash is acceptable to ensure smooth movement and reduce the risk of premature thread wear.

The X- and Y-axis leadscrew backlash is adjusted by using a long 5mm hex wrench to tighten/loosen the cap screw on the leadscrew nut. This adjusts the force the split leadscrew nut exerts on the leadscrew threads.

The X-axis leadscrew nut shown in Figure 45 is accessed from underneath the left side of the table.

X-Axis Leadscrew Nut

Cap Screw

Figure 45. Example of X-axis leadscrew nut cap

screw for adjusting backlash.

The Y-axis leadscrew nut is similar and is accessed from underneath the machine base.

Model G0758 (Mfd. Since 2/14)

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Contents Model G0758 MILL/DRILL Page Table of Contents Introduction Machine Description Manual AccuracyContact Info Identification Right side identification Model G0758 Mfd. Since 2/14Controls Components Machine Data Sheet Table Info Safety Safety Instructions for MachineryPage Additional Safety for Mills/Drills Power Supply AvailabilityFull-Load Current Rating 110V Circuit RequirementsGrounding & Plug Requirements Extension CordsMinimum Gauge Size 16 AWG 50 ftSetup Needed for SetupUnpacking Description QtyInventory Inventory Figure QtyCleanup Before cleaning, gather the followingBasic steps for removing rust preventative Site Considerations Lifting & Placing To lift machine and place it in positionAssembly Bench MountingDiameter of Mounting Hardware WorkbenchJoining Drill Chuck Arbor Lubricating Mill/DrillTo join drill chuck and arbor Test Run Inspections Adjustments Spindle Break-InOperations Operation OverviewUsing Coarse Downfeed Using DROUsing Fine Downfeed Downfeed ControlsHeadstock Movement Raising/Lowering HeadstockTilting Headstock Tools Needed QtyTable Travel Graduated DialsAxis Handwheel Tool Needed QtyInstalling/Removing Tooling Installing ToolingTo install tooling Spindle Speed Removing ToolingDetermining Spindle Speed To remove toolingAccessories T26612-Optional Stand for Model G0758Maintenance Cleaning ProtectingSchedule LubricationTable and Column Ways Axis LeadscrewsTo lubricate Z-axis leadscrew Table Leadscrews Headstock GearsTo lubricate table leadscrews To lubricate headstock gearsReplacing DRO Battery Quill Outside SurfaceQuill Rack Service TroubleshootingSymptom Possible Cause Possible Solution Symptom Possible Cause Possible Solution Adjusting Gibs Adjusting Leadscrew BacklashBrush Replacement To inspect and replace motor brushesWiring Wiring Safety InstructionsG0758 Wiring Overview Wiring overview Model G0758 Mfd. Since 2/14G0758 Wiring GNDRear panel Parts ColumnDescription Electrical Box Headstock Description Chip Guard Labels & Cosmetics Warranty Card CommentsGrizzly INDUSTRIAL, INC BOX BELLINGHAM, WAWarranty & Returns
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