Service Home How To Procedures Linear Scale - X-Axis - Replacement - Jan 1997
Last updated: 12/01/2018

Linear Scale - X-Axis - Replacement - Jan 1997

Linear Scale - X-Axis - Removal

1

Verify machine is level.

Disable the linear scale in the control. Set parameter 266:0 LINSCALE EN to 0.

Set parameter 125 X GRID OFFSET to "0".

Remove the bolts holding the way covers to the table and slide the covers away from the table.

2

Remove the way cover, the saddle end cover and the guide bars from the right side of the machine. VF-10/11, VR-11 and machines with an APC, remove the right front saddle cover.

3

Jog the table to the right. Disconnect the linear scale cable from the extension cable. Remove the cable clips and ties that secure the linear scale cable. 

4

Remove the two metric screws, nuts or nut plate attaching the encoder head to the bracket. The table may have to be jogged to facilitate removal. 

5

Unscrew the two bolts that hold the encoder bracket to the table and remove the bracket.

6

Remove linear scale bolts from the left side of the machine, these are the only ones accessible at this point.

7

Jog the table to the left and remove the remaining linear scale bolts, and remove the scale.

Linear Scale - X-Axis - Installation

1

Clean mounting bracket, and remove any burrs that would affect scale installation.

Using a dial indicator check the parallel runout of the scale mounting bracket. For VF-3 only see the next paragraph for indicating runout.

To indicate the full length of the scale mount; jog table all the way to the left and place the magnetic base on the right side of the table as shown.

Zero the indicator, mark the position of the indicator stylus on the scale mount and obtain reading, full travel to the right. Remove magnetic base and place it on the left side of the table. Zero the indicator at the mark on the scale mount and obtain reading, full travel to the left. (T.I.R. .004).

Align if necessary. Verify bolts are tight. If alignment cannot be made within tolerance, shim stock may be used near mounting bolt locations when mounting the scale.

Indicating full length of the scale mount for VF-3 machines cannot be done as described above. Instead, place the magnetic base on the right side of the table and place the indicator as close as possible to the read head. Indicate as much scale mounting surface as possible.

2

Check the scale and verify that it is a new 'C' version with plastic isolating material on the encoder head mounting surface. See installation diagram below for part number. The pigtail cable should also have a version 'C' label on it. Do not remove the labels.

VF 6-11

VF 6-11

VF 3-5

VF 3-5

3

Install the linear scale using blue loctite on the screws. Check and adjust scale parallelism. Use shim stock as required to obtain parallelism TIR .004.

4

Obtain an initial flatness measurement using a dial indicator. To adjust, tighten the bolt nearest the area where the reading is the average of the total deviation. Tighten the remaining bolts in an outward pattern while adjusting flatness (T.I.R. .004).

5

Check parallelism of the scale, and adjust if necessary (T.I.R. .004). Verify all mounting bolts are tight.

6

Use a new style, electrically isolating encoder bracket for mounting the encoder head. See installation diagram for part number.

For VF 3/4/5 make sure the correct sub-bracket is used (P/N 20-0038A).

See below for old/new part comparison and hole pattern usage. Use the same cylindrical spacers under the sub-bracket.

7

Check all mounting surfaces for burrs that may influence the angle of the bracket. Install encoder bracket to the table or sub-bracket head leaving the bolts loose enough to adjust the bracket. (use a flat washer and a split-lock washer). 

Linear Scale - X-Axis - Alignment

1

Using the horizontal gap tool "set tool" (T-2064), align the encoder bracket to the scale (see illustration) by pinching the tool between the encoder bracket and linear scale and slowly tightening the encoder bracket mounting screws by alternating between screws to prevent shifting the bracket.

Be sure alignment is not made where there are labels on the scale.

Leave the "set tool" in place and check that the bracket surface and the scale surface are parallel. If they are not, use a feeler gauge to measure how out of parallel they are. If they are more than .004" out of parallel shim the encoder bracket.

Remove the "set tool" and verify allowable gapping error by inserting the "go tool" (T-2063) from both sides of the bracket. Insertion of this tool means the gap is not too small.

Attempt to insert "no go tool" (T-2065) from both sides of the bracket. If the tool does not fit then the gap is not too large. This completes alignment of the encoder bracket.

2

The new isolating encoder bracket uses metric screws with flat washers, plastic shoulder washers, and nuts or nut plate as shown in the installation diagram.

3

Align encoder head to scale by pinching vertical gap tool "set tool" (T-2067) between the encoder head and scale and tightening the screws (use blue Loctite).

Be sure any isolating material overhanging the encoder head is not pinched between encoder head and gap tool. Remove "set tool" and verify allowable gapping error by inserting "go tool" (T-2066) from both sides of the encoder head. Insertion of this tool means the gap is not too small.

Attempt to insert "no go tool" (T-2068) from both sides of the encoder head. If the tool does not fit then the gap is not too large. This completes alignment of the encoder head.

4

Do not connect linear scale cable to extension cable at this time. Verify isolation or electrical discontinuity between encoder head and its bracket using an ohmmeter.

5

Connect linear scale cable to extension cable, check cable routing, and secure the cable.

Check that the cable will not interfere with other parts when the table is moved.

Be sure that the cable does not bend too tightly (see illustration). 

6

Enable scale, set grid offset and verify full travel.

7

Remove saddle covers.

Thoroughly clean the seam between the two saddle cover halves.

Use Scotch Brite to remove all traces of old sealant and to rough the sealing surfaces.

Wipe surfaces clean with alcohol. Apply Permatex #2 or Black silicone RTV across entire joint and screw holes before installing the two saddle cover halves.

8

Clean table cover mounting surfaces as described above.

Apply a continous bead of sealant along entire surface as shown.

Attach table covers and smooth out sealant on outside of table cover as shown.

9

Install guide bars, and saddle end cover. Be sure the way cover rider transitions smoothly from the saddle to guide bar. 

10

Clean all mounting surfaces for waycovers (waycovers, table and table cover).

Use Scotch Brite to remove all traces of old sealant and to rough the sealing surfaces.

Wipe surfaces clean with alcohol. Apply Permatex #2 or Black SiliconeRTV across entire joint and around screw holes. 

11

Attach way covers.