Readhead Mounting And Alignment: Methods; Shim Kit (A-9401-0050) - Renishaw ATOM Installation Manual

Readhead mounting and alignment:
There is a range of tools available to assist with readhead installation depending
upon the system design, these are detailed below.
For more details on designing the mounting bracket and selecting the appropriate
mounting tools contact your local Renishaw representative.
Ensure that the disc, readhead optical window and mounting face are clean
u
and free from obstruction. Do not saturate the readhead window with cleaning
solvent as this may cause contamination on the inside of the readhead
window which then cannot be cleaned.
AGC should be switched off before installing the readhead and,
u
when reinstalling, factory defaults should be restored.
NOTE: For FPC readheads the FPC cable must be fitted prior to mounting
the readhead. See page 9 for more details.
IMPORTANT: Whichever method is used to mount the readhead, care should
be taken to ensure the scale surface is not damaged during this operation.
Shim kit
(A-9401-0050)
This method is intended for applications where the rideheight of the
readhead cannot be adjusted.
The system should be designed to achieve a nominal 2.3 mm (±0.2 mm)
from the readhead mounting surface to the disc surface.
Location pins
Mounting
bracket
Disc
Shims of a known thickness are inserted between the mounting face of the
readhead and the bracket to give the correct rideheight.
The kit consists of:
A-9401 A-9401 A-9401
Part Number:
-0041 -0042 -0043
Thickness (µm) 20 40 60
Quantity in pack 10 10 10
ATOM
rotary installation guide
Methods
1
2
3
4
5
6
7
8
9
2.3 ±0.2 mm
10 Adjust longitudinal and radial offset of the readhead to obtain
A-9401 A-9401 A-9401 A-9401
11 Tighten the readhead fixing screws.
-0044 -0045 -0046 -0047
80 100 200 300 12 Proceed with 'System calibration' section.
10 20 20 10
Using a digital dial gauge or similar measure the distance from
the readhead mounting surface to the disc surface.
Care must be taken to ensure the disc surface is not scratched.
Renishaw offer a DTI adapter (A-9401-0105) that can be used
to assist with this process.
– Insert the gauge into the adapter and zero the gauge
on a flat surface.
– Position or fix the gauge/adapter in place of the readhead
and measure the distance to the disc surface.
Contact your local Renishaw representative for details of the
DTI adapter and digital dial guage.
Subtract the distance measured from the nominal rideheight of
2.5 mm to calculate the required shim thickness.
For example if the distance measured is 2.37 mm the required
shim thickness is 130 µm.
Select a combination of two shims that gets within 10 µm
of the difference. For distances less than 100 µm a single shim
should be used, for distances greater than 100 µm select one
thick ( 100 µm) and one thin (<100 µm) shim.
In the above example this could either be:
1 x 100 µm shim and 1 x 40 µm shim or
1 x 100 µm shim and 1 x 20 µm shim.
Place the chosen shim(s) between the readhead and the bracket.
Fix the readhead to the bracket using 2 off M2 x 6 screws in
diagonally opposite fixing holes ensuring readhead is
tightened down evenly and parallel to the bracket face.
Using location pins/shoulder:
Ensure the readhead is pushed back against the location pins
or shoulder.
Tighten the fixing screws.
Check the readhead set-up LED is Green around the full axis
of rotation.
Proceed with 'System calibration' section.
Not using location pins:
a Green readhead set-up LED around the full axis of rotation.
An oscilloscope or Renishaw USB set-up tool kit and software
can be used to help maximise the signal size.
For more information on the Renishaw USB set-up tool kit
contact your local Renishaw representative.
DTI adapter
RCDM
disc
14