Posted: Sun Sep 19, 2010 9:39 pm
Yes, the idler shaft even with the hub mounted can get quite hot. I have used the below Poly-V belt alignment to help lower the temp on some headstocks.
I place the sanding disk on the quill and turn it in the same direction as the motor turns the quill. I find that I first install the Poly-V belt with 2 empty grooves on each side of the Drive Sleeve Pulley. Then install the idler shaft and eccentric bushing. I rotate the Poly-V or Gilmer belt for a few complete turns before checking for alignment. I use a #8 body washer (drilled for a #10 screw) on the screw that stops the eccentric bushing from extending past the back of the headstock casing when turning the speed control handle to SLOW. The factory washer can allow the idler shaft to move past the end of the bushing. I seat the idler bearing and eccentric bushing against the body washer and lightly seat the eccentric bushing set screw. Then I take slack out of the belt by rotating the eccentric bushing. I stand above the headstock and sighting down the edge of the Poly-V belt to the idler shaft pulley. The belt should be flat (straight down) against the idler shaft pulley as it starts or comes off the idler shaft pulley. If there is a bulge on the side of the belt as it clears the pulleys then the pulleys are not in a straight line. If the idler shaft pulley appears to be more toward the end of the headstock casing, I will remove the eccentric bushing and idler shaft so I can move the belt one groove toward the back of the drive sleeve pulley leaving 3 grooves showing at the front of the drive sleeve pulley. I reinstall the idler shaft and eccentric bushing and check alignment again. I can do this task many times faster than I can describe it.
I place the sanding disk on the quill and turn it in the same direction as the motor turns the quill. I find that I first install the Poly-V belt with 2 empty grooves on each side of the Drive Sleeve Pulley. Then install the idler shaft and eccentric bushing. I rotate the Poly-V or Gilmer belt for a few complete turns before checking for alignment. I use a #8 body washer (drilled for a #10 screw) on the screw that stops the eccentric bushing from extending past the back of the headstock casing when turning the speed control handle to SLOW. The factory washer can allow the idler shaft to move past the end of the bushing. I seat the idler bearing and eccentric bushing against the body washer and lightly seat the eccentric bushing set screw. Then I take slack out of the belt by rotating the eccentric bushing. I stand above the headstock and sighting down the edge of the Poly-V belt to the idler shaft pulley. The belt should be flat (straight down) against the idler shaft pulley as it starts or comes off the idler shaft pulley. If there is a bulge on the side of the belt as it clears the pulleys then the pulleys are not in a straight line. If the idler shaft pulley appears to be more toward the end of the headstock casing, I will remove the eccentric bushing and idler shaft so I can move the belt one groove toward the back of the drive sleeve pulley leaving 3 grooves showing at the front of the drive sleeve pulley. I reinstall the idler shaft and eccentric bushing and check alignment again. I can do this task many times faster than I can describe it.
