Shopsmith Forums

You must have some way to keep both the eccentric bushing and the idler shaft bearing within the headstock. For many years on the "A" headstock, I had drilled and tapped a 10-24 hole in the headstock casing above the eccentric bushing. I used a 3/4" body washer with a 10-24 screw and star washer. This is the same setup that the "B" & "C" headstock casings use to hold the eccentric bushing . Recently I have gone back to using the original metal brackets under the eccentric bushing and offset the idler shaft bearing inside the eccentric bushing for the proper belt clearance on the drive sleeve.

billmayo wrote:Sometimes the Gilmer belt will be positioned to far to the back of the headstock so the back of the Gilmer belt tries to ride up on the Gilmer clutch pulley housing. This will fray and damage the Gilmer belt. I investigated the reason and found that the 2 clips holding the eccentric bushing may set the eccentric bushing with the idler shaft too far back in the headstock. I seat the eccentric bushing against the longer leg of the clips and move/tap the idler shaft with the Gilmer belt forward while hand turning the quill shaft the same direction (important) as the motor does. This is with the eccentric bushing bolt and set screw still loose. I go for about 1/16” to 1/8" gap between the Gilmer belt and the drive sleeve pulley shoulder. I tighten the eccentric bushing set screw and adjust the Gilmer belt of 1/16"-1/8" deflection and tighten the eccentric bushing bolt (not too tight, I normally just flatten the lock washer). This may set the Idler Shaft Bearing any where for 0” to ¼” deep into the eccentric bushing. I make sure the Gilmer belt stays tracking really close to the Idler Sheave pulley shoulder. I use a ¼” Knurl-Grip Cup Point Set Screw to securely hold the Idler Shaft bearing within the eccentric bushing for both the Gilmer and Poly-V Drive systems. Do not use the cone point set screw that came in the eccentric bushing for the Gilmer Drive system. This cone point set screw can deform the Idler Shaft Bearing resulting in noise and failure.

I operate the headstock for some time to may sure the Gilmer belt is not touching or creeping toward the drive sleeve pulley shoulder.

So Bill, just to make sure I'm getting this right, when you say you " move/tap the idler shaft with the Gilmer belt forward" you mean that you're tapping the idler shaft further to the inside of the eccentric bearing while the two clips are attached but loose (as well as the set screw)? Then you remove the clips, put a different set screw in and tighten, and then install the clips again? The different set screw is needed since it will not be riding in the groove on the idler shaft anymore?

I looked at my other greenie, which is about 1300 units older (267199) and it has NO clips holding the eccentric bearing in place; no washer at top either. The bearing is just held in by the clamp bolt. The idler shaft is mounted flush within the e. bearing and the whole thing is mounted flush to the headstock. The belt seems to be riding fine on this one and not fraying. I suppose I need to install some clips on it. Do you have two you'll sell?

[quote="mmorris"]So Bill, just to make sure I'm getting this right, when you say you " move/tap the idler shaft with the Gilmer belt forward" you mean that you're tapping the idler shaft further to the inside of the eccentric bearing while the two clips are attached but loose (as well as the set screw)? Then you remove the clips, put a different set screw in and tighten, and then install the clips again? The different set screw is needed since it will not be riding in the groove on the idler shaft anymore?

I looked at my other greenie, which is about 1300 units older (267199) and it has NO clips holding the eccentric bearing in place]

I use a krunled cup point set screw from the start. I use this set screw in all my eccentric bushings for the past few years. I find it is a better holdng set screw. I use longer krunled cup point set screws in other locations too. Once I tap the idler shaft inward to where the belt is riding just off the drive sleeve pulley shoulder, I remove the eccentric bushing bolt and clips, tighten the eccentric bushing set screw and install the clips and bolt again. Some idler shaft bearings did not have a groove in the middle. I believe the cone point set screw should never have been used to secure the idler shaft bearing as it creates distortion to the bearing outter race when tighten. This can cause noise and vibration that is really hard to find. I rotate the ecentric bushing within the clips to tighten the belt.

I firmly believe you need the clips for the Gilmer or the body washer for the Poly-V to keep the idler shaft inside the headstock. I had switch to drilling and tapping the 10-24 screw hole because I could not find 2 clips to use at that time. I still drill and tap this hole wheneven I cannot find the clips. No I do not have extra clips at ths time as I used mine on the recent headstock rebuilds. I find many of the "A" headstock will have the clips missing. Maybe some Forum member has 2 extra clips.

As I unnerstan what Bill is saying:

But first realize the following:

The clips position the eccentric bushing in the casting.

The setscrew positions the bearing in the eccentric bushing.

I defer to Bill's experience with the set screw type.

With the clips positioning the eccentric bushing in the casting, there is no way to adjust the bushing location.

However the positioning of the bearing in the bushing can be adjusted if the pointed set screw and the groove in the bearing are ignored. By using a cup set screw the bearing can be positioned further into the casting away from the inside end of the bushing.

I have encountered this same problem(once), but I believe I made sure the main shaft bearings were installed tight to the steps on the shaft and the main shaft pulley positioned closer to the quill end and the bearings as far into the casting as possible. I think this was possible only because the pulley was not the clutch type.

IIRC the inner bearing was being positioned too far back by the inner retaining ring being improperly installed.

I do not recall if the inner bearing protruded from the casting as far as yours.

Regardless, the belt does not want to ride against the clips.

billmayo wrote:I use a krunled cup point set screw from the start. I use this set screw in all my eccentric bushings for the past few years. I find it is a better holdng set screw. I use longer krunled cup point set screws in other locations too. Once I tap the idler shaft inward to where the belt is riding just off the drive sleeve pulley shoulder, I remove the eccentric bushing bolt and clips, tighten the eccentric bushing set screw and install the clips and bolt again. Some idler shaft bearings did not have a groove in the middle. I believe the cone point set screw should never have been used to secure the idler shaft bearing as it creates distortion to the bearing outter race when tighten. This can cause noise and vibration that is really hard to find. I rotate the ecentric bushing within the clips to tighten the belt.

I firmly believe you need the clips for the Gilmer or the body washer for the Poly-V to keep the idler shaft inside the headstock. I had switch to drilling and tapping the 10-24 screw hole because I could not find 2 clips to use at that time. I still drill and tap this hole wheneven I cannot find the clips. No I do not have extra clips at ths time as I used mine on the recent headstock rebuilds. I find many of the "A" headstock will have the clips missing. Maybe some Forum member has 2 extra clips.

The thought occurred to me while posting above, that the earlier bearings may have not had the groove and the pointed set screw was a later change when the groove was added. That would validate your 'solution'.

I believe your experience with encountering non-grooved bearings establishes credibility to this 'theory'.

I am curious why two clips were used unless it was to minimize side play.

JPG40504 wrote:The thought occurred to me while posting above, that the earlier bearings may have not had the groove and the pointed set screw was a later change when the groove was added. That would validate your 'solution'.

I believe your experience with encountering non-grooved bearings establishes credibility to this 'theory'.

I am curious why two clips were used unless it was to minimize side play.

I believe two clips were used on the Gilmer Drive machines as I found one clip can flop sideways and become somewhat unhooked on the back of the eccentric bushing. The clips are loose fitting under the eccentric bushing. My solution some times was to use washers on each side of a single clip to keep it some straight up to hold the eccentric bushing. Many Gilmer headstocks I was rebuilding had no clips installed when I disassemblied them so I went to doing the drill and tap a 10-24 screw hole above the eccentric bushing. I found that sometimes this placed the Gilmer belt too forward on the Gilmer clutch pulley than I thought proper but lived with it.

The over tightening of the cone point set screw in the eccentric bushing can cause ticking, noise, over heating and failure of the idler shaft bearing. This was very true for the idler shaft bearing with no groove which was installed on some headstocks and was a replacement part for years. I found the use of the ¼” Knurl-Grip Cup Point Set Screw solved these problems. I actually use different lengths of this type set screw for all my arbors, way tubes and other locations. Yes, I do have to file the ridges this set screw makes on some shafts but found the security and peace of not having a loose set screw was worth the effort for me. I replace this set screw after a few uses as the knurl part of the tip will be flatten or worn off.

Thanks for all the help on this.
Using the tapped screw and washer would keep the e. bearing from moving OUTWARD from the headstock, what keeps it from moving inwards? This possibly is a stupid question because I'm not in the shop to look it.

mmorris wrote:Thanks for all the help on this.
Using the tapped screw and washer would keep the e. bearing from moving OUTWARD from the headstock, what keeps it from moving inwards? This possibly is a stupid question because I'm not in the shop to look it.

There is no stupid question whenever you do not know an answer. The speed control quadrant along with the motor belt keeps the idler shaft from going into the headstock. The motor belt is the part that tries to force the idler shaft to exit from the headstock casing if the eccentric bushing set screw or bolt loosens at any time.

The exiting of the bearing/eccentric out the back is the critical failure to prevent. That would allow the pulley to open up too far and then the belt would drop too low and get jammed in the sheave vanes.

IIWM, I would always use the clips(period).

I have learned from this discussion(courtesy of Bill) about the non-grooved eccentrics. The clips design makes far more sense now.

almost done with the rebuild of a well treated Mark V 510. Assembling the sheave and idler-it isn't going back together very well. There is a copper sheave spring/clip getting in the way of everything seating well. The copper clip seems to be holding the keyway bar in place. Is this temporary until the 2 pulley/bearings come together?