Shopsmith Forums

The 16x675 belt is reasonable. Yes it is likely slightly wider and will ride in the pulleys slightly higher.

When it binds at "F", where is the belt riding on the control sheave? ***

It may be that "F" is at the extreme low speed position of the sheaves.

Since you admit confusion re syncing the outer speed indication ring, it may simply be set incorrectly.

I will try to explain how the ring is adjusted to indicate correctly.

First I would again move the belt out of the way. This allows moving parts near the high speed stop (fast) setting.

You will first be setting the high speed stop relative to a purely mechanical limit(interference).

So with the belt out of the way, remove the knob.

Loosen the nut on the high speed stop set screw so the screw may be easily moved manually.

Now by rotating(CW) the worm gear shaft manually, cause the quadrant gear to move against the high speed stop screw. Look at the clearance between the control sheave and the speed control. Back out the stop screw and continue to rotate the worm gear shaft(CW) thus decreasing the clearance between the sheave and the speed control frame/leg/whatever it will eventually hit.

Continue that until the sheave contacts the interfering part. Then rotate the worm gear shaft (CCW) about a half turn(thus providing clearance between the sheave and the speed control.

Adjust the high speed stop screw until it contacts the quadrant gear thus limiting its travel. Tighten the lock nut and verify the control sheave will not contact the speed control when the stop screw is contacted by the quadrant gear.

Yes that is very wordy, but it should get the high speed stop set very close to where it needs to be.

NOW about the ring gear speed indicator ring.

When the speed control is set to the high speed limit, the ring needs to be indicating "FAST". The word fast should be directly under the pointer.

So, place the ring on to the headstock, engage the idler gear and check the range of travel. It should be able to rotate a full revolution(nothing prevents that).

Now position the ring so "fast" is directly under the pointer.

Now comes the possibly tricky part.

Rotate the worm gear shaft(CW) until the quadrant stops against the stop screw.

Without causing either the ring or the worm gear to move. slip the knob onto the worm gear shaft. You must position the knob so the knob set screw will align with the dimple on the shaft. Ya it is a blind thing, but the main thing is to both align the set screw and the dimple while NOT causing the gear on the knob to move the idler gear/ring gear more than a tooth.

Tighten the knob onto the shaft.

Now you should be able to rotate the knob(CCW) towards slow. The speed control parts should not cause the range to stop before the pointer indicates slow. Typically the control sheave closing the pulley will create the lower limit.

That should insure the ring is sync'd correctly.

Now reinstall the belt and move through the speed range carefully.(Manually at first)

IF it still stops at "F", then we need to get out our magnifying glass and take pix of the movable sheaves etc.

***
BTW when it stops at "F" now, what is the position of the control sheave relative to the fixed idler sheave.

NUF fer now.

I followed JPG’s directions. In the process I found a small thing. The snap or retaining ring holding the worm shaft in the bushing was slipping out of its groove allowing the worm shaft to slide into the speed controller causing some kind of issue. I should have replaced it when I put in the new worm shaft. (It’s a 5/16 external.) So I installed a new one. FWIW on adjusting the high speed set screw it is slightly short of the surface of the lock nut.

Without a belt I ran it manually with no problem. Ran it with the belt and the controller stopped at “D”. That seems like progress. But...

At “D” the control sheaves still had about a 1/2” is capacity left. I reasoned that all the items in the chain had been reviewed except the motor sheaves.
At the lower end of the speed range the motor sheaves separate allowing the belt to ride further down into the V. Was something preventing the outer sheave from moving out? I found that while the spring had the capacity to compress more the tube that is part of the outer sheave was in fact flush against the nut holding it onto the motor shaft. We’re at the end of travel. “D” is the bottom limit. That question is answered.

But I’m left with another problem. Remember I’ve put on a new and bigger belt (has 504170 on it) and it’s outer edge is slightly proud of the motor sheave at the “Fast” point. My speeds are too high. At “D” it’s 1660 rpm. At “I” it’s 2170 rpm. And at “M” it’s 2880.

How do I slow it down?

504170 is the poly-v belt.

WHAT is running between the motor pulley and the idler pulley?

At this point I think that belt is too long.

Yes, I confused the issue about the belt number. The belt between the pulleys is the 16x675 belt from Anderson.
If this belt is too long -
•what factors would cause a standard belt to be too long (that is , if in the rebuild I used standard parts and used stock mounting positions how would the distance between the motor shaft and the idler shaft get shortened)? and
•what belt should I use to compensate for this?

oddie wrote:Yes, I confused the issue about the belt number. The belt between the pulleys is the 16x675 belt from Anderson.
If this belt is too long -
•what factors would cause a standard belt to be too long (that is , if in the rebuild I used standard parts and used stock mounting positions how would the distance between the motor shaft and the idler shaft get shortened)? and
•what belt should I use to compensate for this?

A 16x675(15x675?) belt is not a standard Mark 5 belt, but is a near equivalent(unless SS is again deviating from it's original design belts and trying to use a commonly available third party belt).

Since you have replaced the more likely causes of your original problem, I would at least return to using the OEM(SS) belt.

It is not the spacing between the pulleys that 'changes'. It is the movable sheaves that alter the effective spacing by means of moving the sides of each pulley. The length and width of the belt affects the positioning of the sheaves as well. The sheaves must move is opposite but EQUAL distance. That is why the belt MUST be correct for it all to operate as intended. The floating sheave maintains the effective spacing, but it's range is dependent upon the belt dimensions. The control and floating sheave limits are fixed by the parts themselves.

There is something that has not been revealed(yet) and that is the cause of 'premature' stopping/binding when adjusting towards slow.

I understand your frustration so far, but do persist as we shall come to getting this varmit to behave correctly.

I replaced the new belt (15x675) with my original SS belt (504193). I measured the two and my original belt is about 1/2” shorter than the new belt. That difference is relative, not exact. This pic is of one end. The other end is the same. I manually ran through the speeds and it bound up at “C”. Then I ran it under power. Same thing. That’s progress. But it still bound up. The speeds also increased since the test with the new belt.
“C” is now 1580 rpm (previously “D” was 1660)
“I” is 2310 (was 2170)
“M” is 3230 ( was 2880)
I’m afraid to run it at Fast for fear it would tear apart due to very high rpm.

Well the belt lengths explain some of what we have observed.

We are left with the premature stoppage before reaching 'slow'.

I think a pix of each pulley when that premature stop is reached may help reveal the cause. The height of the belt in the pulleys as well as the amount of motion left for the floating sheave to open(spring fully? compressed) and the porkchop position.

These pics show the machine’s state when it binds at “C”.
These are the upper sheaves. These are the lower sheaves. This is the spring. This shows the spring separated reveling the stub on the sheave grounded on the nut. This shows the speed controller as seen from the inspection hole. This blurry pic shows the relationship between the quadrant and the worm shaft.

Hoookey! Glad for the pix. Two meaningful clues. Floating sheave moving all the way to the nut is the cause of stoppage. However the belt position on the control sheave is not what it should be. The belt should be tracking much further out in the pulley.

I cannot see if the quadrant gear is near the end of it's normal slow range.

Regardless the control sheave is NOT as far toward the idler sheave as it should be at 'slow'.(idler pulley not closed enough)

Just for added info, take the same set of pix with it set to fast. I am suspicious of the high speed stop setting. Especially needed is the belt tracking on the motor pulley at fast.

P.S. I just reviewed some earlier posts. Notable was the loose retaining ring on the worm gear shaft. The issue it could cause is to make the high speed stop setting wrong and/or cause the worm gear to move in/out thus reducing the range of quadrant gear movement.

These pics show the machine’s state at “Fast”. A note, I did replace the retaining ring on the worm gear so it’s no longer sliding back and forth.
These are the upper sheaves. These are the lower sheaves. This is the spring. This shows the spring separated reveling the stub on the sheave at some distance from the nut. This shows the speed controller as seen from the inspection hole. This blurry pic shows the relationship between the quadrant and the worm shaft.