Shopsmith Forums

JPG40504 wrote:There is one caveat, and that is whether the worm gear shaft is bent. As far as the sudden binding near the end of its range, that may not be due to a bent shaft. The increasing mis-alignment at the near-end position causes an increasingly binding interference(mashed teeth).

In any event the parts needed are inexpensive and well worth the effort!

If the Speed Control Handle is being forced to turn as it becomes harder to turn, it can bend the worm gear shaft. I find about 1/4 of the Speed Control Assemblies with damaged teeth will also have a bent worm gear shaft.

I have rebuilt assemblies or offer rebuilding services for the Speed Control Assembliy. Many times, the Control Sheave bearing, button and/or retaining loop will need replacing which I have available.

Contact me for a free allen head bolt, star washers and nylock nut along with instructions if you want to change the roll pin yourself. Just need your address. Thanks.

Bill

The shaft appears straight to me, although it could still be out of round and not be discernible to the eye. When rotated, the rule doesn't feel like it lifts anywhere along the threads. However, I'm a bit concerned now that there is too much play in the shaft seat. Should it move a little, in and out of the speed control?

Bill, I'm definitely interested in your bolt replacement fix.

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ddvann79 wrote:The shaft appears straight to me, although it could still be out of round and not be discernible to the eye. When rotated, the rule doesn't feel like it lifts anywhere along the threads. However, I'm a bit concerned now that there is too much play in the shaft seat. Should it move a little, in and out of the speed control?

Bill, I'm definitely interested in your bolt replacement fix.

[ATTACH]11195[/ATTACH]

If that pix shows the total extent of the end play, I would not be concerned!

BTW stop/resist the urge to file those quadrant gear teeth until the worm gear is 'realigned'!;)

Why procrastinate. They need to be cleaned up to be smooth.

BigSky wrote:Why procrastinate. They need to be cleaned up to be smooth.

Yes, why? Especially since that was one of the first things I did.

Yes, that is about as much play as the shaft has - maybe a hair more. I was thinking that the play would have the benefit of relieving some of the bite that develops at the end of the ranges of a rack and pinion system. On the other hand, the thought occurred to me the gap may also allow they worm to cause excessive wear in the soft aluminum if alignment were to get off.

I use to have a 1984 1/2 ton Dodge 4x4, with a 360. My baby. Anyway, I was headed down a gully a little fast one time and I hit the bottom with the front right wheel first - hard. It caused the rack and pinion steering to jump one tooth to the left. I couldn't turn as far to the right after that but I could turn farther to the left. I was lazy about getting it fixed and a year later when I got around to it, I found the rack to be worn excessively at the left end of the range that looked somewhat similar to the wear I see here. Of course, it the wear marks werelongitudinal instead of conical since the SS has a http://upload.wikimedia.org/wikipedia/commons/9/98/Schneckengetriebe02.jpg[/img]]worm shaft as opposed to a pinion gear.

All the same, could it be that the extra play in the worm shaft would create the opportunity for excessive wear? As relatively simple as they are, the geometry of a rack and pinion has to be dead on. Has anyone tightened up the worm shaft so it doesn't move as much.

ddvann79 wrote:Yes, why? Especially since that was one of the first things I did.

Yes, that is about as much play as the shaft has - maybe a hair more. I was thinking that the play would have the benefit of relieving some of the bite that develops at the end of the ranges of a rack and pinion system. On the other hand, the thought occurred to me the gap may also allow they worm to cause excessive wear in the soft aluminum if alignment were to get off.

I use to have a 1984 1/2 ton Dodge 4x4, with a 360. My baby. Anyway, I was headed down a gully a little fast one time and I hit the bottom with the front right wheel first - hard. It caused the rack and pinion steering to jump one tooth to the left. I couldn't turn as far to the right after that but I could turn farther to the left. I was lazy about getting it fixed and a year later when I got around to it, I found the rack to be worn excessively at the left end of the range that looked somewhat similar to the wear I see here. Of course, it the wear marks werelongitudinal instead of conical since the SS has a http://upload.wikimedia.org/wikipedia/commons/9/98/Schneckengetriebe02.jpg[/img]]worm shaft as opposed to a pinion gear.

All the same, could it be that the extra play in the worm shaft would create the opportunity for excessive wear? As relatively simple as they are, the geometry of a rack and pinion has to be dead on. Has anyone tightened up the worm shaft so it doesn't move as much.

I have not read of it being done but could it be shimmed? The gap would be filled and movement would no longer be possible but how would you determine where to shim?

I had some play in mine about a year ago during a rebuild. It was caused by the snap ring that holds the worm gear in position had risen up the shaft toward the control handle. There should be a wavy spring washer on the shaft under the snap ring. I think that this occurs from someone forcing the speed control handle without the machine running. You can seat the snap ring by using a 1/4" drive deep socket to push the snap ring down until it seats in the groove.
BillV

BigSky wrote:Why procrastinate. They need to be cleaned up to be smooth.

Some idiot who shall remain nameless had already created an answer to that question a short time back and after 'reviewing' it neglected to 'submit' it!:o

You would think as often as that happens he would learn!

IIRC, I had three points to make.

Shaft end play: This will cause the control dial to have backlash, and result in the indicator ring having slop as well. Not a serious dilemma! It will not cause abnormal wear of the teeth.

The beveled gear on the quadrant is not shaped like a true driven worm gear. The root and top of the teeth are flat(not curved to match the radius of the worm gear). This results in the mating surfaces being line contact. As a result of the minimal area, any displacement of the leg will cause the worm gear to wear(cold flow) the softer quadrant gear material.

The wear after the leg is bent, will not be in the same location on the quadrant gear as the line of contact when the meshing is 'normal'.

For that reason the removal(filing down) of the displaced material that is causing jamming in the abnormal mesh position will not be doing the same after the normal meshing is reobtained.

Wait and do the filing when you ascertain there is an interference with normal meshing.

[quote="JPG40504"]BTW stop/resist the urge to file those quadrant gear teeth until the worm gear is 'realigned'!]

Too late. That's the first thing I did.

ddvann79 wrote:Too late. That's the first thing I did.

Quite understandable! Been there done that! Also prior to knowing 'the fix'.(or that a fix would be done - filing was the fix at that time)

No damage done! Just that you will probably need to file some more(very little) after 'the fix'.

It would not hurt(too much$) to get a new quadrant gear to have on hand, but, I doubt after 'the fix' you will ever need it! You now know the ramification of dialing down too fast or while sheaves are not rotating.

It amazes me that SS Inc. can develop new stuff, but seems unable(or unwilling) to 'fix' this design inadequacy. A stronger arm in the direction it gets displaced would reduce the frequency and extent of this 'failure'. Surely they are not still using the 'original' molds at this late date!