Mark V fan sheave binding - motor shaft does'nt free Rotate

[booboobear]

Recently I got introduced to Mark V and I love it. I am using a friend's Mark V Shopsmith (planning on buying it) which was working fine till recently. Lately it became difficult to free rotate the shaft with the hand. Now when I turn the motor on it will not rotate.
1. I removed the headstock from the way tubes to strip down the head stock and repair or replace any parts that need replacing.
2. Following Sawdust Session #21 I removed the V-belt off of the Floating Sheave. (see pictures in the attached "Repair Question" presentation)
3. The drive shaft and the idler shaft turn freely - so I suppose their bearings are fine.
4. However the fan sheave seems to rub against the face plate of the motor. When I compress the spring pull the floating sheave off the fan sheave the shaft rotates more freely.

Question what is the problem that needs fixing?
Is it the bearing in the motor or something moved on the fan sheave?
Where can I send the motor for repair?

[RonKlein]

The fan sheave has a key and set screw to lock it to the shaft. The set screw has probably loosened and the fan sheave shifted. There is supposed to be a spacer between the sheave and motor. If you call Shopsmith, they should send you a new spacer.

Ron

[beeg]

Also WHEN was the last time ya lubed it?

[billmayo]

Recently I got introduced to Mark V and I love it. I am using a friend's Mark V Shopsmith (planning on buying it) which was working fine till recently. Lately it became difficult to free rotate the shaft with the hand. Now when I turn the motor on it will not rotate.
1. I removed the headstock from the way tubes to strip down the head stock and repair or replace any parts that need replacing.
2. Following Sawdust Session #21 I removed the V-belt off of the Floating Sheave. (see pictures in the attached "Repair Question" presentation)
3. The drive shaft and the idler shaft turn freely - so I suppose their bearings are fine.
4. However the fan sheave seems to rub against the face plate of the motor. When I compress the spring pull the floating sheave off the fan sheave the shaft rotates more freely.

Question what is the problem that needs fixing?
Is it the bearing in the motor or something moved on the fan sheave?
Where can I send the motor for repair?

A very common problem. The fan sheave set screw has worked loose and/or someone has rotated the belt off the floating sheave and let it snap againest the fan sheave. There is a very thin Sheave Spacer (#124) that cuts into the hub of the fan sheave allowing it to rub againest the motor housing. Since the fan sheave will move when pulling on the floating sheave, the fan sheave set screw has loosen.

You remove the switch nut and push switch inside headstock. Then remove the motor pan and motor from the headstock (5 screws). Remove the motor screws (4) and disconnect switch and power wires from motor. Turn motor so the sheaves are up. I use a 4" X 18" X 3/4" board and bore a 1 1/4" hole half way through the board using a spade bit. Then flip the board and finish drilling a 3/4" hole using the same hole the spade bit made. Using this board on the washer (#115), compress the spring (#116) and remove the retaining/snap ring (#114). Being very careful, slowly release the pressure on the spring. I normally use a glove on my free hand to hang onto the spring.

Now with the motor mounting holes up, you use a 5/32" hex wrench to remove the fan sheave set screw. I use a good pentrating oil in the set screw hole and let set for a while. I use a clamp at the end of the motor shaft to hold the key while loosening the fan sheave. I have several large flat blade screwdrivers that I start with the smallest one. I put the flat blade between the fan sheave hub and motor housing and tap with a hammer. Once the fan sheave starts to move and the screwdriver quits moving the fan sheave, I rotate the screwdriver 90 degrees and continue to move the fan sheave. I repeat this action with each of the larger screwdrivers until the fan sheave can be moved by hand. I remove the clamp holding the key and remove the fan sheave and key.

Shopsmith has made a modification to help prevent this problem in later motors. They went to a thicker sheave spacer that I use even if the original thin spacer cut a groove in the back of the hub. I use LocTite on the set screw when installing the set screw as I find quite a few of the set screws that are lose.

If all else fails, I now have built myself a motor rework and test station. Contact me for more information.

[wlhayesmfs]

Mine did the same thing and what Ron said is what happened. Mine was missing the spacer and I called SS and they sent me one to put in and it has worked great since. About two years. OH by the way they said sorry on the missing spacer and sent me one free.
That is customer service and why I will stay there as long as I can.
Thanks

[booboobear]

Ron

You are on to something. I just read some other treads with fan sheaves sticking and it looks like the key, spacer, and set screw may be the problem (better than the motor bearings - which I was afraid of). Parts exploded view shows the spacer #124 (pointed out by billmayo in another thread) but it does not show the key and the set screw. I suppose I will have to dismantle down to the motor shaft to get to the set screw.
I will find out more next week end when I get around to it.

Thanks
BooBoo

[booboobear]

beeg

I oil it with sewing machine oil every few months before I use it. Now that I have seen Rick's Sawdust Sessions it is getting easier. Oiling may not be a problem - I used it at slow speeds during some large diameter bowl lathe work. The slow speed may be the problem. I still don't understand why slow speed may cause fan sheave issues - but I am learning fast.

BooBoo

[JPG]

Ron

You are on to something. I just read some other treads with fan sheaves sticking and it looks like the key, spacer, and set screw may be the problem (better than the motor bearings - which I was afraid of). Parts exploded view shows the spacer #124 (pointed out by billmayo in another thread) but it does not show the key and the set screw. I suppose I will have to dismantle down to the motor shaft to get to the set screw.
I will find out more next week end when I get around to it.

Thanks
BooBoo

The fan sheave set screw is accessible through a hole in the center of the vent louver located on the bottom of the motor pan.

[JPG]

beeg

I oil it with sewing machine oil every few months before I use it. Now that I have seen Rick's Sawdust Sessions it is getting easier. Oiling may not be a problem - I used it at slow speeds during some large diameter bowl lathe work. The slow speed may be the problem. I still don't understand why slow speed may cause fan sheave issues - but I am learning fast.

BooBoo

At slow speed, the motor sheave is near its travel limit(opened up) and the control sheave is near its travel limit(closed). Thus the motor pulley is a small diameter, and the idler pulley is a large diameter. Any potential problem is more likely to occur at the travel extremes.

When lubricating, it is very important to cycle the sheaves through their entire range so as to effectively distribute the oil. The ends tend to get gummed up due to their seldom being actually used.

[RonKlein]

Quote:
Originally Posted by booboobear
Ron

You are on to something. I just read some other treads with fan sheaves sticking and it looks like the key, spacer, and set screw may be the problem (better than the motor bearings - which I was afraid of). Parts exploded view shows the spacer #124 (pointed out by billmayo in another thread) but it does not show the key and the set screw. I suppose I will have to dismantle down to the motor shaft to get to the set screw.
I will find out more next week end when I get around to it.

Thanks
BooBoo

FYI: The set screw is #118, and the key is #120.

Ron