Shopsmith Forums

After finishing the drive hub alignment on my SS Belt Sander in the horizontal sanding position, I rotated it to the vertical position. The drive hub was then almost 1/8 inch out of alignment in the horizontal axis.

Before doing this I had aligned a bandsaw and it had no horizontal error, in fact I used straight tubes. Based on that I expected the beltsander to need no horizontal offset but it actually needed quite a bit, close to half of the range of the eccentrics. My current thinking is that the offset I needed is because something is wrong.

I'm using standard eccentric tubes. I'm using the 'mystery bolt' but I confirmed it makes no difference whether it is in or not. Sanding belts are tracking correctly. I've disassembled the sander at the trunnion and don't see anything wrong. I didn't see anything in the manual that would relate to this behavior

Any ideas what would cause the sander's alignment to change when it is rotated?

-David

I don't think a small shift is a problem. The power coupler allows small amounts of mis-alignment. If I was worried I'd try to position the belt sander on its mounting tubes such that the error is averaged between the two ideal positions. In your case set things such that each position has one half the error of 1/8" ÷ 2 = 1/16"

I don't recall any movement of the shaft when swapping between vertical and horizontal but then I never really looked for it. I've not had a problem if it does indeed move.

In general you want the shaft to line up pretty well, I personally like to see them as close as I can get but I'm sure being off by 1/16" will not ever be an issue. Not so sure if it is 1/8"??

I will try and make time to check this out tomorrow. I've got several things to do out in the shop so I'll try and do this while I'm out there. Will try and report back tomorrow night.

Ed

DLB wrote:After finishing the drive hub alignment on my SS Belt Sander in the horizontal sanding position, I rotated it to the vertical position. The drive hub was then almost 1/8 inch out of alignment in the horizontal axis.

Before doing this I had aligned a bandsaw and it had no horizontal error, in fact I used straight tubes. Based on that I expected the beltsander to need no horizontal offset but it actually needed quite a bit, close to half of the range of the eccentrics. My current thinking is that the offset I needed is because something is wrong.

I'm using standard eccentric tubes. I'm using the 'mystery bolt' but I confirmed it makes no difference whether it is in or not. Sanding belts are tracking correctly. I've disassembled the sander at the trunnion and don't see anything wrong. I didn't see anything in the manual that would relate to this behavior

Any ideas what would cause the sander's alignment to change when it is rotated?

-David

I really do not understand how the hub could change alignment with the headstock. The reason being that the axis of rotation is firmly attached and does not (at least should not) move as a result of altering the belt sander position.

dusty wrote:

DLB wrote:After finishing the drive hub alignment on my SS Belt Sander in the horizontal sanding position, I rotated it to the vertical position. The drive hub was then almost 1/8 inch out of alignment in the horizontal axis.

Before doing this I had aligned a bandsaw and it had no horizontal error, in fact I used straight tubes. Based on that I expected the beltsander to need no horizontal offset but it actually needed quite a bit, close to half of the range of the eccentrics. My current thinking is that the offset I needed is because something is wrong.

I'm using standard eccentric tubes. I'm using the 'mystery bolt' but I confirmed it makes no difference whether it is in or not. Sanding belts are tracking correctly. I've disassembled the sander at the trunnion and don't see anything wrong. I didn't see anything in the manual that would relate to this behavior

Any ideas what would cause the sander's alignment to change when it is rotated?

-David

I really do not understand how the hub could change alignment with the headstock. The reason being that the axis of rotation is firmly attached and does not (at least should not) move as a result of altering the belt sander position.

Methinks something else is moving.

What direction?(in/out/up/down about the axis of the shaft)

JPG wrote:

dusty wrote:

DLB wrote:After finishing the drive hub alignment on my SS Belt Sander in the horizontal sanding position, I rotated it to the vertical position. The drive hub was then almost 1/8 inch out of alignment in the horizontal axis.

Before doing this I had aligned a bandsaw and it had no horizontal error, in fact I used straight tubes. Based on that I expected the beltsander to need no horizontal offset but it actually needed quite a bit, close to half of the range of the eccentrics. My current thinking is that the offset I needed is because something is wrong.

I'm using standard eccentric tubes. I'm using the 'mystery bolt' but I confirmed it makes no difference whether it is in or not. Sanding belts are tracking correctly. I've disassembled the sander at the trunnion and don't see anything wrong. I didn't see anything in the manual that would relate to this behavior

Any ideas what would cause the sander's alignment to change when it is rotated?

-David

I really do not understand how the hub could change alignment with the headstock. The reason being that the axis of rotation is firmly attached and does not (at least should not) move as a result of altering the belt sander position.

Methinks something else is moving.

What direction?(in/out/up/down about the axis of the shaft)

Logical thinking BUT what else is there to move that would/could effect the hub alignment.

If I correct the alignment while the beltsander is horizontal, then move it to vertical the error will be on what I think of as the front of the SS, the power switch side. Potentially interesting note: if I align it while vertical the eccentrics are in the neutral position where I would have expected them: little or no horizontal offset.

The error seems to be entirely in the horizontal axis. For example if I stopped with the beltsander at 45 degrees, I'd have less error but still all in the horizontal with no vertical component.

Full disclosure - The beltsander is currently disassembled. I took it apart to inspect the castings and the "finger washers" under the bearings and decided one of the bearings needs to be replaced, should be here Monday. (I don't see anything wrong that sheds light on this topic.)

- David

DLB wrote:If I correct the alignment while the beltsander is horizontal, then move it to vertical the error will be on what I think of as the front of the SS, the power switch side. Potentially interesting note: if I align it while vertical the eccentrics are in the neutral position where I would have expected them: little or no horizontal offset.

The error seems to be entirely in the horizontal axis. For example if I stopped with the beltsander at 45 degrees, I'd have less error but still all in the horizontal with no vertical component.

Full disclosure - The beltsander is currently disassembled. I took it apart to inspect the castings and the "finger washers" under the bearings and decided one of the bearings needs to be replaced, should be here Monday. (I don't see anything wrong that sheds light on this topic.)

- David

I am dumbfounded. No matter where I perform the alignment my eccentrics are never in the neutral position. BUT, I can move the beltsander from horizontal to vertical without creating misalignment of the drive hubs. Since you have the beltsander disassembled I trust that you have done a very critical inspection of those parts associated with the beltsander "axis of rotation" from horizontal to vertical.

Dusty - I have inspected it and did not have any aha moments. A couple of observations:
The "cup" that is used between the nut and a flat washer on the trunnion lock is so snug that it actually threads onto the stud. That seems counter-productive to me but the purpose of the cup is not obvious to me either. I've taken the cup off for now, no difference.
The trunnion track on the base is slightly loose, like one of the studs that hold it to the base assembly, is slightly backed out. When assembled, it is squeezed to the support by the trunnion so I don't think this is actually causing a problem. The stud is not our far enough to interfere, I measured .015" clearance.
My 'expectation' of neutral H adjustment is based on that alignment where one uses an extension table base and adjusts the big set screw in the base so that the upper accessory drive is centered, horizontally, between the mounting tubes. So I 'expect' the bandsaw to be centered, even with straight tubes, and it is. My expectation might be wrong, I'm just explaining how it was formed.

Bob - Yes, it is tight.

I'm down to the base assembly with tubes, all parts of the trunnion, and the right side casting with a bearing installed for visual reference. I'm using a drill chuck and bit for reference on the headstock side. The behavior is unchanged. If I'm satisfied that I can align it in this state I'll try the right side of the SS.