Which shaft can handle lateral loads better?

[c-9]

Hi, I'm building a custom belt sander using my Shop Smith, and I would like to know which side I should mount the drive wheel on. The wheel will have a constant tension on it, so it needs to handle constant lateral load.

My Shop Smith is gray, but I think the person I bought it from neglected to mention it was repainted, and he claimed it was 70's era. Judging from the serial number, the green paint on the inside and on some misc parts, the gilmer drive, and the 3/4 GE motor, I believe its actually a 1950's model.

I know the quill shaft can handle some lateral loads, since the disc sander and such is used on it, but to use it for my application, the quill would need to be locked in a fully extended position to extend over the table carriage. I can hear a little slop on the quill side, but it still works fine as a drill press, and I can't visually see any movement. The shaft normally used to drive accessories seems rock solid, and better supported by bearings, but it appears that its normal uses do not include handling a lateral load.

Since the Shop Smith is a gilmer model, I understand that the quill has only a single bearing making it less capable of handling lateral loads, and the quill is not replaceable without also spending lots of money upgrading to a poly-V drive. I don't mind replacing bearings if they are become a bit abused over time, but I think the rattling comes from the movement at the splined end of the quill shaft, and I would very much not like to ruin that.

It would be ideal to use the quill side, because then I an tilt the sander and use it as an edge sander, but I would really not like to damage the machine, since I only have the drill press and disc sander attachments for it, and can't even use it for the other tools. I am worried that lateral load in the fully extended position may damage the splines of the quill shaft, but I am also worried because I have only seen the other end of the Shop Smith used with a coupling device. If you have any information or input, it would be appreciated.

Thanks.

[JPG]

The 'other' end(the SPT coupler mount end) has large double bearings. It is much more capable of withstanding lateral loads than the quill end which introduces the quill splines and the smaller single bearing and the quill extension in to the 'mix'.

Since you have a gilmer drive, the double bearing quill update would probably be cost prohibitive since you would first have to upgrade to a poly-v drive.

IMHO the spt end is a better place for what you have described. I would not rely upon the shaft and bearing for total support though!