harrison m300, spindle run out...bearings?

This is not surprising. A dial indicator is not designed to run on a rapidly revolving shaft. Anything above hand rotation speed is too fast for a dial indicator to keep up with. And it's terrible bad for the dial gauge.

If you have slack in the bearings once the machine has been warmed up, it's best measured by holding a long piece of bar in the chuck and yanking up and down on it with a dial indicator reading off the spindle right behind the chuck.

Your preload test sounds about  right. With a 200mm chuck, radius is circa 4 inches, multiplied by 2lbs, gives 8 inch pounds of torque. (Don't trust my math, I majored in English Lit. at college. Check it yourself.) IIRC target torque is 8 to 10 inch pounds?

But, is there a seal or seals on the spindle to stop swarf getting into the bearings? Often these seals would need to be removed to get a true torque reading because they drag on the spindle. Refer to your manual on that point.

Edited By Hopper on 21/12/2018 07:22:34

Edited By Hopper on 21/12/2018 07:34:02

Sebastian, you may have more luck getting suitable belt from a supplier like Henderson bearings in Ringwood. There must be a similar outfit near you in Exeter. They tend to have a wider knowledge than motor factors.

Hugh

Sorry, only just noticed this location, Unfortunately you have just missed the weekly get together of the Exeter DMES at St Katherine's Priory on Friday mornings. However I will drop a note around some of the retired members to see if they have some free time in this busy time of year.

**LINK**