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Ok I'm new to this. What is the difference between a Gilmer and A poly. Also what is the "runout" that is being refered to so often. Call me a rookie:rolleyes:

futralwoodworks wrote:Ok I'm new to this. What is the difference between a Gilmer and A poly. Also what is the "runout" that is being refered to so often. Call me a rookie:rolleyes:

The older Greenies and early Goldies had a cogged belt(Gilmer) between the idler shaft and the main shaft. The rear shaft and control sheave are the parts that differ(as well as the belt).

The poly-v belt was introduced with the 1 1/8 hp motor in the early sixties. The belt resembles a short automotive 'serpentine' belt. The control sheave and main shaft are different from the Gilmer version.


Runout is the amount of variation from a truely rotating part. A gauge is placed at the end of the shaft and the part is rotated and the deviation thus measured. Similar to eccentricity, but can exist on round shafts with 'wobbley' bearings.

JPG40504 wrote:The older Greenies and early Goldies had a cogged belt(Gilmer) between the idler shaft and the main shaft. The rear shaft and control sheave are the parts that differ(as well as the belt).

The poly-v belt was introduced with the 1 1/8 hp motor in the early sixties. The belt resembles a short automotive 'serpentine' belt. The control sheave and main shaft are different from the Gilmer version.


Runout is the amount of variation from a truely rotating part. A gauge is placed at the end of the shaft and the part is rotated and the deviation thus measured. Similar to eccentricity, but can exist on round shafts with 'wobbley' bearings.

Ok thanks. I have a poly then. Which I might add is totally stripped down right now (hope I can get it back together right). So runout then is a sign that things are wearing down/out?

Yes, it's typically the result of worn bearings, but also could be indicative of a bent spindle.

I guess I should have added that there likely will be a small amount of runout even under ideal conditions. Perhaps a few thousands of an inch would be acceptable. I'm not sure what the factory tolerance for a Mark V would be, but I read where the old 10ER had a maximum runout of .0015" or it would be rejected.

pennview wrote:I guess I should have added that there likely will be a small amount of runout even under ideal conditions. Perhaps a few thousands of an inch would be acceptable. I'm not sure what the factory tolerance for a Mark V would be, but I read where the old 10ER had a maximum runout of .0015" or it would be rejected.

My machine is 25 years old and has a runout of <.002". Saying this I should also comment that I do virtually no turning. I suspect that heavy turning has an effect on runout.

Yes, turning does negatively affect bearing life. Especially if you do large items like bowls and platters and work with green (heavy) wood.

Every lathe I have ever heard of has bearing life issues. Even the high dollar production environment machines tend to eat spindle/shaft bearings. It's a function of side loading the shaft. I suspect that routing and shaping may also cause the bearing to wear faster as well.

futralwoodworks wrote:Ok I'm new to this. What is the difference between a Gilmer and A poly. Also what is the "runout" that is being refered to so often. Call me a rookie:rolleyes:

Also worth mentioning is that Shopsmith has made both a 1 bearing and a 2 bearing quill over the years. The 2 bearing quill is supposed to reduce/minimize runout over the 1 bearing units - although as indicated above, some folks have had great performance with even the 1 bearing quills.

Bob

Thanks for the info guys. I have one I inherited taken completely (and I do mean completly) apart. How do I tell if it is a two bearing and how can I tell if it's a 500, 510, or 520 (I think those are the different numbers I've seend floating around? Also my serial num is 35051 and I couldn't tell from the chart on shopsmith.com what year it was manf. BTW I am loving this site. All you guys are full of knowledge and so willing to share I really appreciate it!!!!!:D