Re: Spindle register issue

Paolo Amedeo

Unfortunately, if the shoulder of your backing plate is not cut correctly and making proper contact with the shoulder on the spindle, your results won't be very meaningful: the chuck could mount fairly repeatably on the spindle you ground the jaws on, even with the shoulders not making contact at all and just the threads being jammed. But, as soon as you mount it on practically any other spindle, it will be off. By using the unthreaded portion of the spindle to align the backplate (sorry, I won't call it a register, since it is not intended to be it), the backplate will be crocked the amount of play between internal and external diameter.

I agree with Jim that the shoulder on SB 9" is ridiculously tiny and that you need to make sure to cut a very sharp shoulder on the backplate.

Damascus, MD

On 6/21/2018 21:47, carbure2003 wrote:
I will do the experiment tomorrow night. I have 3 SB in the basement ( one is not powered, being in storage)

I will turn a piece and move it from lathe to lathe and take measurements.

I am quite sure the lathe with altered register will always be off.

We will see how repetitive readings will be.

I am a strong believer that the altered register has an effect on chuck Alignment. We will also see if the high point repeats as well.

I will publish results tomorrow.
In the meanwhile, the question about register rebuild is in the air.

Worst case scenario, the original 9A spindle will be back in commission until I find a viable solution

Guy Cadrin

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