re: mill/drill questions

Doc,

We discuss all these issues regularly on the yahoo mill drill group.

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., "docholliday01201" <whollid1@m...> wrote:
> A general machining question if you don't mind.
>
>
>
> Over the last three years I have completely worn out the
> sherline milling machine. Over the last one year I have developed
> the CNC conversion to its fullest degree on this machine. However
> over three years of use the X axis ways are completely destroyed.
As
> well the machine is quite small for what I wish to do. So I find
> myself browsing for a new machine.
>
> Two general options come to mind: one would be a full-size
> used Bridgeport milling machine, or Bridgeport clone. Which I
would
> slowly convert to servo based CNC controls, likely using gecko
> drivers,EMC , and servo motors purchased from Ebay. The other
> options is one of the Chinese benchtop milling machine's. What I
do
> not understand is the functional difference between a gear head
> machine, versus a belt driven machine. For equivalent hp ratings
> there appears to be about $300 difference between equally equipped
> machines. I understand the gear head allows for more rapid
spindles
> speed changes but I do not understand the claims of more stable
> spindle speeds. I could see if there was gross belt slippage this
> would be an issue. But I do not understand in general usage how
> driving the spindle by means of gears produces any more efficient
> drive than the use of a belt. I understand from engineering that
the
> gear drive is more efficient than a belt, but very slightly so . I
> could see if this were to be a CNC application where the motor was
to
> have an encoder. But a very slight wavering of the spindle speed
> should have no functional difference in machining.
>
> Any thoughts anyone has, especially comments from individuals
> who have used both machines would be appreciated
>
> The likely application of this machine would be making something
> along the lines of go cart parts, radio control car parts or the
like.