Very cool, John!
Dave
Salt Spring Island
----- Original Message -----
From: John Dammeyer
To: gingery_machines@yahoogroups.com
Sent: Monday, January 17, 2011 11:54 AM
Subject: RE: [gingery_machines] New calculator
Think I'll blow my own horn about the ELS and cutting speeds for a moment.
The ELS has the ability to display distances in either metric mm or
inches. Doesn't really matter what type of screws are on the carriage or
cross slide.
There's another feature that was added for spindle speed display. Instead
of showing spindle RPM the display can show SFM or in metric SMM. The
process for calibrating that is pretty simple.
After you either touch off the tool bit to the work or run a skim pass,
measure the diameter of the work. Zero the X axis DRO and then move the
carriage to a place where you can move the tool toward the centreline half
the distance of the turned work. The DRO display will go negative since
the tool bit is moving away from 0 towards the lathe centreline.
Say the work turned out to be 0.490" diameter. Zero the X DRO, Move cross
slide using jog buttons or MPG until the X DRO reads "-0.245. Then Zero X
again. At this point the tool tip is on the centreline.
Start up the lathe and move the X back out and watch the SFM become faster
and faster the further out the tool goes. If you wanted a specific SFM
value for cutting the work to 0.230 for example you could set the tool at
that depth and adjust the motor speed until you had the desired SFM (or
SMM).
Eventually the plan is to vary the spindle speed maintaining a requested
SFM. Especially handy for facing large surfaces. But haven't gotten
around to that yet. First need to put a variable drive on the Gingery
Lathe (note gingery content in this posting. ;-) )
Cool eh?
John Dammeyer
> I have taken a rather pragmatic approach to speeds on my
> lathe, drill press,
> and mill. I have a small lookup table for steel and another
> for aluminum for
> each machine. Then, for each belt position, I list the ideal
> diameter. In
> each table, it lists diameter in the first column and belt
> position in the
> second column.
>
> I really don't care what the RPMs must be for a given
> diameter, just what
> belt positions to use. Makes my life a bit simpler. The
> generation of the
> tables were done using Excel so I didn't even have to think very much.
>
> Rick
>
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