Re: [CAD_CAM_EDM_DRO] Positioning

on 2014-06-04 10:30:56 UTC

Hi Jon and All:
     Thanks for the information! That is a neat trick. You could easily check
it out with a set of lab pull scales when the screw are out. I used fish scales
to make a quick check on how much drag there was on a machine slide about
seven years ago. It gave us a quick verification that the drive motor was
powerful enough.
     I miss the CNC Workshops also. When I was at NAMES there was talk
about it starting up again next year at the MAKERS workshop in Detroit
area. If you can help give George a call at the Village Press. I have a number
of pictures and spare parts I could show. Also, I could easily spend and hour
just telling the different problems I have worked on to get the lathe as far as
I now have it.
   The CNC lathe should be running in the next couple months if the weather
is bad and I can't work outside on the house roof and cutting down trees.
I am going to be running it on EMC as I swapped out a spare cross slide
ball screw to the fellow out west that had his running. He sent me all the
major electronic pieces (boards and computer) to drive the axes motors.
Last fall I purchased a used VFD that will drive a 7 1/2 hp motor. Now I am
working on removing the 7 1/2 hp motor out of another lathe to put in the
CNC lathe. This will give me the variable speed drive for constant cutting
speed when I am facing a part. The old DC motor drive would not work!
Do you know any use for a 10 hp DC drive motor or any one who could use
it? I also have the old control and spare boards if anyone can use them!!!

   GOD'S BLESSINGS
Bill Thomas

On Tue, 03 Jun 2014 23:15:37 -0500, Jon Elson elson@... [CAD_CAM_EDM_DRO] wrote

>

>
> On 06/03/2014 09:55 PM,

'William Thomas' wthomas@... [CAD_CAM_EDM_DRO] wrote:

>

> Jon, could explain how you came about the .0318 drum diameter? I know
> the force is low, but how did you arrive at this diameter.
>
it is .0318 RADIUS, not diameter. If you had a drum that pulls a
> string 0.200" every revolution, then you have Pi * D = .200, so
> D = .200/Pi or .063", so the radius is half that or .0318"
> The ballscrew with a 5 TPI lead or .200" per rev is a rolled-up
> version of this, the motion is equivalent. This shortcut is a LOT
> easier than figuring the tangent angle to the face of the thread.
> it doesn't work for Acme screws as the friction of the screw/nut
> are quite significant. But, I am pretty sure this way of calculating
> it is pretty close for a ballscrew. (It doesn't take friction into
> account, but that is small of the ballscrew.)
>
> I've been using this shortcut for years, I'm pretty sure it is
> OK, but if somebody can find an error there, I'd be glad to
> be corrected.
>
P.S. Jon how is your sons doing?
>
>
>
>
Posted by: Jon Elson <elson@...>

>

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