Re: [CAD_CAM_EDM_DRO] Re: pictures of RF-45 CNC on onelist web space

At 06:21 PM 4/8/00 +0000, you wrote:

>Dan, thanks for more pictures of your machine, of course that leads
>to questions.... It looks in the picture taken from the rear quarter
>that you have a drive motor on the quill as well as the column, is
>that the case?? Also you mentioned in an earlier post quite a while
>back that you used servo motors that you salvaged from something else
>(maybe a big tape drive???), can you give me an idea how much motor I
>need to come up with when I finally start converting my RF-45?
>Thanks
>Terry May

There is a BIG servo motor on top of the column. It is one that I bought
from C&H sales. It seems like it was an Indiana General 1200 rpm 24 volt-
I can't remember for sure (4" dia X 6" long). It cost about $40 Dan Mauch
is the expert on what to get for this system- he told me exactly what to
buy for this axis. On the X and Y axis', I have Japan Servo P/N 302538-05
motors. They are from the 1980s I think. The label says EMF Const 25.9
V/K rpm. They actually came from a friend, who got them from a tape drive-
I presume. 2.75" dia X 4" long. I have dozens of smaller DC servos that I
salvaged from older, large printers from the 1980s, but I think that these
are too small for this application. I also have 40 DC motors for satellite
dishes, that I bought from a place that was going out of business, but they
have bronze bushings- so they wouldn't work too well for too long. (future
robotics fodder)

The motor on top of the column is controlling the Z axis by itself. I
yanked the column off this machine, cut a 3" hole in the top of it, and
mounted a blanchard ground 1/2" steel plate under it before reinstalling.
It has a Thompson 1" ballscrew and single non-preload type ballnut from
McMaster Carr (MSC has them too). Gravity does the preloading for me.
There is a flange type pillow block mounted to the bottom steel plate and
the same type of bearing on top of the column that the ballscrew rides
between. The ballnut is mounted to a 2" X 2" X 4" piece of CRS that is
attached to what used to be the rack inside the column. I milled this out,
bored and single point threaded it one Saturday. I also cut 2" from the
bottom of the rack, so that the spindle could go 2" closer to the table.

I have been using this machine for a while now, and it works pretty well.
I wouldn't recommend a round column mill/drill to anyone now that I have
used this dovetail column. It's wonderful to be able to retain x and y
position while moving z up 6" to change an end mill holder. It also has
instant reverse on the spindle, so you can tap pretty well with it- while
using the quill manually.

I hope this is more than anyone wanted to hear.....

Thanks,
Dan