RE: DRO

Rudy/Art,

I have also just nearly finished my installation of a DRO based on Steve
Lindsay's program. It works like a champ on my 486/33 laptop (first tried
it on a 386 laptop, but the printer port wasn't up to speed). I paid $150
for 3 linear encoders from usdigital.com, and will contribute some $$ to
Steve for his nice program. So for less than $200, an old laptop, and a
little creative installation, I have a DRO. All I have to do is add two
more encoders for my lathe and I can switch back and forth between the two
machines with the same laptop.

Here are some tips
1. Use shielded wire, especially if you have power table feeds (it may be
overkill, but I individually shielded each conductor)
2. If you use linear encoders, shield them from chips, etc. I installed one
of them under the x table, which required removal of the table, but it is
completely hidden from above. Also, I didn't want to encase them because of
the time and space it would take up.
3. I think the z axis should definitely use a rotary encoder because of the
flying chips and difficulty in shielding from same.


Art,
Yes, please send me any info you have on your DRO project. While the linear
encoders worked well, they are difficult to install and keep chips away
from. I'd like to go with rotary for my lathe.

Here's a question maybe someone can help with: When a DRO is installed on a
small lathe, how many axes are used? I planned to only use two, since my
small 9" swing would make it impractical to fit an encoder on the compound
rest. The problem is the feed is so coarse for the carriage, how does one
get fine control, (and at the same time, account for compound travel)?

Tom

>>>>>>>.............

Message: 20
Date: Wed, 09 Feb 2000 17:34:52 -0500
From: "A. G. Eckstein" <axtein@...>
Subject: Re: DRO

Rudy,
With the help of this list, I am in the process of building a 3 axis DRO
for my mill/drill.

At Goldmine, http://www.goldmine-elec.com/, I found some 24 volt motors
with 1000 line encoders attached ($3.95 each). Be carefull of their specs
as the shafts are 5mm not 3/16" as advertised. Also found some 5mm ID
bearings ($1.49 each)at the same place. Then on the metalworking
newsgroup, found a notice that Steve Lindsey was making his DRO software
available for the download and it works quite well on an old 486 DX 100
that I had laying around. While it should work in a DOS window, I find that
it does not on this machine. Then with a few pieces of Al that I have
laying around, I have had an enjoyable experience making chips on my Mill.

The biggest difference between what I have seen in the metalworking drop
box (and in the material with Steve's program) is that instead of using a
single line to rotate the encoder, I put the encoder in a block on one end
of the table and then have another axle in a block on the other end and
make a loop out of the wire with it fastened on one side in the center of
the table.

If you need additional details, please let me know, and will send something
to you off list as I have some drawings in cad. They are always evolving as
I find ways (in my own mind) to improve the workings. At this point, I have
two axis up and working and the resolution is 1.8 tenths per line on the
encoder. Have a couple of ideas and may(?) be able to get that down to .1
tenth with very little work. Hope to do that this weekend when I finish the
blocks for the Z axis and hope to give it a try.


Art


At 10:52 AM 02/09/2000 +0200, you wrote:

>From: "Rudy du Preez" <Rudi@...>


>Hello,
>
>I have just joined the list - therefore not up do date.
>
>My interest is for a start DRO for my milling machines (DECKEL FP1 and

ACIERA FP1) and lathe (Hardinge HLV). I have some experinece in electronics
and computers for hobbies (automatic battery chargers for NC batteries,
dyno's for small DC motors, speed measurement, etc.).

>
>My hope is to get involved in building my own DRO systems - I hope with

your help!

>
>Anybody would like to give me some hints for circuits, hardware, software,

etc.

>
>Thanks!
>
>Rudy du Preez
>

A. G. Eckstein

axtein@...